import { Injectable } from '@nestjs/common';
import { calcBenefitAmount, calcBenefitSummary, generateCouponNo } from '@dukang/domain';
import { PrismaService } from '../../common/prisma/prisma.module';
import { serializeBigInt } from '../../common/decorators/current-user.decorator';
import { buildBenefitLedgerEvent, benefitLedgerWhere } from '../../common/event/event.helpers';

@Injectable()
export class BenefitService {
  constructor(private readonly prisma: PrismaService) {}

  async grantOnOrderPaid(orderId: bigint) {
    const order = await this.prisma.order.findUniqueOrThrow({
      where: { id: orderId },
    });

    const product = await this.prisma.commonProductItem.findUnique({ where: { id: order.productId } });
    const unitBenefit = calcBenefitAmount({
      price: Number(order.listUnitPrice),
      benefitAmount: product?.benefitAmount ? Number(product.benefitAmount) : null,
    });
    const totalBenefit = unitBenefit * order.quantity;

    const coupon = await this.prisma.benefitCoupon.create({
      data: {
        couponNo: generateCouponNo(),
        userId: order.userId,
        orderId: order.id,
        totalAmount: totalBenefit,
        balance: totalBenefit,
        sourceProduct: order.productName,
      },
    });

    await this.prisma.commonEvent.create({
      data: buildBenefitLedgerEvent({
        userId: order.userId,
        couponId: coupon.id,
        type: 'GRANT',
        amount: totalBenefit,
        balanceAfter: totalBenefit,
        refType: 'ORDER',
        refId: order.id,
        remark: '购酒赠券',
      }),
    });

    return serializeBigInt(coupon);
  }

  async listCoupons(userId: bigint) {
    const list = await this.prisma.benefitCoupon.findMany({
      where: { userId, status: { in: ['ACTIVE', 'USED_UP'] } },
      orderBy: { createdAt: 'desc' },
    });
    return serializeBigInt(list);
  }

  async getSummary(userId: bigint) {
    const coupons = await this.prisma.benefitCoupon.findMany({
      where: { userId, status: 'ACTIVE' },
      orderBy: { createdAt: 'asc' },
    });
    const summary = calcBenefitSummary(
      coupons.map((c) => Number(c.balance)),
    );
    return serializeBigInt(summary);
  }

  async getLedger(userId: bigint, couponId?: bigint) {
    const list = await this.prisma.commonEvent.findMany({
      where: benefitLedgerWhere(userId, couponId),
      orderBy: { createdAt: 'desc' },
    });
    return serializeBigInt(list);
  }

  async getCoupon(userId: bigint, couponId: bigint) {
    const coupon = await this.prisma.benefitCoupon.findFirst({
      where: { id: couponId, userId },
    });
    if (!coupon) return null;
    const ledgers = await this.prisma.commonEvent.findMany({
      where: benefitLedgerWhere(undefined, couponId),
      orderBy: { createdAt: 'desc' },
    });
    return serializeBigInt({ coupon, ledgers });
  }
}