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

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

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

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
+    },
+  }
+}

src/plugin/types/id.ts

@@ -0,0 +1 @@
+export type Id = string | number

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'

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;
 }
-

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;
+}

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;
+}

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