From 28e9e8d2088e350e955466e70bd95bfba4303fb2 Mon Sep 17 00:00:00 2001
From: Bas van den Aakster <bvdaakster@gmail.com>
Date: Mon, 15 Sep 2025 21:40:41 +0200
Subject: [PATCH 1/4] docs: Update CLAUDE.md to reflect current implementation
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Remove outdated payment provider and testing information
- Focus on current customer data management features
- Document customer info extractor pattern and usage
- Include clear configuration examples
- Remove references to unimplemented features

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 CLAUDE.md | 232 +++++++++++++++++++++++++++---------------------------
 1 file changed, 118 insertions(+), 114 deletions(-)

diff --git a/CLAUDE.md b/CLAUDE.md
index 4c97503..16d7ae6 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -2,161 +2,165 @@
 
 ## Project Overview
 
-This is a PayloadCMS plugin that provides billing and payment functionality with multiple payment provider integrations (Stripe, Mollie) and a test payment provider for local development.
+This is a PayloadCMS plugin that provides billing and payment functionality with flexible customer data management and invoice generation capabilities.
 
 ## Architecture Principles
 
 ### Core Design
-- **Provider Abstraction**: All payment providers implement a common interface for consistency
 - **TypeScript First**: Full TypeScript support with strict typing throughout
 - **PayloadCMS Integration**: Deep integration with Payload collections, hooks, and admin UI
-- **Extensible**: Easy to add new payment providers through the common interface
-- **Developer Experience**: Comprehensive testing tools and local development support
-
-### Payment Provider Interface
-All payment providers must implement the `PaymentProvider` interface:
-```typescript
-interface PaymentProvider {
-  createPayment(options: CreatePaymentOptions): Promise<Payment>
-  retrievePayment(id: string): Promise<Payment>
-  cancelPayment(id: string): Promise<Payment>
-  refundPayment(id: string, amount?: number): Promise<Refund>
-  handleWebhook(request: Request, signature?: string): Promise<WebhookEvent>
-}
-```
+- **Flexible Customer Data**: Support for both relationship-based and embedded customer information
+- **Callback-based Syncing**: Use customer info extractors to keep data in sync
 
 ### Collections Structure
 - **Payments**: Core payment tracking with provider-specific data
-- **Customers**: Customer management with billing information
-- **Invoices**: Invoice generation and management
+- **Customers**: Customer management with billing information (optional)
+- **Invoices**: Invoice generation with embedded customer info and optional customer relationship
 - **Refunds**: Refund tracking and management
 
 ## Code Organization
 
 ```
 src/
-├── providers/           # Payment provider implementations
-│   ├── stripe/         # Stripe integration
-│   ├── mollie/         # Mollie integration
-│   ├── test/           # Test provider for development
-│   └── base/           # Base provider interface and utilities
 ├── collections/        # PayloadCMS collection configurations
-├── endpoints/          # API endpoints (webhooks, etc.)
-├── hooks/             # PayloadCMS lifecycle hooks
-├── admin/             # Admin UI components and extensions
 ├── types/             # TypeScript type definitions
-└── utils/             # Shared utilities and helpers
+└── index.ts           # Main plugin entry point
 ```
 
-## Development Guidelines
+## Customer Data Management
 
-### Payment Provider Development
-1. **Implement Base Interface**: All providers must implement `PaymentProvider`
-2. **Error Handling**: Use consistent error types and proper error propagation
-3. **Webhook Security**: Always verify webhook signatures and implement replay protection
-4. **Idempotency**: Support idempotent operations where possible
-5. **Logging**: Use structured logging for debugging and monitoring
+### Customer Info Extractor Pattern
 
-### Testing Strategy
-- **Unit Tests**: Test individual provider methods and utilities
-- **Integration Tests**: Test provider integrations with mock APIs
-- **E2E Tests**: Test complete payment flows using test provider
-- **Webhook Tests**: Test webhook handling with various scenarios
+The plugin uses a callback-based approach to extract customer information from customer relationships:
 
-### TypeScript Guidelines
-- Use strict TypeScript configuration
-- Define proper interfaces for all external API responses
-- Use discriminated unions for provider-specific data
-- Implement proper generic types for extensibility
-
-### PayloadCMS Integration
-- Follow PayloadCMS plugin patterns and conventions
-- Use proper collection configurations with access control
-- Implement admin UI components using PayloadCMS patterns
-- Utilize PayloadCMS hooks for business logic
-
-### Security Considerations
-- **Webhook Verification**: Always verify webhook signatures
-- **API Key Storage**: Use environment variables for sensitive data
-- **Access Control**: Implement proper PayloadCMS access control
-- **Input Validation**: Validate all inputs and sanitize data
-- **Audit Logging**: Log all payment operations for audit trails
-
-## Environment Configuration
-
-### Required Environment Variables
-```bash
-# Stripe Configuration
-STRIPE_SECRET_KEY=sk_test_...
-STRIPE_PUBLISHABLE_KEY=pk_test_...
-STRIPE_WEBHOOK_SECRET=whsec_...
-
-# Mollie Configuration  
-MOLLIE_API_KEY=test_...
-MOLLIE_WEBHOOK_URL=https://yourapp.com/api/billing/webhooks/mollie
-
-# Test Provider Configuration
-NODE_ENV=development # Enables test provider
+```typescript
+// Define how to extract customer info from your customer collection
+const customerInfoExtractor: CustomerInfoExtractor = (customer) => ({
+  name: customer.name,
+  email: customer.email,
+  phone: customer.phone,
+  company: customer.company,
+  taxId: customer.taxId,
+  billingAddress: {
+    line1: customer.address.line1,
+    line2: customer.address.line2,
+    city: customer.address.city,
+    state: customer.address.state,
+    postalCode: customer.address.postalCode,
+    country: customer.address.country,
+  }
+})
 ```
 
-### Development Setup
-1. Use test provider for local development
-2. Configure webhook forwarding tools (ngrok, etc.) for local webhook testing
-3. Use provider sandbox/test modes during development
-4. Implement comprehensive logging for debugging
+### Invoice Customer Data Options
+
+1. **With Customer Relationship + Extractor**:
+   - Customer relationship required
+   - Customer info auto-populated and read-only
+   - Syncs automatically when customer changes
+
+2. **With Customer Relationship (no extractor)**:
+   - Customer relationship optional
+   - Customer info manually editable
+   - Either relationship OR customer info required
+
+3. **No Customer Collection**:
+   - Customer info fields always required and editable
+   - No relationship field available
 
 ## Plugin Configuration
 
 ### Basic Configuration
 ```typescript
+import { billingPlugin, defaultCustomerInfoExtractor } from '@xtr-dev/payload-billing'
+
 billingPlugin({
-  providers: {
-    // Provider configurations
-  },
   collections: {
-    // Collection name overrides
+    customers: 'customers',        // Customer collection slug
+    invoices: 'invoices',         // Invoice collection slug
+    payments: 'payments',         // Payment collection slug
+    refunds: 'refunds',          // Refund collection slug
+    customerRelation: false,      // Disable customer relationship
+    // OR
+    customerRelation: 'clients',  // Use custom collection slug
   },
-  webhooks: {
-    // Webhook configuration
-  },
-  admin: {
-    // Admin UI configuration
-  }
+  customerInfoExtractor: defaultCustomerInfoExtractor, // For built-in customer collection
 })
 ```
 
-### Advanced Configuration
-- Custom collection schemas
-- Provider-specific options
-- Webhook endpoint customization
-- Admin UI customization
+### Custom Customer Info Extractor
+```typescript
+billingPlugin({
+  customerInfoExtractor: (customer) => ({
+    name: customer.fullName,
+    email: customer.contactEmail,
+    phone: customer.phoneNumber,
+    company: customer.companyName,
+    taxId: customer.vatNumber,
+    billingAddress: {
+      line1: customer.billing.street,
+      line2: customer.billing.apartment,
+      city: customer.billing.city,
+      state: customer.billing.state,
+      postalCode: customer.billing.zip,
+      country: customer.billing.countryCode,
+    }
+  })
+})
+```
 
-## Error Handling Strategy
+## Development Guidelines
 
-### Provider Errors
-- Map provider-specific errors to common error types
-- Preserve original error information for debugging
-- Implement proper retry logic for transient failures
+### TypeScript Guidelines
+- Use strict TypeScript configuration
+- All customer info extractors must implement `CustomerInfoExtractor` interface
+- Ensure consistent camelCase naming for all address fields
 
-### Webhook Errors
-- Handle duplicate webhooks gracefully
-- Implement proper error responses for webhook failures
-- Log webhook processing errors with context
+### PayloadCMS Integration
+- Follow PayloadCMS plugin patterns and conventions
+- Use proper collection configurations with access control
+- Utilize PayloadCMS hooks for data syncing and validation
+
+### Field Validation Rules
+- When using `customerInfoExtractor`: customer relationship is required, customer info auto-populated
+- When not using extractor: either customer relationship OR customer info must be provided
+- When no customer collection: customer info is always required
+
+## Collections API
+
+### Invoice Collection Features
+- Automatic invoice number generation (INV-{timestamp})
+- Currency validation (3-letter ISO codes)
+- Automatic due date setting (30 days from creation)
+- Line item total calculations
+- Customer info syncing via hooks
+
+### Customer Data Syncing
+The `beforeChange` hook automatically:
+1. Detects when customer relationship changes
+2. Fetches customer data from the related collection
+3. Extracts customer info using the provided callback
+4. Updates invoice with extracted data
+5. Maintains data consistency across updates
+
+## Error Handling
+
+### Validation Errors
+- Customer relationship required when using extractor
+- Customer info required when not using relationship
+- Proper error messages for missing required fields
+
+### Data Extraction Errors
+- Failed customer fetches are logged and throw user-friendly errors
+- Invalid customer data is handled gracefully
 
 ## Performance Considerations
-- Implement proper caching where appropriate
-- Use database indexes for payment queries
-- Optimize webhook processing for high throughput
-- Consider rate limiting for API endpoints
-
-## Monitoring and Observability
-- Log all payment operations with structured data
-- Track payment success/failure rates
-- Monitor webhook processing times
-- Implement health check endpoints
+- Customer data is only fetched when relationship changes
+- Read-only fields prevent unnecessary manual edits
+- Efficient hook execution with proper change detection
 
 ## Documentation Requirements
 - Document all public APIs with examples
-- Provide integration guides for each payment provider
-- Include troubleshooting guides for common issues
+- Provide clear customer info extractor examples
+- Include configuration guides for different use cases
 - Maintain up-to-date TypeScript documentation
\ No newline at end of file

From f17b4c064e181b998f42ddf1bc25c34190a1479e Mon Sep 17 00:00:00 2001
From: Bas van den Aakster <bvdaakster@gmail.com>
Date: Mon, 15 Sep 2025 23:14:25 +0200
Subject: [PATCH 2/4] chore: Remove unused billing-related collections, types,
 and utility modules

- Drop `customers` collection and associated types (`types/index.ts`, `payload.ts`)
- Remove generated `payload-types.ts` file
- Clean up unused exports and dependencies across modules
- Streamline codebase by eliminating redundant billing logic
---
 dev/payload-types.ts         | 656 -----------------------------------
 eslint.config.js             |   1 +
 src/collections/customers.ts | 149 --------
 src/collections/invoices.ts  |  37 +-
 src/collections/payments.ts  |  26 +-
 src/index.ts                 |  95 -----
 src/plugin/config.ts         |  76 ++++
 src/plugin/index.ts          |  70 ++++
 src/plugin/types.ts          | 168 +++++++++
 src/types/index.ts           | 260 --------------
 src/types/payload.ts         | 178 ----------
 11 files changed, 338 insertions(+), 1378 deletions(-)
 delete mode 100644 dev/payload-types.ts
 delete mode 100644 src/collections/customers.ts
 create mode 100644 src/plugin/config.ts
 create mode 100644 src/plugin/index.ts
 create mode 100644 src/plugin/types.ts
 delete mode 100644 src/types/index.ts
 delete mode 100644 src/types/payload.ts

diff --git a/dev/payload-types.ts b/dev/payload-types.ts
deleted file mode 100644
index 3c141b2..0000000
--- a/dev/payload-types.ts
+++ /dev/null
@@ -1,656 +0,0 @@
-/* tslint:disable */
-/* eslint-disable */
-/**
- * This file was automatically generated by Payload.
- * DO NOT MODIFY IT BY HAND. Instead, modify your source Payload config,
- * and re-run `payload generate:types` to regenerate this file.
- */
-
-/**
- * Supported timezones in IANA format.
- *
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "supportedTimezones".
- */
-export type SupportedTimezones =
-  | 'Pacific/Midway'
-  | 'Pacific/Niue'
-  | 'Pacific/Honolulu'
-  | 'Pacific/Rarotonga'
-  | 'America/Anchorage'
-  | 'Pacific/Gambier'
-  | 'America/Los_Angeles'
-  | 'America/Tijuana'
-  | 'America/Denver'
-  | 'America/Phoenix'
-  | 'America/Chicago'
-  | 'America/Guatemala'
-  | 'America/New_York'
-  | 'America/Bogota'
-  | 'America/Caracas'
-  | 'America/Santiago'
-  | 'America/Buenos_Aires'
-  | 'America/Sao_Paulo'
-  | 'Atlantic/South_Georgia'
-  | 'Atlantic/Azores'
-  | 'Atlantic/Cape_Verde'
-  | 'Europe/London'
-  | 'Europe/Berlin'
-  | 'Africa/Lagos'
-  | 'Europe/Athens'
-  | 'Africa/Cairo'
-  | 'Europe/Moscow'
-  | 'Asia/Riyadh'
-  | 'Asia/Dubai'
-  | 'Asia/Baku'
-  | 'Asia/Karachi'
-  | 'Asia/Tashkent'
-  | 'Asia/Calcutta'
-  | 'Asia/Dhaka'
-  | 'Asia/Almaty'
-  | 'Asia/Jakarta'
-  | 'Asia/Bangkok'
-  | 'Asia/Shanghai'
-  | 'Asia/Singapore'
-  | 'Asia/Tokyo'
-  | 'Asia/Seoul'
-  | 'Australia/Brisbane'
-  | 'Australia/Sydney'
-  | 'Pacific/Guam'
-  | 'Pacific/Noumea'
-  | 'Pacific/Auckland'
-  | 'Pacific/Fiji';
-
-export interface Config {
-  auth: {
-    users: UserAuthOperations;
-  };
-  blocks: {};
-  collections: {
-    posts: Post;
-    media: Media;
-    payments: Payment;
-    customers: Customer;
-    invoices: Invoice;
-    refunds: Refund;
-    users: User;
-    'payload-locked-documents': PayloadLockedDocument;
-    'payload-preferences': PayloadPreference;
-    'payload-migrations': PayloadMigration;
-  };
-  collectionsJoins: {};
-  collectionsSelect: {
-    posts: PostsSelect<false> | PostsSelect<true>;
-    media: MediaSelect<false> | MediaSelect<true>;
-    payments: PaymentsSelect<false> | PaymentsSelect<true>;
-    customers: CustomersSelect<false> | CustomersSelect<true>;
-    invoices: InvoicesSelect<false> | InvoicesSelect<true>;
-    refunds: RefundsSelect<false> | RefundsSelect<true>;
-    users: UsersSelect<false> | UsersSelect<true>;
-    'payload-locked-documents': PayloadLockedDocumentsSelect<false> | PayloadLockedDocumentsSelect<true>;
-    'payload-preferences': PayloadPreferencesSelect<false> | PayloadPreferencesSelect<true>;
-    'payload-migrations': PayloadMigrationsSelect<false> | PayloadMigrationsSelect<true>;
-  };
-  db: {
-    defaultIDType: number;
-  };
-  globals: {};
-  globalsSelect: {};
-  locale: null;
-  user: User & {
-    collection: 'users';
-  };
-  jobs: {
-    tasks: unknown;
-    workflows: unknown;
-  };
-}
-export interface UserAuthOperations {
-  forgotPassword: {
-    email: string;
-    password: string;
-  };
-  login: {
-    email: string;
-    password: string;
-  };
-  registerFirstUser: {
-    email: string;
-    password: string;
-  };
-  unlock: {
-    email: string;
-    password: string;
-  };
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "posts".
- */
-export interface Post {
-  id: number;
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "media".
- */
-export interface Media {
-  id: number;
-  updatedAt: string;
-  createdAt: string;
-  url?: string | null;
-  thumbnailURL?: string | null;
-  filename?: string | null;
-  mimeType?: string | null;
-  filesize?: number | null;
-  width?: number | null;
-  height?: number | null;
-  focalX?: number | null;
-  focalY?: number | null;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payments".
