import { Injectable, Logger } from '@nestjs/common';
import { InjectDataSource } from '@nestjs/typeorm';
import { DataSource } from 'typeorm';
import { PrismaService } from '../../common/prisma.service';
import { GenerateReportDto, ReportType } from './reports.dto';

@Injectable()
export class ReportsService {
  private readonly logger = new Logger(ReportsService.name);
  constructor(
    private prisma: PrismaService,
    @InjectDataSource() private dataSource: DataSource,
  ) {}

  async generateReport(dto: GenerateReportDto) {
    const dateFrom = new Date(dto.dateFrom);
    dateFrom.setHours(0, 0, 0, 0);
    
    const dateTo = new Date(dto.dateTo);
    dateTo.setHours(23, 59, 59, 999);

    let data: any;
    switch (dto.reportType) {
      case ReportType.REVENUE:
        data = await this.generateRevenueReport(dateFrom, dateTo);
        break;
      case ReportType.OCCUPANCY:
        data = await this.generateOccupancyReport(dateFrom, dateTo);
        break;
      case ReportType.AGENT_SALES:
        data = await this.generateAgentSalesReport(dateFrom, dateTo, dto.agentId);
        break;
      case ReportType.CANCELLATIONS:
        data = await this.generateCancellationsReport(dateFrom, dateTo);
        break;
      case ReportType.PAYMENT_METHODS:
        data = await this.generatePaymentMethodsReport(dateFrom, dateTo);
        break;
      default:
        data = {};
    }

    const report = await this.prisma.operationalReport.create({
      data: {
        reportType: dto.reportType,
        dateFrom,
        dateTo,
        data
      }
    });

    return { reportId: report.id, reportType: dto.reportType, data };
  }

  private async generateRevenueReport(dateFrom: Date, dateTo: Date) {
    // Fetch all bookings in date range, regardless of status
    const bookings = await this.prisma.booking.findMany({
      where: {
        createdAt: { gte: dateFrom, lte: dateTo }
      },
      include: { paymentIntent: true }
    });

    const totalRevenue = bookings.reduce((sum, b) => sum + b.totalMinor, 0);
    const byPaymentMethod = bookings.reduce((acc, b) => {
      const method = b.paymentIntent?.method ?? 'UNKNOWN';
      acc[method] = (acc[method] || 0) + b.totalMinor;
      return acc;
    }, {} as Record<string, number>);

    // Group by date for charts
    const byDate = bookings.reduce((acc, b) => {
      const date = b.createdAt.toISOString().split('T')[0];
      if (!acc[date]) {
        acc[date] = { totalMinor: 0, count: 0 };
      }
      acc[date].totalMinor += b.totalMinor;
      acc[date].count += 1;
      return acc;
    }, {} as Record<string, any>);

    return {
      totalBookings: bookings.length,
      totalRevenueMinor: totalRevenue,
      totalRevenue: totalRevenue / 100,
      currency: 'ETB',
      byPaymentMethod,
      byDate,
      cancellationRate: 0
    };
  }

  private async generateOccupancyReport(dateFrom: Date, dateTo: Date) {
    const schedules = await this.prisma.trainSchedule.findMany({
      where: { departureAt: { gte: dateFrom, lte: dateTo } },
      include: {
        coachAssignments: { include: { coach: { include: { seats: true } } } },
        bookings: { include: { seats: { where: { scheduleId: schedule.id } } } },
      },
    });

    const tripData = schedules.map(schedule => {
      const totalSeats = schedule.coachAssignments.reduce((sum, a) => sum + a.coach.seats.length, 0);
      const bookedSeats = schedule.bookings.reduce((sum, b) => sum + b.seats.length, 0);
      const occupancyRate = totalSeats > 0 ? (bookedSeats / totalSeats) * 100 : 0;
      return { scheduleId: schedule.id, departureAt: schedule.departureAt, totalSeats, bookedSeats, occupancyRate: +occupancyRate.toFixed(2) };
    });

    const avgOccupancy = tripData.length > 0 ? tripData.reduce((sum, t) => sum + t.occupancyRate, 0) / tripData.length : 0;
    return { totalSchedules: schedules.length, averageOccupancyRate: +avgOccupancy.toFixed(2), schedules: tripData };
  }

  private async generateAgentSalesReport(dateFrom: Date, dateTo: Date, agentId?: string) {
    const agentBookings = await this.prisma.agentBooking.findMany({
      where: {
        createdAt: { gte: dateFrom, lte: dateTo },
        ...(agentId ? { agentId } : {})
      },
      include: {
        agent: { select: { id: true, iamUserId: true, agentCode: true } },
        booking: true
      }
    });

