import { Injectable, Logger } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { toDateString, startOfDay } from '../common/utils/date.utils';

interface ToolResult {
  success: boolean;
  data?: any;
  error?: string;
  message?: string;
}

@Injectable()
export class CopilotFleetService {
  private readonly logger = new Logger(CopilotFleetService.name);

  constructor(private readonly prisma: PrismaService) {}

  async getAvailableVehicles(filters: Record<string, any>): Promise<ToolResult> {
    const where: any = { deletedAt: null, status: 'AVAILABLE' };

    if (filters.type) {
      where.type = filters.type;
    }

    if (filters.minSeats) {
      where.seatCapacity = { gte: filters.minSeats };
    }

    const vehicles = await this.prisma.vehicle.findMany({
      where,
      orderBy: [{ type: 'asc' }, { seatCapacity: 'desc' }],
    });

    return {
      success: true,
      data: vehicles,
      message: `Found ${vehicles.length} available vehicle(s).`,
    };
  }

  async assignVehicleToEvent(eventId: string, vehicleId: string): Promise<ToolResult> {
    const event = await this.prisma.scheduleEvent.findFirst({
      where: { id: eventId, deletedAt: null },
    });

    if (!event) {
      return { success: false, error: `Event with ID ${eventId} not found.` };
    }

    // If vehicleId is null, we're unassigning
    if (vehicleId === null || vehicleId === 'null') {
      const updatedEvent = await this.prisma.scheduleEvent.update({
        where: { id: eventId },
        data: { vehicleId: null },
        include: {
          driver: true,
        },
      });

      return {
        success: true,
        data: updatedEvent,
        message: `Vehicle unassigned from event "${updatedEvent.title}"`,
      };
    }

    // Verify vehicle exists
    const vehicle = await this.prisma.vehicle.findFirst({
      where: { id: vehicleId, deletedAt: null },
    });

    if (!vehicle) {
      return { success: false, error: `Vehicle with ID ${vehicleId} not found.` };
    }

    const updatedEvent = await this.prisma.scheduleEvent.update({
      where: { id: eventId },
      data: { vehicleId },
      include: {
        driver: true,
        vehicle: true,
      },
    });

    return {
      success: true,
      data: updatedEvent,
      message: `Vehicle ${vehicle.name} assigned to event "${updatedEvent.title}"`,
    };
  }

  async suggestVehicleForEvent(input: Record<string, any>): Promise<ToolResult> {
    const { eventId } = input;

    const event = await this.prisma.scheduleEvent.findFirst({
      where: { id: eventId, deletedAt: null },
    });

    if (!event) {
      return { success: false, error: `Event with ID ${eventId} not found.` };
    }

    // Fetch VIP info to determine party size
    const vips = await this.prisma.vIP.findMany({
      where: { id: { in: event.vipIds } },
      select: { id: true, name: true, partySize: true },
    });

    // Determine required capacity based on total party size
    const requiredSeats = vips.reduce((sum, v) => sum + (v.partySize || 1), 0);

    // Find vehicles not in use during this event time
    const busyVehicleIds = await this.prisma.scheduleEvent.findMany({
      where: {
        deletedAt: null,
        id: { not: eventId },
        status: { not: 'CANCELLED' },
        vehicleId: { not: null },
        OR: [
          {
            startTime: { lte: event.startTime },
            endTime: { gt: event.startTime },
          },
          {
            startTime: { lt: event.endTime },
            endTime: { gte: event.endTime },
          },
        ],
      },
      select: { vehicleId: true },
    });

    const busyIds = busyVehicleIds.map((e) => e.vehicleId).filter((id): id is string => id !== null);

    // Find available vehicles with sufficient capacity
    const suitableVehicles = await this.prisma.vehicle.findMany({
      where: {
        deletedAt: null,
        status: 'AVAILABLE',
        seatCapacity: { gte: requiredSeats },
        id: { notIn: busyIds },
      },
      orderBy: [
        { seatCapacity: 'asc' }, // Prefer smallest suitable vehicle
      ],
    });

