import { Injectable, BadRequestException } from '@nestjs/common';
import { DataSource, IsNull, DeepPartial } from 'typeorm';
import { Occupancy, Room, Student, Deposit, Bed, Locker, Organization } from '../entities';
import { RoomsService } from '../rooms/rooms.service';

class ImportRowSkipped extends Error {}

type StudentUpdateFields = Pick<
  Student,
  | 'studentNo'
  | 'idNumber'
  | 'gender'
  | 'ethnicity'
  | 'emergencyContact'
  | 'emergencyPhone'
  | 'supervisor'
>;

@Injectable()
export class OccupancyImportService {
  constructor(private dataSource: DataSource) {}

  async batchImportCheckIn(
    rows: {
      name: string;
      phone?: string;
      studentNo?: string;
      idNumber?: string;
      gender?: string;
      ethnicity?: string;
      emergencyContact?: string;
      emergencyPhone?: string;
      supervisor?: string;
      roomNumber: string;
      building?: string;
      checkInDate: string;
      billingStartDate?: string;
      checkOutDate?: string;
      bedNumber?: string;
      lockerNumber?: string;
      stayType?: string;
      notes?: string;
    }[],
    options?: { autoDeposit?: boolean; depositAmount?: number },
  ) {
    let imported = 0;
    let skipped = 0;
    let depositsCreated = 0;
    const errors: string[] = [];
    const importDepositAmount = options?.autoDeposit
      ? this.normalizePositiveMoney(options.depositAmount ?? 500, '押金金额')
      : undefined;

    for (let i = 0; i < rows.length; i++) {
      const row = rows[i];
      const rowNum = i + 2; // Excel第2行开始（第1行是表头）

      if (!row.name?.trim() || !row.roomNumber?.trim()) {
        skipped++;
        continue;
      }

      try {
        const result = await this.dataSource.transaction(async (manager) => {
          const occupancyRepo = manager.getRepository(Occupancy);
          const roomRepo = manager.getRepository(Room);
          const studentRepo = manager.getRepository(Student);
          const depositRepo = manager.getRepository(Deposit);
          const bedRepo = manager.getRepository(Bed);
          const lockerRepo = manager.getRepository(Locker);
          const organizationRepo = manager.getRepository(Organization);
          let rowDepositsCreated = 0;

          // 1. 通过手机号关联学生；未找到时创建学生并归入本机构
          const phone = row.phone?.trim();
          if (!phone) throw new BadRequestException('手机号不能为空，无法关联学生');

          let student = await studentRepo.findOne({ where: { phone } });
          if (!student) {
            const hostOrganization = await organizationRepo.findOne({
              where: { isHost: true, status: 'active' },
            });
            if (!hostOrganization) throw new BadRequestException('尚未配置本机构');

            student = await studentRepo.save(
              studentRepo.create({
                name: row.name.trim(),
                phone,
                studentNo: row.studentNo?.trim() || undefined,
                idNumber: row.idNumber?.trim() || undefined,
                gender: row.gender?.trim() || undefined,
                ethnicity: row.ethnicity?.trim() || undefined,
                emergencyContact: row.emergencyContact?.trim() || undefined,
                emergencyPhone: row.emergencyPhone?.trim() || undefined,
                organizationId: hostOrganization.id,
                supervisor: row.supervisor?.trim() || undefined,
              }),
            );
          } else {
            // 更新已有学生的缺失信息
            const updates: Partial<StudentUpdateFields> = {};
            if (!student.studentNo && row.studentNo?.trim())
              updates.studentNo = row.studentNo.trim();
            if (!student.idNumber && row.idNumber?.trim()) updates.idNumber = row.idNumber.trim();
            if (!student.gender && row.gender?.trim()) updates.gender = row.gender.trim();
            if (!student.ethnicity && row.ethnicity?.trim())
              updates.ethnicity = row.ethnicity.trim();
            if (!student.emergencyContact && row.emergencyContact?.trim())
              updates.emergencyContact = row.emergencyContact.trim();
            if (!student.emergencyPhone && row.emergencyPhone?.trim())
              updates.emergencyPhone = row.emergencyPhone.trim();
            if (!student.supervisor && row.supervisor?.trim())
              updates.supervisor = row.supervisor.trim();
            if (Object.keys(updates).length > 0) {
              await studentRepo.update(student.id, updates);
              Object.assign(student, updates);
            }
          }

