Ensure that a PushProvider is available on a device before using it.

It help to fallback to UnifiedPush (if available) if the PlayServices are not installed on the device.

libraries/push/api/src/main/kotlin/io/element/android/libraries/push/api/PushService.kt

@@ -24,6 +24,10 @@ interface PushService {
     // TODO Move away
     fun notificationStyleChanged()
 
+    /**
+     * Return the list of push providers, available at compile time, and
+     * available at runtime, sorted by index.
+     */
     fun getAvailablePushProviders(): List<PushProvider>
 
     /**

libraries/push/impl/src/main/kotlin/io/element/android/libraries/push/impl/DefaultPushService.kt

@@ -38,7 +38,9 @@ class DefaultPushService @Inject constructor(
     }
 
     override fun getAvailablePushProviders(): List<PushProvider> {
-        return pushProviders.sortedBy { it.index }
+        return pushProviders
+            .filter { it.isAvailable() }
+            .sortedBy { it.index }
     }
 
     /**

libraries/pushproviders/api/src/main/kotlin/io/element/android/libraries/pushproviders/api/PushProvider.kt

@@ -32,6 +32,11 @@ interface PushProvider {
      */
     val name: String
 
+    /**
+     * Return true if the push provider is available on this device.
+     */
+    fun isAvailable(): Boolean
+
     fun getDistributors(): List<Distributor>
 
     /**

libraries/pushproviders/firebase/src/main/kotlin/io/element/android/libraries/pushproviders/firebase/FirebasePushProvider.kt

@@ -16,9 +16,13 @@
 
 package io.element.android.libraries.pushproviders.firebase
 
+import android.content.Context
+import com.google.android.gms.common.ConnectionResult
+import com.google.android.gms.common.GoogleApiAvailability
 import com.squareup.anvil.annotations.ContributesMultibinding
 import io.element.android.libraries.core.log.logger.LoggerTag
 import io.element.android.libraries.di.AppScope
+import io.element.android.libraries.di.ApplicationContext
 import io.element.android.libraries.matrix.api.MatrixClient
 import io.element.android.libraries.pushproviders.api.Distributor
 import io.element.android.libraries.pushproviders.api.PushProvider
@@ -30,6 +34,7 @@ private val loggerTag = LoggerTag("FirebasePushProvider", LoggerTag.PushLoggerTa
 
 @ContributesMultibinding(AppScope::class)
 class FirebasePushProvider @Inject constructor(
+    @ApplicationContext private val context: Context,
     private val firebaseStore: FirebaseStore,
     private val firebaseTroubleshooter: FirebaseTroubleshooter,
     private val pusherSubscriber: PusherSubscriber,
@@ -37,6 +42,19 @@ class FirebasePushProvider @Inject constructor(
     override val index = FirebaseConfig.INDEX
     override val name = FirebaseConfig.NAME
 
+    override fun isAvailable(): Boolean {
+        // The PlayServices has to be available
+        val apiAvailability = GoogleApiAvailability.getInstance()
+        val resultCode = apiAvailability.isGooglePlayServicesAvailable(context)
+        return if (resultCode == ConnectionResult.SUCCESS) {
+            Timber.tag(loggerTag.value).d("Google Play Services is available")
+            true
+        } else {
+            Timber.tag(loggerTag.value).w("Google Play Services is not available")
+            false
+        }
+    }
+
     override fun getDistributors(): List<Distributor> {
         return listOf(Distributor("Firebase", "Firebase"))
     }

libraries/pushproviders/unifiedpush/src/main/kotlin/io/element/android/libraries/pushproviders/unifiedpush/UnifiedPushProvider.kt

@@ -19,6 +19,7 @@ package io.element.android.libraries.pushproviders.unifiedpush
 import android.content.Context
 import com.squareup.anvil.annotations.ContributesMultibinding
 import io.element.android.libraries.androidutils.system.getApplicationLabel
+import io.element.android.libraries.core.log.logger.LoggerTag
 import io.element.android.libraries.di.AppScope
 import io.element.android.libraries.di.ApplicationContext
 import io.element.android.libraries.matrix.api.MatrixClient
@@ -26,8 +27,11 @@ import io.element.android.libraries.pushproviders.api.Distributor
 import io.element.android.libraries.pushproviders.api.PushProvider
 import io.element.android.libraries.pushstore.api.clientsecret.PushClientSecret
 import org.unifiedpush.android.connector.UnifiedPush
+import timber.log.Timber
 import javax.inject.Inject
 
+private val loggerTag = LoggerTag("UnifiedPushProvider", LoggerTag.PushLoggerTag)
+
 @ContributesMultibinding(AppScope::class)
 class UnifiedPushProvider @Inject constructor(
     @ApplicationContext private val context: Context,
@@ -38,6 +42,17 @@ class UnifiedPushProvider @Inject constructor(
     override val index = UnifiedPushConfig.INDEX
     override val name = UnifiedPushConfig.NAME
 
+    override fun isAvailable(): Boolean {
+        val isAvailable = getDistributors().isNotEmpty()
+        return if (isAvailable) {
+            Timber.tag(loggerTag.value).d("UnifiedPush is available")
+            true
+        } else {
+            Timber.tag(loggerTag.value).w("UnifiedPush is not available")
+            false
+        }
+    }
+
     override fun getDistributors(): List<Distributor> {
         val distributors = UnifiedPush.getDistributors(context)
         return distributors.mapNotNull {