import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
import { Prisma } from '@prisma/client';
import { PrismaService } from '../../common/prisma/prisma.module';
import { serializeBigInt } from '../../common/decorators/current-user.decorator';
import type { AdminUsersQueryDto } from './dto/admin-query.dto';

const FINISHED_ORDER_STATUSES = ['COMPLETED', 'CANCELLED', 'REFUNDED'] as const;

/** 权益统计口径：VOID（退款作废）不计入，与 C 端 listCoupons 一致 */
const BENEFIT_STAT_STATUSES = ['ACTIVE', 'USED_UP'] as const;

export type UserBenefitStat = {
  /** 累计获得（含已使用） */
  benefitTotalAmount: number;
  /** 已使用（已核销） */
  benefitUsedAmount: number;
  /** 剩余未使用（可核销余额） */
  benefitBalance: number;
};

const EMPTY_BENEFIT_STAT: UserBenefitStat = {
  benefitTotalAmount: 0,
  benefitUsedAmount: 0,
  benefitBalance: 0,
};

function toAmount(v: Prisma.Decimal | number | null | undefined) {
  return v == null ? 0 : Number(v);
}

function mapAdminUserRow(u: {
  id: bigint;
  userNo: string;
  deviceKey: string | null;
  phone: string | null;
  phoneVerifiedAt: Date | null;
  mergedIntoUserId: bigint | null;
  wxOpenId: string | null;
  nickname: string | null;
  status: number;
  sourceType: string;
  sourceRefId: bigint | null;
  sourceLabel: string | null;
  isTest?: boolean;
  createdAt: Date;
  updatedAt: Date;
  _count: { orders: number };
}, benefit: UserBenefitStat = EMPTY_BENEFIT_STAT) {
  return {
    id: u.id,
    userNo: u.userNo,
    deviceKey: u.deviceKey,
    phone: u.phone,
    phoneVerifiedAt: u.phoneVerifiedAt,
    mergedIntoUserId: u.mergedIntoUserId,
    wxOpenId: u.wxOpenId,
    wechatVerified: !!u.wxOpenId,
    nickname: u.nickname,
    status: u.status,
    sourceType: u.sourceType,
    sourceRefId: u.sourceRefId,
    sourceLabel: u.sourceLabel,
    isTest: !!u.isTest,
    createdAt: u.createdAt,
    updatedAt: u.updatedAt,
    orderCount: u._count.orders,
    ...benefit,
  };
}

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

  async list(query: AdminUsersQueryDto) {
    const page = query.page ?? 1;
    const pageSize = query.pageSize ?? 20;
    const where: Prisma.UserWhereInput = {};

    if (query.phone) where.phone = { contains: query.phone };
    if (query.userNo) where.userNo = { contains: query.userNo };
    if (query.deviceKey) where.deviceKey = query.deviceKey;
    if (query.status !== undefined) where.status = query.status;
    if (query.phoneVerified === '1') where.phoneVerifiedAt = { not: null };
    if (query.phoneVerified === '0') where.phoneVerifiedAt = null;
    if (query.excludeTest) where.isTest = false;

    const [items, total] = await Promise.all([
      this.prisma.user.findMany({
        where,
        orderBy: { createdAt: 'desc' },
        skip: (page - 1) * pageSize,
        take: pageSize,
        select: {
          id: true,
          userNo: true,
          deviceKey: true,
          phone: true,
          phoneVerifiedAt: true,
          mergedIntoUserId: true,
          wxOpenId: true,
          nickname: true,
          status: true,
          sourceType: true,
          sourceRefId: true,
          sourceLabel: true,
          isTest: true,
          createdAt: true,
          updatedAt: true,
          _count: { select: { orders: true } },
        },
      }),
      this.prisma.user.count({ where }),
    ]);

    const benefitMap = await this.loadBenefitStats(items.map((u) => u.id));

    return serializeBigInt({
      items: items.map((u) => mapAdminUserRow(u, benefitMap.get(u.id.toString()))),
      total,
      page,
      pageSize,
    });
  }

  /** 批量聚合当前页用户的好客权益金额（累计获得 / 已使用 / 剩余） */
  private async loadBenefitStats(userIds: bigint[]): Promise<Map<string, UserBenefitStat>> {
    const map = new Map<string, UserBenefitStat>();
    if (!userIds.length) return map;

    const grouped = await this.prisma.benefitCoupon.groupBy({
      by: ['userId'],
      where: { userId: { in: userIds }, status: { in: [...BENEFIT_STAT_STATUSES] } },
      _sum: { totalAmount: true, usedAmount: true, balance: true },
    });

    for (const row of grouped) {
      map.set(row.userId.toString(), {
        benefitTotalAmount: toAmount(row._sum.totalAmount),
        benefitUsedAmount: toAmount(row._sum.usedAmount),
        benefitBalance: toAmount(row._sum.balance),
      });
    }
    return map;
  }

  async detail(id: bigint) {
    const user = await this.prisma.user.findUnique({
      where: { id },
      include: {
        cityPreference: true,
        mergedInto: { select: { id: true, userNo: true, phone: true, nickname: true } },
        orders: {
          orderBy: { createdAt: 'desc' },
          select: {
            id: true,
            orderNo: true,
            status: true,
            payAmount: true,
            payStatus: true,
            createdAt: true,
          },
        },
        _count: { select: { mergedFrom: true, orders: true, addresses: true } },
      },
    });
    if (!user) throw new NotFoundException('用户不存在');

