Add Firebase Remote Config support (#391)

* Add Remote Config support

packages/firebase_remote_config/.gitignore

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+.DS_Store
+.atom/
+.idea
+.packages
+.pub/
+build/
+ios/.generated/
+packages
+pubspec.lock

packages/firebase_remote_config/CHANGELOG.md

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+## [0.0.1]
+
+* Implement Firebase Remote Config.

packages/firebase_remote_config/LICENSE

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+Copyright 2018, the Chromium project authors. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google Inc. nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

packages/firebase_remote_config/README.md

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+# firebase_remote_config plugin
+
+A Flutter plugin to use the [Firebase Remote Config API](https://firebase.google.com/products/remote-config/).
+
+[![pub package](https://img.shields.io/pub/v/firebase_remote_config.svg)](https://pub.dartlang.org/packages/firebase_remote_config)
+
+For Flutter plugins for other Firebase products, see [FlutterFire.md](https://github.com/flutter/plugins/blob/master/FlutterFire.md).
+
+*Note*: This plugin is still under development, and some APIs might not be available yet. [Feedback](https://github.com/flutter/flutter/issues) and [Pull Requests](https://github.com/flutter/plugins/pulls) are most welcome!
+
+## Usage
+
+### Import the firebase_remote_config plugin
+To use the firebase_remote_config plugin, follow the [plugin installation instructions](https://pub.dartlang.org/packages/firebase_remote_config#pub-pkg-tab-installing).
+
+### Android integration
+
+Enable the Google services by configuring the Gradle scripts as such.
+
+1. Add the classpath to the `[project]/android/build.gradle` file.
+```
+dependencies {
+  // Example existing classpath
+  classpath 'com.android.tools.build:gradle:3.0.1'
+  // Add the google services classpath
+  classpath 'com.google.gms:google-services:3.1.2'
+}
+```
+
+2. Add the apply plugin to the `[project]/android/app/build.gradle` file.
+```
+// ADD THIS AT THE BOTTOM
+apply plugin: 'com.google.gms.google-services'
+```
+
+*Note:* If this section is not completed you will get an error like this:
+```
+java.lang.IllegalStateException:
+Default FirebaseApp is not initialized in this process [package name].
+Make sure to call FirebaseApp.initializeApp(Context) first.
+```
+
+*Note:* When you are debugging on android, use a device or AVD with Google Play services.
+Otherwise you will not be able to use Firebase Remote Config.
+
+### Use the plugin
+
+Add the following imports to your Dart code:
+```
+import 'package:firebase_auth/firebase_remote_config.dart';
+```
+
+Initialize `RemoteConfig`:
+```
+final RemoteConfig remoteConfig = await RemoteConfig.instance;
+```
+
+You can now use the Firebase `remoteConfig` to fetch remote configurations in your Dart code, e.g.
+```
+final defaults = <String, dynamic>{'welcome': 'default welcome'};
+await remoteConfig.setDefaults(defaults);
+
+await remoteConfig.fetch(expiration: const Duration(hours: 5));
+await remoteConfig.activate();
+print('welcome message: ' + remoteConfig.getString('welcome'));
+```
+
+## Example
+
+See the [example application](https://github.com/flutter/plugins/tree/master/packages/firebase_remote_config/example) source
+for a complete sample app using the Firebase Remote Config.
+
+## Issues and feedback
+
+Please file [issues](https://github.com/flutter/flutter/issues/new)
+to send feedback or report a bug. Thank you!

packages/firebase_remote_config/android/.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures

packages/firebase_remote_config/android/build.gradle

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+group 'io.flutter.plugins.firebase.firebaseremoteconfig'
+version '1.0-SNAPSHOT'
+
+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.0.1'
+    }
+}
+
+rootProject.allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+apply plugin: 'com.android.library'
+
+android {
+    compileSdkVersion 27
+
+    defaultConfig {
+        minSdkVersion 16
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+    }
+    lintOptions {
+        disable 'InvalidPackage'
+    }
+    dependencies {
+        api 'com.google.firebase:firebase-config:[11.4.0,12.0['
+        api 'com.google.firebase:firebase-core:[11.4.0,12.0['
+    }
+}

packages/firebase_remote_config/android/gradle.properties

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+org.gradle.jvmargs=-Xmx1536M

packages/firebase_remote_config/android/settings.gradle

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+rootProject.name = 'firebase_remote_config'

packages/firebase_remote_config/android/src/main/AndroidManifest.xml

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+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  package="io.flutter.plugins.firebase.firebaseremoteconfig">
+</manifest>

packages/firebase_remote_config/android/src/main/java/io/flutter/plugins/firebase/firebaseremoteconfig/FirebaseRemoteConfigPlugin.java

