import { ConflictException, Inject, Injectable, NotFoundException } from '@nestjs/common';
import { generateCode } from '../../../common/utils/generate-code.util';
import { CreatePriorityRuleDto } from '../dto/create-priority-rule.dto';
import { UpdatePriorityRuleDto } from '../dto/update-priority-rule.dto';
import { PriorityRule } from '../entities/priority-rule.entity';
import {
  IPriorityRulesRepository,
  PRIORITY_RULES_REPOSITORY,
} from '../interfaces/priority-rules.repository.interface';

@Injectable()
export class PriorityRulesService {
  constructor(
    @Inject(PRIORITY_RULES_REPOSITORY)
    private readonly repository: IPriorityRulesRepository,
  ) {}

  /** List priority rules with pagination. */
  async findAll(filter: {
    isActive?: boolean;
    page?: number;
    pageSize?: number;
  }): Promise<{ data: PriorityRule[]; 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,
      order: { label: 'ASC' },
      skip: (page - 1) * pageSize,
      take: pageSize,
    });
    return { data, meta: { total, page, pageSize, totalPages: Math.ceil(total / pageSize) } };
  }

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

  /** Create a new priority rule. */
  async create(dto: CreatePriorityRuleDto): Promise<PriorityRule> {
    const code = generateCode(dto.label);
    const existing = await this.repository.findAll({ where: { code } });
    if (existing.length > 0) {
      throw new ConflictException(`Priority rule with label "${dto.label}" conflicts with existing code "${code}"`);
    }
    return this.repository.create({
      code,
      label: dto.label,
      score: dto.score,
      conditionCurrency: dto.conditionCurrency ?? null,
      isActive: dto.isActive ?? false,
    });
  }

  /** Update an existing priority rule. */
  async update(id: string, dto: UpdatePriorityRuleDto): Promise<PriorityRule> {
    await this.findById(id);
    const { ...patch } = dto;
    const updated = await this.repository.update(id, patch);
    if (!updated) throw new NotFoundException(`Priority rule ${id} not found`);
    return updated;
  }

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