Add guarded fake payment lifecycle API

README.md

@@ -4,3 +4,16 @@ This is a template project with best-practice modules:
 - Winterspec for defining the API
 - bun testing
 - Zustand store with zod definition for database state
+
+## Fake payment API
+
+- `POST /payments/send` creates a pending fake payment. The body accepts
+  `recipient_email`, `amount_cents`, optional `currency`, bounty metadata, and an
+  optional `idempotency_key` for retry-safe sends.
+- `GET /payments/list` returns payments. It can filter by `status`,
+  `recipient_email`, and `repository`.
+- `GET /payments/get?payment_id=...` returns one payment or `404`.
+- `POST /payments/complete` marks a pending payment as completed.
+- `POST /payments/cancel` marks a pending payment as canceled.
+
+Completed and canceled payments are terminal; later status changes return `409`.

lib/db/db-client.ts

@@ -1,17 +1,37 @@
-import { createStore, type StoreApi } from "zustand/vanilla"
-import { immer } from "zustand/middleware/immer"
-import { hoist, type HoistedStoreApi } from "zustand-hoist"
+import { hoist } from "zustand-hoist"
+import { createStore } from "zustand/vanilla"
 
-import { databaseSchema, type DatabaseSchema, type Thing } from "./schema.ts"
 import { combine } from "zustand/middleware"
+import {
+  type Payment,
+  type PaymentStatus,
+  type Thing,
+  databaseSchema,
+} from "./schema.ts"
+
+export interface CreatePaymentInput {
+  recipient_email: string
+  amount_cents: number
+  currency?: string
+  bounty_id?: string
+  issue_number?: number
+  repository?: string
+  idempotency_key?: string
+}
+
+export interface ListPaymentsInput {
+  status?: PaymentStatus
+  recipient_email?: string
+  repository?: string
+}
 
 export const createDatabase = () => {
   return hoist(createStore(initializer))
 }
 
 export type DbClient = ReturnType<typeof createDatabase>
 
-const initializer = combine(databaseSchema.parse({}), (set) => ({
+const initializer = combine(databaseSchema.parse({}), (set, get) => ({
   addThing: (thing: Omit<Thing, "thing_id">) => {
     set((state) => ({
       things: [
@@ -21,4 +41,91 @@ const initializer = combine(databaseSchema.parse({}), (set) => ({
       idCounter: state.idCounter + 1,
     }))
   },
+  createPayment: (input: CreatePaymentInput) => {
+    const now = new Date().toISOString()
+    let payment: Payment | undefined
+    let idempotentReplay = false
+
+    set((state) => {
+      if (input.idempotency_key) {
+        const existingPayment = state.payments.find(
+          (candidate) => candidate.idempotency_key === input.idempotency_key,
+        )
+        if (existingPayment) {
+          payment = existingPayment
+          idempotentReplay = true
+          return state
+        }
+      }
+
+      payment = {
+        payment_id: `payment_${state.paymentIdCounter}`,
+        recipient_email: input.recipient_email,
+        amount_cents: input.amount_cents,
+        currency: (input.currency ?? "usd").toLowerCase(),
+        bounty_id: input.bounty_id,
+        issue_number: input.issue_number,
+        repository: input.repository,
+        idempotency_key: input.idempotency_key,
+        status: "pending",
+        created_at: now,
+        updated_at: now,
+      }
+
+      return {
+        payments: [...state.payments, payment],
+        paymentIdCounter: state.paymentIdCounter + 1,
+      }
+    })
+
+    return { payment: payment!, idempotent_replay: idempotentReplay }
+  },
+  listPayments: (filters: ListPaymentsInput = {}) => {
+    return get().payments.filter((payment) => {
+      if (filters.status && payment.status !== filters.status) return false
+      if (
+        filters.recipient_email &&
+        payment.recipient_email !== filters.recipient_email
+      ) {
+        return false
+      }
+      if (filters.repository && payment.repository !== filters.repository) {
+        return false
+      }
+      return true
+    })
+  },
+  getPayment: (paymentId: string) => {
+    return get().payments.find((payment) => payment.payment_id === paymentId)
+  },
+  updatePaymentStatus: (paymentId: string, status: PaymentStatus) => {
+    let updatedPayment: Payment | undefined
+    let error: "not_found" | "terminal_status" | undefined
+    const now = new Date().toISOString()
+
+    set((state) => {
+      const payment = state.payments.find(
+        (candidate) => candidate.payment_id === paymentId,
+      )
+      if (!payment) {
+        error = "not_found"
+        return state
+      }
+      if (payment.status !== "pending") {
+        error = "terminal_status"
+        updatedPayment = payment
+        return state
+      }
+
+      const payments = state.payments.map((candidate) => {
+        if (candidate.payment_id !== paymentId) return candidate
+        updatedPayment = { ...candidate, status, updated_at: now }
+        return updatedPayment
+      })
+
+      return { payments }
+    })
+
+    return { payment: updatedPayment, error }
+  },
 }))

