import {
  Injectable,
  NotFoundException,
  BadRequestException,
  ForbiddenException,
} from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, DataSource } from 'typeorm';
import { Bet } from '../../entities/bet.entity';
import { Appointment } from '../../entities/appointment.entity';
import { Point } from '../../entities/point.entity';
import { GroupMember } from '../../entities/group-member.entity';
import { CreateBetDto, SettleBetDto } from './dto/bet.dto';
import { BetStatus, GroupMemberRole, AppointmentStatus } from '../../common/enums';
import { ErrorCode, ErrorMessage } from '../../common/interfaces/response.interface';

@Injectable()
export class BetsService {
  constructor(
    @InjectRepository(Bet)
    private betRepository: Repository<Bet>,
    @InjectRepository(Appointment)
    private appointmentRepository: Repository<Appointment>,
    @InjectRepository(Point)
    private pointRepository: Repository<Point>,
    @InjectRepository(GroupMember)
    private groupMemberRepository: Repository<GroupMember>,
    private dataSource: DataSource,
  ) {}

  /**
   * 创建竞猜下注
   */
  async create(userId: string, createDto: CreateBetDto) {
    const { appointmentId, amount, betOption } = createDto;

    // 使用事务确保数据一致性
    const queryRunner = this.dataSource.createQueryRunner();
    await queryRunner.connect();
    await queryRunner.startTransaction();

    try {
      // 验证预约存在
      const appointment = await queryRunner.manager.findOne(Appointment, {
        where: { id: appointmentId },
      });

      if (!appointment) {
        throw new NotFoundException({
          code: ErrorCode.APPOINTMENT_NOT_FOUND,
          message: ErrorMessage[ErrorCode.APPOINTMENT_NOT_FOUND],
        });
      }

      // 验证预约状态
      if (appointment.status !== AppointmentStatus.PENDING) {
        throw new BadRequestException({
          code: ErrorCode.INVALID_OPERATION,
          message: '预约已结束，无法下注',
        });
      }

      // 验证用户积分是否足够
      const balance = await queryRunner.manager
        .createQueryBuilder(Point, 'point')
        .select('SUM(point.amount)', 'total')
        .where('point.userId = :userId', { userId })
        .andWhere('point.groupId = :groupId', { groupId: appointment.groupId })
        .getRawOne();

      const currentBalance = parseInt(balance.total || '0');
      if (currentBalance < amount) {
        throw new BadRequestException({
          code: ErrorCode.INSUFFICIENT_POINTS,
          message: '积分不足',
        });
      }

      // 检查是否已下注
      const existingBet = await queryRunner.manager.findOne(Bet, {
        where: { appointmentId, userId },
      });

      if (existingBet) {
        throw new BadRequestException({
          code: ErrorCode.INVALID_OPERATION,
          message: '已下注，不能重复下注',
        });
      }

      const bet = queryRunner.manager.create(Bet, {
        appointmentId,
        userId,
        betOption,
        amount,
      });

      const savedBet = await queryRunner.manager.save(Bet, bet);

      // 扣除积分
      const pointRecord = queryRunner.manager.create(Point, {
        userId,
        groupId: appointment.groupId,
        amount: -amount,
        reason: '竞猜下注',
        description: `预约: ${appointment.title}`,
        relatedId: savedBet.id,
      });

      await queryRunner.manager.save(Point, pointRecord);

      await queryRunner.commitTransaction();
      return savedBet;
    } catch (error) {
      await queryRunner.rollbackTransaction();
      throw error;
    } finally {
      await queryRunner.release();
    }
  }

  /**
   * 查询预约的所有竞猜
   */
  async findAll(appointmentId: string) {
    const bets = await this.betRepository.find({
      where: { appointmentId },
      relations: ['user'],
      order: { createdAt: 'DESC' },
    });

    // 统计各选项的下注情况
    const stats = bets.reduce((acc, bet) => {
      if (!acc[bet.betOption]) {
        acc[bet.betOption] = { count: 0, totalAmount: 0 };
      }
      acc[bet.betOption].count++;
      acc[bet.betOption].totalAmount += bet.amount;
      return acc;
    }, {});

    return {
      bets,
      stats,
      totalBets: bets.length,
      totalAmount: bets.reduce((sum, bet) => sum + bet.amount, 0),
    };
  }

