Implement user model and migration setup; add user data manipulation in Main class

Main.java

@@ -1,11 +1,37 @@
 import java.sql.Connection;
 import java.sql.SQLException;
+import java.util.List;
 
-import src.db.Database;
+import src.models.UserModel;
+import src.models.squirrel.Database;
+import src.models.squirrel.ModelManager;
 
 public class Main {
     public static void main(String[] args) throws SQLException {
+        ModelManager.initializeModels();
+        Database.migrate = conn -> src.Migration.run(conn);
+        Database.getConnection();
+
+        UserModel userModel = ModelManager.get(UserModel.class);
+        List<UserModel> users = userModel.where(java.util.Collections.emptyMap());
+        for (UserModel user : users) {
+            user.set("name", user.get("name") + " Updated");
+            user.save();
+            System.out.println(user);
+        }
+
         Connection conn = Database.getConnection();
+        // Example: Run a simple SQL query
+        try (var stmt = conn.createStatement();
+             var rs = stmt.executeQuery("SELECT COUNT(*) AS user_count FROM users")) {
+            if (rs.next()) {
+                int userCount = rs.getInt("user_count");
+                System.out.println("Total users: " + userCount);
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+
         Database.close();
     }
 }

src/Migration.java

@@ -0,0 +1,59 @@
+package src;
+
+import java.sql.Connection;
+import java.sql.Statement;
+
+public class Migration {
+    public static void run(Connection conn) {
+        try (Statement stmt = conn.createStatement()) {
+            stmt.execute("""
+                CREATE TABLE IF NOT EXISTS users (
+                    id INTEGER PRIMARY KEY AUTOINCREMENT,
+                    name TEXT NOT NULL,
+                    email TEXT NOT NULL UNIQUE,
+                    password_hash TEXT NOT NULL
+                )
+            """);
+
+            stmt.execute("""
+                CREATE TABLE IF NOT EXISTS accounts (
+                    id INTEGER PRIMARY KEY AUTOINCREMENT,
+                    owner_id INTEGER NOT NULL,
+                    type TEXT CHECK(type IN ('CHECKING','SAVINGS','CREDIT')) NOT NULL,
+                    account_number TEXT NOT NULL UNIQUE,
+                    bank_code TEXT NOT NULL,
+                    balance REAL NOT NULL DEFAULT 0,
+                    FOREIGN KEY(owner_id) REFERENCES users(id)
+                )
+            """);
+
+            stmt.execute("""
+                CREATE TABLE IF NOT EXISTS giro_accounts (
+                    id INTEGER PRIMARY KEY,
+                    overdraft_limit REAL DEFAULT 0,
+                    FOREIGN KEY(id) REFERENCES accounts(id) ON DELETE CASCADE
+                )
+            """);
+
+            stmt.execute("""
+                CREATE TABLE IF NOT EXISTS spar_accounts (
+                    id INTEGER PRIMARY KEY,
+                    interest_rate REAL DEFAULT 0,
+                    FOREIGN KEY(id) REFERENCES accounts(id) ON DELETE CASCADE
+                )
+            """);
+
+            stmt.execute("""
+                CREATE TABLE IF NOT EXISTS kredit_accounts (
+                    id INTEGER PRIMARY KEY,
+                    credit_limit REAL DEFAULT 0,
+                    repayment_plan TEXT,
+                    FOREIGN KEY(id) REFERENCES accounts(id) ON DELETE CASCADE
+                )
+            """);
+
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}

src/models/UserModel.java

@@ -0,0 +1,75 @@
+package src.models;
+
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.spec.PBEKeySpec;
+
+import src.models.squirrel.Model;
+import src.models.squirrel.ModelManager;
+
+import java.security.SecureRandom;
+import java.util.Base64;
+import java.util.Arrays;
+import java.util.Map;
+import java.util.List;
+
+public class UserModel extends Model {
+
+    {
+        tableName = "users";
+        columns.add("id");           
+        columns.add("name");         
+        columns.add("email");        
+        columns.add("password_hash");
+    }
+
+    private static final int ITERATIONS = 65536;
+    private static final int KEY_LENGTH = 256;
+
+    public static UserModel register(String name, String email, String password) {
+        if (password == null || password.trim().isEmpty()) {
+            throw new IllegalArgumentException("Password cannot be empty");
+        }
+
+        UserModel userModel = ModelManager.get(UserModel.class);
+        List<UserModel> existingUser = userModel.where(Map.of("email", email));
+        if (existingUser != null && !existingUser.isEmpty()) {
+            throw new IllegalArgumentException("Email already exists");
+        }
+
+        byte[] salt = getSalt();
+        UserModel user = new UserModel();
+
+        user.set("name", name);
+        user.set("email", email);
+        user.set("password_hash", hashPassword(password, salt));
+        user.create();
+        return user;
+    }
+
+    public static String hashPassword(String password, byte[] salt) {
+        try {
+            PBEKeySpec spec = new PBEKeySpec(password.toCharArray(), salt, ITERATIONS, KEY_LENGTH);
+            SecretKeyFactory skf = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
+            byte[] hash = skf.generateSecret(spec).getEncoded();
+            return Base64.getEncoder().encodeToString(hash);
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to hash password", e);
+        }
+    }
+
+    public static byte[] getSalt() {
+        SecureRandom sr = new SecureRandom();
+        byte[] salt = new byte[16];
+        sr.nextBytes(salt);
+        return salt;
+    }
+
+    public static boolean validatePassword(String password, String storedHash, byte[] salt) {
+        try {
+            String newHash = hashPassword(password, salt);
+            return Arrays.equals(Base64.getDecoder().decode(storedHash), Base64.getDecoder().decode(newHash));
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to validate password", e);
+        }
+    }
+}