refactor: migrate backend framework from Express to NestJS

src/database/database.service.ts

@@ -0,0 +1,59 @@
+import { Injectable, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import Database from 'better-sqlite3';
+import * as path from 'path';
+import * as fs from 'fs';
+
+@Injectable()
+export class DatabaseService implements OnModuleInit, OnModuleDestroy {
+  private db: Database.Database;
+  private dbPath: string;
+
+  constructor(private configService: ConfigService) {}
+
+  onModuleInit() {
+    this.dbPath = this.configService.get<string>('DB_PATH', path.join(process.cwd(), 'data/database.sqlite'));
+    const dbDir = path.dirname(this.dbPath);
+    
+    if (!fs.existsSync(dbDir)) {
+      fs.mkdirSync(dbDir, { recursive: true });
+    }
+    
+    this.db = new Database(this.dbPath, { verbose: console.log });
+  }
+
+  onModuleDestroy() {
+    this.db.close();
+  }
+
+  get<T = any>(sql: string, params: any[] = []): T | undefined {
+    try {
+      const stmt = this.db.prepare(sql);
+      return stmt.get(params) as T | undefined;
+    } catch (error) {
+      console.error('数据库查询错误:', error);
+      throw error;
+    }
+  }
+
+  all<T = any>(sql: string, params: any[] = []): T[] {
+    try {
+      const stmt = this.db.prepare(sql);
+      return stmt.all(params) as T[];
+    } catch (error) {
+      console.error('数据库查询错误:', error);
+      throw error;
+    }
+  }
+
+  run(sql: string, params: any[] = []): { id: number; changes: number } {
+    try {
+      const stmt = this.db.prepare(sql);
+      const result = stmt.run(params);
+      return { id: result.lastInsertRowid as number, changes: result.changes };
+    } catch (error) {
+      console.error('数据库操作错误:', error);
+      throw error;
+    }
+  }
+}