import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { DataSource, In, Repository } from 'typeorm';
import { RoomExpense, PersonalExpense, Room, Student } from '../entities';
import { BillsService } from '../bills/bills.service';
import { RoomsService } from '../rooms/rooms.service';
import type { CreatePersonalExpenseDto } from './dto/expense.dto';

@Injectable()
export class ExpenseOperationsService {
  constructor(
    @InjectRepository(RoomExpense) private roomExpRepo: Repository<RoomExpense>,
    @InjectRepository(PersonalExpense) private personalExpRepo: Repository<PersonalExpense>,
    @InjectRepository(Room) private roomRepo: Repository<Room>,
    @InjectRepository(Student) private studentRepo: Repository<Student>,
    private billsService: BillsService,
    private dataSource: DataSource,
  ) {}

  private assertPositiveAmount(amount: number) {
    if (!Number.isFinite(amount) || Math.abs(amount * 100 - Math.round(amount * 100)) > 1e-8) {
      throw new BadRequestException('费用金额最多保留两位小数');
    }
    if (amount <= 0) throw new BadRequestException('费用金额必须大于0');
  }

  private isValidDate(value: string) {
    if (!/^\d{4}-\d{2}-\d{2}$/.test(value || '')) return false;
    const date = new Date(`${value}T00:00:00Z`);
    return !Number.isNaN(date.getTime()) && date.toISOString().slice(0, 10) === value;
  }

  async createPersonalExpense(dto: CreatePersonalExpenseDto, userId?: number) {
    this.assertPositiveAmount(dto.amount);
    const student = await this.studentRepo.findOne({ where: { id: dto.studentId } });
    if (!student) throw new NotFoundException('学生不存在');
    const entity = this.personalExpRepo.create({ ...dto, recordedBy: userId });
    return this.personalExpRepo.save(entity);
  }

  async findPersonalExpenses(query?: { studentId?: number; status?: 'active' | 'archived' }) {
    const status = query?.status ?? 'active';
    if (status !== 'active' && status !== 'archived') throw new BadRequestException('费用状态无效');
    const where: Record<string, unknown> = { status };
    if (query?.studentId) where.studentId = query.studentId;
    return this.personalExpRepo.find({
      where,
      relations: ['student'],
      order: { createdAt: 'DESC' },
    });
  }

  async deletePersonalExpense(id: number) {
    const e = await this.personalExpRepo.findOne({ where: { id } });
    if (!e) throw new NotFoundException('费用记录不存在');
    if (e.billId) throw new BadRequestException('已计入账单的个人费用不能归档，请先取消账单');
    if (e.status === 'archived') throw new BadRequestException('费用记录已归档');
    await this.personalExpRepo.update(id, { status: 'archived' });
    return { message: '已归档' };
  }

  async batchDeletePersonalExpenses(ids: number[]) {
    const uniqueIds = [...new Set(ids || [])];
    if (uniqueIds.length === 0) throw new BadRequestException('请选择要归档的记录');
    const existing = await this.personalExpRepo.find({ where: { id: In(uniqueIds) } });
    if (existing.length !== uniqueIds.length) throw new NotFoundException('部分费用记录不存在');
    if (existing.some((expense) => expense.billId)) {
      throw new BadRequestException('选中记录包含已计入账单的个人费用');
    }
    const result = await this.personalExpRepo
      .createQueryBuilder()
      .update()
      .set({ status: 'archived' })
      .where('id IN (:...ids)', { ids: uniqueIds })
      .execute();
    return { message: `已批量归档 ${result.affected || 0} 条`, archived: result.affected || 0 };
  }

  async batchRestorePersonalExpenses(ids: number[]) {
    const uniqueIds = [...new Set(ids || [])];
    if (uniqueIds.length === 0) throw new BadRequestException('请选择要恢复的记录');
    if (uniqueIds.some((id) => !Number.isInteger(id) || id <= 0)) {
      throw new BadRequestException('费用记录 ID 无效');
    }
    const existing = await this.personalExpRepo.find({ where: { id: In(uniqueIds) } });
    if (existing.length !== uniqueIds.length) throw new NotFoundException('部分费用记录不存在');
    const targets = existing.filter((expense) => expense.status === 'archived');
    if (targets.some((expense) => expense.billId)) {
      throw new BadRequestException('选中记录包含已计入账单的个人费用');
    }

