feat: implement maintenance mode with dedicated activity and UI components

app/src/main/AndroidManifest.xml

@@ -38,6 +38,9 @@
         <activity
             android:name=".activity.VITEventsActivity"
             android:exported="false" />
+        <activity
+            android:name=".activity.MaintenanceActivity"
+            android:exported="false" />
         <activity
             android:name=".activity.NavigationActivity"
             android:exported="false" />

app/src/main/java/com/dscvit/vitty/activity/AuthActivity.kt

@@ -10,6 +10,7 @@ import android.view.View
 import android.widget.Toast
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.activity.OnBackPressedCallback
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.edit
 import androidx.databinding.DataBindingUtil
@@ -24,6 +25,7 @@ import com.dscvit.vitty.util.Constants.TOKEN
 import com.dscvit.vitty.util.Constants.UID
 import com.dscvit.vitty.util.Constants.USER_INFO
 import com.dscvit.vitty.util.NotificationPermissionHelper
+import com.dscvit.vitty.util.MaintenanceChecker
 import com.google.android.gms.auth.api.signin.GoogleSignIn
 import com.google.android.gms.auth.api.signin.GoogleSignInAccount
 import com.google.android.gms.auth.api.signin.GoogleSignInClient
@@ -62,6 +64,22 @@ class AuthActivity : AppCompatActivity() {
 
         configureGoogleSignIn()
         setupUI()
+        setupBackPressedHandler()
+    }
+
+    private fun setupBackPressedHandler() {
+        val callback = object : OnBackPressedCallback(true) {
+            override fun handleOnBackPressed() {
+                binding.apply {
+                    if (introPager.currentItem == 0 || loginClick) {
+                        finish()
+                    } else {
+                        introPager.currentItem--
+                    }
+                }
+            }
+        }
+        onBackPressedDispatcher.addCallback(this, callback)
     }
 
     private fun setupNotificationPermissionLauncher() {
@@ -266,8 +284,9 @@ class AuthActivity : AppCompatActivity() {
                     val email = firebaseAuth.currentUser?.email
                     Timber.d("Firebase authentication successful - uid: $uid, email: $email")
                     saveInfo(acct.idToken, uid)
-                    authViewModel.signInAndGetTimeTable("", "", uid ?: "", "")
-                    leadToNextPage()
+
+                    // Quick maintenance check for new login
+                    checkMaintenanceBeforeProceed()
                 } else {
                     Timber.e("Firebase authentication failed: ${authResult.exception?.message}")
                     logoutFailed()
@@ -278,6 +297,20 @@ class AuthActivity : AppCompatActivity() {
             }
     }
 
+    private fun checkMaintenanceBeforeProceed() {
+        MaintenanceChecker.checkMaintenanceStatusAsync(this) { isUnderMaintenance ->
+            if (isUnderMaintenance) {
+                binding.loadingView.visibility = View.GONE
+                val intent = Intent(this, MaintenanceActivity::class.java)
+                startActivity(intent)
+                finish()
+            } else {
+                authViewModel.signInAndGetTimeTable("", "", firebaseAuth.currentUser?.uid ?: "", "")
+                leadToNextPage()
+            }
+        }
+    }
+
     private fun leadToNextPage() {
         authViewModel.signInResponse.observe(this) {
             if (it != null) {
@@ -323,14 +356,4 @@ class AuthActivity : AppCompatActivity() {
             }
         }
     }
-
-    override fun onBackPressed() {
-        binding.apply {
-            if (introPager.currentItem == 0 || loginClick) {
-                super.onBackPressed()
-            } else {
-                introPager.currentItem--
-            }
-        }
-    }
 }

app/src/main/java/com/dscvit/vitty/activity/MaintenanceActivity.kt

@@ -0,0 +1,52 @@
+package com.dscvit.vitty.activity
+
+import android.content.Intent
+import android.os.Bundle
+import androidx.compose.ui.platform.ViewCompositionStrategy
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.FragmentActivity
+import com.dscvit.vitty.R
+import com.dscvit.vitty.databinding.ActivityMaintenanceBinding
+import com.dscvit.vitty.theme.VittyTheme
+import com.dscvit.vitty.ui.maintenance.MaintenanceScreen
+import com.dscvit.vitty.util.MaintenanceChecker
+
+class MaintenanceActivity : FragmentActivity() {
+
+    private lateinit var binding: ActivityMaintenanceBinding
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        binding = DataBindingUtil.setContentView(this, R.layout.activity_maintenance)
+
+        binding.composeView.apply {
+            setViewCompositionStrategy(
+                ViewCompositionStrategy.DisposeOnLifecycleDestroyed(this@MaintenanceActivity)
+            )
+            setContent {
+                VittyTheme {
+                    MaintenanceScreen(
+                        onRetryClick = { retryConnection() },
+                        onExitClick = { exitApp() }
+                    )
+                }
+            }
+        }
+    }
+
+    private fun retryConnection() {
+        MaintenanceChecker.checkMaintenanceStatusAsync(this) { isUnderMaintenance ->
+            if (!isUnderMaintenance) {
+                val intent = Intent(this, InstructionsActivity::class.java)
+                intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
+                startActivity(intent)
+                finish()
+            }
+        }
+    }
+
+    private fun exitApp() {
+        finishAffinity()
+    }
+}

app/src/main/java/com/dscvit/vitty/network/api/community/APICommunity.kt

@@ -29,6 +29,9 @@ import retrofit2.http.Path
 import retrofit2.http.Query
 
 interface APICommunity {
+    @GET("/")
+    fun checkServerStatus(): Call<String>
+
     @Headers("Content-Type: application/json")
     @POST("/api/v3/auth/check-username")
     fun checkUsername(

app/src/main/java/com/dscvit/vitty/network/api/community/APICommunityRestClient.kt

