import { BadRequestException, Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, IsNull, Not, MoreThanOrEqual, In } from 'typeorm';
import { Room } from '../entities/room.entity';
import { Student } from '../entities/student.entity';
import { Occupancy } from '../entities/occupancy.entity';
import { Bill } from '../entities/bill.entity';
import { RoomExpense } from '../entities/room-expense.entity';
import { Classroom } from '../entities/classroom.entity';
import { ClassSchedule } from '../entities/class-schedule.entity';
import { AttendanceRecord } from '../entities/attendance-record.entity';
import { Class } from '../entities/class.entity';
import { Deposit } from '../entities/deposit.entity';
import { ClassroomRental } from '../entities/classroom-rental.entity';
import { ClassTeacher } from '../entities/class-teacher.entity';
import { ClassStudent } from '../entities/class-student.entity';

@Injectable()
export class DashboardService {
  constructor(
    @InjectRepository(Room) private roomRepo: Repository<Room>,
    @InjectRepository(Student) private studentRepo: Repository<Student>,
    @InjectRepository(Occupancy) private occRepo: Repository<Occupancy>,
    @InjectRepository(Bill) private billRepo: Repository<Bill>,
    @InjectRepository(RoomExpense) private expRepo: Repository<RoomExpense>,
    @InjectRepository(Classroom) private classroomRepo: Repository<Classroom>,
    @InjectRepository(ClassSchedule) private scheduleRepo: Repository<ClassSchedule>,
    @InjectRepository(AttendanceRecord) private attendanceRepo: Repository<AttendanceRecord>,
    @InjectRepository(Class) private classRepo: Repository<Class>,
    @InjectRepository(Deposit) private depositRepo: Repository<Deposit>,
    @InjectRepository(ClassroomRental) private rentalRepo: Repository<ClassroomRental>,
    @InjectRepository(ClassTeacher) private classTeacherRepo: Repository<ClassTeacher>,
    @InjectRepository(ClassStudent) private classStudentRepo: Repository<ClassStudent>,
  ) {}

  async getAccessibleClassIds(userId: number, canManageAll = false): Promise<number[] | undefined> {
    if (canManageAll) return undefined;
    const assignments = await this.classTeacherRepo.find({ where: { userId } });
    return [...new Set(assignments.map((assignment) => assignment.classId))];
  }

  async getStats(accessibleClassIds?: number[]) {
    const todayStr = this.getChinaDate(new Date());
    const currentMonth = todayStr.slice(0, 7); // YYYY-MM

    const totalRooms = await this.roomRepo.count({ where: { status: Not('archived') } });
    const totalStudents = accessibleClassIds
      ? await this.countStudentsInClasses(accessibleClassIds)
      : await this.studentRepo.count({ where: { status: 'active' } });
    const occupiedBeds = await this.occRepo.count({ where: { checkOutDate: IsNull() } });
    const capQb = this.roomRepo
      .createQueryBuilder('r')
      .select('SUM(r.capacity)', 'total')
      .where('r.status != :archived', { archived: 'archived' });
    const totalCapacity = await capQb.getRawOne();
    const cap = totalCapacity?.total || 0;
    const occupancyRate = cap > 0 ? ((occupiedBeds / cap) * 100).toFixed(1) : 0;

    const billStatsQb = this.billRepo
      .createQueryBuilder('b')
      .select('b.status', 'status')
      .addSelect('COUNT(*)', 'count')
      .addSelect('SUM(b.totalAmount)', 'total')
      .groupBy('b.status');
    const billStats = await billStatsQb.getRawMany();