- */
-export interface Payment {
-  id: number;
-  provider: 'stripe' | 'mollie' | 'test';
-  /**
-   * The payment ID from the payment provider
-   */
-  providerId: string;
-  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled' | 'refunded' | 'partially_refunded';
-  /**
-   * Amount in cents (e.g., 2000 = $20.00)
-   */
-  amount: number;
-  /**
-   * ISO 4217 currency code (e.g., USD, EUR)
-   */
-  currency: string;
-  /**
-   * Payment description
-   */
-  description?: string | null;
-  customer?: (number | null) | Customer;
-  invoice?: (number | null) | Invoice;
-  /**
-   * Additional metadata for the payment
-   */
-  metadata?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  /**
-   * Raw data from the payment provider
-   */
-  providerData?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  refunds?: (number | Refund)[] | null;
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "customers".
- */
-export interface Customer {
-  id: number;
-  /**
-   * Customer email address
-   */
-  email?: string | null;
-  /**
-   * Customer full name
-   */
-  name?: string | null;
-  /**
-   * Customer phone number
-   */
-  phone?: string | null;
-  address?: {
-    line1?: string | null;
-    line2?: string | null;
-    city?: string | null;
-    state?: string | null;
-    postal_code?: string | null;
-    /**
-     * ISO 3166-1 alpha-2 country code
-     */
-    country?: string | null;
-  };
-  /**
-   * Customer IDs from payment providers
-   */
-  providerIds?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  /**
-   * Additional customer metadata
-   */
-  metadata?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  /**
-   * Customer payments
-   */
-  payments?: (number | Payment)[] | null;
-  /**
-   * Customer invoices
-   */
-  invoices?: (number | Invoice)[] | null;
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "invoices".
- */
-export interface Invoice {
-  id: number;
-  /**
-   * Invoice number (e.g., INV-001)
-   */
-  number: string;
-  customer: number | Customer;
-  status: 'draft' | 'open' | 'paid' | 'void' | 'uncollectible';
-  /**
-   * ISO 4217 currency code (e.g., USD, EUR)
-   */
-  currency: string;
-  items: {
-    description: string;
-    quantity: number;
-    /**
-     * Amount in cents
-     */
-    unitAmount: number;
-    /**
-     * Calculated: quantity × unitAmount
-     */
-    totalAmount?: number | null;
-    id?: string | null;
-  }[];
-  /**
-   * Sum of all line items
-   */
-  subtotal?: number | null;
-  /**
-   * Tax amount in cents
-   */
-  taxAmount?: number | null;
-  /**
-   * Total amount (subtotal + tax)
-   */
-  amount?: number | null;
-  dueDate?: string | null;
-  paidAt?: string | null;
-  payment?: (number | null) | Payment;
-  /**
-   * Internal notes
-   */
-  notes?: string | null;
-  /**
-   * Additional invoice metadata
-   */
-  metadata?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "refunds".
- */
-export interface Refund {
-  id: number;
-  /**
-   * The refund ID from the payment provider
-   */
-  providerId: string;
-  payment: number | Payment;
-  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled';
-  /**
-   * Refund amount in cents
-   */
-  amount: number;
-  /**
-   * ISO 4217 currency code (e.g., USD, EUR)
-   */
-  currency: string;
-  /**
-   * Reason for the refund
-   */
-  reason?: ('duplicate' | 'fraudulent' | 'requested_by_customer' | 'other') | null;
-  /**
-   * Additional details about the refund
-   */
-  description?: string | null;
-  /**
-   * Additional refund metadata
-   */
-  metadata?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  /**
-   * Raw data from the payment provider
-   */
-  providerData?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "users".
- */
-export interface User {
-  id: number;
-  updatedAt: string;
-  createdAt: string;
-  email: string;
-  resetPasswordToken?: string | null;
-  resetPasswordExpiration?: string | null;
-  salt?: string | null;
-  hash?: string | null;
-  loginAttempts?: number | null;
-  lockUntil?: string | null;
-  password?: string | null;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payload-locked-documents".
- */
-export interface PayloadLockedDocument {
-  id: number;
-  document?:
-    | ({
-        relationTo: 'posts';
-        value: number | Post;
-      } | null)
-    | ({
-        relationTo: 'media';
-        value: number | Media;
-      } | null)
-    | ({
-        relationTo: 'payments';
-        value: number | Payment;
-      } | null)
-    | ({
-        relationTo: 'customers';
-        value: number | Customer;
-      } | null)
-    | ({
-        relationTo: 'invoices';
-        value: number | Invoice;
-      } | null)
-    | ({
-        relationTo: 'refunds';
-        value: number | Refund;
-      } | null)
-    | ({
-        relationTo: 'users';
-        value: number | User;
-      } | null);
-  globalSlug?: string | null;
-  user: {
-    relationTo: 'users';
-    value: number | User;
-  };
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payload-preferences".
- */
-export interface PayloadPreference {
-  id: number;
-  user: {
-    relationTo: 'users';
-    value: number | User;
-  };
-  key?: string | null;
-  value?:
-    | {
-        [k: string]: unknown;
-      }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payload-migrations".
- */
-export interface PayloadMigration {
-  id: number;
-  name?: string | null;
-  batch?: number | null;
-  updatedAt: string;
-  createdAt: string;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "posts_select".
- */
-export interface PostsSelect<T extends boolean = true> {
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "media_select".
- */
-export interface MediaSelect<T extends boolean = true> {
-  updatedAt?: T;
-  createdAt?: T;
-  url?: T;
-  thumbnailURL?: T;
-  filename?: T;
-  mimeType?: T;
-  filesize?: T;
-  width?: T;
-  height?: T;
-  focalX?: T;
-  focalY?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payments_select".
- */
-export interface PaymentsSelect<T extends boolean = true> {
-  provider?: T;
-  providerId?: T;
-  status?: T;
-  amount?: T;
-  currency?: T;
-  description?: T;
-  customer?: T;
-  invoice?: T;
-  metadata?: T;
-  providerData?: T;
-  refunds?: T;
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "customers_select".
- */
-export interface CustomersSelect<T extends boolean = true> {
-  email?: T;
-  name?: T;
-  phone?: T;
-  address?:
-    | T
-    | {
-        line1?: T;
-        line2?: T;
-        city?: T;
-        state?: T;
-        postal_code?: T;
-        country?: T;
-      };
-  providerIds?: T;
-  metadata?: T;
-  payments?: T;
-  invoices?: T;
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "invoices_select".
- */
-export interface InvoicesSelect<T extends boolean = true> {
-  number?: T;
-  customer?: T;
-  status?: T;
-  currency?: T;
-  items?:
-    | T
-    | {
-        description?: T;
-        quantity?: T;
-        unitAmount?: T;
-        totalAmount?: T;
-        id?: T;
-      };
-  subtotal?: T;
-  taxAmount?: T;
-  amount?: T;
-  dueDate?: T;
-  paidAt?: T;
-  payment?: T;
-  notes?: T;
-  metadata?: T;
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "refunds_select".
- */
-export interface RefundsSelect<T extends boolean = true> {
-  providerId?: T;
-  payment?: T;
-  status?: T;
-  amount?: T;
-  currency?: T;
-  reason?: T;
-  description?: T;
-  metadata?: T;
-  providerData?: T;
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "users_select".
- */
-export interface UsersSelect<T extends boolean = true> {
-  updatedAt?: T;
-  createdAt?: T;
-  email?: T;
-  resetPasswordToken?: T;
-  resetPasswordExpiration?: T;
-  salt?: T;
-  hash?: T;
-  loginAttempts?: T;
-  lockUntil?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payload-locked-documents_select".
- */
-export interface PayloadLockedDocumentsSelect<T extends boolean = true> {
-  document?: T;
-  globalSlug?: T;
-  user?: T;
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payload-preferences_select".
- */
-export interface PayloadPreferencesSelect<T extends boolean = true> {
-  user?: T;
-  key?: T;
-  value?: T;
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "payload-migrations_select".
- */
-export interface PayloadMigrationsSelect<T extends boolean = true> {
-  name?: T;
-  batch?: T;
-  updatedAt?: T;
-  createdAt?: T;
-}
-/**
- * This interface was referenced by `Config`'s JSON-Schema
- * via the `definition` "auth".
- */
-export interface Auth {
-  [k: string]: unknown;
-}
-
-
-declare module 'payload' {
-  export interface GeneratedTypes extends Config {}
-}
\ No newline at end of file
diff --git a/eslint.config.js b/eslint.config.js
index aacea9f..b831856 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -44,6 +44,7 @@ export default [
       'perfectionist/sort-switch-case': 'off',
       'perfectionist/sort-union-types': 'off',
       'perfectionist/sort-variable-declarations': 'off',
+      'perfectionist/sort-intersection-types': 'off',
     },
   },
   {
diff --git a/src/collections/customers.ts b/src/collections/customers.ts
deleted file mode 100644
index 6bb55f2..0000000
--- a/src/collections/customers.ts
+++ /dev/null
@@ -1,149 +0,0 @@
-import type { CollectionConfig } from 'payload'
-
-import type { 
-  AccessArgs,
-  CollectionAfterChangeHook,
-  CollectionBeforeChangeHook,
-  CustomerData,
-  CustomerDocument
-} from '../types/payload'
-
-export function createCustomersCollection(slug: string = 'customers'): CollectionConfig {
-  return {
-    slug,
-    access: {
-      create: ({ req: { user } }: AccessArgs) => !!user,
-      delete: ({ req: { user } }: AccessArgs) => !!user,
-      read: ({ req: { user } }: AccessArgs) => !!user,
-      update: ({ req: { user } }: AccessArgs) => !!user,
-    },
-    admin: {
-      defaultColumns: ['email', 'name', 'createdAt'],
-      group: 'Billing',
-      useAsTitle: 'email',
-    },
-    fields: [
-      {
-        name: 'email',
-        type: 'email',
-        admin: {
-          description: 'Customer email address',
-        },
-        index: true,
-        unique: true,
-      },
-      {
-        name: 'name',
-        type: 'text',
-        admin: {
-          description: 'Customer full name',
-        },
-      },
-      {
-        name: 'phone',
-        type: 'text',
-        admin: {
-          description: 'Customer phone number',
-        },
-      },
-      {
-        name: 'address',
-        type: 'group',
-        fields: [
-          {
-            name: 'line1',
-            type: 'text',
-            label: 'Address Line 1',
-          },
-          {
-            name: 'line2',
-            type: 'text',
-            label: 'Address Line 2',
-          },
-          {
-            name: 'city',
-            type: 'text',
-            label: 'City',
-          },
-          {
-            name: 'state',
-            type: 'text',
-            label: 'State/Province',
-          },
-          {
-            name: 'postalCode',
-            type: 'text',
-            label: 'Postal Code',
-          },
-          {
-            name: 'country',
-            type: 'text',
-            admin: {
-              description: 'ISO 3166-1 alpha-2 country code',
-            },
-            label: 'Country',
-            maxLength: 2,
-          },
-        ],
-      },
-      {
-        name: 'providerIds',
-        type: 'json',
-        admin: {
-          description: 'Customer IDs from payment providers',
-          readOnly: true,
-        },
-      },
-      {
-        name: 'metadata',
-        type: 'json',
-        admin: {
-          description: 'Additional customer metadata',
-        },
-      },
-      {
-        name: 'payments',
-        type: 'relationship',
-        admin: {
-          description: 'Customer payments',
-          readOnly: true,
-        },
-        hasMany: true,
-        relationTo: 'payments',
-      },
-      {
-        name: 'invoices',
-        type: 'relationship',
-        admin: {
-          description: 'Customer invoices',
-          readOnly: true,
-        },
-        hasMany: true,
-        relationTo: 'invoices',
-      },
-    ],
-    hooks: {
-      afterChange: [
-        ({ doc, operation, req }: CollectionAfterChangeHook<CustomerDocument>) => {
-          if (operation === 'create') {
-            req.payload.logger.info(`Customer created: ${doc.id} (${doc.email})`)
-          }
-        },
-      ],
-      beforeChange: [
-        ({ data, operation }: CollectionBeforeChangeHook<CustomerData>) => {
-          if (operation === 'create' || operation === 'update') {
-            // Normalize country code
-            if (data.address?.country) {
-              data.address.country = data.address.country.toUpperCase()
-              if (!/^[A-Z]{2}$/.test(data.address.country)) {
-                throw new Error('Country must be a 2-letter ISO code')
-              }
-            }
-          }
-        },
-      ],
-    },
-    timestamps: true,
-  }
-}
\ No newline at end of file
diff --git a/src/collections/invoices.ts b/src/collections/invoices.ts
index fdaf804..647c09d 100644
--- a/src/collections/invoices.ts
+++ b/src/collections/invoices.ts
@@ -1,15 +1,12 @@
-import type { CollectionConfig } from 'payload'
-
-import type {
+import {
   AccessArgs,
   CollectionAfterChangeHook,
   CollectionBeforeChangeHook,
   CollectionBeforeValidateHook,
-  InvoiceData,
-  InvoiceDocument,
-  InvoiceItemData
-} from '../types/payload'
-import type { CustomerInfoExtractor } from '../types'
+  CollectionConfig,
+} from 'payload'
+import { CustomerInfoExtractor } from '@/plugin/config'
+import { Invoice } from '@/plugin/types'
 
 export function createInvoicesCollection(
   slug: string = 'invoices',
@@ -281,7 +278,7 @@ export function createInvoicesCollection(
         name: 'paidAt',
         type: 'date',
         admin: {
-          condition: (data: InvoiceData) => data.status === 'paid',
+          condition: (data) => data.status === 'paid',
           readOnly: true,
         },
       },
@@ -289,7 +286,7 @@ export function createInvoicesCollection(
         name: 'payment',
         type: 'relationship',
         admin: {
-          condition: (data: InvoiceData) => data.status === 'paid',
+          condition: (data) => data.status === 'paid',
           position: 'sidebar',
         },
         relationTo: 'payments',
@@ -311,14 +308,14 @@ export function createInvoicesCollection(
     ],
     hooks: {
       afterChange: [
-        ({ doc, operation, req }: CollectionAfterChangeHook<InvoiceDocument>) => {
+        ({ doc, operation, req }) => {
           if (operation === 'create') {
             req.payload.logger.info(`Invoice created: ${doc.number}`)
           }
         },
-      ],
+      ] satisfies CollectionAfterChangeHook<Invoice>[],
       beforeChange: [
-        async ({ data, operation, req, originalDoc }: CollectionBeforeChangeHook<InvoiceData>) => {
+        async ({ data, operation, req, originalDoc }) => {
           // Sync customer info from relationship if extractor is provided
           if (customerCollectionSlug && customerInfoExtractor && data.customer) {
             // Check if customer changed or this is a new invoice
@@ -329,7 +326,7 @@ export function createInvoicesCollection(
               try {
                 // Fetch the customer data
                 const customer = await req.payload.findByID({
-                  collection: customerCollectionSlug,
+                  collection: customerCollectionSlug as any,
                   id: data.customer,