          // 2. 查找或创建宿舍（使用智能解析）
          let room = await roomRepo.findOne({ where: { roomNumber: row.roomNumber.trim() } });
          if (!room) {
            const parsed = RoomsService.parseRoomNumber(row.roomNumber.trim());
            room = await roomRepo.save(
              roomRepo.create({
                roomNumber: row.roomNumber.trim(),
                building: row.building?.trim() || parsed.building || undefined,
                floor: parsed.floor || undefined,
                capacity: parsed.capacity || 4,
                roomType: parsed.roomType || undefined,
              }),
            );
          }

          const checkInDate = row.checkInDate?.trim() || new Date().toISOString().split('T')[0];
          const checkOutDate = row.checkOutDate?.trim();
          const billingStartDate = row.billingStartDate?.trim() || checkInDate;
          const isHistoricalRecord = Boolean(checkOutDate);
          this.assertDateOnly(checkInDate, '入住日期');
          this.assertDateOnly(billingStartDate, '计费起始日');
          this.assertDateOrder(checkInDate, billingStartDate, '计费起始日不能早于入住日期');
          if (checkOutDate) {
            this.assertDateOnly(checkOutDate, '退宿日期');
            this.assertDateOrder(checkInDate, checkOutDate, '退宿日期不能早于入住日期');
            this.assertDateOrder(billingStartDate, checkOutDate, '退宿日期不能早于计费起始日');
          }

          // 3. 检查是否已有活跃入住（历史记录不影响当前入住）
          const existing = await occupancyRepo.findOne({
            where: { studentId: student.id, checkOutDate: IsNull() },
            relations: ['room'],
          });
          if (existing && !isHistoricalRecord) {
            throw new ImportRowSkipped(
              `第${rowNum}行: ${row.name} 已在住（${existing.room?.roomNumber || '房间' + existing.roomId}），跳过`,
            );
          }

          // 4. 检查宿舍容量
          const count = await occupancyRepo.count({
            where: { roomId: room.id, checkOutDate: IsNull() },
          });
          if (!isHistoricalRecord && count >= (room.capacity ?? 0)) {
            throw new ImportRowSkipped(
              `第${rowNum}行: 宿舍 ${row.roomNumber} 已满（${count}/${room.capacity ?? '?'}），跳过 ${row.name}`,
            );
          }

          // 5. 匹配或创建床位、柜子，并校验是否可用
          let bed: Bed | null = null;
          if (row.bedNumber?.trim()) {
            const bedNumber = row.bedNumber.trim();
            bed = await bedRepo.findOne({ where: { roomId: room.id, bedNumber } });
            if (!bed) {
              const existingBedCount = await bedRepo.count({ where: { roomId: room.id } });
              if (existingBedCount >= (room.capacity ?? 0)) {
                throw new BadRequestException(
                  `宿舍 ${room.roomNumber} 已有 ${existingBedCount} 张床位，不能超过额定人数 ${room.capacity ?? '?'}`,
                );
              }
              bed = await bedRepo.save(
                bedRepo.create({ roomId: room.id, bedNumber, status: 'available' }),
              );
            }
            if (!isHistoricalRecord && bed.status !== 'available') {
              throw new BadRequestException(`床位 ${bedNumber} 已被占用或维修中`);
            }
          }

          let locker: Locker | null = null;
          if (row.lockerNumber?.trim()) {
            const lockerNumber = row.lockerNumber.trim();
            locker = await lockerRepo.findOne({ where: { roomId: room.id, lockerNumber } });
            if (!locker) {
              locker = await lockerRepo.save(
                lockerRepo.create({ roomId: room.id, lockerNumber, status: 'available' }),
              );
            }
            if (!isHistoricalRecord && locker.status !== 'available') {
              throw new BadRequestException(`柜子 ${lockerNumber} 已被占用或维修中`);
            }
          }