    // New fields
    const classroomCount = await this.classroomRepo.count({ where: {} });

    const occQb = this.scheduleRepo
      .createQueryBuilder('s')
      .select('COUNT(DISTINCT s.classroomId)', 'cnt')
      .where('s.status = :active', { active: 'active' })
      .andWhere('s.startDate <= :today', { today: todayStr })
      .andWhere('s.endDate >= :today', { today: todayStr });
    const occResult = await occQb.getRawOne();
    const occupiedClassrooms = parseInt(occResult?.cnt || '0', 10);
    const classroomOccupancyRate =
      classroomCount > 0 ? ((occupiedClassrooms / classroomCount) * 100).toFixed(1) : 0;

    const attTodayQb = this.attendanceRepo
      .createQueryBuilder('a')
      .select('a.status', 'status')
      .addSelect('COUNT(*)', 'count')
      .where('a.attendanceDate = :today', { today: todayStr });
    this.applyClassScope(attTodayQb, 'a', accessibleClassIds);
    attTodayQb.groupBy('a.status');
    const attTodayStats = await attTodayQb.getRawMany();
    const todayTotal = attTodayStats.reduce((sum, r) => sum + parseInt(r.count, 10), 0);
    const todayPresent = attTodayStats
      .filter((r) => r.status === 'present')
      .reduce((sum, r) => sum + parseInt(r.count, 10), 0);
    const todayAttendanceRate = todayTotal > 0 ? ((todayPresent / todayTotal) * 100).toFixed(1) : 0;

    const incomeQb = this.billRepo
      .createQueryBuilder('b')
      .select('SUM(b.totalAmount)', 'total')
      .where('b.status = :paid', { paid: 'paid' })
      .andWhere('b.periodStart >= :start', { start: `${currentMonth}-01` })
      .andWhere('b.periodStart < :end', { end: this.nextMonth(currentMonth) });
    const incomeResult = await incomeQb.getRawOne();
    const monthlyIncome = parseFloat(incomeResult?.total || '0');

    const attendanceTrend = await this.getAttendanceTrend(todayStr, accessibleClassIds);
    const incomeTrend = await this.getIncomeTrend(currentMonth);

    // --- New stats ---
    const classCount = accessibleClassIds
      ? accessibleClassIds.length
      : await this.classRepo.count({ where: {} });

    const teacherResult = await this.classTeacherRepo
      .createQueryBuilder('ct')
      .select('COUNT(DISTINCT ct.userId)', 'cnt')
      .getRawOne();
    const teacherCount = parseInt(teacherResult?.cnt || '0', 10);

    const pendingQb = this.depositRepo
      .createQueryBuilder('d')
      .select('SUM(d.amount)', 'total')
      .where('d.status = :paid', { paid: 'paid' });
    const pendingResult = await pendingQb.getRawOne();
    const pendingDeposits = parseFloat(pendingResult?.total || '0');

    const activeRentals = await this.rentalRepo.count({
      where: { status: 'active' as const, endDate: MoreThanOrEqual(todayStr) },
    });

    const occByBldQb = this.occRepo
      .createQueryBuilder('o')
      .leftJoin('o.room', 'r')
      .select('r.building', 'building')
      .addSelect('COUNT(*)', 'count')
      .where('o.checkOutDate IS NULL');
    const occupancyByBuilding = await occByBldQb.groupBy('r.building').getRawMany();

    const attendanceByStatus = attTodayStats.reduce(
      (acc, r) => {
        acc[r.status] = parseInt(r.count, 10);
        return acc;
      },
      {} as Record<string, number>,
    );

    const expByTypeQb = this.expRepo
      .createQueryBuilder('e')
      .select('e.expenseType', 'type')
      .addSelect('SUM(e.amount)', 'total')
      .where('e.periodStart >= :start', { start: `${currentMonth}-01` })
      .andWhere('e.periodEnd <= :end', { end: this.nextMonth(currentMonth) });
    const expenseByType = await expByTypeQb.groupBy('e.expenseType').getRawMany();

    return {
      totalRooms,
      totalStudents,
      occupiedBeds,
      totalCapacity: cap,
      occupancyRate,
      billStats,
      classroomCount,
      classroomOccupancyRate,
      todayPresent,
      monthlyIncome,
      classCount,
      teacherCount,
      pendingDeposits,
      activeRentals,
      occupancyByBuilding,
      attendanceByStatus,
      expenseByType,
      attendanceTrend,
      incomeTrend,
    };
  }

  private applyClassScope(
    qb: { andWhere: (condition: string, parameters?: Record<string, unknown>) => unknown },
    alias: string,
    accessibleClassIds?: number[],
  ) {
    if (accessibleClassIds) {
      if (accessibleClassIds.length === 0) {
        qb.andWhere('1 = 0');
        return;
      }
      qb.andWhere(`${alias}.classId IN (:...accessibleClassIds)`, { accessibleClassIds });
    }
  }