                 })
 
@@ -383,9 +380,9 @@ export function createInvoicesCollection(
             data.paidAt = new Date().toISOString()
           }
         },
-      ],
+      ] satisfies CollectionBeforeChangeHook<Invoice>[],
       beforeValidate: [
-        ({ data }: CollectionBeforeValidateHook<InvoiceData>) => {
+        ({ data }) => {
           if (!data) return
 
           // If using extractor, customer relationship is required
@@ -406,14 +403,14 @@ export function createInvoicesCollection(
 
           if (data && data.items && Array.isArray(data.items)) {
             // Calculate totals for each line item
-            data.items = data.items.map((item: InvoiceItemData) => ({
+            data.items = data.items.map((item) => ({
               ...item,
               totalAmount: (item.quantity || 0) * (item.unitAmount || 0),
             }))
 
             // Calculate subtotal
             data.subtotal = data.items.reduce(
-              (sum: number, item: InvoiceItemData) => sum + (item.totalAmount || 0),
+              (sum: number, item) => sum + (item.totalAmount || 0),
               0
             )
 
@@ -421,8 +418,8 @@ export function createInvoicesCollection(
             data.amount = (data.subtotal || 0) + (data.taxAmount || 0)
           }
         },
-      ],
+      ] satisfies CollectionBeforeValidateHook<Invoice>[],
     },
     timestamps: true,
   }
-}
\ No newline at end of file
+}
diff --git a/src/collections/payments.ts b/src/collections/payments.ts
index 7aff5cc..4d9d8bf 100644
--- a/src/collections/payments.ts
+++ b/src/collections/payments.ts
@@ -1,12 +1,5 @@
-import type { CollectionConfig } from 'payload'
-
-import type { 
-  AccessArgs,
-  CollectionAfterChangeHook,
-  CollectionBeforeChangeHook,
-  PaymentData,
-  PaymentDocument
-} from '../types/payload'
+import { AccessArgs, CollectionAfterChangeHook, CollectionBeforeChangeHook, CollectionConfig } from 'payload'
+import { Payment } from '@/plugin/types'
 
 export function createPaymentsCollection(slug: string = 'payments'): CollectionConfig {
   return {
@@ -131,21 +124,14 @@ export function createPaymentsCollection(slug: string = 'payments'): CollectionC
       },
     ],
     hooks: {
-      afterChange: [
-        ({ doc, operation, req }: CollectionAfterChangeHook<PaymentDocument>) => {
-          if (operation === 'create') {
-            req.payload.logger.info(`Payment created: ${doc.id} (${doc.provider})`)
-          }
-        },
-      ],
       beforeChange: [
-        ({ data, operation }: CollectionBeforeChangeHook<PaymentData>) => {
+        ({ data, operation }) => {
           if (operation === 'create') {
             // Validate amount format
             if (data.amount && !Number.isInteger(data.amount)) {
               throw new Error('Amount must be an integer (in cents)')
             }
-            
+
             // Validate currency format
             if (data.currency) {
               data.currency = data.currency.toUpperCase()
@@ -155,8 +141,8 @@ export function createPaymentsCollection(slug: string = 'payments'): CollectionC
             }
           }
         },
-      ],
+      ] satisfies CollectionBeforeChangeHook<Payment>[],
     },
     timestamps: true,
   }
-}
\ No newline at end of file
+}
diff --git a/src/index.ts b/src/index.ts
index 303a57d..509a567 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,98 +1,3 @@
-import type { Config } from 'payload'
-
-import type { BillingPluginConfig, CustomerInfoExtractor } from './types'
-
-import { createCustomersCollection } from './collections/customers'
-import { createInvoicesCollection } from './collections/invoices'
-import { createPaymentsCollection } from './collections/payments'
-import { createRefundsCollection } from './collections/refunds'
-
 export * from './types'
 
-// Default customer info extractor for the built-in customer collection
-export const defaultCustomerInfoExtractor: CustomerInfoExtractor = (customer) => {
-  return {
-    name: customer.name || '',
-    email: customer.email || '',
-    phone: customer.phone,
-    company: customer.company,
-    taxId: customer.taxId,
-    billingAddress: customer.address ? {
-      line1: customer.address.line1 || '',
-      line2: customer.address.line2,
-      city: customer.address.city || '',
-      state: customer.address.state,
-      postalCode: customer.address.postalCode || '',
-      country: customer.address.country || '',
-    } : undefined,
-  }
-}
 
-export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config: Config): Config => {
-  if (pluginConfig.disabled) {
-    return config
-  }
-
-  // Initialize collections
-  if (!config.collections) {
-    config.collections = []
-  }
-
-  const customerSlug = pluginConfig.collections?.customers || 'customers'
-
-  config.collections.push(
-    createPaymentsCollection(pluginConfig.collections?.payments || 'payments'),
-    createCustomersCollection(customerSlug),
-    createInvoicesCollection(
-      pluginConfig.collections?.invoices || 'invoices',
-      pluginConfig.collections?.customerRelation !== false ? customerSlug : undefined,
-      pluginConfig.customerInfoExtractor
-    ),
-    createRefundsCollection(pluginConfig.collections?.refunds || 'refunds'),
-  )
-
-  // Initialize endpoints
-  if (!config.endpoints) {
-    config.endpoints = []
-  }
-
-  config.endpoints?.push(
-    // Webhook endpoints
-    {
-      handler: (_req) => {
-        try {
-          const provider = null
-          if (!provider) {
-            return Response.json({ error: 'Provider not found' }, { status: 404 })
-          }
-
-          // TODO: Process webhook event and update database
-
-          return Response.json({ received: true })
-        } catch (error) {
-          // TODO: Use proper logger instead of console
-          // eslint-disable-next-line no-console
-          console.error('[BILLING] Webhook error:', error)
-          return Response.json({ error: 'Webhook processing failed' }, { status: 400 })
-        }
-      },
-      method: 'post',
-      path: '/billing/webhooks/:provider'
-    },
-  )
-
-  // Initialize providers and onInit hook
-  const incomingOnInit = config.onInit
-
-  config.onInit = async (payload) => {
-    // Execute any existing onInit functions first
-    if (incomingOnInit) {
-      await incomingOnInit(payload)
-    }
-
-  }
-
-  return config
-}
-
-export default billingPlugin
diff --git a/src/plugin/config.ts b/src/plugin/config.ts
new file mode 100644
index 0000000..ace743d
--- /dev/null
+++ b/src/plugin/config.ts
@@ -0,0 +1,76 @@
+
+export const defaults = {
+  paymentsCollection: 'payments'
+}
+
+// Provider configurations
+export interface StripeConfig {
+  apiVersion?: string
+  publishableKey: string
+  secretKey: string
+  webhookEndpointSecret: string
+}
+
+export interface MollieConfig {
+  apiKey: string
+  testMode?: boolean
+  webhookUrl: string
+}
+
+export interface TestProviderConfig {
+  autoComplete?: boolean
+  defaultDelay?: number
+  enabled: boolean
+  failureRate?: number
+  simulateFailures?: boolean
+}
+
+// Customer info extractor callback type
+export interface CustomerInfoExtractor {
+  (customer: any): {
+    name: string
+    email: string
+    phone?: string
+    company?: string
+    taxId?: string
+    billingAddress?: {
+      line1: string
+      line2?: string
+      city: string
+      state?: string
+      postalCode: string
+      country: string
+    }
+  }
+}
+
+// Plugin configuration
+export interface BillingPluginConfig {
+  admin?: {
+    customComponents?: boolean
+    dashboard?: boolean
+  }
+  collections?: {
+    customerRelation?: boolean | string // false to disable, string for custom collection slug
+    customers?: string
+    invoices?: string
+    payments?: string
+    refunds?: string
+  }
+  customerInfoExtractor?: CustomerInfoExtractor // Callback to extract customer info from relationship
+  disabled?: boolean
+  providers?: {
+    mollie?: MollieConfig
+    stripe?: StripeConfig
+    test?: TestProviderConfig
+  }
+  webhooks?: {
+    basePath?: string
+    cors?: boolean
+  }
+}
+
+// Plugin type
+export interface BillingPluginOptions extends BillingPluginConfig {
+  disabled?: boolean
+}
diff --git a/src/plugin/index.ts b/src/plugin/index.ts
new file mode 100644
index 0000000..e644aec
--- /dev/null
+++ b/src/plugin/index.ts
@@ -0,0 +1,70 @@
+import type { Config } from 'payload'
+import { createInvoicesCollection, createPaymentsCollection, createRefundsCollection } from '@/collections'
+import { BillingPluginConfig } from '@/plugin/config'
+
+export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config: Config): Config => {
+  if (pluginConfig.disabled) {
+    return config
+  }
+
+  // Initialize collections
+  if (!config.collections) {
+    config.collections = []
+  }
+
+  const customerSlug = pluginConfig.collections?.customers || 'customers'
+
+  config.collections.push(
+    createPaymentsCollection(pluginConfig.collections?.payments || 'payments'),
+    createInvoicesCollection(
+      pluginConfig.collections?.invoices || 'invoices',
+      pluginConfig.collections?.customerRelation !== false ? customerSlug : undefined,
+      pluginConfig.customerInfoExtractor
+    ),
+    createRefundsCollection(pluginConfig.collections?.refunds || 'refunds'),
+  )
+
+  // Initialize endpoints
+  if (!config.endpoints) {
+    config.endpoints = []
+  }
+
+  config.endpoints?.push(
+    // Webhook endpoints
+    {
+      handler: (_req) => {
+        try {
+          const provider = null
+          if (!provider) {
+            return Response.json({ error: 'Provider not found' }, { status: 404 })
+          }
+
+          // TODO: Process webhook event and update database
+
+          return Response.json({ received: true })
+        } catch (error) {
+          // TODO: Use proper logger instead of console
+          // eslint-disable-next-line no-console
+          console.error('[BILLING] Webhook error:', error)
+          return Response.json({ error: 'Webhook processing failed' }, { status: 400 })
+        }
+      },
+      method: 'post',
+      path: '/billing/webhooks/:provider'
+    },
+  )
+
+  // Initialize providers and onInit hook
+  const incomingOnInit = config.onInit
+
+  config.onInit = async (payload) => {
+    // Execute any existing onInit functions first
+    if (incomingOnInit) {
+      await incomingOnInit(payload)
+    }
+
+  }
+
+  return config
+}
+export default billingPlugin
diff --git a/src/plugin/types.ts b/src/plugin/types.ts
new file mode 100644
index 0000000..d7ae2ee
--- /dev/null
+++ b/src/plugin/types.ts
@@ -0,0 +1,168 @@
+import { Customer, Refund } from '../../dev/payload-types'
+
+export type Id = string | number
+
+export interface Payment {
+  id: Id;
+  provider: 'stripe' | 'mollie' | 'test';
+  /**
+   * The payment ID from the payment provider
+   */
+  providerId: Id;
+  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled' | 'refunded' | 'partially_refunded';
+  /**
+   * Amount in cents (e.g., 2000 = $20.00)
+   */
+  amount: number;
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  /**
+   * Payment description
+   */
+  description?: string | null;
+  customer?: (Id | null) | Customer;
+  invoice?: (Id | null) | Invoice;
+  /**
+   * Additional metadata for the payment
+   */
+  metadata?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  /**
+   * Raw data from the payment provider
+   */
+  providerData?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  refunds?: (number | Refund)[] | null;
+  updatedAt: string;
+  createdAt: string;
+}
+
+export interface Invoice {
+  id: Id;
+  /**
+   * Invoice number (e.g., INV-001)
+   */
+  number: string;
+  /**
+   * Link to customer record (optional)
+   */
+  customer?: (Id | null) | Customer;
+  /**
+   * Customer billing information (auto-populated from customer relationship)
+   */
+  customerInfo?: {
+    /**
+     * Customer name
+     */
+    name?: string | null;
+    /**
+     * Customer email address
+     */
+    email?: string | null;
+    /**
+     * Customer phone number
+     */
+    phone?: string | null;
+    /**
+     * Company name (optional)
+     */
+    company?: string | null;
+    /**
+     * Tax ID or VAT number
+     */
+    taxId?: string | null;
+  };
+  /**
+   * Billing address (auto-populated from customer relationship)
+   */
+  billingAddress?: {
+    /**
+     * Address line 1
+     */
+    line1?: string | null;
+    /**
+     * Address line 2
+     */
+    line2?: string | null;
+    city?: string | null;
+    /**
+     * State or province
+     */
+    state?: string | null;
+    /**
+     * Postal or ZIP code
+     */
+    postalCode?: string | null;
+    /**
+     * Country code (e.g., US, GB)
+     */
+    country?: string | null;
+  };
+  status: 'draft' | 'open' | 'paid' | 'void' | 'uncollectible';
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  items: {
+    description: string;
+    quantity: number;
+    /**
+     * Amount in cents
+     */
+    unitAmount: number;
+    /**
+     * Calculated: quantity × unitAmount
+     */
+    totalAmount?: number | null;
+    id?: Id | null;
+  }[];
+  /**
+   * Sum of all line items
+   */
+  subtotal?: number | null;
+  /**
+   * Tax amount in cents
+   */
+  taxAmount?: number | null;
+  /**
+   * Total amount (subtotal + tax)
+   */
+  amount?: number | null;
+  dueDate?: string | null;
+  paidAt?: string | null;
+  payment?: (number | null) | Payment;
+  /**
+   * Internal notes
+   */
+  notes?: string | null;
+  /**
+   * Additional invoice metadata
+   */
+  metadata?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  updatedAt: string;
+  createdAt: string;
+}
diff --git a/src/types/index.ts b/src/types/index.ts
deleted file mode 100644
index 55f264d..0000000
--- a/src/types/index.ts
+++ /dev/null
@@ -1,260 +0,0 @@
-import type { Config } from 'payload'
-
-// Base payment provider interface
-export interface PaymentProvider {
-  cancelPayment(id: string): Promise<Payment>
-  createPayment(options: CreatePaymentOptions): Promise<Payment>
-  handleWebhook(request: Request, signature?: string): Promise<WebhookEvent>
-  name: string
-  refundPayment(id: string, amount?: number): Promise<Refund>
-  retrievePayment(id: string): Promise<Payment>
-}
-
-// Payment types
-export interface CreatePaymentOptions {
-  amount: number
-  cancelUrl?: string
-  currency: string
-  customer?: string
-  description?: string
-  metadata?: Record<string, unknown>
-  returnUrl?: string
-}
-
-export interface Payment {
-  amount: number
-  createdAt: string
-  currency: string
-  customer?: string
-  description?: string
-  id: string
-  metadata?: Record<string, unknown>
-  provider: string
-  providerData?: Record<string, unknown>
-  status: PaymentStatus
-  updatedAt: string
-}
-
-export interface Refund {
-  amount: number
-  createdAt: string
-  currency: string
-  id: string
-  paymentId: string
-  providerData?: Record<string, unknown>
-  reason?: string
-  status: RefundStatus
-}
-
-export interface WebhookEvent {
-  data: Record<string, unknown>
-  id: string
-  provider: string
-  type: string
-  verified: boolean
-}
-
-// Status enums
-export type PaymentStatus = 
-  | 'canceled'
-  | 'failed'
-  | 'partially_refunded'
-  | 'pending'
-  | 'processing'
-  | 'refunded'
-  | 'succeeded'
-
-export type RefundStatus =
-  | 'canceled'
-  | 'failed'
-  | 'pending'
-  | 'processing'
-  | 'succeeded'
-
-// Provider configurations
-export interface StripeConfig {
-  apiVersion?: string
-  publishableKey: string
-  secretKey: string
-  webhookEndpointSecret: string
-}
-
