feat(auth): implement user authentication system

backend/node_modules/mysql2/lib/promise/pool_cluster.js

@@ -0,0 +1,54 @@
+'use strict';
+
+const PromisePoolConnection = require('./pool_connection');
+const makeDoneCb = require('./make_done_cb');
+
+class PromisePoolNamespace {
+  constructor(poolNamespace, thePromise) {
+    this.poolNamespace = poolNamespace;
+    this.Promise = thePromise || Promise;
+  }
+
+  getConnection() {
+    const corePoolNamespace = this.poolNamespace;
+    return new this.Promise((resolve, reject) => {
+      corePoolNamespace.getConnection((err, coreConnection) => {
+        if (err) {
+          reject(err);
+        } else {
+          resolve(new PromisePoolConnection(coreConnection, this.Promise));
+        }
+      });
+    });
+  }
+
+  query(sql, values) {
+    const corePoolNamespace = this.poolNamespace;
+    const localErr = new Error();
+    if (typeof values === 'function') {
+      throw new Error(
+        'Callback function is not available with promise clients.'
+      );
+    }
+    return new this.Promise((resolve, reject) => {
+      const done = makeDoneCb(resolve, reject, localErr);
+      corePoolNamespace.query(sql, values, done);
+    });
+  }
+
+  execute(sql, values) {
+    const corePoolNamespace = this.poolNamespace;
+    const localErr = new Error();
+    if (typeof values === 'function') {
+      throw new Error(
+        'Callback function is not available with promise clients.'
+      );
+    }
+    return new this.Promise((resolve, reject) => {
+      const done = makeDoneCb(resolve, reject, localErr);
+      corePoolNamespace.execute(sql, values, done);
+    });
+  }
+}
+
+module.exports = PromisePoolNamespace;