Add blog post admin CRUD API.

Expose JWT-protected /blog-posts endpoints for draft creation, listing, update, and delete.

backend/src/modules/blog/services/BlogPostsService.ts

@@ -0,0 +1,73 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import type { PaginatedResponse } from '../../../types/PaginatedResponse';
+import type { ListBlogPostsQueryDto } from '../dto/ListBlogPostsQueryDto';
+import { UpdateBlogPostDto } from '../dto/UpdateBlogPostDto';
+import { BlogPost } from '../entities/BlogPost';
+
+@Injectable()
+export class BlogPostsService {
+    constructor(
+        @InjectRepository(BlogPost)
+        private readonly blogPostRepo: Repository<BlogPost>
+    ) {}
+
+    async findAll({ page = 1, limit = 20 }: ListBlogPostsQueryDto): Promise<PaginatedResponse<BlogPost>> {
+        const [items, total] = await this.blogPostRepo.findAndCount({
+            order: { createdAt: 'DESC' },
+            skip: (page - 1) * limit,
+            take: limit
+        });
+
+        return { items, total, page, limit };
+    }
+
+    async createDraft(): Promise<BlogPost> {
+        const entity = this.blogPostRepo.create({
+            title: '',
+            contentHtml: '',
+            isDraft: true
+        });
+
+        await this.blogPostRepo.insert(entity);
+
+        return this.findOne(entity.id);
+    }
+
+    async findOne(id: string): Promise<BlogPost> {
+        const entity = await this.blogPostRepo.findOne({ where: { id } });
+
+        if (!entity) {
+            throw new NotFoundException();
+        }
+
+        return entity;
+    }
+
+    async update(id: string, { title, contentHtml, isDraft }: UpdateBlogPostDto): Promise<BlogPost> {
+        const exists = await this.blogPostRepo.exists({ where: { id } });
+
+        if (!exists) {
+            throw new NotFoundException();
+        }
+
+        await this.blogPostRepo.update(id, {
+            title: title.trim(),
+            contentHtml,
+            isDraft
+        });
+
+        return this.findOne(id);
+    }
+
+    async remove(id: string): Promise<void> {
+        const exists = await this.blogPostRepo.exists({ where: { id } });
+
+        if (!exists) {
+            throw new NotFoundException();
+        }
+
+        await this.blogPostRepo.delete(id);
+    }
+}