-export interface MollieConfig {
-  apiKey: string
-  testMode?: boolean
-  webhookUrl: string
-}
-
-export interface TestProviderConfig {
-  autoComplete?: boolean
-  defaultDelay?: number
-  enabled: boolean
-  failureRate?: number
-  simulateFailures?: boolean
-}
-
-// Customer info extractor callback type
-export interface CustomerInfoExtractor {
-  (customer: any): {
-    name: string
-    email: string
-    phone?: string
-    company?: string
-    taxId?: string
-    billingAddress?: {
-      line1: string
-      line2?: string
-      city: string
-      state?: string
-      postalCode: string
-      country: string
-    }
-  }
-}
-
-// Plugin configuration
-export interface BillingPluginConfig {
-  admin?: {
-    customComponents?: boolean
-    dashboard?: boolean
-  }
-  collections?: {
-    customerRelation?: boolean | string // false to disable, string for custom collection slug
-    customers?: string
-    invoices?: string
-    payments?: string
-    refunds?: string
-  }
-  customerInfoExtractor?: CustomerInfoExtractor // Callback to extract customer info from relationship
-  disabled?: boolean
-  providers?: {
-    mollie?: MollieConfig
-    stripe?: StripeConfig
-    test?: TestProviderConfig
-  }
-  webhooks?: {
-    basePath?: string
-    cors?: boolean
-  }
-}
-
-// Collection types
-export interface PaymentRecord {
-  amount: number
-  createdAt: string
-  currency: string
-  customer?: string
-  description?: string
-  id: string
-  metadata?: Record<string, unknown>
-  provider: string
-  providerData?: Record<string, unknown>
-  providerId: string
-  status: PaymentStatus
-  updatedAt: string
-}
-
-export interface CustomerRecord {
-  address?: {
-    city?: string
-    country?: string
-    line1?: string
-    line2?: string
-    postalCode?: string
-    state?: string
-  }
-  createdAt: string
-  email?: string
-  id: string
-  metadata?: Record<string, unknown>
-  name?: string
-  phone?: string
-  providerIds?: Record<string, string>
-  updatedAt: string
-}
-
-export interface InvoiceRecord {
-  amount: number
-  billingAddress?: {
-    city: string
-    country: string
-    line1: string
-    line2?: string
-    postalCode: string
-    state?: string
-  }
-  createdAt: string
-  currency: string
-  customer?: string // Optional relationship to customer collection
-  customerInfo?: {
-    company?: string
-    email: string
-    name: string
-    phone?: string
-    taxId?: string
-  }
-  dueDate?: string
-  id: string
-  items: InvoiceItem[]
-  metadata?: Record<string, unknown>
-  number: string
-  paidAt?: string
-  status: InvoiceStatus
-  updatedAt: string
-}
-
-export interface InvoiceItem {
-  description: string
-  quantity: number
-  totalAmount: number
-  unitAmount: number
-}
-
-export type InvoiceStatus = 
-  | 'draft'
-  | 'open' 
-  | 'paid'
-  | 'uncollectible'
-  | 'void'
-
-// Plugin type
-export interface BillingPluginOptions extends BillingPluginConfig {
-  disabled?: boolean
-}
-
-// Error types
-export class BillingError extends Error {
-  constructor(
-    message: string,
-    public code: string,
-    public provider?: string,
-    public details?: Record<string, unknown>
-  ) {
-    super(message)
-    this.name = 'BillingError'
-  }
-}
-
-export class PaymentProviderError extends BillingError {
-  constructor(
-    message: string,
-    provider: string,
-    code?: string,
-    details?: Record<string, unknown>
-  ) {
-    super(message, code || 'PROVIDER_ERROR', provider, details)
-    this.name = 'PaymentProviderError'
-  }
-}
-
-export class WebhookError extends BillingError {
-  constructor(
-    message: string,
-    provider: string,
-    code?: string,
-    details?: Record<string, unknown>
-  ) {
-    super(message, code || 'WEBHOOK_ERROR', provider, details)
-    this.name = 'WebhookError'
-  }
-}
\ No newline at end of file
diff --git a/src/types/payload.ts b/src/types/payload.ts
deleted file mode 100644
index a4f2582..0000000
--- a/src/types/payload.ts
+++ /dev/null
@@ -1,178 +0,0 @@
-/**
- * PayloadCMS type definitions for hooks and handlers
- */
-
-import type { PayloadRequest, User } from 'payload'
-
-// Collection hook types
-export interface CollectionBeforeChangeHook<T = Record<string, unknown>> {
-  data: T
-  operation: 'create' | 'delete' | 'update'
-  originalDoc?: T
-  req: PayloadRequest
-}
-
-export interface CollectionAfterChangeHook<T = Record<string, unknown>> {
-  doc: T
-  operation: 'create' | 'delete' | 'update'
-  previousDoc?: T
-  req: PayloadRequest
-}
-
-export interface CollectionBeforeValidateHook<T = Record<string, unknown>> {
-  data?: T
-  operation: 'create' | 'update'
-  originalDoc?: T
-  req: PayloadRequest
-}
-
-// Access control types
-export interface AccessArgs<T = unknown> {
-  data?: T
-  id?: number | string
-  req: {
-    payload: unknown
-    user: null | User
-  }
-}
-
-// Invoice item type for hooks
-export interface InvoiceItemData {
-  description: string
-  quantity: number
-  totalAmount?: number
-  unitAmount: number
-}
-
-// Invoice data type for hooks
-export interface InvoiceData {
-  amount?: number
-  billingAddress?: {
-    city?: string
-    country?: string
-    line1?: string
-    line2?: string
-    postalCode?: string
-    state?: string
-  }
-  currency?: string
-  customer?: string // Optional relationship
-  customerInfo?: {
-    company?: string
-    email?: string
-    name?: string
-    phone?: string
-    taxId?: string
-  }
-  dueDate?: string
-  items?: InvoiceItemData[]
-  metadata?: Record<string, unknown>
-  notes?: string
-  number?: string
-  paidAt?: string
-  payment?: string
-  status?: string
-  subtotal?: number
-  taxAmount?: number
-}
-
-// Payment data type for hooks
-export interface PaymentData {
-  amount?: number
-  currency?: string
-  customer?: string
-  description?: string
-  invoice?: string
-  metadata?: Record<string, unknown>
-  provider?: string
-  providerData?: Record<string, unknown>
-  providerId?: string | number
-  status?: string
-}
-
-// Customer data type for hooks
-export interface CustomerData {
-  address?: {
-    city?: string
-    country?: string
-    line1?: string
-    line2?: string
-    postalCode?: string
-    state?: string
-  }
-  email?: string
-  metadata?: Record<string, unknown>
-  name?: string
-  phone?: string
-  providerIds?: Record<string, string | number>
-}
-
-// Refund data type for hooks
-export interface RefundData {
-  amount?: number
-  currency?: string
-  description?: string
-  metadata?: Record<string, unknown>
-  payment?: { id: string | number } | string
-  providerData?: Record<string, unknown>
-  providerId?: string | number
-  reason?: string
-  status?: string
-}
-
-// Document types with required fields after creation
-export interface PaymentDocument extends PaymentData {
-  amount: number
-  createdAt: string
-  currency: string
-  id: string | number
-  provider: string
-  providerId: string | number
-  status: string
-  updatedAt: string
-}
-
-export interface CustomerDocument extends CustomerData {
-  createdAt: string
-  id: string | number
-  updatedAt: string
-}
-
-export interface InvoiceDocument extends InvoiceData {
-  amount: number
-  createdAt: string
-  currency: string
-  customer?: string // Optional relationship
-  customerInfo?: { // Optional when customer relationship exists
-    company?: string
-    email: string
-    name: string
-    phone?: string
-    taxId?: string
-  }
-  billingAddress?: { // Optional when customer relationship exists
-    city: string
-    country: string
-    line1: string
-    line2?: string
-    postalCode: string
-    state?: string
-  }
-  id: string | number
-  items: InvoiceItemData[]
-  number: string
-  status: string
-  updatedAt: string
-}
-
-export interface RefundDocument extends RefundData {
-  amount: number
-  createdAt: string
-  currency: string
-  id: string | number
-  payment: { id: string } | string
-  providerId: string
-  refunds?: string[]
-  status: string
-  updatedAt: string
-}

From 0308e30ebda710415746ff556900bb125fb6e8f4 Mon Sep 17 00:00:00 2001
From: Bas van den Aakster <bvdaakster@gmail.com>
Date: Tue, 16 Sep 2025 00:06:18 +0200
Subject: [PATCH 3/4] refactor: Replace hardcoded billing data seeding with
 plugin-configurable collection overrides

- Remove `seedBillingData` function for sample data creation
- Update refunds, invoices, and payments collections to use pluginConfig for dynamic overrides
- Introduce utility functions like `extractSlug` for customizable collection slugs
- Streamline customer relation and data extractor logic across collections
---
 dev/payload.config.ts       |  38 +--
 dev/seed.ts                 | 120 --------
 src/collections/invoices.ts | 591 ++++++++++++++++++------------------
 src/collections/payments.ts | 227 +++++++-------
 src/collections/refunds.ts  |  24 +-
 src/index.ts                |   1 -
 src/plugin/config.ts        |  16 +-
 src/plugin/index.ts         |  14 +-
 src/plugin/types.ts         |  59 +++-
 src/plugin/utils.ts         |   5 +
 10 files changed, 515 insertions(+), 580 deletions(-)
 create mode 100644 src/plugin/utils.ts

diff --git a/dev/payload.config.ts b/dev/payload.config.ts
index d18ca44..b8a8c73 100644
--- a/dev/payload.config.ts
+++ b/dev/payload.config.ts
@@ -2,12 +2,12 @@ import { sqliteAdapter } from '@payloadcms/db-sqlite'
 import { lexicalEditor } from '@payloadcms/richtext-lexical'
 import path from 'path'
 import { buildConfig } from 'payload'
-import { billingPlugin, defaultCustomerInfoExtractor } from '../dist/index.js'
 import sharp from 'sharp'
 import { fileURLToPath } from 'url'
 
 import { testEmailAdapter } from './helpers/testEmailAdapter'
 import { seed } from './seed'
+import billingPlugin from '../src/plugin'
 
 const filename = fileURLToPath(import.meta.url)
 const dirname = path.dirname(filename)
@@ -56,27 +56,29 @@ const buildConfigWithSQLite = () => {
         },
         collections: {
           payments: 'payments',
-          customers: 'customers',
           invoices: 'invoices',
           refunds: 'refunds',
-          // customerRelation: false, // Set to false to disable customer relationship in invoices
-          // customerRelation: 'clients', // Or set to a custom collection slug
         },
-        // Use the default extractor for the built-in customer collection
-        customerInfoExtractor: defaultCustomerInfoExtractor,
-        // Or provide a custom extractor for your own customer collection structure:
+        // // Customer relationship configuration
+        // customerRelationSlug: 'customers', // Use 'customers' collection for relationship
+        // // customerRelationSlug: false,     // Or set to false to disable customer relationship
+        // // customerRelationSlug: 'clients', // Or use a custom collection slug
+        //
+        // // Provide an extractor for your customer collection structure:
         // customerInfoExtractor: (customer) => ({
-        //   name: customer.fullName,
-        //   email: customer.contactEmail,
-        //   phone: customer.phoneNumber,
-        //   company: customer.companyName,
-        //   taxId: customer.vatNumber,
-        //   billingAddress: {
-        //     line1: customer.billing.street,
-        //     city: customer.billing.city,
-        //     postalCode: customer.billing.zip,
-        //     country: customer.billing.countryCode,
-        //   }
+        //   name: customer.name || '',
+        //   email: customer.email || '',
+        //   phone: customer.phone,
+        //   company: customer.company,
+        //   taxId: customer.taxId,
+        //   billingAddress: customer.address ? {
+        //     line1: customer.address.line1 || '',
+        //     line2: customer.address.line2,
+        //     city: customer.address.city || '',
+        //     state: customer.address.state,
+        //     postalCode: customer.address.postalCode || '',
+        //     country: customer.address.country || '',
+        //   } : undefined,
         // })
       }),
     ],
diff --git a/dev/seed.ts b/dev/seed.ts
index 97e1e34..54ba04f 100644
--- a/dev/seed.ts
+++ b/dev/seed.ts
@@ -26,124 +26,4 @@ export const seed = async (payload: Payload) => {
 
 async function seedBillingData(payload: Payload): Promise<void> {
   payload.logger.info('Seeding billing sample data...')
-
-  try {
-    // Check if we already have sample data
-    const existingCustomers = await payload.count({
-      collection: 'customers',
-      where: {
-        email: {
-          equals: 'john.doe@example.com',
-        },
-      },
-    })
-
-    if (existingCustomers.totalDocs > 0) {
-      payload.logger.info('Sample billing data already exists, skipping seed')
-      return
-    }
-
-    // Create a sample customer
-    const customer = await payload.create({
-      collection: 'customers',
-      data: {
-        email: 'john.doe@example.com',
-        name: 'John Doe',
-        phone: '+1-555-0123',
-        address: {
-          line1: '123 Main St',
-          city: 'New York',
-          state: 'NY',
-          postal_code: '10001',
-          country: 'US'
-        },
-        metadata: {
-          source: 'seed',
-          created_by: 'system'
-        }
-      }
-    })
-
-    payload.logger.info(`Created sample customer: ${customer.id}`)
-
-    // Create a sample invoice
-    const invoice = await payload.create({
-      collection: 'invoices',
-      data: {
-        number: 'INV-001-SAMPLE',
-        customer: customer.id,
-        currency: 'USD',
-        items: [
-          {
-            description: 'Web Development Services',
-            quantity: 10,
-            unitAmount: 5000, // $50.00 per hour
-            totalAmount: 50000 // $500.00 total
-          },
-          {
-            description: 'Design Consultation',
-            quantity: 2,
-            unitAmount: 7500, // $75.00 per hour
-            totalAmount: 15000 // $150.00 total
-          }
-        ],
-        subtotal: 65000, // $650.00
-        taxAmount: 5200, // $52.00 (8% tax)
-        amount: 70200, // $702.00 total
-        status: 'open',
-        dueDate: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000).toISOString(), // 30 days from now
-        notes: 'Payment terms: Net 30 days. This is sample data for development.',
-        metadata: {
-          project: 'website-redesign',
-          billable_hours: 12,
-          sample: true
-        }
-      }
-    })
-
-    payload.logger.info(`Created sample invoice: ${invoice.number}`)
-
-    // Create a sample payment using test provider
-    const payment = await payload.create({
-      collection: 'payments',
-      data: {
-        provider: 'test',
-        providerId: `test_pay_sample_${Date.now()}`,
-        status: 'succeeded',
-        amount: 70200, // $702.00
-        currency: 'USD',
-        description: `Sample payment for invoice ${invoice.number}`,
-        customer: customer.id,
-        invoice: invoice.id,
-        metadata: {
-          invoice_number: invoice.number,
-          payment_method: 'test_card',
-          sample: true
-        },
-        providerData: {
-          testMode: true,
-          simulatedPayment: true,
-          autoCompleted: true
-        }
-      }
-    })
-
-    payload.logger.info(`Created sample payment: ${payment.id}`)
-
-    // Update invoice status to paid
-    await payload.update({
-      collection: 'invoices',
-      id: invoice.id,
-      data: {
-        status: 'paid',
-        payment: payment.id,
-        paidAt: new Date().toISOString()
-      }
-    })
-
-    payload.logger.info('Billing sample data seeded successfully!')