    return {
      success: true,
      data: {
        eventId,
        eventTitle: event.title,
        vipNames: vips.map((v) => v.name),
        requiredSeats,
        suggestions: suitableVehicles.map((v) => ({
          id: v.id,
          name: v.name,
          type: v.type,
          seatCapacity: v.seatCapacity,
        })),
      },
      message:
        suitableVehicles.length > 0
          ? `Found ${suitableVehicles.length} suitable vehicle(s) for this event (requires ${requiredSeats} seat(s)).`
          : `No available vehicles found with capacity for ${requiredSeats} passenger(s) during this time.`,
    };
  }

  async getVehicleSchedule(input: Record<string, any>): Promise<ToolResult> {
    const { vehicleName, vehicleId, startDate, endDate } = input;

    let vehicle;

    if (vehicleId) {
      vehicle = await this.prisma.vehicle.findFirst({
        where: { id: vehicleId, deletedAt: null },
      });
    } else if (vehicleName) {
      const vehicles = await this.prisma.vehicle.findMany({
        where: {
          deletedAt: null,
          name: { contains: vehicleName, mode: 'insensitive' },
        },
      });

      if (vehicles.length === 0) {
        return { success: false, error: `No vehicle found matching "${vehicleName}".` };
      }

      if (vehicles.length > 1) {
        return {
          success: false,
          error: `Multiple vehicles match "${vehicleName}": ${vehicles.map((v) => v.name).join(', ')}. Please be more specific.`,
        };
      }

      vehicle = vehicles[0];
    } else {
      return { success: false, error: 'Either vehicleName or vehicleId is required.' };
    }

    if (!vehicle) {
      return { success: false, error: 'Vehicle not found.' };
    }

    const dateStart = startOfDay(new Date(startDate));
    const dateEnd = new Date(endDate);
    dateEnd.setHours(23, 59, 59, 999);

    const events = await this.prisma.scheduleEvent.findMany({
      where: {
        deletedAt: null,
        vehicleId: vehicle.id,
        startTime: { gte: dateStart, lte: dateEnd },
        status: { not: 'CANCELLED' },
      },
      include: {
        driver: true,
      },
      orderBy: { startTime: 'asc' },
    });

    // Fetch VIP names for all events
    const allVipIds = events.flatMap((e) => e.vipIds);
    const uniqueVipIds = [...new Set(allVipIds)];
    const vips = await this.prisma.vIP.findMany({
      where: { id: { in: uniqueVipIds } },
      select: { id: true, name: true },
    });
    const vipMap = new Map(vips.map((v) => [v.id, v.name]));

    const totalHours =
      events.reduce((sum, e) => {
        return sum + (e.endTime.getTime() - e.startTime.getTime());
      }, 0) / 3600000;

    return {
      success: true,
      data: {
        vehicle: {
          id: vehicle.id,
          name: vehicle.name,
          type: vehicle.type,
          seatCapacity: vehicle.seatCapacity,
          status: vehicle.status,
        },
        dateRange: {
          start: toDateString(dateStart),
          end: toDateString(dateEnd),
        },
        eventCount: events.length,
        totalHours: Math.round(totalHours * 10) / 10,
        events: events.map((e) => ({
          eventId: e.id,
          title: e.title,
          type: e.type,
          startTime: e.startTime,
          endTime: e.endTime,
          vipNames: e.vipIds.map((id) => vipMap.get(id) || 'Unknown'),
          driverName: e.driver?.name || null,
          pickupLocation: e.pickupLocation,
          dropoffLocation: e.dropoffLocation,
          location: e.location,
        })),
      },
      message: `Vehicle ${vehicle.name} has ${events.length} scheduled event(s) (${Math.round(totalHours * 10) / 10} hours total).`,
    };
  }

  async searchDrivers(filters: Record<string, any>): Promise<ToolResult> {
    const where: any = { deletedAt: null };

    if (filters.name) {
      where.name = { contains: filters.name, mode: 'insensitive' };
    }

    if (filters.department) {
      where.department = filters.department;
    }

    if (filters.availableOnly) {
      where.isAvailable = true;
    }

    const drivers = await this.prisma.driver.findMany({
      where,
      orderBy: { name: 'asc' },
    });

    return {
      success: true,
      data: drivers,
      message: `Found ${drivers.length} driver(s) matching the criteria.`,
    };
  }

  async getDriverSchedule(
    driverId: string,
    startDate?: string,
    endDate?: string,
  ): Promise<ToolResult> {
    const driver = await this.prisma.driver.findFirst({
      where: { id: driverId, deletedAt: null },
    });

    if (!driver) {
      return { success: false, error: `Driver with ID ${driverId} not found.` };
    }

    const where: any = {
      deletedAt: null,
      driverId,
      status: { not: 'CANCELLED' },
    };

    if (startDate) {
      where.startTime = { gte: new Date(startDate) };
    }

    if (endDate) {
      where.endTime = { lte: new Date(endDate) };
    }

    const events = await this.prisma.scheduleEvent.findMany({
      where,
      include: {
        vehicle: true,
      },
      orderBy: { startTime: 'asc' },
    });

