import { Injectable, NotFoundException } from '@nestjs/common';
import { PrismaService } from 'src/shared/services/prisma.service';
import { EventEmitter2 } from '@nestjs/event-emitter';
import { CreateServiceDto } from '../dto/create.service.dto';
import { UpdateServiceDto } from '../dto/update.service.dto';
import { CreatePlanDto } from '../dto/create.plan.dto';
import { UpdatePlanDto } from '../dto/update.plan.dto';
import { ServiceWithPlans, PlanEntity } from '../entities/service.entity';

@Injectable()
export class ServiceManagementService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly eventEmitter: EventEmitter2,
  ) {}

  // ==================== SERVICE METHODS ====================

  /**
   * Create a new service for a merchant
   */
  async createService(dto: CreateServiceDto): Promise<ServiceWithPlans> {
    // Check if merchant exists
    const merchant = await this.prisma.merchantPartner.findUnique({
      where: { id: dto.merchantPartnerId },
    });

    if (!merchant) {
      throw new NotFoundException(
        `Merchant with ID ${dto.merchantPartnerId} not found`,
      );
    }

    const service = await this.prisma.service.create({
      data: {
        name: dto.name,
        description: dto.description,
        merchantPartnerId: dto.merchantPartnerId,
      },
      include: {
        plans: true,
        merchantPartner: true,
      },
    });

    this.eventEmitter.emit('service.created', {
      serviceId: service.id,
      serviceName: service.name,
      merchantId: dto.merchantPartnerId,
      timestamp: new Date(),
    });

    return service;
  }

  /**
   * Find all services for a merchant
   */
  async findAllByMerchant(merchantId: number): Promise<ServiceWithPlans[]> {
    // Check if merchant exists
    const merchant = await this.prisma.merchantPartner.findUnique({
      where: { id: merchantId },
    });

    if (!merchant) {
      throw new NotFoundException(`Merchant with ID ${merchantId} not found`);
    }

    return this.prisma.service.findMany({
      where: { merchantPartnerId: merchantId },
      include: {
        plans: true,
        merchantPartner: true,
      },
      orderBy: {
        createdAt: 'desc',
      },
    });
  }

  /**
   * Find service by ID
   */
  async findOneService(id: number): Promise<ServiceWithPlans> {
    const service = await this.prisma.service.findUnique({
      where: { id },
      include: {
        plans: true,
        merchantPartner: true,
      },
    });

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

    return service;
  }

  /**
   * Update service
   */
  async updateService(
    id: number,
    dto: UpdateServiceDto,
  ): Promise<ServiceWithPlans> {
    await this.findOneService(id); // Check if exists

    const service = await this.prisma.service.update({
      where: { id },
      data: {
        name: dto.name,
        description: dto.description,
      },
      include: {
        plans: true,
        merchantPartner: true,
      },
    });

    this.eventEmitter.emit('service.updated', {
      serviceId: id,
      serviceName: service.name,
      timestamp: new Date(),
    });

    return service;
  }

  /**
   * Delete service
   */
  async removeService(id: number): Promise<void> {
    await this.findOneService(id); // Check if exists

    await this.prisma.service.delete({
      where: { id },
    });

    this.eventEmitter.emit('service.deleted', {
      serviceId: id,
      timestamp: new Date(),
    });
  }

  // ==================== PLAN METHODS ====================

  /**
   * Create a new plan for a service
   */
  async createPlan(
    serviceId: number,
    dto: CreatePlanDto,
  ): Promise<PlanEntity> {
    // Check if service exists
    await this.findOneService(serviceId);

    const plan = await this.prisma.plan.create({
      data: {
        name: dto.name,
        type: dto.type,
        amount: dto.amount,
        tax: dto.tax,
        currency: dto.currency,
        periodicity: dto.periodicity,
        serviceId,
      },
      include: {
        service: true,
      },
    });

    this.eventEmitter.emit('plan.created', {
      planId: plan.id,
      planName: plan.name,
      serviceId,
      amount: plan.amount,
      currency: plan.currency,
      timestamp: new Date(),
    });

    return plan;
  }

  /**
   * Find all plans for a service
   */
  async findAllPlansByService(serviceId: number): Promise<PlanEntity[]> {
    // Check if service exists
    await this.findOneService(serviceId);

    return this.prisma.plan.findMany({
      where: { serviceId },
      include: {
        service: true,
      },
      orderBy: {
        amount: 'asc',
      },
    });
  }

  /**
   * Find plan by ID
   */
  async findOnePlan(id: number): Promise<PlanEntity> {
    const plan = await this.prisma.plan.findUnique({
      where: { id },
      include: {
        service: true,
      },
    });

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

    return plan;
  }

  /**
   * Update plan
   */
  async updatePlan(id: number, dto: UpdatePlanDto): Promise<PlanEntity> {
    await this.findOnePlan(id); // Check if exists

    const plan = await this.prisma.plan.update({
      where: { id },
      data: {
        name: dto.name,
        type: dto.type,
        amount: dto.amount,
        tax: dto.tax,
        currency: dto.currency,
        periodicity: dto.periodicity,
      },
      include: {
        service: true,
      },
    });

    this.eventEmitter.emit('plan.updated', {
      planId: id,
      planName: plan.name,
      amount: plan.amount,
      timestamp: new Date(),
    });

    return plan;
  }

  /**
   * Delete plan
   */
  async removePlan(id: number): Promise<void> {
    await this.findOnePlan(id); // Check if exists

    await this.prisma.plan.delete({
      where: { id },
    });

    this.eventEmitter.emit('plan.deleted', {
      planId: id,
      timestamp: new Date(),
    });
  }
}