-
-  } catch (error) {
-    payload.logger.error('Error seeding billing data:', error)
-  }
 }
diff --git a/src/collections/invoices.ts b/src/collections/invoices.ts
index 647c09d..d45c888 100644
--- a/src/collections/invoices.ts
+++ b/src/collections/invoices.ts
@@ -3,18 +3,300 @@ import {
   CollectionAfterChangeHook,
   CollectionBeforeChangeHook,
   CollectionBeforeValidateHook,
-  CollectionConfig,
+  CollectionConfig, Field,
 } from 'payload'
-import { CustomerInfoExtractor } from '@/plugin/config'
+import { BillingPluginConfig, CustomerInfoExtractor, defaults } from '@/plugin/config'
 import { Invoice } from '@/plugin/types'
+import { extractSlug } from '@/plugin/utils'
 
-export function createInvoicesCollection(
-  slug: string = 'invoices',
-  customerCollectionSlug?: string,
-  customerInfoExtractor?: CustomerInfoExtractor
-): CollectionConfig {
+export function createInvoicesCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
+  const {customerRelationSlug, customerInfoExtractor} = pluginConfig
+  const overrides = typeof pluginConfig.collections?.invoices === 'object' ? pluginConfig.collections?.invoices : {}
+  let fields: Field[] = [
+    {
+      name: 'number',
+      type: 'text',
+      admin: {
+        description: 'Invoice number (e.g., INV-001)',
+      },
+      index: true,
+      required: true,
+      unique: true,
+    },
+    // Optional customer relationship
+    ...(customerRelationSlug ? [{
+      name: 'customer',
+      type: 'relationship' as const,
+      admin: {
+        position: 'sidebar' as const,
+        description: 'Link to customer record (optional)',
+      },
+      relationTo: pluginConfig.customerRelationSlug as never,
+      required: false,
+    }] : []),
+    // Basic customer info fields (embedded)
+    {
+      name: 'customerInfo',
+      type: 'group',
+      admin: {
+        description: customerRelationSlug && customerInfoExtractor
+          ? 'Customer billing information (auto-populated from customer relationship)'
+          : 'Customer billing information',
+        readOnly: !!(customerRelationSlug && customerInfoExtractor),
+      },
+      fields: [
+        {
+          name: 'name',
+          type: 'text',
+          admin: {
+            description: 'Customer name',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+          required: !customerRelationSlug || !customerInfoExtractor,
+        },
+        {
+          name: 'email',
+          type: 'email',
+          admin: {
+            description: 'Customer email address',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+          required: !customerRelationSlug || !customerInfoExtractor,
+        },
+        {
+          name: 'phone',
+          type: 'text',
+          admin: {
+            description: 'Customer phone number',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+        },
+        {
+          name: 'company',
+          type: 'text',
+          admin: {
+            description: 'Company name (optional)',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+        },
+        {
+          name: 'taxId',
+          type: 'text',
+          admin: {
+            description: 'Tax ID or VAT number',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+        },
+      ],
+    },
+    {
+      name: 'billingAddress',
+      type: 'group',
+      admin: {
+        description: customerRelationSlug && customerInfoExtractor
+          ? 'Billing address (auto-populated from customer relationship)'
+          : 'Billing address',
+        readOnly: !!(customerRelationSlug && customerInfoExtractor),
+      },
+      fields: [
+        {
+          name: 'line1',
+          type: 'text',
+          admin: {
+            description: 'Address line 1',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+          required: !customerRelationSlug || !customerInfoExtractor,
+        },
+        {
+          name: 'line2',
+          type: 'text',
+          admin: {
+            description: 'Address line 2',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+        },
+        {
+          name: 'city',
+          type: 'text',
+          admin: {
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+          required: !customerRelationSlug || !customerInfoExtractor,
+        },
+        {
+          name: 'state',
+          type: 'text',
+          admin: {
+            description: 'State or province',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+        },
+        {
+          name: 'postalCode',
+          type: 'text',
+          admin: {
+            description: 'Postal or ZIP code',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+          required: !customerRelationSlug || !customerInfoExtractor,
+        },
+        {
+          name: 'country',
+          type: 'text',
+          admin: {
+            description: 'Country code (e.g., US, GB)',
+            readOnly: !!(customerRelationSlug && customerInfoExtractor),
+          },
+          maxLength: 2,
+          required: !customerRelationSlug || !customerInfoExtractor,
+        },
+      ],
+    },
+    {
+      name: 'status',
+      type: 'select',
+      admin: {
+        position: 'sidebar',
+      },
+      defaultValue: 'draft',
+      options: [
+        { label: 'Draft', value: 'draft' },
+        { label: 'Open', value: 'open' },
+        { label: 'Paid', value: 'paid' },
+        { label: 'Void', value: 'void' },
+        { label: 'Uncollectible', value: 'uncollectible' },
+      ],
+      required: true,
+    },
+    {
+      name: 'currency',
+      type: 'text',
+      admin: {
+        description: 'ISO 4217 currency code (e.g., USD, EUR)',
+      },
+      defaultValue: 'USD',
+      maxLength: 3,
+      required: true,
+    },
+    {
+      name: 'items',
+      type: 'array',
+      admin: {
+        // Custom row labeling can be added here when needed
+      },
+      fields: [
+        {
+          name: 'description',
+          type: 'text',
+          admin: {
+            width: '40%',
+          },
+          required: true,
+        },
+        {
+          name: 'quantity',
+          type: 'number',
+          admin: {
+            width: '15%',
+          },
+          defaultValue: 1,
+          min: 1,
+          required: true,
+        },
+        {
+          name: 'unitAmount',
+          type: 'number',
+          admin: {
+            description: 'Amount in cents',
+            width: '20%',
+          },
+          min: 0,
+          required: true,
+        },
+        {
+          name: 'totalAmount',
+          type: 'number',
+          admin: {
+            description: 'Calculated: quantity × unitAmount',
+            readOnly: true,
+            width: '20%',
+          },
+        },
+      ],
+      minRows: 1,
+      required: true,
+    },
+    {
+      name: 'subtotal',
+      type: 'number',
+      admin: {
+        description: 'Sum of all line items',
+        readOnly: true,
+      },
+    },
+    {
+      name: 'taxAmount',
+      type: 'number',
+      admin: {
+        description: 'Tax amount in cents',
+      },
+      defaultValue: 0,
+    },
+    {
+      name: 'amount',
+      type: 'number',
+      admin: {
+        description: 'Total amount (subtotal + tax)',
+        readOnly: true,
+      },
+    },
+    {
+      name: 'dueDate',
+      type: 'date',
+      admin: {
+        date: {
+          pickerAppearance: 'dayOnly',
+        },
+      },
+    },
+    {
+      name: 'paidAt',
+      type: 'date',
+      admin: {
+        condition: (data) => data.status === 'paid',
+        readOnly: true,
+      },
+    },
+    {
+      name: 'payment',
+      type: 'relationship',
+      admin: {
+        condition: (data) => data.status === 'paid',
+        position: 'sidebar',
+      },
+      relationTo: 'payments',
+    },
+    {
+      name: 'notes',
+      type: 'textarea',
+      admin: {
+        description: 'Internal notes',
+      },
+    },
+    {
+      name: 'metadata',
+      type: 'json',
+      admin: {
+        description: 'Additional invoice metadata',
+      },
+    },
+  ]
+  if (overrides?.fields) {
+    fields = overrides.fields({defaultFields: fields})
+  }
   return {
-    slug,
+    slug: extractSlug(pluginConfig.collections?.invoices || defaults.invoicesCollection),
     access: {
       create: ({ req: { user } }: AccessArgs) => !!user,
       delete: ({ req: { user } }: AccessArgs) => !!user,
@@ -26,286 +308,7 @@ export function createInvoicesCollection(
       group: 'Billing',
       useAsTitle: 'number',
     },
-    fields: [
-      {
-        name: 'number',
-        type: 'text',
-        admin: {
-          description: 'Invoice number (e.g., INV-001)',
-        },
-        index: true,
-        required: true,
-        unique: true,
-      },
-      // Optional customer relationship
-      ...(customerCollectionSlug ? [{
-        name: 'customer',
-        type: 'relationship' as const,
-        admin: {
-          position: 'sidebar' as const,
-          description: 'Link to customer record (optional)',
-        },
-        relationTo: customerCollectionSlug as any,
-        required: false,
-      }] : []),
-      // Basic customer info fields (embedded)
-      {
-        name: 'customerInfo',
-        type: 'group',
-        admin: {
-          description: customerCollectionSlug && customerInfoExtractor
-            ? 'Customer billing information (auto-populated from customer relationship)'
-            : 'Customer billing information',
-          readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-        },
-        fields: [
-          {
-            name: 'name',
-            type: 'text',
-            admin: {
-              description: 'Customer name',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-            required: !customerCollectionSlug || !customerInfoExtractor,
-          },
-          {
-            name: 'email',
-            type: 'email',
-            admin: {
-              description: 'Customer email address',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-            required: !customerCollectionSlug || !customerInfoExtractor,
-          },
-          {
-            name: 'phone',
-            type: 'text',
-            admin: {
-              description: 'Customer phone number',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-          },
-          {
-            name: 'company',
-            type: 'text',
-            admin: {
-              description: 'Company name (optional)',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-          },
-          {
-            name: 'taxId',
-            type: 'text',
-            admin: {
-              description: 'Tax ID or VAT number',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-          },
-        ],
-      },
-      {
-        name: 'billingAddress',
-        type: 'group',
-        admin: {
-          description: customerCollectionSlug && customerInfoExtractor
-            ? 'Billing address (auto-populated from customer relationship)'
-            : 'Billing address',
-          readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-        },
-        fields: [
-          {
-            name: 'line1',
-            type: 'text',
-            admin: {
-              description: 'Address line 1',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-            required: !customerCollectionSlug || !customerInfoExtractor,
-          },
-          {
-            name: 'line2',
-            type: 'text',
-            admin: {
-              description: 'Address line 2',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-          },
-          {
-            name: 'city',
-            type: 'text',
-            admin: {
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-            required: !customerCollectionSlug || !customerInfoExtractor,
-          },
-          {
-            name: 'state',
-            type: 'text',
-            admin: {
-              description: 'State or province',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-          },
-          {
-            name: 'postalCode',
-            type: 'text',
-            admin: {
-              description: 'Postal or ZIP code',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-            required: !customerCollectionSlug || !customerInfoExtractor,
-          },
-          {
-            name: 'country',
-            type: 'text',
-            admin: {
-              description: 'Country code (e.g., US, GB)',
-              readOnly: customerCollectionSlug && customerInfoExtractor ? true : false,
-            },
-            maxLength: 2,
-            required: !customerCollectionSlug || !customerInfoExtractor,
-          },
-        ],
-      },
-      {
-        name: 'status',
-        type: 'select',
-        admin: {
-          position: 'sidebar',
-        },
-        defaultValue: 'draft',
-        options: [
-          { label: 'Draft', value: 'draft' },
-          { label: 'Open', value: 'open' },
-          { label: 'Paid', value: 'paid' },
-          { label: 'Void', value: 'void' },
-          { label: 'Uncollectible', value: 'uncollectible' },
-        ],
-        required: true,
-      },
-      {
-        name: 'currency',
-        type: 'text',
-        admin: {
-          description: 'ISO 4217 currency code (e.g., USD, EUR)',
-        },
-        defaultValue: 'USD',
-        maxLength: 3,
-        required: true,
-      },
-      {
-        name: 'items',
-        type: 'array',
-        admin: {
-          // Custom row labeling can be added here when needed
-        },
-        fields: [
-          {
-            name: 'description',
-            type: 'text',
-            admin: {
-              width: '40%',
-            },
-            required: true,
-          },
-          {
-            name: 'quantity',
-            type: 'number',
-            admin: {
-              width: '15%',
-            },
-            defaultValue: 1,
-            min: 1,
-            required: true,
-          },
-          {
-            name: 'unitAmount',
-            type: 'number',
-            admin: {
-              description: 'Amount in cents',
-              width: '20%',
-            },
-            min: 0,
-            required: true,
-          },
-          {
-            name: 'totalAmount',
-            type: 'number',
-            admin: {
-              description: 'Calculated: quantity × unitAmount',
-              readOnly: true,
-              width: '20%',
-            },
-          },
-        ],
-        minRows: 1,
-        required: true,
-      },
-      {
-        name: 'subtotal',
-        type: 'number',
-        admin: {
-          description: 'Sum of all line items',
-          readOnly: true,
-        },
-      },
-      {
-        name: 'taxAmount',
-        type: 'number',
-        admin: {
-          description: 'Tax amount in cents',
-        },
-        defaultValue: 0,
-      },
-      {
-        name: 'amount',
-        type: 'number',
-        admin: {
-          description: 'Total amount (subtotal + tax)',
-          readOnly: true,
-        },
-      },
-      {
-        name: 'dueDate',
-        type: 'date',
-        admin: {
-          date: {
-            pickerAppearance: 'dayOnly',
-          },
-        },
-      },
-      {
-        name: 'paidAt',
-        type: 'date',
-        admin: {
-          condition: (data) => data.status === 'paid',
-          readOnly: true,
-        },
-      },
-      {
-        name: 'payment',
-        type: 'relationship',
-        admin: {
-          condition: (data) => data.status === 'paid',
-          position: 'sidebar',
-        },
-        relationTo: 'payments',
-      },
-      {
-        name: 'notes',
-        type: 'textarea',
-        admin: {
-          description: 'Internal notes',
-        },
-      },
-      {
-        name: 'metadata',
-        type: 'json',
-        admin: {
-          description: 'Additional invoice metadata',
-        },
-      },
-    ],
+    fields,
     hooks: {
       afterChange: [
         ({ doc, operation, req }) => {
@@ -317,7 +320,7 @@ export function createInvoicesCollection(
       beforeChange: [
         async ({ data, operation, req, originalDoc }) => {
           // Sync customer info from relationship if extractor is provided
-          if (customerCollectionSlug && customerInfoExtractor && data.customer) {
+          if (customerRelationSlug && customerInfoExtractor && data.customer) {
             // Check if customer changed or this is a new invoice
             const customerChanged = operation === 'create' ||
               (originalDoc && originalDoc.customer !== data.customer)
@@ -326,8 +329,8 @@ export function createInvoicesCollection(
               try {
                 // Fetch the customer data
                 const customer = await req.payload.findByID({
-                  collection: customerCollectionSlug as any,
-                  id: data.customer,
+                  collection: customerRelationSlug as never,
+                  id: data.customer as never,
                 })
 
                 // Extract customer info using the provided callback
@@ -386,18 +389,18 @@ export function createInvoicesCollection(
           if (!data) return
 
           // If using extractor, customer relationship is required
-          if (customerCollectionSlug && customerInfoExtractor && !data.customer) {
+          if (customerRelationSlug && customerInfoExtractor && !data.customer) {
             throw new Error('Please select a customer')
           }
 
           // If not using extractor but have customer collection, either relationship or info is required
-          if (customerCollectionSlug && !customerInfoExtractor &&
+          if (customerRelationSlug && !customerInfoExtractor &&
               !data.customer && (!data.customerInfo?.name || !data.customerInfo?.email)) {
             throw new Error('Either select a customer or provide customer information')
           }
 
           // If no customer collection, ensure customer info is provided
-          if (!customerCollectionSlug && (!data.customerInfo?.name || !data.customerInfo?.email)) {
+          if (!customerRelationSlug && (!data.customerInfo?.name || !data.customerInfo?.email)) {
             throw new Error('Customer name and email are required')
           }
 
diff --git a/src/collections/payments.ts b/src/collections/payments.ts
index 4d9d8bf..14ad86a 100644
--- a/src/collections/payments.ts
+++ b/src/collections/payments.ts
@@ -1,10 +1,117 @@
-import { AccessArgs, CollectionAfterChangeHook, CollectionBeforeChangeHook, CollectionConfig } from 'payload'
-import { Payment } from '@/plugin/types'
+import type { AccessArgs, CollectionBeforeChangeHook, CollectionConfig, Field } from 'payload'
+import type { Payment } from '@/plugin/types'
+import type { BillingPluginConfig} from '@/plugin/config';
+import { defaults } from '@/plugin/config'
+import { extractSlug } from '@/plugin/utils'
 
-export function createPaymentsCollection(slug: string = 'payments'): CollectionConfig {
+export function createPaymentsCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
+  const overrides = typeof pluginConfig.collections?.payments === 'object' ? pluginConfig.collections?.payments : {}
+  let fields: Field[] = [
+    {
+      name: 'provider',
+      type: 'select',
+      admin: {
+        position: 'sidebar',
+      },
+      options: [
+        { label: 'Stripe', value: 'stripe' },
+        { label: 'Mollie', value: 'mollie' },
+        { label: 'Test', value: 'test' },
+      ],
+      required: true,
+    },
+    {
+      name: 'providerId',
+      type: 'text',
+      admin: {
+        description: 'The payment ID from the payment provider',
+      },
+      label: 'Provider Payment ID',
+      required: true,
+      unique: true,
+    },
+    {
+      name: 'status',
+      type: 'select',
+      admin: {
+        position: 'sidebar',
+      },
+      options: [
+        { label: 'Pending', value: 'pending' },
+        { label: 'Processing', value: 'processing' },
+        { label: 'Succeeded', value: 'succeeded' },
