import { ConflictException, Inject, Injectable, NotFoundException } from '@nestjs/common';
import { generateCode } from '../../../common/utils/generate-code.util';
import { CreateSurchargeTypeDto } from '../dto/create-surcharge-type.dto';
import { UpdateSurchargeTypeDto } from '../dto/update-surcharge-type.dto';
import { SurchargeType } from '../entities/surcharge-type.entity';
import {
  ISurchargeTypesRepository,
  SURCHARGE_TYPES_REPOSITORY,
} from '../interfaces/surcharge-types.repository.interface';

@Injectable()
export class SurchargeTypesService {
  constructor(
    @Inject(SURCHARGE_TYPES_REPOSITORY)
    private readonly repository: ISurchargeTypesRepository,
  ) {}

  /** List surcharge types with pagination. */
  async findAll(filter: {
    isActive?: boolean;
    page?: number;
    pageSize?: number;
  }): Promise<{ data: SurchargeType[]; meta: { total: number; page: number; pageSize: number; totalPages: number } }> {
    const page = filter.page ?? 1;
    const pageSize = filter.pageSize ?? 20;
    const where: Record<string, unknown> = {};
    if (filter.isActive !== undefined) where.isActive = filter.isActive;

    const [data, total] = await this.repository.findAndCount({
      where,
      relations: { rate: true },
      order: { label: 'ASC' },
      skip: (page - 1) * pageSize,
      take: pageSize,
    });
    return { data, meta: { total, page, pageSize, totalPages: Math.ceil(total / pageSize) } };
  }

  /** Get a single surcharge type by ID. */
  async findById(id: string): Promise<SurchargeType> {
    const entity = await this.repository.findById(id);
    if (!entity) throw new NotFoundException(`Surcharge type ${id} not found`);
    return entity;
  }

  /** Create a new surcharge type. */
  async create(dto: CreateSurchargeTypeDto): Promise<SurchargeType> {
    const code = generateCode(dto.label);
    const existing = await this.repository.findByCode(code);
    if (existing) throw new ConflictException(`Surcharge type with label "${dto.label}" conflicts with existing code "${code}"`);
    return this.repository.create({
      code,
      label: dto.label,
      triggerCondition: dto.triggerCondition as SurchargeType['triggerCondition'],
      rateId: dto.rateId,
      isActive: dto.isActive ?? true,
    });
  }

  /** Update an existing surcharge type. */
  async update(id: string, dto: UpdateSurchargeTypeDto): Promise<SurchargeType> {
    await this.findById(id);
    const patch: Partial<SurchargeType> = {};
    if (dto.label !== undefined) patch.label = dto.label;
    if (dto.triggerCondition !== undefined) patch.triggerCondition = dto.triggerCondition as SurchargeType['triggerCondition'];
    if (dto.rateId !== undefined) patch.rateId = dto.rateId;
    if (dto.isActive !== undefined) patch.isActive = dto.isActive;
    const updated = await this.repository.update(id, patch);
    if (!updated) throw new NotFoundException(`Surcharge type ${id} not found`);
    return updated;
  }

  /** Soft-delete a surcharge type. */
  async remove(id: string): Promise<void> {
    await this.findById(id);
    await this.repository.softDelete(id);
  }
}