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+package io.flutter.plugins.firebase.firebaseremoteconfig;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.support.annotation.NonNull;
+import com.google.android.gms.tasks.OnCompleteListener;
+import com.google.android.gms.tasks.Task;
+import com.google.firebase.remoteconfig.FirebaseRemoteConfig;
+import com.google.firebase.remoteconfig.FirebaseRemoteConfigFetchThrottledException;
+import com.google.firebase.remoteconfig.FirebaseRemoteConfigInfo;
+import com.google.firebase.remoteconfig.FirebaseRemoteConfigSettings;
+import com.google.firebase.remoteconfig.FirebaseRemoteConfigValue;
+import io.flutter.plugin.common.MethodCall;
+import io.flutter.plugin.common.MethodChannel;
+import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
+import io.flutter.plugin.common.MethodChannel.Result;
+import io.flutter.plugin.common.PluginRegistry.Registrar;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/** FirebaseRemoteConfigPlugin */
+public class FirebaseRemoteConfigPlugin implements MethodCallHandler {
+
+  public static final String TAG = "FirebaseRemoteConfigPlugin";
+  public static final String PREFS_NAME =
+      "io.flutter.plugins.firebase.firebaseremoteconfig.FirebaseRemoteConfigPlugin";
+  public static final String DEFAULT_PREF_KEY = "default_keys";
+
+  private static SharedPreferences sharedPreferences;
+  private final MethodChannel channel;
+
+  public static void registerWith(Registrar registrar) {
+    final MethodChannel channel =
+        new MethodChannel(registrar.messenger(), "plugins.flutter.io/firebase_remote_config");
+    channel.setMethodCallHandler(new FirebaseRemoteConfigPlugin(channel));
+    sharedPreferences = registrar.context().getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
+  }
+
+  private FirebaseRemoteConfigPlugin(MethodChannel channel) {
+    this.channel = channel;
+  }
+
+  @Override
+  public void onMethodCall(MethodCall call, final Result result) {
+    switch (call.method) {
+      case "RemoteConfig#instance":
+        {
+          FirebaseRemoteConfigInfo firebaseRemoteConfigInfo =
+              FirebaseRemoteConfig.getInstance().getInfo();
+
+          Map<String, Object> properties = new HashMap<>();
+          properties.put("lastFetchTime", firebaseRemoteConfigInfo.getFetchTimeMillis());
+          properties.put(
+              "lastFetchStatus", mapLastFetchStatus(firebaseRemoteConfigInfo.getLastFetchStatus()));
+          properties.put(
+              "inDebugMode", firebaseRemoteConfigInfo.getConfigSettings().isDeveloperModeEnabled());
+          properties.put("parameters", getConfigParameters());
+          result.success(properties);
+          break;
+        }
+      case "RemoteConfig#setConfigSettings":
+        {
+          boolean debugMode = call.argument("debugMode");
+          final FirebaseRemoteConfig firebaseRemoteConfig = FirebaseRemoteConfig.getInstance();
+          FirebaseRemoteConfigSettings settings =
+              new FirebaseRemoteConfigSettings.Builder().setDeveloperModeEnabled(debugMode).build();
+          firebaseRemoteConfig.setConfigSettings(settings);
+          result.success(null);
+          break;
+        }
+      case "RemoteConfig#fetch":
+        {
+          long expiration = ((Number) call.argument("expiration")).longValue();
+          final FirebaseRemoteConfig firebaseRemoteConfig = FirebaseRemoteConfig.getInstance();
+          firebaseRemoteConfig
+              .fetch(expiration)
+              .addOnCompleteListener(
+                  new OnCompleteListener<Void>() {
+                    @Override
+                    public void onComplete(@NonNull Task<Void> task) {
+                      FirebaseRemoteConfigInfo firebaseRemoteConfigInfo =
+                          firebaseRemoteConfig.getInfo();
+                      Map<String, Object> properties = new HashMap<>();
+                      properties.put(
+                          "lastFetchTime", firebaseRemoteConfigInfo.getFetchTimeMillis());
+                      properties.put(
+                          "lastFetchStatus",
+                          mapLastFetchStatus(firebaseRemoteConfigInfo.getLastFetchStatus()));
+                      if (!task.isSuccessful()) {
+                        final Exception exception = task.getException();
+
+                        if (exception instanceof FirebaseRemoteConfigFetchThrottledException) {
+                          properties.put(
