Refactoring the backend

backend/src/services/DatabaseService.ts

@@ -0,0 +1,38 @@
+import { Sequelize, QueryTypes } from "sequelize";
+
+export class DatabaseService {
+  private sequelize: Sequelize;
+
+  constructor() {
+    this.sequelize = new Sequelize({
+      dialect: "sqlite",
+      storage: "./data/database.sqlite",
+    });
+  }
+
+  async initialize(): Promise<void> {
+    try {
+      await this.sequelize.query("PRAGMA foreign_keys = OFF");
+      await this.cleanupBackupTables();
+      await this.sequelize.sync({ alter: true });
+      await this.sequelize.query("PRAGMA foreign_keys = ON");
+    } catch (error) {
+      throw new Error(`数据库初始化失败: ${(error as Error).message}`);
+    }
+  }
+
+  private async cleanupBackupTables(): Promise<void> {
+    const backupTables = await this.sequelize.query<{ name: string }>(
+      "SELECT name FROM sqlite_master WHERE type='table' AND name LIKE '%\\_backup%' ESCAPE '\\'",
+      { type: QueryTypes.SELECT }
+    );
+
+    for (const table of backupTables) {
+      if (table?.name) {
+        await this.sequelize.query(`DROP TABLE IF EXISTS ${table.name}`);
+      }
+    }
+  }
+
+  // ... 其他数据库相关方法
+}