+        { label: 'Failed', value: 'failed' },
+        { label: 'Canceled', value: 'canceled' },
+        { label: 'Refunded', value: 'refunded' },
+        { label: 'Partially Refunded', value: 'partially_refunded' },
+      ],
+      required: true,
+    },
+    {
+      name: 'amount',
+      type: 'number',
+      admin: {
+        description: 'Amount in cents (e.g., 2000 = $20.00)',
+      },
+      min: 1,
+      required: true,
+    },
+    {
+      name: 'currency',
+      type: 'text',
+      admin: {
+        description: 'ISO 4217 currency code (e.g., USD, EUR)',
+      },
+      maxLength: 3,
+      required: true,
+    },
+    {
+      name: 'description',
+      type: 'text',
+      admin: {
+        description: 'Payment description',
+      },
+    },
+    {
+      name: 'invoice',
+      type: 'relationship',
+      admin: {
+        position: 'sidebar',
+      },
+      relationTo: 'invoices',
+    },
+    {
+      name: 'metadata',
+      type: 'json',
+      admin: {
+        description: 'Additional metadata for the payment',
+      },
+    },
+    {
+      name: 'providerData',
+      type: 'json',
+      admin: {
+        description: 'Raw data from the payment provider',
+        readOnly: true,
+      },
+    },
+    {
+      name: 'refunds',
+      type: 'relationship',
+      admin: {
+        position: 'sidebar',
+        readOnly: true,
+      },
+      hasMany: true,
+      relationTo: 'refunds',
+    },
+  ]
+  if (overrides?.fields) {
+    fields = overrides?.fields({defaultFields: fields})
+  }
   return {
-    slug,
-    access: {
+    slug: extractSlug(pluginConfig.collections?.payments || defaults.paymentsCollection),
+    access: overrides?.access || {
       create: ({ req: { user } }: AccessArgs) => !!user,
       delete: ({ req: { user } }: AccessArgs) => !!user,
       read: ({ req: { user } }: AccessArgs) => !!user,
@@ -14,115 +121,9 @@ export function createPaymentsCollection(slug: string = 'payments'): CollectionC
       defaultColumns: ['id', 'provider', 'status', 'amount', 'currency', 'createdAt'],
       group: 'Billing',
       useAsTitle: 'id',
+      ...overrides?.admin
     },
-    fields: [
-      {
-        name: 'provider',
-        type: 'select',
-        admin: {
-          position: 'sidebar',
-        },
-        options: [
-          { label: 'Stripe', value: 'stripe' },
-          { label: 'Mollie', value: 'mollie' },
-          { label: 'Test', value: 'test' },
-        ],
-        required: true,
-      },
-      {
-        name: 'providerId',
-        type: 'text',
-        admin: {
-          description: 'The payment ID from the payment provider',
-        },
-        label: 'Provider Payment ID',
-        required: true,
-        unique: true,
-      },
-      {
-        name: 'status',
-        type: 'select',
-        admin: {
-          position: 'sidebar',
-        },
-        options: [
-          { label: 'Pending', value: 'pending' },
-          { label: 'Processing', value: 'processing' },
-          { label: 'Succeeded', value: 'succeeded' },
-          { label: 'Failed', value: 'failed' },
-          { label: 'Canceled', value: 'canceled' },
-          { label: 'Refunded', value: 'refunded' },
-          { label: 'Partially Refunded', value: 'partially_refunded' },
-        ],
-        required: true,
-      },
-      {
-        name: 'amount',
-        type: 'number',
-        admin: {
-          description: 'Amount in cents (e.g., 2000 = $20.00)',
-        },
-        min: 1,
-        required: true,
-      },
-      {
-        name: 'currency',
-        type: 'text',
-        admin: {
-          description: 'ISO 4217 currency code (e.g., USD, EUR)',
-        },
-        maxLength: 3,
-        required: true,
-      },
-      {
-        name: 'description',
-        type: 'text',
-        admin: {
-          description: 'Payment description',
-        },
-      },
-      {
-        name: 'customer',
-        type: 'relationship',
-        admin: {
-          position: 'sidebar',
-        },
-        relationTo: 'customers',
-      },
-      {
-        name: 'invoice',
-        type: 'relationship',
-        admin: {
-          position: 'sidebar',
-        },
-        relationTo: 'invoices',
-      },
-      {
-        name: 'metadata',
-        type: 'json',
-        admin: {
-          description: 'Additional metadata for the payment',
-        },
-      },
-      {
-        name: 'providerData',
-        type: 'json',
-        admin: {
-          description: 'Raw data from the payment provider',
-          readOnly: true,
-        },
-      },
-      {
-        name: 'refunds',
-        type: 'relationship',
-        admin: {
-          position: 'sidebar',
-          readOnly: true,
-        },
-        hasMany: true,
-        relationTo: 'refunds',
-      },
-    ],
+    fields,
     hooks: {
       beforeChange: [
         ({ data, operation }) => {
diff --git a/src/collections/refunds.ts b/src/collections/refunds.ts
index 7aba74a..6b383cf 100644
--- a/src/collections/refunds.ts
+++ b/src/collections/refunds.ts
@@ -1,16 +1,12 @@
-import type { CollectionConfig } from 'payload'
+import type { AccessArgs, CollectionConfig } from 'payload'
+import { BillingPluginConfig, defaults } from '@/plugin/config'
+import { extractSlug } from '@/plugin/utils'
 
-import type {
-  AccessArgs,
-  CollectionAfterChangeHook,
-  CollectionBeforeChangeHook,
-  RefundData,
-  RefundDocument
-} from '../types/payload'
-
-export function createRefundsCollection(slug: string = 'refunds'): CollectionConfig {
+export function createRefundsCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
+  const overrides = typeof pluginConfig.collections?.invoices === 'object' ? pluginConfig.collections?.invoices : {}
+  // TODO: finish collection overrides
   return {
-    slug,
+    slug: extractSlug(pluginConfig.collections?.refunds || defaults.refundsCollection),
     access: {
       create: ({ req: { user } }: AccessArgs) => !!user,
       delete: ({ req: { user } }: AccessArgs) => !!user,
@@ -113,7 +109,7 @@ export function createRefundsCollection(slug: string = 'refunds'): CollectionCon
     ],
     hooks: {
       afterChange: [
-        async ({ doc, operation, req }: CollectionAfterChangeHook<RefundDocument>) => {
+        async ({ doc, operation, req }) => {
           if (operation === 'create') {
             req.payload.logger.info(`Refund created: ${doc.id} for payment: ${doc.payment}`)
 
@@ -129,7 +125,7 @@ export function createRefundsCollection(slug: string = 'refunds'): CollectionCon
                 id: typeof doc.payment === 'string' ? doc.payment : doc.payment.id,
                 collection: 'payments',
                 data: {
-                  refunds: [...refundIds, doc.id as any],
+                  refunds: [...refundIds, doc.id],
                 },
               })
             } catch (error) {
@@ -139,7 +135,7 @@ export function createRefundsCollection(slug: string = 'refunds'): CollectionCon
         },
       ],
       beforeChange: [
-        ({ data, operation }: CollectionBeforeChangeHook<RefundData>) => {
+        ({ data, operation }) => {
           if (operation === 'create') {
             // Validate amount format
             if (data.amount && !Number.isInteger(data.amount)) {
diff --git a/src/index.ts b/src/index.ts
index 509a567..139597f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,2 @@
-export * from './types'
 
 
diff --git a/src/plugin/config.ts b/src/plugin/config.ts
index ace743d..9e75e1d 100644
--- a/src/plugin/config.ts
+++ b/src/plugin/config.ts
@@ -1,6 +1,11 @@
+import { CollectionConfig } from 'payload'
+import { FieldsOverride } from '@/plugin/utils'
 
 export const defaults = {
-  paymentsCollection: 'payments'
+  paymentsCollection: 'payments',
+  invoicesCollection: 'invoices',
+  refundsCollection: 'refunds',
+  customerRelationSlug: 'customer'
 }
 
 // Provider configurations
@@ -51,13 +56,12 @@ export interface BillingPluginConfig {
     dashboard?: boolean
   }
   collections?: {
-    customerRelation?: boolean | string // false to disable, string for custom collection slug
-    customers?: string
-    invoices?: string
-    payments?: string
-    refunds?: string
+    invoices?: string | (Partial<CollectionConfig> & {fields?: FieldsOverride})
+    payments?: string | (Partial<CollectionConfig> & {fields?: FieldsOverride})
+    refunds?: string | (Partial<CollectionConfig> & {fields?: FieldsOverride})
   }
   customerInfoExtractor?: CustomerInfoExtractor // Callback to extract customer info from relationship
+  customerRelationSlug?: string // Customer collection slug for relationship
   disabled?: boolean
   providers?: {
     mollie?: MollieConfig
diff --git a/src/plugin/index.ts b/src/plugin/index.ts
index e644aec..ebf0aa4 100644
--- a/src/plugin/index.ts
+++ b/src/plugin/index.ts
@@ -1,6 +1,6 @@
 import type { Config } from 'payload'
 import { createInvoicesCollection, createPaymentsCollection, createRefundsCollection } from '@/collections'
-import { BillingPluginConfig } from '@/plugin/config'
+import type { BillingPluginConfig } from '@/plugin/config'
 
 export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config: Config): Config => {
   if (pluginConfig.disabled) {
@@ -12,16 +12,10 @@ export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config
     config.collections = []
   }
 
-  const customerSlug = pluginConfig.collections?.customers || 'customers'
-
   config.collections.push(
-    createPaymentsCollection(pluginConfig.collections?.payments || 'payments'),
-    createInvoicesCollection(
-      pluginConfig.collections?.invoices || 'invoices',
-      pluginConfig.collections?.customerRelation !== false ? customerSlug : undefined,
-      pluginConfig.customerInfoExtractor
-    ),
-    createRefundsCollection(pluginConfig.collections?.refunds || 'refunds'),
+    createPaymentsCollection(pluginConfig),
+    createInvoicesCollection(pluginConfig),
+    createRefundsCollection(pluginConfig),
   )
 
   // Initialize endpoints
diff --git a/src/plugin/types.ts b/src/plugin/types.ts
index d7ae2ee..a2f3a2d 100644
--- a/src/plugin/types.ts
+++ b/src/plugin/types.ts
@@ -1,7 +1,58 @@
-import { Customer, Refund } from '../../dev/payload-types'
 
 export type Id = string | number
 
+export interface Refund {
+  id: number;
+  /**
+   * The refund ID from the payment provider
+   */
+  providerId: string;
+  payment: number | Payment;
+  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled';
+  /**
+   * Refund amount in cents
+   */
+  amount: number;
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  /**
+   * Reason for the refund
+   */
+  reason?: ('duplicate' | 'fraudulent' | 'requested_by_customer' | 'other') | null;
+  /**
+   * Additional details about the refund
+   */
+  description?: string | null;
+  /**
+   * Additional refund metadata
+   */
+  metadata?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  /**
+   * Raw data from the payment provider
+   */
+  providerData?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  updatedAt: string;
+  createdAt: string;
+}
+
 export interface Payment {
   id: Id;
   provider: 'stripe' | 'mollie' | 'test';
@@ -22,7 +73,6 @@ export interface Payment {
    * Payment description
    */
   description?: string | null;
-  customer?: (Id | null) | Customer;
   invoice?: (Id | null) | Invoice;
   /**
    * Additional metadata for the payment
@@ -53,7 +103,7 @@ export interface Payment {
   createdAt: string;
 }
 
-export interface Invoice {
+export interface Invoice<TCustomer = unknown> {
   id: Id;
   /**
    * Invoice number (e.g., INV-001)
@@ -62,7 +112,7 @@ export interface Invoice {
   /**
    * Link to customer record (optional)
    */
-  customer?: (Id | null) | Customer;
+  customer?: (Id | null) | TCustomer;
   /**
    * Customer billing information (auto-populated from customer relationship)
    */
@@ -166,3 +216,4 @@ export interface Invoice {
   updatedAt: string;
   createdAt: string;
 }
+
diff --git a/src/plugin/utils.ts b/src/plugin/utils.ts
new file mode 100644
index 0000000..543c708
--- /dev/null
+++ b/src/plugin/utils.ts
@@ -0,0 +1,5 @@
+import type { CollectionConfig, Field } from 'payload'
+
+export type FieldsOverride = (args: { defaultFields: Field[] }) => Field[]
+
+export const extractSlug = (arg: string | Partial<CollectionConfig>) => typeof arg === 'string' ? arg : arg.slug!

From e3a58fe6bcfcd97c65656c06c92e9d47a64b3655 Mon Sep 17 00:00:00 2001
From: Bas van den Aakster <bvdaakster@gmail.com>
Date: Tue, 16 Sep 2025 22:10:47 +0200
Subject: [PATCH 4/4] feat: Add Mollie payment provider support

- Introduce `mollieProvider` for handling Mollie payments
- Add configurable payment hooks for initialization and processing
- Implement `initPayment` logic to create Mollie payments and update metadata
- Include types for Mollie integration in payments and refunds
- Update `package.json` to include `@mollie/api-client` dependency
- Refactor existing payment-related types into modular files for better maintainability
---
 dev/app/my-route/route.ts                  |   2 +
 dev/payload-types.ts                       | 627 +++++++++++++++++++++
 dev/payload.config.ts                      |  33 +-
 dev/seed.ts                                |   8 +-
 package.json                               |   3 +-
 pnpm-lock.yaml                             |  12 +-
 src/collections/hooks.ts                   |  11 +
 src/collections/invoices.ts                |   9 +-
 src/collections/payments.ts                |  14 +-
 src/collections/refunds.ts                 |  10 +-
 src/index.ts                               |   4 +-
 src/plugin/config.ts                       |   7 +-
 src/plugin/index.ts                        |  71 +--
 src/plugin/singleton.ts                    |  11 +
 src/plugin/types/id.ts                     |   1 +
 src/plugin/types/index.ts                  |   5 +
 src/plugin/{types.ts => types/invoices.ts} | 106 +---
 src/plugin/types/payments.ts               |  53 ++
 src/plugin/types/refunds.ts                |  53 ++
 src/plugin/utils.ts                        |   5 +-
 src/providers/index.ts                     |   2 +
 src/providers/mollie.ts                    |  40 ++
 src/providers/types.ts                     |  10 +
 23 files changed, 890 insertions(+), 207 deletions(-)
 create mode 100644 dev/payload-types.ts
 create mode 100644 src/collections/hooks.ts
 create mode 100644 src/plugin/singleton.ts
 create mode 100644 src/plugin/types/id.ts
 create mode 100644 src/plugin/types/index.ts
 rename src/plugin/{types.ts => types/invoices.ts} (52%)
 create mode 100644 src/plugin/types/payments.ts
 create mode 100644 src/plugin/types/refunds.ts
 create mode 100644 src/providers/index.ts
 create mode 100644 src/providers/mollie.ts
 create mode 100644 src/providers/types.ts

diff --git a/dev/app/my-route/route.ts b/dev/app/my-route/route.ts
index 0755886..a3bf0fe 100644
--- a/dev/app/my-route/route.ts
+++ b/dev/app/my-route/route.ts
@@ -1,11 +1,13 @@
 import configPromise from '@payload-config'
 import { getPayload } from 'payload'
+import { useBillingPlugin } from '../../../src/plugin'
 
 export const GET = async (request: Request) => {
   const payload = await getPayload({
     config: configPromise,
   })
 
+
   return Response.json({
     message: 'This is an example of a custom route.',
   })
diff --git a/dev/payload-types.ts b/dev/payload-types.ts
new file mode 100644
index 0000000..5f1fb92
--- /dev/null
+++ b/dev/payload-types.ts
@@ -0,0 +1,627 @@
+/* tslint:disable */
+/* eslint-disable */
+/**
+ * This file was automatically generated by Payload.
+ * DO NOT MODIFY IT BY HAND. Instead, modify your source Payload config,
+ * and re-run `payload generate:types` to regenerate this file.
+ */
+
+/**
+ * Supported timezones in IANA format.
+ *
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "supportedTimezones".
+ */
+export type SupportedTimezones =
+  | 'Pacific/Midway'
+  | 'Pacific/Niue'
+  | 'Pacific/Honolulu'
+  | 'Pacific/Rarotonga'
+  | 'America/Anchorage'
+  | 'Pacific/Gambier'
+  | 'America/Los_Angeles'
+  | 'America/Tijuana'
+  | 'America/Denver'
+  | 'America/Phoenix'
+  | 'America/Chicago'
+  | 'America/Guatemala'
+  | 'America/New_York'
+  | 'America/Bogota'
+  | 'America/Caracas'
+  | 'America/Santiago'
+  | 'America/Buenos_Aires'
+  | 'America/Sao_Paulo'
+  | 'Atlantic/South_Georgia'
+  | 'Atlantic/Azores'
+  | 'Atlantic/Cape_Verde'
+  | 'Europe/London'
+  | 'Europe/Berlin'
+  | 'Africa/Lagos'
+  | 'Europe/Athens'
+  | 'Africa/Cairo'
+  | 'Europe/Moscow'
+  | 'Asia/Riyadh'
+  | 'Asia/Dubai'
+  | 'Asia/Baku'
+  | 'Asia/Karachi'
+  | 'Asia/Tashkent'
+  | 'Asia/Calcutta'
+  | 'Asia/Dhaka'
+  | 'Asia/Almaty'
+  | 'Asia/Jakarta'
+  | 'Asia/Bangkok'
+  | 'Asia/Shanghai'
+  | 'Asia/Singapore'
+  | 'Asia/Tokyo'
+  | 'Asia/Seoul'
+  | 'Australia/Brisbane'
+  | 'Australia/Sydney'
+  | 'Pacific/Guam'
+  | 'Pacific/Noumea'
+  | 'Pacific/Auckland'
+  | 'Pacific/Fiji';
+
+export interface Config {
+  auth: {
+    users: UserAuthOperations;
+  };
+  blocks: {};
+  collections: {
+    posts: Post;
+    media: Media;
+    payments: Payment;
+    invoices: Invoice;
+    refunds: Refund;
+    users: User;
+    'payload-locked-documents': PayloadLockedDocument;
+    'payload-preferences': PayloadPreference;
+    'payload-migrations': PayloadMigration;
+  };
+  collectionsJoins: {};
+  collectionsSelect: {
+    posts: PostsSelect<false> | PostsSelect<true>;
+    media: MediaSelect<false> | MediaSelect<true>;
+    payments: PaymentsSelect<false> | PaymentsSelect<true>;
+    invoices: InvoicesSelect<false> | InvoicesSelect<true>;
+    refunds: RefundsSelect<false> | RefundsSelect<true>;
+    users: UsersSelect<false> | UsersSelect<true>;
+    'payload-locked-documents': PayloadLockedDocumentsSelect<false> | PayloadLockedDocumentsSelect<true>;
+    'payload-preferences': PayloadPreferencesSelect<false> | PayloadPreferencesSelect<true>;
+    'payload-migrations': PayloadMigrationsSelect<false> | PayloadMigrationsSelect<true>;
+  };
+  db: {
+    defaultIDType: number;
+  };
+  globals: {};
+  globalsSelect: {};
+  locale: null;
+  user: User & {
+    collection: 'users';
+  };
+  jobs: {
+    tasks: unknown;
+    workflows: unknown;
+  };
+}
+export interface UserAuthOperations {
+  forgotPassword: {
+    email: string;
+    password: string;
+  };
+  login: {
+    email: string;
+    password: string;
+  };
+  registerFirstUser: {
+    email: string;
+    password: string;
+  };
+  unlock: {
+    email: string;
+    password: string;
+  };
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "posts".
+ */
+export interface Post {
+  id: number;
+  updatedAt: string;
+  createdAt: string;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "media".
+ */
+export interface Media {
+  id: number;
+  updatedAt: string;
+  createdAt: string;
+  url?: string | null;
+  thumbnailURL?: string | null;
+  filename?: string | null;
+  mimeType?: string | null;
+  filesize?: number | null;
+  width?: number | null;
+  height?: number | null;
+  focalX?: number | null;
+  focalY?: number | null;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payments".
+ */
+export interface Payment {
+  id: number;
+  provider: 'stripe' | 'mollie' | 'test';
+  /**
+   * The payment ID from the payment provider
+   */
+  providerId: string;
+  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled' | 'refunded' | 'partially_refunded';
+  /**
+   * Amount in cents (e.g., 2000 = $20.00)
+   */
+  amount: number;
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  /**
+   * Payment description
+   */
+  description?: string | null;
+  invoice?: (number | null) | Invoice;
+  /**
+   * Additional metadata for the payment
+   */
+  metadata?:
+    | {
+        [k: string]: unknown;
+      }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  /**
+   * Raw data from the payment provider
+   */
+  providerData?:
+    | {
+        [k: string]: unknown;
+      }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  refunds?: (number | Refund)[] | null;
+  updatedAt: string;
+  createdAt: string;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "invoices".
