Restaurant Database Management System

src/main/java/dev/service/AuthService.java

@@ -1,23 +1,79 @@
 package dev.service;
 
+import dev.dao.UserDao;
 import dev.model.User;
 
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
 public class AuthService {
 
+    private final UserDao userDao = new UserDao();
+
+    /**
+     * Registers a new user. Checks the username is free and that the fields
+     * are not empty, then stores the password as a SHA-256 hash.
+     * Returns true only if the account was actually created.
+     */
     public boolean register(String username, String password, String email) {
 
-        // TODO:
-        // Validate and register user
+        if (username == null || username.isBlank()
+                || password == null || password.isBlank()) {
+            System.out.println("Username and password are required.");
+            return false;
+        }
 
-        return false;
+        // Username must be unique.
+        if (userDao.findByUsername(username) != null) {
+            System.out.println("That username is already taken.");
+            return false;
+        }
+
+        User user = new User();
+        user.setUsername(username);
+        user.setPassword(hash(password));      // never store plain text
+        user.setEmail(email == null || email.isBlank() ? null : email);
+
+        return userDao.save(user);
     }
 
+    /**
+     * Checks the given credentials against the database.
+     * Returns the User on success, or null if the username does not exist
+     * or the password is wrong.
+     */
     public User login(String username, String password) {
 
-        // TODO:
-        // Authenticate user
+        User user = userDao.findByUsername(username);
+        if (user == null) {
+            return null;   // no such username
+        }
 
-        return null;
+        // Hash the entered password and compare with the stored hash.
+        if (user.getPassword().equals(hash(password))) {
+            return user;
+        }
+
+        return null;       // wrong password
     }
 
-}
+    /** Hashes text with SHA-256 and returns it as a lowercase hex string. */
+    private String hash(String text) {
+        try {
+            MessageDigest digest = MessageDigest.getInstance("SHA-256");
+            byte[] bytes = digest.digest(text.getBytes(StandardCharsets.UTF_8));
+
+            StringBuilder sb = new StringBuilder();
+            for (byte b : bytes) {
+                sb.append(String.format("%02x", b));
+            }
+            return sb.toString();
+
+        } catch (NoSuchAlgorithmException e) {
+            // SHA-256 is always available, so this should never happen.
+            throw new RuntimeException("SHA-256 not available", e);
+        }
+    }
+
+}