    const targetIds = targets.map((expense) => expense.id);
    const skipped = existing.length - targetIds.length;
    let restored = 0;
    if (targetIds.length > 0) {
      const result = await this.personalExpRepo
        .createQueryBuilder()
        .update()
        .set({ status: 'active' })
        .where('id IN (:...ids)', { ids: targetIds })
        .execute();
      restored = result.affected || 0;
    }
    return { message: `已批量恢复 ${restored} 条个人费用`, restored, skipped };
  }

  async purgePersonalExpense(id: number) {
    const e = await this.personalExpRepo.findOne({ where: { id } });
    if (!e) throw new NotFoundException('费用记录不存在');
    if (e.status !== 'archived') throw new BadRequestException('仅已归档费用可以永久删除，请先归档');
    if (e.billId) throw new BadRequestException('已计入账单的个人费用不能永久删除，请先取消账单');
    const billed = await this.dataSource
      .getRepository('bill_items')
      .count({ where: { personalExpenseId: id } });
    if (billed) throw new BadRequestException('已计入账单明细的个人费用不能永久删除，请先取消账单');
    await this.personalExpRepo.delete(id);
    return { message: '已永久删除个人费用（不可恢复）' };
  }

  async batchPurgePersonalExpenses(ids: number[]) {
    const uniqueIds = [...new Set(ids || [])];
    if (uniqueIds.length === 0) throw new BadRequestException('请选择要永久删除的个人费用');
    if (uniqueIds.some((id) => !Number.isInteger(id) || id <= 0)) {
      throw new BadRequestException('费用记录 ID 无效');
    }
    const existing = await this.personalExpRepo.find({ where: { id: In(uniqueIds) } });
    if (existing.length !== uniqueIds.length) throw new NotFoundException('部分费用记录不存在');
    const billed = await this.dataSource
      .getRepository('bill_items')
      .count({ where: { personalExpenseId: In(uniqueIds) } });
    if (billed) throw new BadRequestException('选中记录包含已计入账单明细的个人费用');
    if (existing.some((expense) => expense.billId)) {
      throw new BadRequestException('选中记录包含已计入账单的个人费用');
    }

    const deleted: number[] = [];
    const skipped: string[] = [];
    for (const e of existing) {
      if (e.status !== 'archived') {
        skipped.push(`记录${e.id}（未归档）`);
        continue;
      }
      await this.personalExpRepo.delete(e.id);
      deleted.push(e.id);
    }
    const message =
      skipped.length > 0
        ? `已永久删除 ${deleted.length} 条；${skipped.length} 条被跳过（${skipped.slice(0, 5).join('、')}${skipped.length > 5 ? '…' : ''}）`
        : `已永久删除 ${deleted.length} 条个人费用（不可恢复）`;
    return { message, deleted: deleted.length, skipped: skipped.length };
  }

  async updatePersonalExpense(id: number, dto: Partial<CreatePersonalExpenseDto>) {
    const e = await this.personalExpRepo.findOne({ where: { id } });
    if (!e) throw new NotFoundException('费用记录不存在');
    if (e.billId) throw new BadRequestException('已计入账单的个人费用不能修改，请先取消账单');
    if (dto.amount !== undefined) this.assertPositiveAmount(dto.amount);
    if (dto.studentId !== undefined && dto.studentId !== e.studentId) {
      const student = await this.studentRepo.findOne({ where: { id: dto.studentId } });
      if (!student) throw new NotFoundException('学生不存在');
    }
    Object.assign(e, dto);
    return this.personalExpRepo.save(e);
  }