lib/db/schema.ts

@@ -9,8 +9,28 @@ export const thingSchema = z.object({
 })
 export type Thing = z.infer<typeof thingSchema>
 
+export const paymentStatusSchema = z.enum(["pending", "completed", "canceled"])
+export type PaymentStatus = z.infer<typeof paymentStatusSchema>
+
+export const paymentSchema = z.object({
+  payment_id: z.string(),
+  recipient_email: z.string().email(),
+  amount_cents: z.number().int().positive(),
+  currency: z.string().length(3),
+  bounty_id: z.string().optional(),
+  issue_number: z.number().int().positive().optional(),
+  repository: z.string().optional(),
+  idempotency_key: z.string().optional(),
+  status: paymentStatusSchema,
+  created_at: z.string(),
+  updated_at: z.string(),
+})
+export type Payment = z.infer<typeof paymentSchema>
+
 export const databaseSchema = z.object({
   idCounter: z.number().default(0),
+  paymentIdCounter: z.number().default(0),
   things: z.array(thingSchema).default([]),
+  payments: z.array(paymentSchema).default([]),
 })
 export type DatabaseSchema = z.infer<typeof databaseSchema>

lib/middleware/with-db.ts

@@ -2,14 +2,25 @@ import type { DbClient } from "lib/db/db-client"
 import { createDatabase } from "lib/db/db-client"
 import type { Middleware } from "winterspec"
 
+let defaultDb: DbClient | undefined
+
+export const getDefaultDb = () => {
+  defaultDb ??= createDatabase()
+  return defaultDb
+}
+
+export const resetDefaultDbForTests = () => {
+  defaultDb = createDatabase()
+}
+
 export const withDb: Middleware<
   {},
   {
     db: DbClient
   }
 > = async (req, ctx, next) => {
   if (!ctx.db) {
-    ctx.db = createDatabase()
+    ctx.db = getDefaultDb()
   }
   return next(req, ctx)
 }

lib/payments/route-schemas.ts

@@ -0,0 +1,50 @@
+import { paymentSchema, paymentStatusSchema } from "lib/db/schema"
+import { z } from "zod"
+
+export const sendPaymentBodySchema = z.object({
+  recipient_email: z.string().email(),
+  amount_cents: z.number().int().positive(),
+  currency: z.string().length(3).default("usd"),
+  bounty_id: z.string().min(1).optional(),
+  issue_number: z.number().int().positive().optional(),
+  repository: z.string().min(1).optional(),
+  idempotency_key: z.string().min(1).optional(),
+})
+
+export const listPaymentsQuerySchema = z.object({
+  status: paymentStatusSchema.optional(),
+  recipient_email: z.string().email().optional(),
+  repository: z.string().min(1).optional(),
+})
+
+export const paymentIdBodySchema = z.object({
+  payment_id: z.string().min(1),
+})
+
+export const paymentIdQuerySchema = paymentIdBodySchema
+
+export const paymentSuccessResponseSchema = z.object({
+  ok: z.literal(true),
+  payment: paymentSchema,
+})
+
+export const paymentErrorResponseSchema = z.object({
+  ok: z.literal(false),
+  error: z.string(),
+})
+
+export const paymentLookupResponseSchema = z.union([
+  paymentSuccessResponseSchema,
+  paymentErrorResponseSchema,
+])
+
+export const sendPaymentResponseSchema = z.object({
+  ok: z.literal(true),
+  payment: paymentSchema,
+  idempotent_replay: z.boolean(),
+})
+
+export const listPaymentsResponseSchema = z.object({
+  ok: z.literal(true),
+  payments: z.array(paymentSchema),
+})

