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/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)
+}

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',

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>[],

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],
                 },

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'

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

src/providers/index.ts

@@ -0,0 +1,2 @@
+export * from './mollie'
+export * from './types'

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
+}

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
+}