    const iamUserIds = [...new Set(
      agentBookings.map(ab => ab.agent.iamUserId).filter(Boolean) as string[]
    )];
    const iamRows = iamUserIds.length > 0
      ? await this.dataSource.query<{ id: string; name: { en?: string; am?: string } | null }[]>(
          `SELECT id, name FROM iam.users WHERE id = ANY($1)`,
          [iamUserIds],
        )
      : [];
    const iamMap = new Map(iamRows.map(r => [r.id, r]));

    const byAgent = agentBookings.reduce((acc, ab) => {
      const iam = ab.agent.iamUserId ? iamMap.get(ab.agent.iamUserId) : undefined;
      const agentName = iam?.name?.en ?? iam?.name?.am ?? ab.agent.agentCode;
      if (!acc[agentName]) {
        acc[agentName] = { bookings: 0, revenueMinor: 0, cashCollected: 0 };
      }
      acc[agentName].bookings += 1;
      acc[agentName].revenueMinor += ab.booking.totalMinor;
      acc[agentName].cashCollected += ab.cashReceived ?? 0;
      return acc;
    }, {} as Record<string, any>);

    return {
      totalAgentBookings: agentBookings.length,
      byAgent
    };
  }

  private async generateCancellationsReport(dateFrom: Date, dateTo: Date) {
    const cancellations = await this.prisma.bookingCancellation.findMany({
      where: { createdAt: { gte: dateFrom, lte: dateTo } },
      include: { booking: true }
    });

    const totalRefunded = cancellations.reduce((sum, c) => sum + c.refundAmount, 0);

    return {
      totalCancellations: cancellations.length,
      totalRefundedMinor: totalRefunded,
      totalRefunded: totalRefunded / 100,
      currency: 'ETB'
    };
  }

  private async generatePaymentMethodsReport(dateFrom: Date, dateTo: Date) {
    const payments = await this.prisma.paymentIntent.findMany({
      where: {
        createdAt: { gte: dateFrom, lte: dateTo },
        status: 'SUCCEEDED'
      }
    });

    const byMethod = payments.reduce((acc, p) => {
      const method = p.method;
      if (!acc[method]) {
        acc[method] = { count: 0, totalMinor: 0 };
      }
      acc[method].count += 1;
      acc[method].totalMinor += p.amountMinor;
      return acc;
    }, {} as Record<string, any>);

    return {
      totalPayments: payments.length,
      byMethod
    };
  }

  async getOccupancyBySchedule(scheduleId: string) {
    const schedule = await this.prisma.trainSchedule.findUnique({
      where: { id: scheduleId },
      include: {
        originStation: true,
        destinationStation: true,
        train: true,
        coachAssignments: {
          include: {
            coach: {
              include: {
                coachType: true,
                seats: { select: { id: true } },
              },
            },
          },
        },
        bookings: {
          where: { status: { in: ['CONFIRMED', 'BOARDED'] } },
          include: {
            seats: {
              where: { scheduleId },
              include: {
                seat: { include: { coach: { include: { coachType: true } } } },
              },
            },
          },
        },
        stopTimes: { include: { station: true }, orderBy: { sequence: 'asc' } },
      },
    });

    if (!schedule) return null;

    const totalSeats = (schedule as any).coachAssignments.reduce((s: number, a: any) => s + a.coach.seats.length, 0);
    const allBookingSeats = (schedule as any).bookings.flatMap((b: any) => b.seats);
    const totalPassengers = allBookingSeats.length;
    const occupancyRate = totalSeats > 0 ? +((totalPassengers / totalSeats) * 100).toFixed(1) : 0;

    const coachMap = new Map<string, { coachNumber: string; coachType: string; totalSeats: number; booked: number }>();
    for (const assignment of (schedule as any).coachAssignments) {
      const c = assignment.coach;
      coachMap.set(c.id, { coachNumber: c.number, coachType: (c as any).coachType?.name ?? 'Unknown', totalSeats: c.seats.length, booked: 0 });
    }
    for (const bs of allBookingSeats) {
      const coachId = bs.seat?.coachId;
      if (coachId && coachMap.has(coachId)) coachMap.get(coachId)!.booked++;
    }
    const byCoach = [...coachMap.values()].map(c => ({ ...c, occupancyRate: c.totalSeats > 0 ? +((c.booked / c.totalSeats) * 100).toFixed(1) : 0 }));

