feat: add salePrice field to Product model and update related files

- Added salePrice field to Product model in Prisma schema and generated files.
- Updated Product scalar field enums in both TypeScript files.
- Modified aggregate output types to include salePrice.
- Enhanced input types for creating and updating products to support salePrice.
- Updated migration file to add salePrice column to Products table.
- Created DTOs for inventory management in POS module.
- Implemented POS controller and service with methods for stock and product categories.

src/pos/pos.service.ts

@@ -0,0 +1,116 @@
+import { Injectable } from '@nestjs/common'
+import { ResponseMapper } from '../common/response/response-mapper'
+import { Prisma } from '../generated/prisma/client'
+import { PrismaService } from '../prisma/prisma.service'
+
+@Injectable()
+export class PosService {
+  constructor(private prisma: PrismaService) {}
+
+  async getDefaultInventoryId() {
+    const inventory = await this.prisma.inventory.findFirst({
+      where: { isPointOfSale: true },
+      select: { id: true },
+    })
+    return inventory?.id || null
+  }
+
+  async getInfo() {
+    const info = await this.prisma.inventory.findFirst({
+      where: { isPointOfSale: true },
+      select: {
+        id: true,
+        name: true,
+      },
+    })
+
+    return ResponseMapper.single({ store: info })
+  }
+
+  async getStock(inventoryId: number, isAvailable?: boolean, page = 1, pageSize = 50) {
+    const query: Prisma.StockBalanceFindManyArgs = {
+      where: {
+        inventoryId,
+        quantity:
+          isAvailable === true
+            ? { gt: 0 }
+            : isAvailable === false
+              ? { lte: 0 }
+              : undefined,
+      },
+    }
+    const [items, count] = await this.prisma.$transaction([
+      this.prisma.stockBalance.findMany({
+        where: query.where,
+        include: {
+          product: {
+            select: {
+              id: true,
+              name: true,
+              sku: true,
+              salePrice: true,
+              category: {
+                select: { id: true, name: true },
+              },
+            },
+          },
+        },
+        orderBy: {
+          quantity: 'desc',
+        },
+        skip: (page - 1) * pageSize,
+        take: pageSize,
+      }),
+      this.prisma.stockBalance.count({ where: query.where }),
+    ])
+
+    const mapped = items.map(item => ({
+      id: item.id,
+      quantity: Number(item.quantity),
+      product: item.product,
+    }))
+
+    return ResponseMapper.paginate(mapped, count, page, pageSize)
+  }
+
+  async getProductCategories(inventoryId: number) {
+    const balances = await this.prisma.stockBalance.findMany({
+      where: { inventoryId },
+      select: {
+        product: { select: { id: true, category: { select: { id: true, name: true } } } },
+        quantity: true,
+      },
+    })
+
+    const map = new Map<
+      number,
+      { id: number; name: string; totalQuantity: number; productCount: number }
+    >()
+
+    for (const b of balances) {
+      const product = b.product
+      const cat = product?.category
+      if (!cat) continue // skip products without category
+      const existing = map.get(cat.id)
+      if (existing) {
+        existing.totalQuantity += Number(b.quantity)
+        existing.productCount += 1
+      } else {
+        map.set(cat.id, {
+          id: cat.id,
+          name: cat.name,
+          totalQuantity: Number(b.quantity),
+          productCount: 1,
+        })
+      }
+    }
+
+    const categories = Array.from(map.values())
+    return ResponseMapper.list(categories)
+  }
+
+  async createSaleInvoice(data: any) {
+    const item = await this.prisma.salesInvoice.create({ data })
+    return ResponseMapper.create(item)
+  }
+}