Initial commit: NestJS backend for Child Gold Land

Co-authored-by: Cursor <cursoragent@cursor.com>

src/store/dto/purchase-store-item.dto.ts

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+import { IsNotEmpty, IsString } from 'class-validator'
+
+export class PurchaseStoreItemDto {
+  @IsString()
+  @IsNotEmpty()
+  productId!: string
+}

src/store/store.controller.ts

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+import { Body, Controller, Get, HttpCode, Inject, Post } from '@nestjs/common'
+import { CurrentUser } from '../common/decorators/current-user.decorator'
+import { strictBodyPipe } from '../common/pipes/strict-body.pipe'
+import { PurchaseStoreItemDto } from './dto/purchase-store-item.dto'
+import { StoreService } from './store.service'
+
+@Controller('api/store')
+export class StoreController {
+  constructor(@Inject(StoreService) private readonly store: StoreService) {}
+
+  @Get('products')
+  getProducts() {
+    return this.store.getProducts()
+  }
+
+  @HttpCode(200)
+  @Post('purchases')
+  purchase(
+    @CurrentUser() userId: string,
+    @Body(strictBodyPipe(PurchaseStoreItemDto)) dto: PurchaseStoreItemDto,
+  ) {
+    return this.store.purchaseStoreItem(userId, dto.productId)
+  }
+}

src/store/store.module.ts

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+import { Module } from '@nestjs/common'
+import { DatabaseModule } from '../database/database.module'
+import { UsersModule } from '../users/users.module'
+import { StoreController } from './store.controller'
+import { StoreService } from './store.service'
+
+@Module({
+  imports: [DatabaseModule, UsersModule],
+  controllers: [StoreController],
+  providers: [StoreService],
+})
+export class StoreModule {}

src/store/store.service.ts

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+import {
+  BadRequestException,
+  ConflictException,
+  Inject,
+  Injectable,
+  NotFoundException,
+} from '@nestjs/common'
+import { DatabaseService } from '../database/database.service'
+import { STORE_PRODUCTS, type StoreProduct } from '../shared/catalog/store.constants'
+import { addTransaction } from '../shared/economy/user-economy.helpers'
+import type { MeResponse } from '../shared/types/user.types'
+import { UsersService } from '../users/users.service'
+
+@Injectable()
+export class StoreService {
+  constructor(
+    @Inject(DatabaseService) private readonly database: DatabaseService,
+    @Inject(UsersService) private readonly users: UsersService,
+  ) {}
+
+  getProducts(): StoreProduct[] {
+    return STORE_PRODUCTS
+  }
+
+  purchaseStoreItem(userId: string, productId: string): MeResponse {
+    const product = STORE_PRODUCTS.find((p) => p.id === productId)
+    if (!product) {
+      throw new NotFoundException('محصول پیدا نشد')
+    }
+
+    return this.database.transaction(() => {
+      const state = this.users.getUserState(userId)
+
+      if (state.ownedItems.includes(productId)) {
+        throw new ConflictException('قبلاً خریدی!')
+      }
+      if (state.coins < product.price) {
+        throw new BadRequestException('سکه کافی نداری!')
+      }
+
+      state.coins -= product.price
+      state.ownedItems.push(productId)
+      addTransaction(state, {
+        type: 'expense',
+        title: `خرید ${product.title}`,
+        amount: product.price,
+        unit: 'سکه',
+      })
+      this.users.saveUserState(state)
+      return this.users.toMeResponse(state)
+    })
+  }
+}