    const originMap = new Map<string, { stationName: string; passengers: number }>();
    for (const booking of (schedule as any).bookings) {
      const stationId = booking.originStationId ?? schedule.originStationId;
      const stationName = (schedule as any).stopTimes.find((st: any) => st.stationId === stationId)?.station?.name ?? (schedule as any).originStation?.name ?? stationId;
      if (!originMap.has(stationId)) originMap.set(stationId, { stationName, passengers: 0 });
      originMap.get(stationId)!.passengers += booking.seats.length;
    }

    const destMap = new Map<string, { stationName: string; passengers: number }>();
    for (const booking of (schedule as any).bookings) {
      const stationId = booking.destinationStationId ?? schedule.destinationStationId;
      const stationName = (schedule as any).stopTimes.find((st: any) => st.stationId === stationId)?.station?.name ?? (schedule as any).destinationStation?.name ?? stationId;
      if (!destMap.has(stationId)) destMap.set(stationId, { stationName, passengers: 0 });
      destMap.get(stationId)!.passengers += booking.seats.length;
    }

    const classMap = new Map<string, { className: string; totalSeats: number; booked: number }>();
    for (const assignment of (schedule as any).coachAssignments) {
      const typeName = (assignment.coach as any).coachType?.name ?? 'Unknown';
      if (!classMap.has(typeName)) classMap.set(typeName, { className: typeName, totalSeats: 0, booked: 0 });
      classMap.get(typeName)!.totalSeats += assignment.coach.seats.length;
    }
    for (const bs of allBookingSeats) {
      const typeName = bs.seat?.coach?.coachType?.name ?? 'Unknown';
      if (!classMap.has(typeName)) classMap.set(typeName, { className: typeName, totalSeats: 0, booked: 0 });
      classMap.get(typeName)!.booked++;
    }
    const byClass = [...classMap.values()].map(c => ({ ...c, occupancyRate: c.totalSeats > 0 ? +((c.booked / c.totalSeats) * 100).toFixed(1) : 0 }));

    return {
      schedule: {
        id: schedule.id,
        trainName: (schedule as any).train?.name ?? (schedule as any).train?.number,
        origin: (schedule as any).originStation?.name,
        destination: (schedule as any).destinationStation?.name,
        departureAt: schedule.departureAt,
        arrivalAt: schedule.arrivalAt,
      },
      summary: { totalSeats, totalPassengers, occupancyRate },
      byCoach,
      byClass,
      byOrigin: [...originMap.values()].sort((a, b) => b.passengers - a.passengers),
      byDestination: [...destMap.values()].sort((a, b) => b.passengers - a.passengers),
    };
  }

  async listSchedulesForPicker() {
    const schedules = await this.prisma.trainSchedule.findMany({
      select: {
        id: true,
        departureAt: true,
        train: { select: { number: true } },
        originStation: { select: { name: true } },
        destinationStation: { select: { name: true } },
      },
      orderBy: { departureAt: 'desc' },
      take: 200,
    });
    return schedules.map(s => ({
      id: s.id,
      label: `${s.train.number} · ${s.originStation.name} → ${s.destinationStation.name} · ${new Date(s.departureAt).toLocaleString('en-GB', { dateStyle: 'medium', timeStyle: 'short' })}`,
    }));
  }

  async getPassengerList(scheduleId: string) {
    const seats = await this.prisma.bookingSeat.findMany({
      where: {
        scheduleId,
        booking: { status: { in: ['CONFIRMED', 'BOARDED'] } },
      },
      include: {
        booking: { select: { bookingRef: true, status: true } },
        seat: { include: { coach: { select: { number: true, coachType: { select: { name: true } } } } } },
      },
      orderBy: [{ seat: { coach: { number: 'asc' } } }],
    });
    return seats.map(bs => ({
      bookingRef: bs.booking.bookingRef,
      bookingStatus: bs.booking.status,
      passengerName: bs.passengerName,
      passengerCategory: bs.passengerCategory,
      idDocumentType: bs.idDocumentType,
      idDocumentNumber: bs.idDocumentNumber,
      passportNumber: bs.passportNumber,
      passportCountry: bs.passportCountry,
      seatLabel: bs.seatLabelSnapshot,
      coachNumber: bs.seat?.coach?.number ?? null,
      coachType: (bs.seat?.coach as any)?.coachType?.name ?? null,
    }));
  }

  async getReport(reportId: string) {
    return this.prisma.operationalReport.findUnique({ where: { id: reportId } });
  }

  async listReports(reportType?: string) {
    return this.prisma.operationalReport.findMany({
      where: reportType ? { reportType } : {},
      orderBy: { createdAt: 'desc' },
      take: 50
    });
  }
}