  /**
   * 结算竞猜（管理员）
   */
  async settle(userId: string, appointmentId: string, settleDto: SettleBetDto) {
    const { winningOption } = settleDto;

    // 验证预约存在
    const appointment = await this.appointmentRepository.findOne({
      where: { id: appointmentId },
    });

    if (!appointment) {
      throw new NotFoundException({
        code: ErrorCode.APPOINTMENT_NOT_FOUND,
        message: ErrorMessage[ErrorCode.APPOINTMENT_NOT_FOUND],
      });
    }

    // 验证权限
    const membership = await this.groupMemberRepository.findOne({
      where: { groupId: appointment.groupId, userId },
    });

    if (!membership || (membership.role !== GroupMemberRole.ADMIN && membership.role !== GroupMemberRole.OWNER)) {
      throw new ForbiddenException({
        code: ErrorCode.NO_PERMISSION,
        message: '需要管理员权限',
      });
    }

    // 使用事务确保数据一致性
    const queryRunner = this.dataSource.createQueryRunner();
    await queryRunner.connect();
    await queryRunner.startTransaction();

    try {
      // 获取所有下注
      const bets = await queryRunner.manager.find(Bet, {
        where: { appointmentId },
      });

      // 计算总奖池和赢家总下注
      const totalPool = bets.reduce((sum, bet) => sum + bet.amount, 0);
      const winningBets = bets.filter((bet) => bet.betOption === winningOption);
      const winningTotal = winningBets.reduce((sum, bet) => sum + bet.amount, 0);

      if (winningTotal === 0) {
        throw new BadRequestException({
          code: ErrorCode.INVALID_OPERATION,
          message: '没有人下注该选项',
        });
      }

      // 按比例分配奖池，修复精度损失问题
      let distributedAmount = 0;

      for (let i = 0; i < winningBets.length; i++) {
        const bet = winningBets[i];
        let winAmount: number;

        if (i === winningBets.length - 1) {
          // 最后一个赢家获得剩余所有积分，避免精度损失
          winAmount = totalPool - distributedAmount;
        } else {
          winAmount = Math.floor((bet.amount / winningTotal) * totalPool);
          distributedAmount += winAmount;
        }

        bet.winAmount = winAmount;
        bet.status = BetStatus.WON;

        // 返还积分
        const pointRecord = queryRunner.manager.create(Point, {
          userId: bet.userId,
          groupId: appointment.groupId,
          amount: winAmount,
          reason: '竞猜获胜',
          description: `预约: ${appointment.title}`,
          relatedId: bet.id,
        });

        await queryRunner.manager.save(Point, pointRecord);
        await queryRunner.manager.save(Bet, bet);
      }

      // 更新输家状态
      for (const bet of bets) {
        if (bet.betOption !== winningOption) {
          bet.status = BetStatus.LOST;
          await queryRunner.manager.save(Bet, bet);
        }
      }

      await queryRunner.commitTransaction();

      return {
        message: '结算成功',
        winningOption,
        totalPool,
        winners: winningBets.length,
      };
    } catch (error) {
      await queryRunner.rollbackTransaction();
      throw error;
    } finally {
      await queryRunner.release();
    }
  }

  /**
   * 取消竞猜（预约取消时）
   */
  async cancel(appointmentId: string) {
    // 使用事务确保数据一致性
    const queryRunner = this.dataSource.createQueryRunner();
    await queryRunner.connect();
    await queryRunner.startTransaction();

    try {
      const bets = await queryRunner.manager.find(Bet, {
        where: { appointmentId },
        relations: ['appointment'],
      });

      for (const bet of bets) {
        if (bet.status === BetStatus.PENDING) {
          bet.status = BetStatus.CANCELLED;
          await queryRunner.manager.save(Bet, bet);

          // 退还积分
          const pointRecord = queryRunner.manager.create(Point, {
            userId: bet.userId,
            groupId: bet.appointment.groupId,
            amount: bet.amount,
            reason: '竞猜取消退款',
            description: `预约: ${bet.appointment.title}`,
            relatedId: bet.id,
          });

          await queryRunner.manager.save(Point, pointRecord);
        }
      }

      await queryRunner.commitTransaction();
      return { message: '竞猜已取消，积分已退还' };
    } catch (error) {
      await queryRunner.rollbackTransaction();
      throw error;
    } finally {
      await queryRunner.release();
    }
  }
}