@@ -1050,4 +1050,30 @@ class APICommunityRestClient {
             },
         )
     }
+
+    fun checkServerStatus(
+        retrofitServerStatusListener: RetrofitServerStatusListener,
+    ) {
+        mApiUser = retrofit.create<APICommunity>(APICommunity::class.java)
+        val apiServerStatusCall = mApiUser!!.checkServerStatus()
+        apiServerStatusCall.enqueue(
+            object : Callback<String> {
+                override fun onResponse(
+                    call: Call<String>,
+                    response: Response<String>,
+                ) {
+                    Timber.d("ServerStatus: ${response.body()}")
+                    retrofitServerStatusListener.onSuccess(call, response.body(), response.isSuccessful)
+                }
+
+                override fun onFailure(
+                    call: Call<String>,
+                    t: Throwable,
+                ) {
+                    Timber.d("ServerStatusError: ${t.message}")
+                    retrofitServerStatusListener.onError(call, t)
+                }
+            },
+        )
+    }
 }

app/src/main/java/com/dscvit/vitty/network/api/community/RetrofitCommunityListener.kt

@@ -169,3 +169,15 @@ interface RetrofitActiveFriendsListener {
         t: Throwable,
     )
 }
+
+interface RetrofitServerStatusListener {
+    fun onSuccess(
+        call: Call<String>,
+        response: String?,
+        isSuccessful: Boolean
+    )
+    fun onError(
+        call: Call<String>,
+        t: Throwable
+    )
+}

app/src/main/java/com/dscvit/vitty/ui/main/MainComposeApp.kt

@@ -103,8 +103,10 @@ import com.dscvit.vitty.ui.schedule.ScheduleViewModel
 import com.dscvit.vitty.util.Analytics
 import com.dscvit.vitty.util.Constants
 import com.dscvit.vitty.util.LogoutHelper
+import com.dscvit.vitty.util.MaintenanceChecker
 import com.dscvit.vitty.util.SemesterUtils
 import com.dscvit.vitty.util.UtilFunctions
+import com.dscvit.vitty.ui.maintenance.MaintenanceBannerDialog
 import com.google.gson.Gson
 import com.google.gson.reflect.TypeToken
 import java.net.URLDecoder
@@ -113,6 +115,7 @@ import java.nio.charset.StandardCharsets
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import timber.log.Timber
 
 @Composable
 fun MainComposeApp() {
@@ -129,6 +132,9 @@ fun MainComposeApp() {
 
     var campus by remember { mutableStateOf(prefs.getString(Constants.COMMUNITY_CAMPUS, "") ?: "") }
     var showCampusDialog by remember { mutableStateOf(campus.isEmpty()) }
+
+    // Maintenance banner state
+    var showMaintenanceBanner by remember { mutableStateOf(false) }
 
     DisposableEffect(Unit) {
         val listener =
@@ -208,13 +214,24 @@ fun MainComposeApp() {
         }
     }
 
+    LaunchedEffect(Unit) {
+        if (UtilFunctions.isNetworkAvailable(context)) {
+            MaintenanceChecker.checkMaintenanceStatusAsync(context) { isUnderMaintenance ->
+                Timber.d("Dialog check result: isUnderMaintenance=%s", isUnderMaintenance)
+                showMaintenanceBanner = isUnderMaintenance
+            }
+        } else {
+            Timber.d("No network available")
+        }
+    }
+
     VittyTheme {
         ModalNavigationDrawer(
                 drawerState = drawerState,
                 drawerContent = {
                     DrawerContent(
                             navController = navController,
-                            onCloseDrawer = { scope.launch { drawerState.close() } },
+                            onCloseDrawer = { scope.launch { drawerState.close() } }
                     )
                 },
         ) {
@@ -866,6 +883,19 @@ fun MainComposeApp() {
                             onDismiss = { showCampusDialog = false },
                     )
                 }
+
+                // Maintenance Banner Dialog
+                MaintenanceBannerDialog(
+                    isVisible = showMaintenanceBanner,
+                    onDismiss = { 
+                        showMaintenanceBanner = false 
+                    },
+                    onRetryClick = {
+                        MaintenanceChecker.checkMaintenanceStatusAsync(context) { isUnderMaintenance ->
+                            showMaintenanceBanner = isUnderMaintenance
+                        }
+                    }
+                )
             }
         }
     }
@@ -1091,7 +1121,7 @@ fun NavigationItem(
 @Composable
 fun DrawerContent(
         navController: NavHostController,
-        onCloseDrawer: () -> Unit,
+        onCloseDrawer: () -> Unit
 ) {
     val context = LocalContext.current
     val prefs = remember { context.getSharedPreferences(Constants.USER_INFO, 0) }