Created the user controller

server/controller/user.js

@@ -0,0 +1,31 @@
+const User = require('../models/User');
+const bcrypt = require('bcrypt');
+const {Op} = require("sequelize");
+
+module.exports.createUser = async (username, email, password) => {
+    let user = await User.findOne({where: {[Op.or]: [{username}, {email}]}});
+    if (user !== null) return;
+
+    const salt = await bcrypt.genSalt(10);
+    const hashedPassword = await bcrypt.hash(password, salt);
+
+    await User.create({username, email, hashedPassword});
+}
+
+module.exports.authUser = async (username, password) => {
+    let user = await User.findOne({where: {username: username}});
+    if (user === null) return;
+
+    const isValid = await bcrypt.compare(password, user.password);
+    if (!isValid) return;
+
+    return user;
+}
+
+module.exports.getUserById = async (id) => {
+    return await User.findOne({where: {id}});
+}
+
+module.exports.getUserByName = async (username) => {
+    return await User.findOne({where: {username}});
+}