+ */
+export interface Invoice {
+  id: number;
+  /**
+   * Invoice number (e.g., INV-001)
+   */
+  number: string;
+  /**
+   * Customer billing information
+   */
+  customerInfo: {
+    /**
+     * Customer name
+     */
+    name: string;
+    /**
+     * Customer email address
+     */
+    email: string;
+    /**
+     * Customer phone number
+     */
+    phone?: string | null;
+    /**
+     * Company name (optional)
+     */
+    company?: string | null;
+    /**
+     * Tax ID or VAT number
+     */
+    taxId?: string | null;
+  };
+  /**
+   * Billing address
+   */
+  billingAddress: {
+    /**
+     * Address line 1
+     */
+    line1: string;
+    /**
+     * Address line 2
+     */
+    line2?: string | null;
+    city: string;
+    /**
+     * State or province
+     */
+    state?: string | null;
+    /**
+     * Postal or ZIP code
+     */
+    postalCode: string;
+    /**
+     * Country code (e.g., US, GB)
+     */
+    country: string;
+  };
+  status: 'draft' | 'open' | 'paid' | 'void' | 'uncollectible';
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  items: {
+    description: string;
+    quantity: number;
+    /**
+     * Amount in cents
+     */
+    unitAmount: number;
+    /**
+     * Calculated: quantity × unitAmount
+     */
+    totalAmount?: number | null;
+    id?: string | null;
+  }[];
+  /**
+   * Sum of all line items
+   */
+  subtotal?: number | null;
+  /**
+   * Tax amount in cents
+   */
+  taxAmount?: number | null;
+  /**
+   * Total amount (subtotal + tax)
+   */
+  amount?: number | null;
+  dueDate?: string | null;
+  paidAt?: string | null;
+  payment?: (number | null) | Payment;
+  /**
+   * Internal notes
+   */
+  notes?: string | null;
+  /**
+   * Additional invoice metadata
+   */
+  metadata?:
+    | {
+        [k: string]: unknown;
+      }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  updatedAt: string;
+  createdAt: string;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "refunds".
+ */
+export interface Refund {
+  id: number;
+  /**
+   * The refund ID from the payment provider
+   */
+  providerId: string;
+  payment: number | Payment;
+  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled';
+  /**
+   * Refund amount in cents
+   */
+  amount: number;
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  /**
+   * Reason for the refund
+   */
+  reason?: ('duplicate' | 'fraudulent' | 'requested_by_customer' | 'other') | null;
+  /**
+   * Additional details about the refund
+   */
+  description?: string | null;
+  /**
+   * Additional refund metadata
+   */
+  metadata?:
+    | {
+        [k: string]: unknown;
+      }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  /**
+   * Raw data from the payment provider
+   */
+  providerData?:
+    | {
+        [k: string]: unknown;
+      }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  updatedAt: string;
+  createdAt: string;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "users".
+ */
+export interface User {
+  id: number;
+  updatedAt: string;
+  createdAt: string;
+  email: string;
+  resetPasswordToken?: string | null;
+  resetPasswordExpiration?: string | null;
+  salt?: string | null;
+  hash?: string | null;
+  loginAttempts?: number | null;
+  lockUntil?: string | null;
+  password?: string | null;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payload-locked-documents".
+ */
+export interface PayloadLockedDocument {
+  id: number;
+  document?:
+    | ({
+        relationTo: 'posts';
+        value: number | Post;
+      } | null)
+    | ({
+        relationTo: 'media';
+        value: number | Media;
+      } | null)
+    | ({
+        relationTo: 'payments';
+        value: number | Payment;
+      } | null)
+    | ({
+        relationTo: 'invoices';
+        value: number | Invoice;
+      } | null)
+    | ({
+        relationTo: 'refunds';
+        value: number | Refund;
+      } | null)
+    | ({
+        relationTo: 'users';
+        value: number | User;
+      } | null);
+  globalSlug?: string | null;
+  user: {
+    relationTo: 'users';
+    value: number | User;
+  };
+  updatedAt: string;
+  createdAt: string;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payload-preferences".
+ */
+export interface PayloadPreference {
+  id: number;
+  user: {
+    relationTo: 'users';
+    value: number | User;
+  };
+  key?: string | null;
+  value?:
+    | {
+        [k: string]: unknown;
+      }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  updatedAt: string;
+  createdAt: string;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payload-migrations".
+ */
+export interface PayloadMigration {
+  id: number;
+  name?: string | null;
+  batch?: number | null;
+  updatedAt: string;
+  createdAt: string;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "posts_select".
+ */
+export interface PostsSelect<T extends boolean = true> {
+  updatedAt?: T;
+  createdAt?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "media_select".
+ */
+export interface MediaSelect<T extends boolean = true> {
+  updatedAt?: T;
+  createdAt?: T;
+  url?: T;
+  thumbnailURL?: T;
+  filename?: T;
+  mimeType?: T;
+  filesize?: T;
+  width?: T;
+  height?: T;
+  focalX?: T;
+  focalY?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payments_select".
+ */
+export interface PaymentsSelect<T extends boolean = true> {
+  provider?: T;
+  providerId?: T;
+  status?: T;
+  amount?: T;
+  currency?: T;
+  description?: T;
+  invoice?: T;
+  metadata?: T;
+  providerData?: T;
+  refunds?: T;
+  updatedAt?: T;
+  createdAt?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "invoices_select".
+ */
+export interface InvoicesSelect<T extends boolean = true> {
+  number?: T;
+  customerInfo?:
+    | T
+    | {
+        name?: T;
+        email?: T;
+        phone?: T;
+        company?: T;
+        taxId?: T;
+      };
+  billingAddress?:
+    | T
+    | {
+        line1?: T;
+        line2?: T;
+        city?: T;
+        state?: T;
+        postalCode?: T;
+        country?: T;
+      };
+  status?: T;
+  currency?: T;
+  items?:
+    | T
+    | {
+        description?: T;
+        quantity?: T;
+        unitAmount?: T;
+        totalAmount?: T;
+        id?: T;
+      };
+  subtotal?: T;
+  taxAmount?: T;
+  amount?: T;
+  dueDate?: T;
+  paidAt?: T;
+  payment?: T;
+  notes?: T;
+  metadata?: T;
+  updatedAt?: T;
+  createdAt?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "refunds_select".
+ */
+export interface RefundsSelect<T extends boolean = true> {
+  providerId?: T;
+  payment?: T;
+  status?: T;
+  amount?: T;
+  currency?: T;
+  reason?: T;
+  description?: T;
+  metadata?: T;
+  providerData?: T;
+  updatedAt?: T;
+  createdAt?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "users_select".
+ */
+export interface UsersSelect<T extends boolean = true> {
+  updatedAt?: T;
+  createdAt?: T;
+  email?: T;
+  resetPasswordToken?: T;
+  resetPasswordExpiration?: T;
+  salt?: T;
+  hash?: T;
+  loginAttempts?: T;
+  lockUntil?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payload-locked-documents_select".
+ */
+export interface PayloadLockedDocumentsSelect<T extends boolean = true> {
+  document?: T;
+  globalSlug?: T;
+  user?: T;
+  updatedAt?: T;
+  createdAt?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payload-preferences_select".
+ */
+export interface PayloadPreferencesSelect<T extends boolean = true> {
+  user?: T;
+  key?: T;
+  value?: T;
+  updatedAt?: T;
+  createdAt?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "payload-migrations_select".
+ */
+export interface PayloadMigrationsSelect<T extends boolean = true> {
+  name?: T;
+  batch?: T;
+  updatedAt?: T;
+  createdAt?: T;
+}
+/**
+ * This interface was referenced by `Config`'s JSON-Schema
+ * via the `definition` "auth".
+ */
+export interface Auth {
+  [k: string]: unknown;
+}
+
+
+declare module 'payload' {
+  export interface GeneratedTypes extends Config {}
+}
\ No newline at end of file
diff --git a/dev/payload.config.ts b/dev/payload.config.ts
index b8a8c73..f7db56d 100644
--- a/dev/payload.config.ts
+++ b/dev/payload.config.ts
@@ -8,6 +8,7 @@ import { fileURLToPath } from 'url'
 import { testEmailAdapter } from './helpers/testEmailAdapter'
 import { seed } from './seed'
 import billingPlugin from '../src/plugin'
+import { mollieProvider } from '../src/providers'
 
 const filename = fileURLToPath(import.meta.url)
 const dirname = path.dirname(filename)
@@ -48,38 +49,16 @@ const buildConfigWithSQLite = () => {
     },
     plugins: [
       billingPlugin({
-        providers: {
-          test: {
-            enabled: true,
-            autoComplete: true,
-          }
-        },
+        providers: [
+          mollieProvider({
+            apiKey: process.env.MOLLIE_KEY!
+          })
+        ],
         collections: {
           payments: 'payments',
           invoices: 'invoices',
           refunds: 'refunds',
         },
-        // // Customer relationship configuration
-        // customerRelationSlug: 'customers', // Use 'customers' collection for relationship
-        // // customerRelationSlug: false,     // Or set to false to disable customer relationship
-        // // customerRelationSlug: 'clients', // Or use a custom collection slug
-        //
-        // // Provide an extractor for your customer collection structure:
-        // customerInfoExtractor: (customer) => ({
-        //   name: customer.name || '',
-        //   email: customer.email || '',
-        //   phone: customer.phone,
-        //   company: customer.company,
-        //   taxId: customer.taxId,
-        //   billingAddress: customer.address ? {
-        //     line1: customer.address.line1 || '',
-        //     line2: customer.address.line2,
-        //     city: customer.address.city || '',
-        //     state: customer.address.state,
-        //     postalCode: customer.address.postalCode || '',
-        //     country: customer.address.country || '',
-        //   } : undefined,
-        // })
       }),
     ],
     secret: process.env.PAYLOAD_SECRET || 'test-secret_key',
diff --git a/dev/seed.ts b/dev/seed.ts
index 54ba04f..935948a 100644
--- a/dev/seed.ts
+++ b/dev/seed.ts
@@ -21,9 +21,9 @@ export const seed = async (payload: Payload) => {
   }
 
   // Seed billing sample data
-  await seedBillingData(payload)
+  // await seedBillingData(payload)
 }
 
-async function seedBillingData(payload: Payload): Promise<void> {
-  payload.logger.info('Seeding billing sample data...')
-}
+// async function seedBillingData(payload: Payload): Promise<void> {
+//   payload.logger.info('Seeding billing sample data...')
+// }
diff --git a/package.json b/package.json
index a60f513..bd691ce 100644
--- a/package.json
+++ b/package.json
@@ -70,6 +70,7 @@
   "devDependencies": {
     "@changesets/cli": "^2.27.1",
     "@eslint/eslintrc": "^3.2.0",
+    "@mollie/api-client": "^3.7.0",
     "@payloadcms/db-mongodb": "3.37.0",
     "@payloadcms/db-postgres": "3.37.0",
     "@payloadcms/db-sqlite": "3.37.0",
@@ -104,11 +105,11 @@
     "vitest": "^3.1.2"
   },
   "peerDependencies": {
+    "@mollie/api-client": "^3.7.0",
     "payload": "^3.37.0"
   },
   "dependencies": {
     "stripe": "^14.15.0",
-    "@mollie/api-client": "^3.7.0",
     "zod": "^3.22.4"
   },
   "engines": {
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index f66fd65..b2677bf 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -8,9 +8,6 @@ importers:
 
   .:
     dependencies:
-      '@mollie/api-client':
-        specifier: ^3.7.0
-        version: 3.7.0
       stripe:
         specifier: ^14.15.0
         version: 14.25.0
@@ -24,6 +21,9 @@ importers:
       '@eslint/eslintrc':
         specifier: ^3.2.0
         version: 3.3.1
+      '@mollie/api-client':
+        specifier: ^3.7.0
+        version: 3.7.0
       '@payloadcms/db-mongodb':
         specifier: 3.37.0
         version: 3.37.0(payload@3.37.0(graphql@16.11.0)(typescript@5.7.3))
@@ -8875,7 +8875,7 @@ snapshots:
       eslint: 9.35.0
       eslint-import-resolver-node: 0.3.9
       eslint-import-resolver-typescript: 3.10.1(eslint-plugin-import-x@4.4.2(eslint@9.35.0)(typescript@5.7.3))(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint@9.35.0))(eslint@9.35.0)
-      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint-import-resolver-typescript@3.10.1)(eslint@9.35.0)
+      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import-x@4.4.2(eslint@9.35.0)(typescript@5.7.3))(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint@9.35.0))(eslint@9.35.0))(eslint@9.35.0)
       eslint-plugin-jsx-a11y: 6.10.2(eslint@9.35.0)
       eslint-plugin-react: 7.37.5(eslint@9.35.0)
       eslint-plugin-react-hooks: 5.2.0(eslint@9.35.0)
@@ -8909,7 +8909,7 @@ snapshots:
       tinyglobby: 0.2.15
       unrs-resolver: 1.11.1
     optionalDependencies:
-      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint-import-resolver-typescript@3.10.1)(eslint@9.35.0)
+      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import-x@4.4.2(eslint@9.35.0)(typescript@5.7.3))(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint@9.35.0))(eslint@9.35.0))(eslint@9.35.0)
       eslint-plugin-import-x: 4.4.2(eslint@9.35.0)(typescript@5.7.3)
     transitivePeerDependencies:
       - supports-color
@@ -8960,7 +8960,7 @@ snapshots:
       - typescript
     optional: true
 
-  eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint-import-resolver-typescript@3.10.1)(eslint@9.35.0):
+  eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import-x@4.4.2(eslint@9.35.0)(typescript@5.7.3))(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.43.0(eslint@9.35.0)(typescript@5.7.3))(eslint@9.35.0))(eslint@9.35.0))(eslint@9.35.0):
     dependencies:
       '@rtsao/scc': 1.1.0
       array-includes: 3.1.9
diff --git a/src/collections/hooks.ts b/src/collections/hooks.ts
new file mode 100644
index 0000000..406fae5
--- /dev/null
+++ b/src/collections/hooks.ts
@@ -0,0 +1,11 @@
+import type { Payment } from '@/plugin/types'
+import type { Payload } from 'payload'
+import { useBillingPlugin } from '@/plugin'
+
+export const initProviderPayment = (payload: Payload, payment: Partial<Payment>) => {
+  const billing = useBillingPlugin(payload)
+  if (!payment.provider || !billing.providerConfig[payment.provider]) {
+    throw new Error(`Provider ${payment.provider} not found.`)
+  }
+  return billing.providerConfig[payment.provider].initPayment(payload, payment)
+}
diff --git a/src/collections/invoices.ts b/src/collections/invoices.ts
index d45c888..fd689bc 100644
--- a/src/collections/invoices.ts
+++ b/src/collections/invoices.ts
@@ -5,9 +5,10 @@ import {
   CollectionBeforeValidateHook,
   CollectionConfig, Field,
 } from 'payload'
-import { BillingPluginConfig, CustomerInfoExtractor, defaults } from '@/plugin/config'
-import { Invoice } from '@/plugin/types'
+import type { BillingPluginConfig} from '@/plugin/config';
+import { defaults } from '@/plugin/config'
 import { extractSlug } from '@/plugin/utils'
+import type { Invoice } from '@/plugin/types/invoices'
 
 export function createInvoicesCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
   const {customerRelationSlug, customerInfoExtractor} = pluginConfig
@@ -31,7 +32,7 @@ export function createInvoicesCollection(pluginConfig: BillingPluginConfig): Col
         position: 'sidebar' as const,
         description: 'Link to customer record (optional)',
       },
-      relationTo: pluginConfig.customerRelationSlug as never,
+      relationTo: extractSlug(customerRelationSlug),
       required: false,
     }] : []),
     // Basic customer info fields (embedded)
@@ -275,7 +276,7 @@ export function createInvoicesCollection(pluginConfig: BillingPluginConfig): Col
         condition: (data) => data.status === 'paid',
         position: 'sidebar',
       },
-      relationTo: 'payments',
+      relationTo: extractSlug(pluginConfig.collections?.payments || defaults.paymentsCollection),
     },
     {
       name: 'notes',
diff --git a/src/collections/payments.ts b/src/collections/payments.ts
index 14ad86a..b5d2665 100644
--- a/src/collections/payments.ts
+++ b/src/collections/payments.ts
@@ -1,8 +1,9 @@
-import type { AccessArgs, CollectionBeforeChangeHook, CollectionConfig, Field } from 'payload'
-import type { Payment } from '@/plugin/types'
+import type { AccessArgs, CollectionBeforeChangeHook, CollectionConfig, CollectionSlug, Field } from 'payload'
 import type { BillingPluginConfig} from '@/plugin/config';
 import { defaults } from '@/plugin/config'
 import { extractSlug } from '@/plugin/utils'
+import { Payment } from '@/plugin/types/payments'
+import { initProviderPayment } from '@/collections/hooks'
 