  private async countStudentsInClasses(accessibleClassIds: number[]) {
    if (accessibleClassIds.length === 0) return 0;
    const classStudents = await this.classStudentRepo.find({
      where: { classId: In(accessibleClassIds), status: 'active' },
    });
    return new Set(classStudents.map((item) => item.studentId)).size;
  }

  private async getAttendanceTrend(todayStr: string, accessibleClassIds?: number[]) {
    const thirtyDaysAgo = new Date(todayStr);
    thirtyDaysAgo.setDate(thirtyDaysAgo.getDate() - 29);
    const startStr = thirtyDaysAgo.toISOString().slice(0, 10);

    const trendQb = this.attendanceRepo
      .createQueryBuilder('a')
      .select('a.attendanceDate', 'date')
      .addSelect('a.status', 'status')
      .addSelect('COUNT(*)', 'count')
      .where('a.attendanceDate >= :start', { start: startStr })
      .andWhere('a.attendanceDate <= :today', { today: todayStr });
    this.applyClassScope(trendQb, 'a', accessibleClassIds);

    const rows = await trendQb
      .groupBy('a.attendanceDate')
      .addGroupBy('a.status')
      .orderBy('a.attendanceDate', 'ASC')
      .getRawMany();

    const dayMap = new Map<string, { total: number; present: number }>();
    for (const row of rows) {
      const d = dayMap.get(row.date) || { total: 0, present: 0 };
      const cnt = parseInt(row.count, 10);
      d.total += cnt;
      if (row.status === 'present') d.present += cnt;
      dayMap.set(row.date, d);
    }

    return Array.from(dayMap.entries()).map(([date, d]) => ({
      date,
      rate: d.total > 0 ? ((d.present / d.total) * 100).toFixed(1) : 0,
    }));
  }

  private async getIncomeTrend(currentMonth: string) {
    const results: { month: string; amount: number }[] = [];

    for (let i = 5; i >= 0; i--) {
      const d = new Date(`${currentMonth}-01`);
      d.setMonth(d.getMonth() - i);
      const m = d.toISOString().slice(0, 7);

      const row = await this.billRepo
        .createQueryBuilder('b')
        .select('SUM(b.totalAmount)', 'total')
        .where('b.status = :paid', { paid: 'paid' })
        .andWhere('b.periodStart >= :start', { start: `${m}-01` })
        .andWhere('b.periodStart < :end', { end: this.nextMonth(m) })
        .getRawOne();

      results.push({
        month: m,
        amount: parseFloat(row?.total || '0'),
      });
    }

    return results;
  }

  private nextMonth(ym: string): string {
    const d = new Date(`${ym}-01`);
    d.setMonth(d.getMonth() + 1);
    return d.toISOString().slice(0, 7) + '-01';
  }

  // 甘特图数据：每个宿舍的入住时间线
  async getGanttData(query?: { periodStart?: string; periodEnd?: string; building?: string }) {
    this.assertPeriodRange(query?.periodStart, query?.periodEnd);
    const qb = this.occRepo
      .createQueryBuilder('o')
      .leftJoinAndSelect('o.student', 'student')
      .leftJoinAndSelect('o.room', 'room')
      .where('room.status != :archived', { archived: 'archived' })
      .orderBy('room.roomNumber', 'ASC')
      .addOrderBy('o.checkInDate', 'ASC');

    if (query?.building) {
      qb.andWhere('room.building = :building', { building: query.building });
    }
    if (query?.periodStart) {
      qb.andWhere('(o.checkOutDate IS NULL OR o.checkOutDate >= :ps)', { ps: query.periodStart });
    }
    if (query?.periodEnd) {
      qb.andWhere('o.checkInDate <= :pe', { pe: query.periodEnd });
    }

    const records = await qb.getMany();