  /**
   * 水电费Excel批量导入
   * Excel格式: 序号|时间|房间号|房间电量|电费|冷水用量(吨)|水费|应缴金额
   * 时间格式: "2026-01-21 - 2026-02-08"
   */
  async batchImportUtilityExpenses(
    rows: {
      periodStr: string;
      roomNumber: string;
      electricityAmount: number;
      electricityFee: number;
      waterAmount: number;
      waterFee: number;
      totalFee: number;
    }[],
    userId?: number,
  ) {
    let imported = 0;
    let skipped = 0;
    const errors: string[] = [];

    for (let i = 0; i < rows.length; i++) {
      const row = rows[i];
      const rowNum = i + 2;

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

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

        // 解析时间段 "2026-01-21 - 2026-02-08" 或 "2026-01-21~2026-02-08"
        let periodStart = '';
        let periodEnd = '';
        if (row.periodStr) {
          // 先尝试用" - "或" ~ "分割（带空格的分隔符，避免拆分日期内部的连字符）
          let parts = row.periodStr.split(/\s+[-~～]\s+/);
          if (parts.length < 2) {
            // 回退：尝试用正则提取 YYYY-MM-DD 格式的日期
            const dateMatches = row.periodStr.match(/(\d{4}-\d{1,2}-\d{1,2})/g);
            if (dateMatches && dateMatches.length >= 2) {
              parts = [dateMatches[0], dateMatches[1]];
            }
          }
          if (parts.length >= 2) {
            periodStart = this.normalizeDate(parts[0].trim());
            periodEnd = this.normalizeDate(parts[1].trim());
          }
        }
        if (!periodStart || !periodEnd) {
          errors.push(`第${rowNum}行: 时间格式无法解析 "${row.periodStr}"`);
          skipped++;
          continue;
        }
        if (!this.isValidDate(periodStart) || !this.isValidDate(periodEnd) || periodEnd < periodStart) {
          errors.push(`第${rowNum}行: ${row.roomNumber} 账期无效（${periodStart} ~ ${periodEnd}），已跳过`);
          skipped++;
          continue;
        }

        // 关键校验：电费 + 水费 都为 0 时，多半是 Excel 公式未正确计算或字段缺失，
        // 必须给出明确错误，避免出现"提示成功但无数据"的迷之现象。
        if ((row.electricityFee || 0) <= 0 && (row.waterFee || 0) <= 0) {
          errors.push(
            `第${rowNum}行: ${row.roomNumber} 电费和水费均为 0，可能 Excel 中是未生效的公式（请打开文件让公式重算后再保存导入），已跳过`,
          );
          skipped++;
          continue;
        }

        const existing = await this.roomExpRepo.find({
          where: [
            { importKey: `${room.id}:${periodStart}:${periodEnd}:electricity` },
            { importKey: `${room.id}:${periodStart}:${periodEnd}:water` },
          ],
        });
        const byType = new Map(existing.map((expense) => [expense.expenseType, expense]));

        let savedAny = false;
        if (row.electricityFee > 0) {
          await this.importUtilityExpense(
            room.id,
            'electricity',
            periodStart,
            periodEnd,
            row.electricityFee,
            `电量${row.electricityAmount}kWh`,
            byType,
            userId!,
          );
          savedAny = true;
        }

        if (row.waterFee > 0) {
          await this.importUtilityExpense(
            room.id,
            'water',
            periodStart,
            periodEnd,
            row.waterFee,
            `用水${row.waterAmount}吨`,
            byType,
            userId!,
          );
          savedAny = true;
        }

        if (savedAny) imported++;
        else {
          skipped++;
          errors.push(`第${rowNum}行: ${row.roomNumber} 无有效金额`);
        }
      } catch (e: any) {
        errors.push(`第${rowNum}行: ${row.roomNumber} 导入失败 - ${e.message}`);
        skipped++;
      }
    }

    return {
      message:
        imported > 0
          ? `成功导入 ${imported} 间宿舍水电费${skipped > 0 ? `，跳过 ${skipped} 条` : ''}`
          : `未导入任何记录${skipped > 0 ? `，共 ${skipped} 条被跳过` : ''}`,
      imported,
      skipped,
      errors: errors.length > 0 ? errors : undefined,
    };
  }

