show update prompt in the app when there is a new update

app/build.gradle

@@ -216,5 +216,12 @@ dependencies {
     annotationProcessor 'androidx.room:room-compiler:2.6.1' // For Java projects, replace with the correct version
     ksp 'androidx.room:room-compiler:2.6.1'
 
+    // This dependency is downloaded from the Google's Maven repository.
+    // So, make sure you also include that repository in your project's build.gradle file.
+    implementation("com.google.android.play:app-update:2.1.0")
+
+    // For Kotlin users also import the Kotlin extensions library for Play In-App Update:
+    implementation("com.google.android.play:app-update-ktx:2.1.0")
+
     implementation(platform("org.jetbrains.kotlin:kotlin-bom:2.1.21"))
 }

app/src/main/java/org/cis_india/wsreader/MainActivity.kt

@@ -17,8 +17,11 @@
 package org.cis_india.wsreader
 
 import android.os.Bundle
+import android.widget.Toast
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.activity.result.ActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AppCompatActivity
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.MaterialTheme
@@ -35,16 +38,29 @@ import org.cis_india.wsreader.ui.theme.AdjustEdgeToEdge
 import org.cis_india.wsreader.ui.theme.WikisourceReaderTheme
 import dagger.hilt.android.AndroidEntryPoint
 import androidx.navigation.NavController
+import com.google.android.play.core.appupdate.AppUpdateManager
+import com.google.android.play.core.appupdate.AppUpdateManagerFactory
+import com.google.android.play.core.appupdate.AppUpdateOptions
+import com.google.android.play.core.install.InstallStateUpdatedListener
+import com.google.android.play.core.install.model.AppUpdateType
+import com.google.android.play.core.install.model.InstallStatus
+import com.google.android.play.core.install.model.UpdateAvailability
 
 
 @AndroidEntryPoint
 class MainActivity : AppCompatActivity() {
-
+    private lateinit var appUpdateManager: AppUpdateManager
     private lateinit var networkObserver: NetworkObserver
     lateinit var settingsViewModel: SettingsViewModel
     private lateinit var mainViewModel: MainViewModel
     private lateinit var navController: NavController
 
+    private val installStateUpdatedListener = InstallStateUpdatedListener { state ->
+        if (state.installStatus() == InstallStatus.DOWNLOADED) {
+            popupSnackbarForCompleteUpdate()
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
@@ -59,6 +75,11 @@ class MainActivity : AppCompatActivity() {
 
         enableEdgeToEdge() // enable edge to edge for the activity.
 
+        appUpdateManager = AppUpdateManagerFactory.create(this)
+
+        appUpdateManager.registerListener(installStateUpdatedListener)
+        checkUpdates()
+
         setContent {
             WikisourceReaderTheme(settingsViewModel = settingsViewModel) {
                 AdjustEdgeToEdge(
@@ -85,6 +106,63 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    private fun checkUpdates(){
+        val appUpdateInfoTask = appUpdateManager.appUpdateInfo
+        appUpdateInfoTask.addOnSuccessListener { appUpdateInfo ->
+            if (appUpdateInfo.updateAvailability() == UpdateAvailability.UPDATE_AVAILABLE
+                && appUpdateInfo.isUpdateTypeAllowed(AppUpdateType.FLEXIBLE)) {
+
+                appUpdateManager.startUpdateFlowForResult(
+                    // Pass the intent that is returned by 'getAppUpdateInfo()'.
+                    appUpdateInfo,
+                    // an activity result launcher registered via registerForActivityResult
+                    activityResultLauncher,
+                    // Or pass 'AppUpdateType.FLEXIBLE' to newBuilder() for
+                    // flexible updates.
+                    AppUpdateOptions.newBuilder(AppUpdateType.FLEXIBLE).build())
+            }
+        }
+    }
+
+
+    private val activityResultLauncher = registerForActivityResult(
+        ActivityResultContracts.StartIntentSenderForResult()
+    ){ result : ActivityResult ->
+
+        if (result.resultCode != RESULT_OK) {
+            println("Update flow failed! Result code: " + result.resultCode);
+            // If the update is canceled or fails,
+            // you can request to start the update again.
+        }
+
+    }
+
+    private fun popupSnackbarForCompleteUpdate() {
+        // Since you are using Compose, you might prefer calling a function in your
+        // MainViewModel to show a Compose Snackbar, but here is a standard one:
+        Toast.makeText(
+            this,
+            "An update has just been downloaded.",
+            Toast.LENGTH_LONG
+        ).show()
+
+        appUpdateManager.completeUpdate()
+    }
+
+    override fun onResume() {
+        super.onResume()
+        appUpdateManager.appUpdateInfo.addOnSuccessListener { info ->
+            if (info.installStatus() == InstallStatus.DOWNLOADED) {
+                popupSnackbarForCompleteUpdate()
+            }
+        }
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        appUpdateManager.unregisterListener(installStateUpdatedListener)
+    }
+
     override fun onPause() {
         super.onPause()
     }