    // 按宿舍分组
    const roomMap = new Map<string, Record<string, unknown>[]>();
    for (const r of records) {
      const key = r.room?.roomNumber || String(r.roomId);
      if (!roomMap.has(key)) roomMap.set(key, []);
      roomMap.get(key)!.push({
        studentName: r.student?.name || '未知',
        studentId: r.studentId,
        checkInDate: r.checkInDate,
        checkOutDate: r.checkOutDate,
        billingStartDate: r.billingStartDate,
        billingEndDate: r.billingEndDate,
      });
    }

    return Array.from(roomMap.entries()).map(([roomNumber, occupancies]) => ({
      roomNumber,
      occupancies,
    }));
  }
  // 费用统计
  async getExpenseStats(periodStart?: string, periodEnd?: string) {
    this.assertPeriodRange(periodStart, periodEnd);
    const qb = this.expRepo
      .createQueryBuilder('e')
      .select('e.expenseType', 'type')
      .addSelect('SUM(e.amount)', 'total')
      .groupBy('e.expenseType');
    if (periodStart) qb.andWhere('e.periodStart >= :ps', { ps: periodStart });
    if (periodEnd) qb.andWhere('e.periodEnd <= :pe', { pe: periodEnd });
    return qb.getRawMany();
  }

  // 各宿舍费用排行
  async getRoomExpenseRanking(periodStart?: string, periodEnd?: string) {
    this.assertPeriodRange(periodStart, periodEnd);
    const qb = this.expRepo
      .createQueryBuilder('e')
      .leftJoin('e.room', 'room')
      .select('room.roomNumber', 'roomNumber')
      .addSelect('SUM(e.amount)', 'total')
      .where('room.status != :archived', { archived: 'archived' })
      .groupBy('e.roomId')
      .orderBy('total', 'DESC')
      .limit(20);
    if (periodStart) qb.andWhere('e.periodStart >= :ps', { ps: periodStart });
    if (periodEnd) qb.andWhere('e.periodEnd <= :pe', { pe: periodEnd });
    return qb.getRawMany();
  }

  // 班级考勤排行
  async getClassAttendanceRanking(accessibleClassIds?: number[]) {
    if (accessibleClassIds?.length === 0) return { top: [], bottom: [] };
    const qb = this.attendanceRepo
      .createQueryBuilder('a')
      .leftJoin('a.class', 'class')
      .select('class.id', 'classId')
      .addSelect('class.name', 'className')
      .addSelect('a.status', 'status')
      .addSelect('COUNT(*)', 'count');
    this.applyClassScope(qb, 'a', accessibleClassIds);
    qb.groupBy('class.id').addGroupBy('class.name').addGroupBy('a.status');
    const raw = await qb.getRawMany();

    const classMap = new Map<number, { className: string; present: number; total: number }>();
    for (const r of raw) {
      if (!r.classId) continue;
      if (!classMap.has(Number(r.classId)))
        classMap.set(Number(r.classId), { className: r.className, present: 0, total: 0 });
      const entry = classMap.get(Number(r.classId))!;
      const n = parseInt(r.count, 10);
      entry.total += n;
      if (r.status === 'present') entry.present += n;
    }

    const ranked = Array.from(classMap.values())
      .map((e) => ({
        ...e,
        rate: e.total > 0 ? parseFloat(((e.present / e.total) * 100).toFixed(1)) : 0,
      }))
      .sort((a, b) => b.rate - a.rate);

