018c - התחברות במייל ובסיסמה עם View Binding

 [versions]
+googleServices = "4.4.1"
+firebaseBom = "34.16.0"

 [libraries]
+firebase-bom = { group = "com.google.firebase", name = "firebase-bom", version.ref = "firebaseBom" }
+firebase-auth = { group = "com.google.firebase", name = "firebase-auth" }
+firebase-database = { group = "com.google.firebase", name = "firebase-database" }

 [plugins]
+google-services = { id = "com.google.gms.google-services", version.ref = "googleServices" }

 plugins {
     alias(libs.plugins.android.application)
+    alias(libs.plugins.google.services)
 }

 dependencies {
+    implementation(platform(libs.firebase.bom))
+    implementation(libs.firebase.auth)
+    implementation(libs.firebase.database)
 }

 import android.content.SharedPreferences;
 import android.os.Bundle;
-import android.os.Handler;
-import android.os.Looper;
+import android.text.TextUtils;
 import android.view.View;
 import android.widget.Toast;

 import com.example.tictacmenu.databinding.ActivityLoginBinding;
+import com.example.tictacmenu.services.FBRef;
 import com.example.tictacmenu.shell.MenuActivity;
+import com.google.firebase.auth.FirebaseUser;

 public class LoginActivity extends AppCompatActivity {

-    private static final long LOGIN_SHELL_DELAY_MS = 4000;
     private static final String PREFS_NAME = "PREFS_NAME";
     private static final String KEY_STAY_CONNECT = "stayConnect";

     private ActivityLoginBinding binding;
     private SharedPreferences settings;
-    private final Handler handler = new Handler(Looper.getMainLooper());
+    private boolean loginInProgress;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         EdgeToEdge.enable(this);
         binding = ActivityLoginBinding.inflate(getLayoutInflater());
         setContentView(binding.getRoot());

         ViewCompat.setOnApplyWindowInsetsListener(binding.main, (v, insets) -> {
             Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
             v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
             return insets;
         });

         settings = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
         binding.cBstayconnect.setChecked(settings.getBoolean(KEY_STAY_CONNECT, false));
         binding.cBstayconnect.setOnCheckedChangeListener((buttonView, isChecked) ->
                 settings.edit().putBoolean(KEY_STAY_CONNECT, isChecked).apply()
         );

-        handler.postDelayed(() -> {
-            settings.edit().putBoolean(KEY_STAY_CONNECT, binding.cBstayconnect.isChecked()).apply();
-            startActivity(new Intent(LoginActivity.this, MenuActivity.class));
-            finish();
-        }, LOGIN_SHELL_DELAY_MS);
+        setLoginInProgress(false);
+    }
+
+    @Override
+    protected void onStart() {
+        super.onStart();
+        boolean stayConnected = settings.getBoolean(KEY_STAY_CONNECT, false);
+        FirebaseUser currentUser = FBRef.refAuth.getCurrentUser();
+        if (currentUser != null && stayConnected) {
+            FBRef.getUser(currentUser);
+            openMenu();
+        }
     }

     public void onLoginClick(View view) {
-        Toast.makeText(this, "Email/password auth is added in a later lesson", Toast.LENGTH_SHORT).show();
+        if (loginInProgress) return;
+
+        String email = binding.eTemail.getText().toString().trim();
+        String password = binding.eTpass.getText().toString();
+
+        if (TextUtils.isEmpty(email)) {
+            binding.eTemail.setError("Enter e-mail");
+            binding.eTemail.requestFocus();
+            return;
+        }
+        if (TextUtils.isEmpty(password)) {
+            binding.eTpass.setError("Enter password");
+            binding.eTpass.requestFocus();
+            return;
+        }
+
+        setLoginInProgress(true);
+        FBRef.refAuth.signInWithEmailAndPassword(email, password)
+                .addOnCompleteListener(this, task -> {
+                    setLoginInProgress(false);
+                    if (task.isSuccessful()) {
+                        FirebaseUser user = FBRef.refAuth.getCurrentUser();
+                        if (user == null) {
+                            Toast.makeText(this, "Login succeeded but no user was returned", Toast.LENGTH_SHORT).show();
+                            return;
+                        }
+                        FBRef.getUser(user);
+                        settings.edit().putBoolean(KEY_STAY_CONNECT,
+                                binding.cBstayconnect.isChecked()).apply();
+                        Toast.makeText(this, "Login success", Toast.LENGTH_SHORT).show();
+                        openMenu();
+                        return;
+                    }
+                    String errorMessage = (task.getException() != null)
+                            ? task.getException().getLocalizedMessage()
+                            : "Login failed";
+                    Toast.makeText(this, "Login failed: " + errorMessage, Toast.LENGTH_LONG).show();
+                });
+    }
+
+    private void setLoginInProgress(boolean inProgress) {
+        loginInProgress = inProgress;
+        binding.btnLogin.setEnabled(!inProgress);
+        binding.btnLogin.setText(inProgress ? "Logging in..." : "Login");
+    }
+
+    private void openMenu() {
+        startActivity(new Intent(this, MenuActivity.class));
+        finish();
     }

     public void onGoogleLoginClick(View view) {
-        Toast.makeText(this, "Google sign-in is an advanced later phase", Toast.LENGTH_SHORT).show();
-    }
-
-    @Override
-    protected void onDestroy() {
-        super.onDestroy();
-        handler.removeCallbacksAndMessages(null);
+        Toast.makeText(this, "Google sign-in is added in 018d (requires SHA1)", Toast.LENGTH_SHORT).show();
     }
 }