Decorating feature showing and updating offline snackbar (#189)

* Add network status feature

* Add observable network status implementation

* Add proper string for offline state

* Update dependency and use default callbacks to avoid boilerplate

* Remove exra empty lines

client/build.gradle

@@ -76,6 +76,7 @@ dependencies {
   api project(':core-android')
   api project(':lib:identity')
   api project(':lib:dynamic-features')
+  api project(':lib:network-status')
   api project(':feature:push')
   api project(':feature:users')
   api project(':feature:settings_entrance')

client/src/main/java/com/jraska/github/client/AppComponent.kt

@@ -10,6 +10,7 @@ import com.jraska.github.client.dynamicbase.DynamicFeaturesModule
 import com.jraska.github.client.http.HttpComponent
 import com.jraska.github.client.identity.IdentityModule
 import com.jraska.github.client.identity.IdentityProvider
+import com.jraska.github.client.networkstatus.NetworkStatusModule
 import com.jraska.github.client.push.PushModule
 import com.jraska.github.client.settings.entrance.SettingsEntranceModule
 import com.jraska.github.client.shortcuts.ShortcutsModule
@@ -25,6 +26,7 @@ import dagger.Subcomponent
     NavigationModule::class,
     DynamicFeaturesModule::class,
     IdentityModule::class,
+    NetworkStatusModule::class,
     UsersModule::class,
     PushModule::class,
     SettingsEntranceModule::class,

lib/network-status/.gitignore

@@ -0,0 +1 @@
+/build

lib/network-status/build.gradle

@@ -0,0 +1,27 @@
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-kapt'
+
+android {
+  compileSdkVersion 28
+  defaultConfig {
+    minSdkVersion 21
+  }
+
+  compileOptions {
+    sourceCompatibility JavaVersion.VERSION_1_8
+    targetCompatibility JavaVersion.VERSION_1_8
+  }
+}
+
+dependencies {
+  api project(':core')
+  api project(':core-android')
+
+  kapt 'com.google.dagger:dagger-compiler:2.24'
+  api 'com.google.dagger:dagger:2.24'
+
+  implementation 'com.google.android.material:material:1.1.0-beta01'
+
+  testImplementation 'junit:junit:4.12'
+}

lib/network-status/src/main/AndroidManifest.xml

@@ -0,0 +1,5 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  package="com.jraska.github.client.networkstatus">
+
+  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+</manifest>

lib/network-status/src/main/java/com/jraska/github/client/networkstatus/NetworkStatusModule.kt

@@ -0,0 +1,23 @@
+package com.jraska.github.client.networkstatus
+
+import android.app.Application
+import com.jraska.github.client.core.android.OnAppCreate
+import com.jraska.github.client.networkstatus.internal.NetworkStatusDisplayer
+import dagger.Module
+import dagger.Provides
+import dagger.multibindings.IntoSet
+
+@Module
+object NetworkStatusModule {
+  @JvmStatic
+  @Provides
+  @IntoSet
+  internal fun addNetworkStatusDisplayer(networkStatusDisplayer: NetworkStatusDisplayer): OnAppCreate {
+    return object : OnAppCreate {
+      override fun onCreate(app: Application) {
+        val callbacks = NetworkStatusDisplayer.Callbacks(networkStatusDisplayer)
+        app.registerActivityLifecycleCallbacks(callbacks)
+      }
+    }
+  }
+}

lib/network-status/src/main/java/com/jraska/github/client/networkstatus/internal/NetworkObservable.kt

@@ -0,0 +1,47 @@
+package com.jraska.github.client.networkstatus.internal
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.Network
+import android.net.NetworkRequest
+import io.reactivex.Observable
+import io.reactivex.subjects.BehaviorSubject
+import javax.inject.Inject
+
+internal class NetworkObservable @Inject constructor(
+  private val context: Context
+) {
+  private val networkObservable: Observable<Boolean> by lazy {
+    setupNetworkObservable()
+  }
+
+  fun connectedObservable(): Observable<Boolean> {
+    return networkObservable
+  }
+
+  private val connectivityManager
+    get() = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
+
+  private fun setupNetworkObservable(): Observable<Boolean> {
+    val behaviorSubject = BehaviorSubject.createDefault(isConnected())
+
+    connectivityManager.registerNetworkCallback(allChangesRequest(), object : ConnectivityManager.NetworkCallback() {
+      override fun onAvailable(network: Network) {
+        behaviorSubject.onNext(isConnected())
+      }
+
+      override fun onLost(network: Network) {
+        behaviorSubject.onNext(isConnected())
+      }
+    })
+
+    return behaviorSubject.distinctUntilChanged()
+  }
+
+  private fun allChangesRequest() = NetworkRequest.Builder().build()
+
+  private fun isConnected(): Boolean {
+    val activeNetwork = connectivityManager.activeNetworkInfo
+    return activeNetwork != null && activeNetwork.isConnected
+  }
+}

lib/network-status/src/main/java/com/jraska/github/client/networkstatus/internal/NetworkStatusDisplayer.kt

@@ -0,0 +1,67 @@
+package com.jraska.github.client.networkstatus.internal
+
+import android.app.Activity
+import android.view.View
+import com.google.android.material.snackbar.Snackbar
+import com.jraska.github.client.core.android.DefaultActivityCallbacks
+import com.jraska.github.client.networkstatus.R
+import com.jraska.github.client.rx.AppSchedulers
+import io.reactivex.disposables.CompositeDisposable
+import javax.inject.Inject
+
+internal class NetworkStatusDisplayer @Inject constructor(
+  private val networkObservable: NetworkObservable,
+  private val appSchedulers: AppSchedulers
+) {
+
+  private val compositeDisposable = CompositeDisposable()
+  private var offlineSnackbar: Snackbar? = null
+
+  fun onActivityResumed(activity: Activity) {
+    networkObservable.connectedObservable()
+      .observeOn(appSchedulers.mainThread)
+      .subscribe { showState(activity, it) }
+      .also { compositeDisposable.add(it) }
+  }
+
+  fun onActivityPaused() {
+    dismissAnySnackbar()
+    compositeDisposable.clear()
+  }
+
+  private fun dismissAnySnackbar() {
+    offlineSnackbar?.dismiss()
+    offlineSnackbar = null
+  }
+
+  private fun showState(activity: Activity, isOnline: Boolean) {
+    if (isOnline) {
+      dismissAnySnackbar()
+    } else {
+      showOfflineSnackbar(activity)
+    }
+  }
+
+  private fun showOfflineSnackbar(activity: Activity) {
+    dismissAnySnackbar()
+
+    val view = activity.findViewById<View>(android.R.id.content)
+
+    val snackbar = Snackbar.make(view, R.string.status_is_offline, Snackbar.LENGTH_INDEFINITE)
+    snackbar.show()
+    offlineSnackbar = snackbar
+  }
+
+  internal class Callbacks(
+    private val displayer: NetworkStatusDisplayer
+  ) : DefaultActivityCallbacks() {
+
+    override fun onActivityResumed(activity: Activity) {
+      displayer.onActivityResumed(activity)
+    }
+
+    override fun onActivityPaused(activity: Activity) {
+      displayer.onActivityPaused()
+    }
+  }
+}

lib/network-status/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+  <string name="status_is_offline">You\'re offline</string>
+</resources>

settings.gradle

@@ -6,6 +6,7 @@ include ':client',
 
   ':lib:identity',
   ':lib:dynamic-features',
+  ':lib:network-status',
 
   ':feature:users',
   ':feature:push',