    let sourcePromo: { id: bigint; code: string; name: string } | null = null;
    if (user.sourceType === 'PROMO_CODE' && user.sourceRefId) {
      sourcePromo = await this.prisma.commonPromoCode.findUnique({
        where: { id: user.sourceRefId },
        select: { id: true, code: true, name: true },
      });
    }

    const benefitMap = await this.loadBenefitStats([user.id]);

    return serializeBigInt({
      ...user,
      ...(benefitMap.get(user.id.toString()) ?? EMPTY_BENEFIT_STAT),
      wechatVerified: !!user.wxOpenId,
      mergedFromCount: user._count.mergedFrom,
      orderCount: user._count.orders,
      addressCount: user._count.addresses,
      sourcePromo,
      _count: undefined,
    });
  }

  async previewBatchDelete(ids: bigint[]) {
    const uniqueIds = [...new Set(ids)];
    if (!uniqueIds.length) {
      return { items: [], hasRisk: false, total: 0 };
    }

    const users = await this.prisma.user.findMany({
      where: { id: { in: uniqueIds } },
      select: {
        id: true,
        userNo: true,
        nickname: true,
        phone: true,
        orders: {
          where: { status: { notIn: [...FINISHED_ORDER_STATUSES] } },
          select: { id: true, orderNo: true, status: true, payAmount: true, createdAt: true },
          orderBy: { createdAt: 'desc' },
        },
        redeemRecords: {
          select: {
            id: true,
            redeemNo: true,
            amount: true,
            createdAt: true,
            payout: { select: { status: true } },
          },
          orderBy: { createdAt: 'desc' },
        },
      },
      orderBy: { createdAt: 'desc' },
    });

    const foundIds = new Set(users.map((u) => u.id.toString()));
    const missing = uniqueIds.filter((id) => !foundIds.has(id.toString()));
    if (missing.length) {
      throw new NotFoundException('部分用户不存在');
    }

    const items = users.map((u) => {
      const unfinishedOrders = u.orders;
      const redeemRecords = u.redeemRecords.map((r) => ({
        id: r.id,
        redeemNo: r.redeemNo,
        amount: r.amount,
        createdAt: r.createdAt,
        payoutStatus: r.payout?.status ?? null,
      }));
      const hasRisk = unfinishedOrders.length > 0 || redeemRecords.length > 0;
      return {
        id: u.id,
        userNo: u.userNo,
        nickname: u.nickname,
        phone: u.phone,
        unfinishedOrders,
        redeemRecords,
        hasRisk,
      };
    });

    return serializeBigInt({
      items,
      hasRisk: items.some((i) => i.hasRisk),
      total: items.length,
    });
  }

  async batchDeleteUsers(ids: bigint[], confirmRisk: boolean) {
    const preview = await this.previewBatchDelete(ids);
    if (preview.hasRisk && !confirmRisk) {
      const riskyUsers = preview.items.filter((i) => i.hasRisk);
      throw new BadRequestException({
        message: '所选用户存在未完成订单或核销记录，需二次确认后删除',
        code: 'USER_DELETE_RISK',
        riskyUsers: riskyUsers.map((u) => ({
          id: u.id,
          userNo: u.userNo,
          unfinishedOrderCount: u.unfinishedOrders.length,
          redeemRecordCount: u.redeemRecords.length,
        })),
      });
    }

    const userIds = preview.items.map((i) => BigInt(String(i.id)));
    await this.prisma.$transaction(async (tx) => {
      for (const id of userIds) {
        await this.deleteUserInTx(tx, id);
      }
    });

    return {
      ok: true,
      deleted: userIds.length,
      message: '用户及关联业务数据已删除，行为日志已保留',
    };
  }

  async deleteUser(id: bigint) {
    const user = await this.prisma.user.findUnique({ where: { id } });
    if (!user) throw new NotFoundException('用户不存在');

    await this.prisma.$transaction(async (tx) => {
      await this.deleteUserInTx(tx, id);
    });

    return {
      ok: true,
      message: '用户及关联业务数据已删除，行为日志已保留',
    };
  }

  private async deleteUserInTx(tx: Prisma.TransactionClient, id: bigint) {
    const user = await tx.user.findUnique({ where: { id } });
    if (!user) return;

    await tx.user.updateMany({
      where: { mergedIntoUserId: id },
      data: { mergedIntoUserId: null },
    });

    const orderIds = (
      await tx.order.findMany({ where: { userId: id }, select: { id: true } })
    ).map((o) => o.id);

    const redeemIds = (
      await tx.redeemRecord.findMany({ where: { userId: id }, select: { id: true } })
    ).map((r) => r.id);

    if (redeemIds.length) {
      await tx.storePayout.deleteMany({ where: { redeemRecordId: { in: redeemIds } } });
      await tx.storeRating.deleteMany({ where: { redeemRecordId: { in: redeemIds } } });
      await tx.redeemRecord.deleteMany({ where: { id: { in: redeemIds } } });
    }

    await tx.benefitCoupon.deleteMany({ where: { userId: id } });

    if (orderIds.length) {
      await tx.order.updateMany({
        where: { originOrderId: { in: orderIds } },
        data: { originOrderId: null },
      });
      await tx.commonTicket.deleteMany({
        where: { refType: 'ORDER', refId: { in: orderIds } },
      });
      await tx.order.deleteMany({ where: { id: { in: orderIds } } });
    }

    if (user.avatarResourceId) {
      await tx.commonResource.updateMany({
        where: { id: user.avatarResourceId, ownerType: 'USER', ownerId: id },
        data: { status: 'DELETED' },
      });
    }

    await tx.user.delete({ where: { id } });
  }
}