import { Injectable } from '@nestjs/common'
import { ResponseMapper } from '../../common/response/response-mapper'
import { Prisma } from '../../generated/prisma/client'
import { PrismaService } from '../../prisma/prisma.service'
import { CreateOrderDto } from './dto/create-pos.dto'

@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 createOrder(data: CreateOrderDto, inventoryId: number) {
    const { customerId, ...res } = data
    const preparedOrder = { ...res } as any
    const lastCode = await this.prisma.salesInvoice
      .findFirst({
        orderBy: { code: 'desc' },
        select: { code: true },
      })
      .then(si => si?.code || '0')

    preparedOrder.code = String(Number(lastCode) + 1)

    preparedOrder.totalAmount = data.items.reduce(
      (acc, item) => acc + Number(item.fee),
      0,
    )

    preparedOrder.inventory = { connect: { id: inventoryId } }
    preparedOrder.customer = { connect: { id: customerId } }

    if (Object.prototype.hasOwnProperty.call(preparedOrder, 'items')) {
      preparedOrder.items = {
        create: preparedOrder.items.map((item: any) => ({
          product: { connect: { id: Number(item.productId) } },
          count: item.count,
          fee: item.fee,
          total: item.count * item.fee,
        })),
      }
    }

    const item = await this.prisma.salesInvoice.create({ data: preparedOrder })
    return ResponseMapper.create(item)
  }
}