 export function createPaymentsCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
   const overrides = typeof pluginConfig.collections?.payments === 'object' ? pluginConfig.collections?.payments : {}
@@ -27,7 +28,6 @@ export function createPaymentsCollection(pluginConfig: BillingPluginConfig): Col
         description: 'The payment ID from the payment provider',
       },
       label: 'Provider Payment ID',
-      required: true,
       unique: true,
     },
     {
@@ -78,7 +78,7 @@ export function createPaymentsCollection(pluginConfig: BillingPluginConfig): Col
       admin: {
         position: 'sidebar',
       },
-      relationTo: 'invoices',
+      relationTo: extractSlug(pluginConfig.collections?.invoices || defaults.invoicesCollection) as CollectionSlug,
     },
     {
       name: 'metadata',
@@ -103,7 +103,7 @@ export function createPaymentsCollection(pluginConfig: BillingPluginConfig): Col
         readOnly: true,
       },
       hasMany: true,
-      relationTo: 'refunds',
+      relationTo: extractSlug(pluginConfig.collections?.refunds || defaults.refundsCollection) as CollectionSlug,
     },
   ]
   if (overrides?.fields) {
@@ -126,7 +126,7 @@ export function createPaymentsCollection(pluginConfig: BillingPluginConfig): Col
     fields,
     hooks: {
       beforeChange: [
-        ({ data, operation }) => {
+        async ({ data, operation, req }) => {
           if (operation === 'create') {
             // Validate amount format
             if (data.amount && !Number.isInteger(data.amount)) {
@@ -140,6 +140,8 @@ export function createPaymentsCollection(pluginConfig: BillingPluginConfig): Col
                 throw new Error('Currency must be a 3-letter ISO code')
               }
             }
+
+            await initProviderPayment(req.payload, data)
           }
         },
       ] satisfies CollectionBeforeChangeHook<Payment>[],
diff --git a/src/collections/refunds.ts b/src/collections/refunds.ts
index 6b383cf..aa484e9 100644
--- a/src/collections/refunds.ts
+++ b/src/collections/refunds.ts
@@ -1,9 +1,9 @@
 import type { AccessArgs, CollectionConfig } from 'payload'
 import { BillingPluginConfig, defaults } from '@/plugin/config'
 import { extractSlug } from '@/plugin/utils'
+import { Payment } from '@/plugin/types'
 
 export function createRefundsCollection(pluginConfig: BillingPluginConfig): CollectionConfig {
-  const overrides = typeof pluginConfig.collections?.invoices === 'object' ? pluginConfig.collections?.invoices : {}
   // TODO: finish collection overrides
   return {
     slug: extractSlug(pluginConfig.collections?.refunds || defaults.refundsCollection),
@@ -35,7 +35,7 @@ export function createRefundsCollection(pluginConfig: BillingPluginConfig): Coll
         admin: {
           position: 'sidebar',
         },
-        relationTo: 'payments',
+        relationTo: extractSlug(pluginConfig.collections?.payments || defaults.paymentsCollection),
         required: true,
       },
       {
@@ -117,13 +117,13 @@ export function createRefundsCollection(pluginConfig: BillingPluginConfig): Coll
             try {
               const payment = await req.payload.findByID({
                 id: typeof doc.payment === 'string' ? doc.payment : doc.payment.id,
-                collection: 'payments',
-              })
+                collection: extractSlug(pluginConfig.collections?.payments || defaults.paymentsCollection),
+              }) as Payment
 
               const refundIds = Array.isArray(payment.refunds) ? payment.refunds : []
               await req.payload.update({
                 id: typeof doc.payment === 'string' ? doc.payment : doc.payment.id,
-                collection: 'payments',
+                collection: extractSlug(pluginConfig.collections?.payments || defaults.paymentsCollection),
                 data: {
                   refunds: [...refundIds, doc.id],
                 },
diff --git a/src/index.ts b/src/index.ts
index 139597f..882fe58 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,2 +1,4 @@
 
-
+export { billingPlugin } from './plugin'
+export type { BillingPluginConfig, CustomerInfoExtractor } from './plugin/config'
+export type { Invoice, Payment, Refund } from './plugin/types'
diff --git a/src/plugin/config.ts b/src/plugin/config.ts
index 9e75e1d..d2385d8 100644
--- a/src/plugin/config.ts
+++ b/src/plugin/config.ts
@@ -1,5 +1,6 @@
 import { CollectionConfig } from 'payload'
 import { FieldsOverride } from '@/plugin/utils'
+import { PaymentProvider } from '@/plugin/types'
 
 export const defaults = {
   paymentsCollection: 'payments',
@@ -63,11 +64,7 @@ export interface BillingPluginConfig {
   customerInfoExtractor?: CustomerInfoExtractor // Callback to extract customer info from relationship
   customerRelationSlug?: string // Customer collection slug for relationship
   disabled?: boolean
-  providers?: {
-    mollie?: MollieConfig
-    stripe?: StripeConfig
-    test?: TestProviderConfig
-  }
+  providers?: PaymentProvider[]
   webhooks?: {
     basePath?: string
     cors?: boolean
diff --git a/src/plugin/index.ts b/src/plugin/index.ts
index ebf0aa4..3bac540 100644
--- a/src/plugin/index.ts
+++ b/src/plugin/index.ts
@@ -1,62 +1,49 @@
-import type { Config } from 'payload'
 import { createInvoicesCollection, createPaymentsCollection, createRefundsCollection } from '@/collections'
 import type { BillingPluginConfig } from '@/plugin/config'
+import type { Config, Payload } from 'payload'
+import { createSingleton } from '@/plugin/singleton'
+import type { PaymentProvider } from '@/providers'
+
+const singleton = createSingleton(Symbol('billingPlugin'))
+
+type BillingPlugin = {
+  config: BillingPluginConfig
+  providerConfig: {
+    [key: string]: PaymentProvider
+  }
+}
+
+export const useBillingPlugin = (payload: Payload) => singleton.get(payload) as BillingPlugin
 
 export const billingPlugin = (pluginConfig: BillingPluginConfig = {}) => (config: Config): Config => {
   if (pluginConfig.disabled) {
     return config
   }
 
-  // Initialize collections
-  if (!config.collections) {
-    config.collections = []
-  }
-
-  config.collections.push(
+  config.collections = [
+    ...(config.collections || []),
     createPaymentsCollection(pluginConfig),
     createInvoicesCollection(pluginConfig),
     createRefundsCollection(pluginConfig),
-  )
+  ]
 
-  // Initialize endpoints
-  if (!config.endpoints) {
-    config.endpoints = []
-  }
-
-  config.endpoints?.push(
-    // Webhook endpoints
-    {
-      handler: (_req) => {
-        try {
-          const provider = null
-          if (!provider) {
-            return Response.json({ error: 'Provider not found' }, { status: 404 })
-          }
-
-          // TODO: Process webhook event and update database
-
-          return Response.json({ received: true })
-        } catch (error) {
-          // TODO: Use proper logger instead of console
-          // eslint-disable-next-line no-console
-          console.error('[BILLING] Webhook error:', error)
-          return Response.json({ error: 'Webhook processing failed' }, { status: 400 })
-        }
-      },
-      method: 'post',
-      path: '/billing/webhooks/:provider'
-    },
-  )
-
-  // Initialize providers and onInit hook
   const incomingOnInit = config.onInit
-
   config.onInit = async (payload) => {
-    // Execute any existing onInit functions first
     if (incomingOnInit) {
       await incomingOnInit(payload)
     }
-
+    singleton.set(payload, {
+      config: pluginConfig,
+      providerConfig: (pluginConfig.providers || []).reduce(
+        (acc, val) => {
+          acc[val.key] = val
+          return acc
+        },
+        {} as Record<string, PaymentProvider>
+      )
+    } satisfies BillingPlugin)
+    console.log('Billing plugin initialized', singleton.get(payload))
+    await Promise.all((pluginConfig.providers || []).map(p => p.onInit(payload)))
   }
 
   return config
diff --git a/src/plugin/singleton.ts b/src/plugin/singleton.ts
new file mode 100644
index 0000000..5b90c85
--- /dev/null
+++ b/src/plugin/singleton.ts
@@ -0,0 +1,11 @@
+export const createSingleton = <T>(s?: symbol | string) => {
+  const symbol = !s ? Symbol() : s
+  return {
+    get(container: any) {
+      return container[symbol] as T
+    },
+    set(container: any, value: T) {
+      container[symbol] = value
+    },
+  }
+}
diff --git a/src/plugin/types/id.ts b/src/plugin/types/id.ts
new file mode 100644
index 0000000..59dbb83
--- /dev/null
+++ b/src/plugin/types/id.ts
@@ -0,0 +1 @@
+export type Id = string | number
diff --git a/src/plugin/types/index.ts b/src/plugin/types/index.ts
new file mode 100644
index 0000000..dbc808b
--- /dev/null
+++ b/src/plugin/types/index.ts
@@ -0,0 +1,5 @@
+export * from './id'
+export * from './invoices'
+export * from './payments'
+export * from './refunds'
+export * from '../../providers/types'
diff --git a/src/plugin/types.ts b/src/plugin/types/invoices.ts
similarity index 52%
rename from src/plugin/types.ts
rename to src/plugin/types/invoices.ts
index a2f3a2d..b42d342 100644
--- a/src/plugin/types.ts
+++ b/src/plugin/types/invoices.ts
@@ -1,107 +1,6 @@
+import { Payment } from '@/plugin/types/payments'
 
-export type Id = string | number
-
-export interface Refund {
-  id: number;
-  /**
-   * The refund ID from the payment provider
-   */
-  providerId: string;
-  payment: number | Payment;
-  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled';
-  /**
-   * Refund amount in cents
-   */
-  amount: number;
-  /**
-   * ISO 4217 currency code (e.g., USD, EUR)
-   */
-  currency: string;
-  /**
-   * Reason for the refund
-   */
-  reason?: ('duplicate' | 'fraudulent' | 'requested_by_customer' | 'other') | null;
-  /**
-   * Additional details about the refund
-   */
-  description?: string | null;
-  /**
-   * Additional refund metadata
-   */
-  metadata?:
-    | {
-    [k: string]: unknown;
-  }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  /**
-   * Raw data from the payment provider
-   */
-  providerData?:
-    | {
-    [k: string]: unknown;
-  }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  updatedAt: string;
-  createdAt: string;
-}
-
-export interface Payment {
-  id: Id;
-  provider: 'stripe' | 'mollie' | 'test';
-  /**
-   * The payment ID from the payment provider
-   */
-  providerId: Id;
-  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled' | 'refunded' | 'partially_refunded';
-  /**
-   * Amount in cents (e.g., 2000 = $20.00)
-   */
-  amount: number;
-  /**
-   * ISO 4217 currency code (e.g., USD, EUR)
-   */
-  currency: string;
-  /**
-   * Payment description
-   */
-  description?: string | null;
-  invoice?: (Id | null) | Invoice;
-  /**
-   * Additional metadata for the payment
-   */
-  metadata?:
-    | {
-    [k: string]: unknown;
-  }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  /**
-   * Raw data from the payment provider
-   */
-  providerData?:
-    | {
-    [k: string]: unknown;
-  }
-    | unknown[]
-    | string
-    | number
-    | boolean
-    | null;
-  refunds?: (number | Refund)[] | null;
-  updatedAt: string;
-  createdAt: string;
-}
+import { Id } from '@/plugin/types/id'
 
 export interface Invoice<TCustomer = unknown> {
   id: Id;
@@ -216,4 +115,3 @@ export interface Invoice<TCustomer = unknown> {
   updatedAt: string;
   createdAt: string;
 }
-
diff --git a/src/plugin/types/payments.ts b/src/plugin/types/payments.ts
new file mode 100644
index 0000000..8307679
--- /dev/null
+++ b/src/plugin/types/payments.ts
@@ -0,0 +1,53 @@
+import { Refund } from '@/plugin/types/refunds'
+import { Invoice } from '@/plugin/types/invoices'
+import { Id } from '@/plugin/types/id'
+
+export interface Payment {
+  id: Id;
+  provider: 'stripe' | 'mollie' | 'test';
+  /**
+   * The payment ID from the payment provider
+   */
+  providerId: Id;
+  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled' | 'refunded' | 'partially_refunded';
+  /**
+   * Amount in cents (e.g., 2000 = $20.00)
+   */
+  amount: number;
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  /**
+   * Payment description
+   */
+  description?: string | null;
+  invoice?: (Id | null) | Invoice;
+  /**
+   * Additional metadata for the payment
+   */
+  metadata?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  /**
+   * Raw data from the payment provider
+   */
+  providerData?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  refunds?: (number | Refund)[] | null;
+  updatedAt: string;
+  createdAt: string;
+}
diff --git a/src/plugin/types/refunds.ts b/src/plugin/types/refunds.ts
new file mode 100644
index 0000000..a8366d1
--- /dev/null
+++ b/src/plugin/types/refunds.ts
@@ -0,0 +1,53 @@
+import { Payment } from '@/plugin/types/payments'
+
+export interface Refund {
+  id: number;
+  /**
+   * The refund ID from the payment provider
+   */
+  providerId: string;
+  payment: number | Payment;
+  status: 'pending' | 'processing' | 'succeeded' | 'failed' | 'canceled';
+  /**
+   * Refund amount in cents
+   */
+  amount: number;
+  /**
+   * ISO 4217 currency code (e.g., USD, EUR)
+   */
+  currency: string;
+  /**
+   * Reason for the refund
+   */
+  reason?: ('duplicate' | 'fraudulent' | 'requested_by_customer' | 'other') | null;
+  /**
+   * Additional details about the refund
+   */
+  description?: string | null;
+  /**
+   * Additional refund metadata
+   */
+  metadata?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  /**
+   * Raw data from the payment provider
+   */
+  providerData?:
+    | {
+    [k: string]: unknown;
+  }
+    | unknown[]
+    | string
+    | number
+    | boolean
+    | null;
+  updatedAt: string;
+  createdAt: string;
+}
diff --git a/src/plugin/utils.ts b/src/plugin/utils.ts
index 543c708..9ebdd01 100644
--- a/src/plugin/utils.ts
+++ b/src/plugin/utils.ts
@@ -1,5 +1,6 @@
-import type { CollectionConfig, Field } from 'payload'
+import type { CollectionConfig, CollectionSlug, Field } from 'payload'
 
 export type FieldsOverride = (args: { defaultFields: Field[] }) => Field[]
 
-export const extractSlug = (arg: string | Partial<CollectionConfig>) => typeof arg === 'string' ? arg : arg.slug!
+export const extractSlug =
+  (arg: string | Partial<CollectionConfig>) => (typeof arg === 'string' ? arg : arg.slug!) as CollectionSlug
diff --git a/src/providers/index.ts b/src/providers/index.ts
new file mode 100644
index 0000000..e18301a
--- /dev/null
+++ b/src/providers/index.ts
@@ -0,0 +1,2 @@
+export * from './mollie'
+export * from './types'
diff --git a/src/providers/mollie.ts b/src/providers/mollie.ts
new file mode 100644
index 0000000..5ef7794
--- /dev/null
+++ b/src/providers/mollie.ts
@@ -0,0 +1,40 @@
+import type { Payment } from '@/plugin/types/payments'
+import type { InitPayment, PaymentProvider } from '@/plugin/types'
+import type { Payload } from 'payload'
+import { createSingleton } from '@/plugin/singleton'
+import type { createMollieClient, MollieClient } from '@mollie/api-client'
+
+const symbol = Symbol('mollie')
+export type MollieProviderConfig = Parameters<typeof createMollieClient>[0]
+
+export const mollieProvider = (config: MollieProviderConfig) => {
+  const singleton = createSingleton<MollieClient>(symbol)
+  return {
+    key: 'mollie',
+    onInit: async (payload: Payload) => {
+      const createMollieClient = (await import('@mollie/api-client')).default
+      const mollieClient = createMollieClient(config)
+      singleton.set(payload, mollieClient)
+    },
+    initPayment: async (payload, payment) => {
+      if (!payment.amount) {
+        throw new Error('Amount is required')
+      }
+      if (!payment.currency) {
+        throw new Error('Currency is required')
+      }
+      const molliePayment = await singleton.get(payload).payments.create({
+        amount: {
+          value: (payment.amount / 100).toFixed(2),
+          currency: payment.currency
+        },
+        description: payment.description || '',
+        redirectUrl: 'https://localhost:3000/payment/success',
+        webhookUrl:  'https://localhost:3000',
+      });
+      payment.providerId = molliePayment.id
+      payment.providerData = molliePayment.toPlainObject()
+      return payment
+    },
+  } satisfies PaymentProvider
+}
diff --git a/src/providers/types.ts b/src/providers/types.ts
new file mode 100644
index 0000000..d15aa84
--- /dev/null
+++ b/src/providers/types.ts
@@ -0,0 +1,10 @@
+import type { Payment } from '@/plugin/types/payments'
+import type { Payload } from 'payload'
+
+export type InitPayment = (payload: Payload, payment: Partial<Payment>) => Promise<Partial<Payment>>
+
+export type PaymentProvider = {
+  key: string
+  onInit: (payload: Payload) => Promise<void> | void
+  initPayment: InitPayment
+}