import { Injectable, NotFoundException, Logger } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { CreateVehicleDto, UpdateVehicleDto } from './dto';
import { executeHardDelete } from '../common/utils';

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

  private readonly vehicleInclude = {
    currentDriver: true,
    events: {
      where: { deletedAt: null },
      include: { driver: true, vehicle: true },
      orderBy: { startTime: 'asc' as const },
    },
  } as const;

  constructor(private prisma: PrismaService) {}

  async create(createVehicleDto: CreateVehicleDto) {
    this.logger.log(`Creating vehicle: ${createVehicleDto.name}`);

    return this.prisma.vehicle.create({
      data: createVehicleDto,
      include: this.vehicleInclude,
    });
  }

  async findAll() {
    return this.prisma.vehicle.findMany({
      where: { deletedAt: null },
      include: this.vehicleInclude,
      orderBy: { name: 'asc' },
    });
  }

  async findAvailable() {
    return this.prisma.vehicle.findMany({
      where: {
        deletedAt: null,
        status: 'AVAILABLE',
      },
      include: {
        currentDriver: true,
      },
      orderBy: { name: 'asc' },
    });
  }

  async findOne(id: string) {
    const vehicle = await this.prisma.vehicle.findFirst({
      where: { id, deletedAt: null },
      include: this.vehicleInclude,
    });

    if (!vehicle) {
      throw new NotFoundException(`Vehicle with ID ${id} not found`);
    }

    return vehicle;
  }

  async update(id: string, updateVehicleDto: UpdateVehicleDto) {
    const vehicle = await this.findOne(id);

    this.logger.log(`Updating vehicle ${id}: ${vehicle.name}`);

    return this.prisma.vehicle.update({
      where: { id: vehicle.id },
      data: updateVehicleDto,
      include: this.vehicleInclude,
    });
  }

  async remove(id: string, hardDelete = false, userRole?: string) {
    return executeHardDelete({
      id,
      hardDelete,
      userRole,
      findOne: (id) => this.findOne(id),
      performHardDelete: (id) => this.prisma.vehicle.delete({ where: { id } }),
      performSoftDelete: (id) =>
        this.prisma.vehicle.update({
          where: { id },
          data: { deletedAt: new Date() },
        }),
      entityName: 'Vehicle',
      logger: this.logger,
    });
  }

  /**
   * Get vehicle utilization statistics
   */
  async getUtilization() {
    const now = new Date();

    // Fetch vehicles with only upcoming events (filtered at database level)
    const vehicles = await this.prisma.vehicle.findMany({
      where: { deletedAt: null },
      include: {
        currentDriver: true,
        events: {
          where: {
            deletedAt: null,
            startTime: { gt: now }, // Only fetch upcoming events
          },
          include: { driver: true, vehicle: true },
          orderBy: { startTime: 'asc' },
        },
      },
      orderBy: { name: 'asc' },
    });

    const stats = vehicles.map((vehicle) => ({
      id: vehicle.id,
      name: vehicle.name,
      type: vehicle.type,
      seatCapacity: vehicle.seatCapacity,
      status: vehicle.status,
      upcomingTrips: vehicle.events.length, // Already filtered at DB level
      currentDriver: vehicle.currentDriver?.name,
    }));

    return {
      totalVehicles: vehicles.length,
      available: vehicles.filter((v) => v.status === 'AVAILABLE').length,
      inUse: vehicles.filter((v) => v.status === 'IN_USE').length,
      maintenance: vehicles.filter((v) => v.status === 'MAINTENANCE').length,
      reserved: vehicles.filter((v) => v.status === 'RESERVED').length,
      vehicles: stats,
    };
  }
}