          // 6. 创建入住记录
          const occData: DeepPartial<Occupancy> = {
            studentId: student.id,
            roomId: room.id,
            checkInDate,
            billingStartDate,
            stayType: row.stayType || undefined,
            responsibleOrganizationId: student.organizationId,
            notes: row.notes || undefined,
            bedId: bed?.id,
            lockerId: locker?.id,
          };
          // 如果有退宿日期，直接记录
          if (checkOutDate) {
            occData.checkOutDate = checkOutDate;
            occData.billingEndDate = checkOutDate;
          }
          await occupancyRepo.save(occupancyRepo.create(occData));

          // 7. 更新床位、柜子和宿舍状态
          if (!isHistoricalRecord) {
            if (bed) await bedRepo.update(bed.id, { status: 'occupied' });
            if (locker) await lockerRepo.update(locker.id, { status: 'occupied' });
            if (count + 1 >= (room.capacity ?? 0)) {
              await roomRepo.update(room.id, { status: 'full' });
            }
          }

          // 9. 自动收取押金（仅对新入住且非历史记录的学生）
          if (options?.autoDeposit && !isHistoricalRecord) {
            const existingDeposit = await depositRepo.findOne({
              where: { studentId: student.id },
            });
            const depositAmount = importDepositAmount!;
            const hasPaidDeposit =
              existingDeposit?.status === 'paid' && Number(existingDeposit.amount || 0) > 0;
            if (hasPaidDeposit) {
              // 导入重试或重复导入时，已有已缴押金不重复收取。
            } else if (existingDeposit) {
              existingDeposit.amount = depositAmount;
              existingDeposit.status = 'paid';
              existingDeposit.paidDate = checkInDate;
              (existingDeposit as { refundDate: string | null }).refundDate = null;
              (existingDeposit as { refundAmount: number | null }).refundAmount = null;
              (existingDeposit as { refundedBy: number | null }).refundedBy = null;
              (existingDeposit as { refundedAt: Date | null }).refundedAt = null;
              existingDeposit.notes = '入住导入自动收取';
              await depositRepo.save(existingDeposit);
              rowDepositsCreated++;
            } else {
              await depositRepo.save(
                depositRepo.create({
                  studentId: student.id,
                  amount: depositAmount,
                  paidDate: checkInDate,
                  status: 'paid',
                  notes: '入住导入自动收取',
                }),
              );
              rowDepositsCreated++;
            }
          }

          return { depositsCreated: rowDepositsCreated };
        });

        imported++;
        depositsCreated += result.depositsCreated;
      } catch (e: unknown) {
        errors.push(
          e instanceof ImportRowSkipped
            ? e.message
            : `第${rowNum}行: ${row.name} 导入失败 - ${e instanceof Error ? e.message : String(e)}`,
        );
        skipped++;
      }
    }

    const depositMsg = depositsCreated > 0 ? `，自动收取 ${depositsCreated} 笔押金` : '';
    return {
      message: `成功导入 ${imported} 条入住记录，跳过 ${skipped} 条${depositMsg}`,
      imported,
      skipped,
      depositsCreated,
      errors: errors.length > 0 ? errors : undefined,
    };
  }

  private normalizePositiveMoney(value: number, label: string): number {
    const amount = value;
    if (!Number.isFinite(amount) || Math.abs(amount * 100 - Math.round(amount * 100)) > 1e-8) {
      throw new BadRequestException(`${label}最多保留两位小数`);
    }
    if (amount <= 0) throw new BadRequestException(`${label}必须大于0`);
    return Number(amount.toFixed(2));
  }

  private assertDateOnly(value: string, label: string): void {
    if (!/^\d{4}-\d{2}-\d{2}$/.test(value)) {
      throw new BadRequestException(`${label}必须为有效的 YYYY-MM-DD 日期`);
    }
    const [year, month, day] = value.split('-').map(Number);
    const date = new Date(Date.UTC(year, month - 1, day));
    if (
      date.getUTCFullYear() !== year ||
      date.getUTCMonth() + 1 !== month ||
      date.getUTCDate() !== day
    ) {
      throw new BadRequestException(`${label}必须为有效的 YYYY-MM-DD 日期`);
    }
  }

  private assertDateOrder(start: string, end: string | undefined, message: string): void {
    this.assertDateOnly(start, '起始日期');
    if (!end) return;
    this.assertDateOnly(end, '结束日期');
    if (end < start) throw new BadRequestException(message);
  }
}