  private async importUtilityExpense(
    roomId: number,
    expenseType: 'electricity' | 'water',
    periodStart: string,
    periodEnd: string,
    amount: number,
    description: string,
    byType: Map<string, RoomExpense>,
    recordedBy: number,
  ): Promise<void> {
    const expense = byType.get(expenseType) || this.roomExpRepo.create({
      roomId,
      expenseType,
      periodStart,
      periodEnd,
      importKey: `${roomId}:${periodStart}:${periodEnd}:${expenseType}`,
    });
    if (expense.id && await this.dataSource?.getRepository('bill_items').count({ where: { roomExpenseId: expense.id } })) {
      throw new BadRequestException(`该周期${expenseType === 'electricity' ? '电费' : '水费'}已计入账单，不能覆盖`);
    }
    expense.amount = amount;
    expense.description = description;
    expense.recordedBy = recordedBy;
    await this.roomExpRepo.save(expense);
  }

  /** 把 2026/4/1、2026-4-1 之类格式归一化为 YYYY-MM-DD */
  private normalizeDate(s: string): string {
    if (!s) return '';
    if (/^\d{4}-\d{2}-\d{2}$/.test(s)) return s;
    const m = s.match(/(\d{4})[-/.](\d{1,2})[-/.](\d{1,2})/);
    if (m) return `${m[1]}-${m[2].padStart(2, '0')}-${m[3].padStart(2, '0')}`;
    return s;
  }

  /**
   * 个人附加费Excel批量导入
   * Excel格式: 学生姓名|费用类型|金额|费用日期|说明
   */
  async batchImportPersonalExpenses(
    rows: {
      studentName: string;
      expenseType: string;
      amount: number;
      expenseDate: string;
      description?: string;
    }[],
    userId?: number,
  ) {
    let imported = 0;
    let skipped = 0;
    const errors: string[] = [];


    for (let i = 0; i < rows.length; i++) {
      const row = rows[i];
      const rowNum = i + 2;

      if (!row.studentName?.trim()) {
        skipped++;
        continue;
      }

      try {
        // 查找学生
        const student = await this.studentRepo.findOne({ where: { name: row.studentName.trim() } });
        if (!student) {
          errors.push(`第${rowNum}行: 学生"${row.studentName}"未找到`);
          skipped++;
          continue;
        }

        // 解析费用类型
        const expenseType = row.expenseType?.trim() || '';
        if (!expenseType) {
          errors.push(`第${rowNum}行: 费用类型不能为空`);
          skipped++;
          continue;
        }

        // 解析日期
        let expenseDate = row.expenseDate?.trim() || '';
        if (!expenseDate.match(/^\d{4}-\d{2}-\d{2}$/)) {
          // 尝试从各种格式解析
          const dateMatch = expenseDate.match(/(\d{4})[-/](\d{1,2})[-/](\d{1,2})/);
          if (dateMatch) {
            expenseDate = `${dateMatch[1]}-${dateMatch[2].padStart(2, '0')}-${dateMatch[3].padStart(2, '0')}`;
          } else {
            errors.push(`第${rowNum}行: 日期格式"${row.expenseDate}"无效，需要YYYY-MM-DD`);
            skipped++;
            continue;
          }
        }

        // 校验金额
        try {
          this.assertPositiveAmount(row.amount);
        } catch (e: any) {
          errors.push(`第${rowNum}行: ${row.studentName} ${e.message}`);
          skipped++;
          continue;
        }

        await this.personalExpRepo.save(
          this.personalExpRepo.create({
            studentId: student.id,
            expenseType,
            amount: row.amount,
            expenseDate,
            description: row.description || undefined,
            recordedBy: userId,
          }),
        );

        imported++;
      } catch (e: any) {
        errors.push(`第${rowNum}行: ${row.studentName} 导入失败 - ${e.message}`);
        skipped++;
      }
    }

    return {
      message: `成功导入 ${imported} 条个人附加费，跳过 ${skipped} 条`,
      imported,
      skipped,
      errors: errors.length > 0 ? errors : undefined,
    };
  }
}