routes/payments/cancel.ts

@@ -0,0 +1,23 @@
+import { withRouteSpec } from "lib/middleware/with-winter-spec"
+import {
+  paymentIdBodySchema,
+  paymentLookupResponseSchema,
+} from "lib/payments/route-schemas"
+
+export default withRouteSpec({
+  methods: ["POST"],
+  jsonBody: paymentIdBodySchema,
+  jsonResponse: paymentLookupResponseSchema,
+})((req, ctx) => {
+  const { payment, error } = ctx.db.updatePaymentStatus(
+    req.jsonBody.payment_id,
+    "canceled",
+  )
+  if (error === "not_found") {
+    return ctx.json({ ok: false, error: "payment_not_found" }).status(404)
+  }
+  if (error === "terminal_status") {
+    return ctx.json({ ok: false, error: "payment_is_not_pending" }).status(409)
+  }
+  return ctx.json({ ok: true, payment: payment! })
+})

routes/payments/complete.ts

@@ -0,0 +1,23 @@
+import { withRouteSpec } from "lib/middleware/with-winter-spec"
+import {
+  paymentIdBodySchema,
+  paymentLookupResponseSchema,
+} from "lib/payments/route-schemas"
+
+export default withRouteSpec({
+  methods: ["POST"],
+  jsonBody: paymentIdBodySchema,
+  jsonResponse: paymentLookupResponseSchema,
+})((req, ctx) => {
+  const { payment, error } = ctx.db.updatePaymentStatus(
+    req.jsonBody.payment_id,
+    "completed",
+  )
+  if (error === "not_found") {
+    return ctx.json({ ok: false, error: "payment_not_found" }).status(404)
+  }
+  if (error === "terminal_status") {
+    return ctx.json({ ok: false, error: "payment_is_not_pending" }).status(409)
+  }
+  return ctx.json({ ok: true, payment: payment! })
+})

routes/payments/get.ts

@@ -0,0 +1,17 @@
+import { withRouteSpec } from "lib/middleware/with-winter-spec"
+import {
+  paymentIdQuerySchema,
+  paymentLookupResponseSchema,
+} from "lib/payments/route-schemas"
+
+export default withRouteSpec({
+  methods: ["GET"],
+  queryParams: paymentIdQuerySchema,
+  jsonResponse: paymentLookupResponseSchema,
+})((req, ctx) => {
+  const payment = ctx.db.getPayment(req.query.payment_id)
+  if (!payment) {
+    return ctx.json({ ok: false, error: "payment_not_found" }).status(404)
+  }
+  return ctx.json({ ok: true, payment })
+})

routes/payments/list.ts

@@ -0,0 +1,16 @@
+import { withRouteSpec } from "lib/middleware/with-winter-spec"
+import {
+  listPaymentsQuerySchema,
+  listPaymentsResponseSchema,
+} from "lib/payments/route-schemas"
+
+export default withRouteSpec({
+  methods: ["GET"],
+  queryParams: listPaymentsQuerySchema,
+  jsonResponse: listPaymentsResponseSchema,
+})((req, ctx) => {
+  return ctx.json({
+    ok: true,
+    payments: ctx.db.listPayments(req.query),
+  })
+})

routes/payments/send.ts

@@ -0,0 +1,14 @@
+import { withRouteSpec } from "lib/middleware/with-winter-spec"
+import {
+  sendPaymentBodySchema,
+  sendPaymentResponseSchema,
+} from "lib/payments/route-schemas"
+
+export default withRouteSpec({
+  methods: ["POST"],
+  jsonBody: sendPaymentBodySchema,
+  jsonResponse: sendPaymentResponseSchema,
+})(async (req, ctx) => {
+  const { payment, idempotent_replay } = ctx.db.createPayment(req.jsonBody)
+  return ctx.json({ ok: true, payment, idempotent_replay })
+})