    // Fetch VIP names for all events
    const allVipIds = events.flatMap((e) => e.vipIds);
    const uniqueVipIds = [...new Set(allVipIds)];
    const vips = await this.prisma.vIP.findMany({
      where: { id: { in: uniqueVipIds } },
      select: { id: true, name: true },
    });
    const vipMap = new Map(vips.map((v) => [v.id, v.name]));

    const eventsWithVipNames = events.map((event) => ({
      ...event,
      vipNames: event.vipIds.map((id) => vipMap.get(id) || 'Unknown'),
    }));

    return {
      success: true,
      data: {
        driver,
        events: eventsWithVipNames,
        eventCount: events.length,
      },
      message: `Driver ${driver.name} has ${events.length} scheduled event(s).`,
    };
  }

  async listAllDrivers(input: Record<string, any>): Promise<ToolResult> {
    const { includeUnavailable = true } = input;

    const where: any = { deletedAt: null };

    if (!includeUnavailable) {
      where.isAvailable = true;
    }

    const drivers = await this.prisma.driver.findMany({
      where,
      orderBy: { name: 'asc' },
      select: {
        id: true,
        name: true,
        phone: true,
        department: true,
        isAvailable: true,
      },
    });

    return {
      success: true,
      data: drivers,
      message: `Found ${drivers.length} driver(s) in the system.`,
    };
  }

  async findAvailableDriversForTimerange(input: Record<string, any>): Promise<ToolResult> {
    const { startTime, endTime, preferredDepartment } = input;

    // Get all drivers
    const where: any = { deletedAt: null, isAvailable: true };

    if (preferredDepartment) {
      where.department = preferredDepartment;
    }

    const allDrivers = await this.prisma.driver.findMany({
      where,
    });

    // Find drivers with conflicting events
    const busyDriverIds = await this.prisma.scheduleEvent.findMany({
      where: {
        deletedAt: null,
        driverId: { not: null },
        status: { not: 'CANCELLED' },
        OR: [
          {
            startTime: { lte: new Date(startTime) },
            endTime: { gt: new Date(startTime) },
          },
          {
            startTime: { lt: new Date(endTime) },
            endTime: { gte: new Date(endTime) },
          },
        ],
      },
      select: { driverId: true },
    });

    const busyIds = new Set(busyDriverIds.map((e) => e.driverId));

    const availableDrivers = allDrivers.filter((d) => !busyIds.has(d.id));

    return {
      success: true,
      data: availableDrivers,
      message: `Found ${availableDrivers.length} available driver(s) for the specified time range.`,
    };
  }

  async updateDriver(input: Record<string, any>): Promise<ToolResult> {
    const { driverId, ...updates } = input;

    const existingDriver = await this.prisma.driver.findFirst({
      where: { id: driverId, deletedAt: null },
    });

    if (!existingDriver) {
      return { success: false, error: `Driver with ID ${driverId} not found.` };
    }

    const updateData: any = {};
    if (updates.name !== undefined) updateData.name = updates.name;
    if (updates.phone !== undefined) updateData.phone = updates.phone;
    if (updates.department !== undefined) updateData.department = updates.department;
    if (updates.isAvailable !== undefined) updateData.isAvailable = updates.isAvailable;
    if (updates.shiftStartTime !== undefined) updateData.shiftStartTime = updates.shiftStartTime;
    if (updates.shiftEndTime !== undefined) updateData.shiftEndTime = updates.shiftEndTime;

    const driver = await this.prisma.driver.update({
      where: { id: driverId },
      data: updateData,
    });

    this.logger.log(`Driver updated: ${driverId}`);

    return {
      success: true,
      data: driver,
      message: `Driver ${driver.name} updated successfully.`,
    };
  }
}