[Room List] Show offline indicator when the device is offline (#239)

* Implement the network status indicator.

* Add `networkmonitor` feature.

features/networkmonitor/impl/build.gradle.kts

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// TODO: Remove once https://youtrack.jetbrains.com/issue/KTIJ-19369 is fixed
+@Suppress("DSL_SCOPE_VIOLATION")
+plugins {
+    id("io.element.android-library")
+    alias(libs.plugins.anvil)
+}
+
+anvil {
+    generateDaggerFactories.set(true)
+}
+
+android {
+    namespace = "io.element.android.features.networkmonitor.impl"
+}
+
+dependencies {
+    implementation(libs.coroutines.core)
+    implementation(libs.dagger)
+    implementation(projects.libraries.core)
+    implementation(projects.libraries.di)
+    api(projects.features.networkmonitor.api)
+}

features/networkmonitor/impl/src/main/AndroidManifest.xml

@@ -0,0 +1,19 @@
+<!--
+  ~ Copyright (c) 2023 New Vector Ltd
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+</manifest>

features/networkmonitor/impl/src/main/kotlin/io/element/android/features/networkmonitor/impl/NetworkMonitorImpl.kt

@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.networkmonitor.impl
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.Network
+import android.net.NetworkCapabilities
+import android.net.NetworkRequest
+import com.squareup.anvil.annotations.ContributesBinding
+import io.element.android.features.networkmonitor.api.NetworkMonitor
+import io.element.android.features.networkmonitor.api.NetworkStatus
+import io.element.android.libraries.di.AppScope
+import io.element.android.libraries.di.ApplicationContext
+import io.element.android.libraries.di.SingleIn
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import timber.log.Timber
+import javax.inject.Inject
+
+@ContributesBinding(scope = AppScope::class)
+@SingleIn(AppScope::class)
+class NetworkMonitorImpl @Inject constructor(
+    @ApplicationContext context: Context
+) : NetworkMonitor {
+
+    private val connectivityManager: ConnectivityManager = context.getSystemService(ConnectivityManager::class.java)
+
+    private val callback = object : ConnectivityManager.NetworkCallback() {
+        override fun onAvailable(network: Network) {
+            _connectivity.value = connectivityManager.currentConnectionStatus()
+            Timber.v("Connectivity status (available): ${connectivityManager.currentConnectionStatus()}")
+        }
+
+        override fun onLost(network: Network) {
+            _connectivity.value = connectivityManager.currentConnectionStatus()
+            Timber.v("Connectivity status (lost): ${connectivityManager.currentConnectionStatus()}")
+        }
+
+        override fun onCapabilitiesChanged(
+            network: Network,
+            networkCapabilities: NetworkCapabilities
+        ) {
+            _connectivity.value = connectivityManager.currentConnectionStatus()
+            Timber.v("Connectivity status (changed): ${connectivityManager.currentConnectionStatus()}")
+        }
+    }
+
+    private val _connectivity = MutableStateFlow(NetworkStatus.Online)
+    override val connectivity: Flow<NetworkStatus> = _connectivity
+
+    override val currentConnectivityStatus: NetworkStatus get() = _connectivity.value
+
+    init {
+        listenToConnectionChanges()
+    }
+
+    private fun listenToConnectionChanges() {
+        val request = NetworkRequest.Builder()
+            .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
+            .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
+            .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
+            .build()
+        connectivityManager.registerNetworkCallback(request, callback)
+
+        _connectivity.tryEmit(connectivityManager.currentConnectionStatus())
+    }
+
+    private fun ConnectivityManager.currentConnectionStatus(): NetworkStatus {
+        val hasInternet = activeNetwork?.let(::getNetworkCapabilities)
+            ?.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
+            ?: false
+        return if (hasInternet) {
+            NetworkStatus.Online
+        } else {
+            NetworkStatus.Offline
+        }
+    }
+}