import { DataSource, Repository, ObjectLiteral, DeepPartial } from 'typeorm';
import { z } from '@hono/zod-openapi';

export abstract class GenericCrudService<T extends ObjectLiteral> {
  protected repository: Repository<T>;
  
  constructor(
    protected dataSource: DataSource,
    protected entity: new () => T
  ) {
    this.repository = this.dataSource.getRepository(entity);
  }

  /**
   * 获取分页列表
   */
  /**
   * 获取分页列表，支持高级查询
   */
  async getList(
    page: number = 1,
    pageSize: number = 10,
    keyword?: string,
    searchFields?: string[],
    where?: Partial<T>,
    relations: string[] = [],
    order: { [P in keyof T]?: 'ASC' | 'DESC' } = {}
  ): Promise<[T[], number]> {
    const skip = (page - 1) * pageSize;
    const query = this.repository.createQueryBuilder('entity');
    
    // 关联查询
    if (relations.length > 0) {
      relations.forEach(relation => {
        query.leftJoinAndSelect(`entity.${relation}`, relation);
      });
    }
    
    // 关键词搜索
    if (keyword && searchFields && searchFields.length > 0) {
      query.andWhere(searchFields.map(field => `entity.${field} LIKE :keyword`).join(' OR '), {
        keyword: `%${keyword}%`
      });
    }
    
    // 条件查询
    if (where) {
      Object.entries(where).forEach(([key, value]) => {
        if (value !== undefined && value !== null) {
          query.andWhere(`entity.${key} = :${key}`, { [key]: value });
        }
      });
    }
    
    // 排序
    Object.entries(order).forEach(([key, direction]) => {
      query.orderBy(`entity.${key}`, direction);
    });
    
    return query.skip(skip).take(pageSize).getManyAndCount();
  }

  /**
   * 高级查询方法
   */
  createQueryBuilder(alias: string = 'entity') {
    return this.repository.createQueryBuilder(alias);
  }

  /**
   * 根据ID获取单个实体
   */
  async getById(id: number): Promise<T | null> {
    return this.repository.findOneBy({ id } as any);
  }

  /**
   * 创建实体
   */
  async create(data: DeepPartial<T>): Promise<T> {
    const entity = this.repository.create(data as DeepPartial<T>);
    return this.repository.save(entity);
  }

  /**
   * 更新实体
   */
  async update(id: number, data: Partial<T>): Promise<T | null> {
    await this.repository.update(id, data);
    return this.getById(id);
  }

  /**
   * 删除实体
   */
  async delete(id: number): Promise<boolean> {
    const result = await this.repository.delete(id);
    return result.affected === 1;
  }
}

export type CrudOptions<T extends ObjectLiteral> = {
  entity: new () => T;
  createSchema: z.ZodSchema;
  updateSchema: z.ZodSchema;
  getSchema: z.ZodSchema;
  listSchema: z.ZodSchema;
  searchFields?: string[];
  middleware?: any[];
};