import { DataSource, Repository, In } from 'typeorm';
import debug from 'debug';
import { z } from '@hono/zod-openapi';
import { PostEntity as Post } from './post.entity';
import { FollowEntity } from '../follows/follow.entity';
import { UserEntity as User } from '../users/user.entity';
import { UserService } from '../users/user.service';
import type { CreatePostDto, UpdatePostDto } from './post.entity';
import { HTTPException } from 'hono/http-exception';
import { DeleteStatus } from '@/share/types';

const logger = debug('backend:posts:service');

export class PostService {
  private postRepository: Repository<Post>;
  private userRepository: Repository<User>;
  private userService: UserService;

  constructor(dataSource: DataSource) {
    this.postRepository = dataSource.getRepository(Post);
    this.userRepository = dataSource.getRepository(User);
    this.userService = new UserService(dataSource);
  }

  /**
   * 创建帖子
   */
  async createPost(userId: number, data: z.infer<typeof CreatePostDto>): Promise<Post> {
    // 验证用户是否存在
    const user = await this.userRepository.findOneBy({ id: userId });
    if (!user) {
      throw new Error('用户不存在');
    }

    const post = this.postRepository.create({
      userId,
      ...data,
      likesCount: 0,
      commentsCount: 0
    });

    const savedPost = await this.postRepository.save(post);
    return savedPost as unknown as Post;
  }

  /**
   * 获取帖子详情
   */
  async getPostById(id: number): Promise<Post | null> {
    const post = await this.postRepository.findOne({
      where: { id, isDeleted: DeleteStatus.NOT_DELETED },
      relations: ['user']
    });

    return post;
  }

  /**
   * 更新帖子
   */
  async updatePost(postId: number, userId: number, data: z.infer<typeof UpdatePostDto>): Promise<Post | null> {
    // 验证帖子是否存在且属于当前用户
    const post = await this.postRepository.findOneBy({
      id: postId,
      userId,
      isDeleted: DeleteStatus.NOT_DELETED
    });

    if (!post) {
      throw new Error('帖子不存在或没有权限');
    }

    Object.assign(post, data);
    return this.postRepository.save(post);
  }

  /**
   * 删除帖子（软删除）
   */
  async deletePost(postId: number, userId: number): Promise<boolean> {
    const result = await this.postRepository.update(
      { id: postId, userId, isDeleted: DeleteStatus.NOT_DELETED },
      { isDeleted: DeleteStatus.DELETED }
    );

    return (result.affected || 0) > 0;
  }

  /**
   * 获取用户帖子列表
   */
  async getUserPosts(userId: number, page: number = 1, pageSize: number = 10): Promise<[Post[], number]> {
    const skip = (page - 1) * pageSize;
    
    const [posts, total] = await this.postRepository.findAndCount({
      where: { userId, isDeleted: DeleteStatus.NOT_DELETED },
      relations: ['user'],
      skip,
      take: pageSize,
      order: { createdAt: 'DESC' }
    });

    return [posts, total];
  }

  /**
   * 获取关注用户的帖子流
   */
  async getFollowingFeed(followerId: number, page: number = 1, pageSize: number = 10): Promise<[Post[], number]> {
    const skip = (page - 1) * pageSize;
    
    // 直接查询关注用户的帖子，假设follow表存在且有关联
    logger('Building following feed query for followerId: %d, page: %d, pageSize: %d', followerId, page, pageSize);
    
    // 创建主查询用于获取分页数据
    const query = this.postRepository
      .createQueryBuilder('post')
      .leftJoin('follows', 'f', 'f.following_id = post.user_id')
      .where('f.follower_id = :followerId', { followerId })
      .andWhere('post.is_deleted = :notDeleted', { notDeleted: DeleteStatus.NOT_DELETED })
      .leftJoinAndSelect('post.user', 'user')
      .orderBy('post.created_at', 'DESC')
      .skip(skip)
      .take(pageSize);

    // 创建计数查询
    const countQuery = this.postRepository
      .createQueryBuilder('post')
      .leftJoin('follows', 'f', 'f.following_id = post.user_id')
      .where('f.follower_id = :followerId', { followerId })
      .andWhere('post.is_deleted = :notDeleted', { notDeleted: DeleteStatus.NOT_DELETED });

    // 记录生成的SQL和参数
    const sql = query.getSql();
    const parameters = query.getParameters();
    logger('Following feed query: %s', sql);
    logger('Query parameters: %o', parameters);
    
    const [posts, total] = await Promise.all([
      query.getRawMany(),
      countQuery.getCount()
    ]);
    
    logger('Following feed results: %d posts, total: %d', posts.length, total);
    return [posts, total];
  }

  /**
   * 点赞帖子
   */
  async likePost(postId: number): Promise<Post | null> {
    const post = await this.postRepository.findOneBy({
      id: postId,
      isDeleted: DeleteStatus.NOT_DELETED
    });

    if (!post) {
      throw new Error('帖子不存在');
    }

    post.likesCount += 1;
    return this.postRepository.save(post);
  }

  /**
   * 取消点赞帖子
   */
  async unlikePost(postId: number): Promise<Post | null> {
    const post = await this.postRepository.findOneBy({
      id: postId,
      isDeleted: DeleteStatus.NOT_DELETED
    });

    if (!post) {
      throw new Error('帖子不存在');
    }

    if (post.likesCount > 0) {
      post.likesCount -= 1;
      return this.postRepository.save(post);
    }

    return post;
  }

  /**
   * 根据用户ID列表获取帖子
   */
  async getPostsByUserIds(userIds: number[], page: number = 1, pageSize: number = 10): Promise<[Post[], number]> {
    const skip = (page - 1) * pageSize;
    
    const [posts, total] = await this.postRepository.findAndCount({
      where: {
        userId: In(userIds),
        isDeleted: DeleteStatus.NOT_DELETED
      },
      relations: ['user'],
      skip,
      take: pageSize,
      order: { createdAt: 'DESC' }
    });

    return [posts, total];
  }

  /**
   * 获取推荐用户的帖子
   */
  async getRecommendedPosts(currentUserId: number, page: number = 1, pageSize: number = 10): Promise<[Post[], number]> {
    // 获取推荐用户
    const recommendedUsers = await this.userService.getRecommendedUsers(currentUserId);
    const recommendedUserIds = recommendedUsers.map(u => u.id);
    
    if (recommendedUserIds.length > 0) {
      return this.getPostsByUserIds(recommendedUserIds, page, pageSize);
    }
    
    return [[], 0];
  }
  /**
   * 获取热门帖子（按点赞数和创建时间排序）
   */
  async getPopularPosts(page: number = 1, pageSize: number = 10): Promise<[Post[], number]> {
    const skip = (page - 1) * pageSize;
    
    const [posts, total] = await this.postRepository.findAndCount({
      where: { isDeleted: DeleteStatus.NOT_DELETED },
      relations: ['user'],
      skip,
      take: pageSize,
      order: { 
        likesCount: 'DESC', 
        createdAt: 'DESC' 
      }
    });

    return [posts, total];
  }

}