    return { top: ranked.slice(0, 5), bottom: ranked.slice(-5).reverse() };
  }

  async getClassroomOccupancy() {
    const classrooms = await this.classroomRepo.find({
      where: { status: 'available' as const },
      order: { building: 'ASC', name: 'ASC' },
    });
    const today = this.getChinaDate(new Date());
    const schedQb = this.scheduleRepo
      .createQueryBuilder('s')
      .select('s.classroomId', 'classroomId')
      .addSelect('COUNT(DISTINCT s.weekDay)', 'weekDays')
      .where('s.status = :active', { active: 'active' })
      .andWhere('s.scheduleType = :type', { type: 'INTERNAL' })
      .andWhere('s.startDate <= :today AND s.endDate >= :today', { today })
      .groupBy('s.classroomId');
    const schedules = await schedQb.getRawMany();
    const rentalQb = this.rentalRepo
      .createQueryBuilder('r')
      .select('r.classroomId', 'classroomId')
      .addSelect('COUNT(*)', 'rentalCount')
      .where('r.status = :active', { active: 'active' })
      .andWhere('r.startDate <= :today AND r.endDate >= :today', { today })
      .groupBy('r.classroomId');
    const rentals = await rentalQb.getRawMany();
    const sMap: Record<number, number> = {};
    const rMap: Record<number, number> = {};
    for (const s of schedules) sMap[s.classroomId] = parseInt(s.weekDays, 10);
    for (const r of rentals) rMap[r.classroomId] = parseInt(r.rentalCount, 10);
    return classrooms.map((c) => ({
      name: c.name,
      building: c.building || '',
      capacity: c.capacity,
      scheduleDays: sMap[c.id] || 0,
      rentalCount: rMap[c.id] || 0,
      occupancy: Math.min(((sMap[c.id] || 0) + (rMap[c.id] || 0) * 3) / 7, 1),
    }));
  }

  private assertPeriodRange(periodStart?: string, periodEnd?: string) {
    if (periodStart && periodEnd && periodStart > periodEnd) {
      throw new BadRequestException('结束日期不能早于开始日期');
    }
  }

  private getChinaDate(date: Date): string {
    const parts = new Intl.DateTimeFormat('en-CA', {
      timeZone: 'Asia/Shanghai',
      year: 'numeric',
      month: '2-digit',
      day: '2-digit',
    }).formatToParts(date);
    const values = Object.fromEntries(
      parts.filter((part) => part.type !== 'literal').map((part) => [part.type, part.value]),
    );
    return `${values.year}-${values.month}-${values.day}`;
  }

  async getClassroomUtilizationStats() {
    const totalClassrooms = await this.classroomRepo.count({
      where: { status: 'available' as const },
    });

    const today = this.getChinaDate(new Date());

    // Count classrooms with active schedules today
    const schedQb = this.scheduleRepo
      .createQueryBuilder('s')
      .select('COUNT(DISTINCT s.classroomId)', 'cnt')
      .where('s.status = :active', { active: 'active' })
      .andWhere('s.scheduleType = :type', { type: 'INTERNAL' })
      .andWhere('s.startDate <= :today AND s.endDate >= :today', { today });
    const schedResult = await schedQb.getRawOne();

    // Count classrooms with active rentals today
    const rentalQb = this.rentalRepo
      .createQueryBuilder('r')
      .select('COUNT(DISTINCT r.classroomId)', 'cnt')
      .where('r.status = :active', { active: 'active' })
      .andWhere('r.startDate <= :today AND r.endDate >= :today', { today });
    const rentalResult = await rentalQb.getRawOne();

    // Combine: use Set merge of both
    const combinedQb = this.scheduleRepo
      .createQueryBuilder('s')
      .select('s.classroomId')
      .where('s.status = :active', { active: 'active' })
      .andWhere('s.scheduleType = :type', { type: 'INTERNAL' })
      .andWhere('s.startDate <= :today AND s.endDate >= :today', { today })
      .groupBy('s.classroomId');
    const schedIds = await combinedQb.getRawMany();

    const combinedRentalQb = this.rentalRepo
      .createQueryBuilder('r')
      .select('r.classroomId')
      .where('r.status = :active', { active: 'active' })
      .andWhere('r.startDate <= :today AND r.endDate >= :today', { today })
      .groupBy('r.classroomId');
    const rentalIds = await combinedRentalQb.getRawMany();

    const allInUseIds = new Set([
      ...schedIds.map((s) => s.classroomId),
      ...rentalIds.map((r) => r.classroomId),
    ]);

    const scheduleCount = parseInt(schedResult?.cnt || '0', 10);
    const rentalCount = parseInt(rentalResult?.cnt || '0', 10);
    const inUseCount = allInUseIds.size;
    const utilizationRate =
      totalClassrooms > 0 ? ((inUseCount / totalClassrooms) * 100).toFixed(1) : '0';

    return {
      totalClassrooms,
      inUseCount,
      utilizationRate,
      scheduleCount,
      rentalCount,
    };
  }
}