first commit

src/modules/likes/likes.service.ts

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+import { Injectable, NotFoundException } from '@nestjs/common';
+import { CommentsRepository } from '../comments/comments.repository';
+import { PostsRepository } from '../posts/posts.repository';
+import { LikesRepository } from './likes.repository';
+import { ToggleLikeDto } from './dto/toggle-like.dto';
+
+@Injectable()
+export class LikesService {
+  constructor(
+    private readonly likesRepository: LikesRepository,
+    private readonly postsRepository: PostsRepository,
+    private readonly commentsRepository: CommentsRepository,
+  ) {}
+
+  async toggle(userId: string, dto: ToggleLikeDto): Promise<{ liked: boolean; targetId: string; targetType: string }> {
+    const existing = await this.likesRepository.findOne(userId, dto.targetId, dto.targetType);
+    return existing ? this.unlike(userId, dto) : this.like(userId, dto);
+  }
+
+  async like(userId: string, dto: ToggleLikeDto): Promise<{ liked: boolean; targetId: string; targetType: string }> {
+    await this.assertTargetExists(dto);
+
+    const existing = await this.likesRepository.findOne(userId, dto.targetId, dto.targetType);
+    if (existing) {
+      return { liked: true, targetId: dto.targetId, targetType: dto.targetType };
+    }
+
+    await this.likesRepository.create(userId, dto.targetId, dto.targetType);
+    if (dto.targetType === 'post') {
+      await this.postsRepository.incrementLikesCount(dto.targetId, 1);
+    }
+
+    return { liked: true, targetId: dto.targetId, targetType: dto.targetType };
+  }
+
+  async unlike(userId: string, dto: ToggleLikeDto): Promise<{ liked: boolean; targetId: string; targetType: string }> {
+    await this.assertTargetExists(dto);
+
+    const existing = await this.likesRepository.findOne(userId, dto.targetId, dto.targetType);
+    if (!existing) {
+      return { liked: false, targetId: dto.targetId, targetType: dto.targetType };
+    }
+
+    await this.likesRepository.deleteById(existing.id);
+    if (dto.targetType === 'post') {
+      await this.postsRepository.incrementLikesCount(dto.targetId, -1);
+    }
+
+    return { liked: false, targetId: dto.targetId, targetType: dto.targetType };
+  }
+
+  async getStatus(userId: string, dto: ToggleLikeDto): Promise<{ liked: boolean; targetId: string; targetType: string }> {
+    const targetExists = await this.targetExists(dto);
+    if (!targetExists) {
+      return { liked: false, targetId: dto.targetId, targetType: dto.targetType };
+    }
+
+    const existing = await this.likesRepository.findOne(userId, dto.targetId, dto.targetType);
+    return { liked: !!existing, targetId: dto.targetId, targetType: dto.targetType };
+  }
+
+  private async assertTargetExists(dto: ToggleLikeDto): Promise<void> {
+    const targetExists = await this.targetExists(dto);
+    if (!targetExists) {
+      throw new NotFoundException(dto.targetType === 'post' ? 'Post not found' : 'Comment not found');
+    }
+  }
+
+  private async targetExists(dto: ToggleLikeDto): Promise<boolean> {
+    if (dto.targetType === 'post') {
+      const post = await this.postsRepository.findById(dto.targetId);
+      return !!post;
+    }
+
+    const comment = await this.commentsRepository.findById(dto.targetId);
+    return !!comment;
+  }
+}