feat: Implement PostgreSQL connection

packages/backend/src/apps/postgresql/index.ts

@@ -0,0 +1,38 @@
+import { Client } from 'pg';
+import App from '../../models/app';
+
+export default class PostgreSQL {
+  client: any
+  connectionData: any
+  appData: any
+
+  constructor(connectionData: any) {
+    this.client = new Client({
+      host: connectionData.host,
+      port: connectionData.port,
+      database: connectionData.database,
+      user: connectionData.username,
+      password: connectionData.password,
+    })
+
+    this.connectionData = connectionData;
+    this.appData = App.findOneByKey('postgresql');
+  }
+
+  async verifyCredentials() {
+    await this.client.connect()
+
+    return {
+      screenName: this.connectionData.database
+    }
+  }
+
+  async isStillVerified() {
+    try {
+      await this.client.connect()
+      return true;
+    } catch(error) {
+      return false
+    }
+  }
+}