+                              "fetchThrottledEnd",
+                              ((FirebaseRemoteConfigFetchThrottledException) exception)
+                                  .getThrottleEndTimeMillis());
+                          String errorMessage =
+                              "Fetch has been throttled. See the error's "
+                                  + "FETCH_THROTTLED_END field for throttle end time.";
+                          result.error("fetchFailedThrottled", errorMessage, properties);
+                        } else {
+                          String errorMessage =
+                              "Unable to complete fetch. Reason is unknown "
+                                  + "but this could be due to lack of connectivity.";
+                          result.error("fetchFailed", errorMessage, properties);
+                        }
+                      } else {
+                        result.success(properties);
+                      }
+                    }
+                  });
+          break;
+        }
+      case "RemoteConfig#activate":
+        {
+          boolean newConfig = FirebaseRemoteConfig.getInstance().activateFetched();
+          Map<String, Object> properties = new HashMap<>();
+          properties.put("parameters", getConfigParameters());
+          properties.put("newConfig", newConfig);
+          result.success(properties);
+          break;
+        }
+      case "RemoteConfig#setDefaults":
+        {
+          Map<String, Object> defaults = call.argument("defaults");
+          FirebaseRemoteConfig.getInstance().setDefaults(defaults);
+          SharedPreferences.Editor editor = sharedPreferences.edit();
+          editor.putStringSet(DEFAULT_PREF_KEY, defaults.keySet()).apply();
+          result.success(null);
+          break;
+        }
+      default:
+        {
+          result.notImplemented();
+          break;
+        }
+    }
+  }
+
+  private Map<String, Object> getConfigParameters() {
+    FirebaseRemoteConfig firebaseRemoteConfig = FirebaseRemoteConfig.getInstance();
+    Map<String, Object> parameterMap = new HashMap<>();
+    Set<String> keys = firebaseRemoteConfig.getKeysByPrefix("");
+    for (String key : keys) {
+      FirebaseRemoteConfigValue remoteConfigValue = firebaseRemoteConfig.getValue(key);
+      parameterMap.put(key, createRemoteConfigValueMap(remoteConfigValue));
+    }
+    // Add default parameters if missing since `getKeysByPrefix` does not return default keys.
+    Set<String> defaultKeys =
+        sharedPreferences.getStringSet(DEFAULT_PREF_KEY, new HashSet<String>());
+    for (String defaultKey : defaultKeys) {
+      if (!parameterMap.containsKey(defaultKey)) {
+        FirebaseRemoteConfigValue remoteConfigValue = firebaseRemoteConfig.getValue(defaultKey);
+        parameterMap.put(defaultKey, createRemoteConfigValueMap(remoteConfigValue));
+      }
+    }
+    return parameterMap;
+  }
+
+  private Map<String, Object> createRemoteConfigValueMap(
+      FirebaseRemoteConfigValue remoteConfigValue) {
+    Map<String, Object> valueMap = new HashMap<>();
+    valueMap.put("value", remoteConfigValue.asByteArray());
+    valueMap.put("source", mapValueSource(remoteConfigValue.getSource()));
+    return valueMap;
+  }
+
+  private String mapLastFetchStatus(int status) {
+    switch (status) {
+      case FirebaseRemoteConfig.LAST_FETCH_STATUS_SUCCESS:
+        return "success";
+      case FirebaseRemoteConfig.LAST_FETCH_STATUS_FAILURE:
+        return "failure";
+      case FirebaseRemoteConfig.LAST_FETCH_STATUS_THROTTLED:
+        return "throttled";
+      case FirebaseRemoteConfig.LAST_FETCH_STATUS_NO_FETCH_YET:
+        return "noFetchYet";
+      default:
+        return "failure";
+    }
+  }
+
+  private String mapValueSource(int source) {
+    switch (source) {
+      case FirebaseRemoteConfig.VALUE_SOURCE_STATIC:
+        return "static";
+      case FirebaseRemoteConfig.VALUE_SOURCE_DEFAULT:
+        return "default";
+      case FirebaseRemoteConfig.VALUE_SOURCE_REMOTE:
+        return "remote";
+      default:
+        return "static";
+    }
+  }
+}

packages/firebase_remote_config/example/.gitignore

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+.DS_Store
+.atom/
+.idea
+.vscode/
+.packages
+.pub/
+build/
+ios/.generated/
+packages
+pubspec.lock
+.flutter-plugins

packages/firebase_remote_config/example/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 538ba522eeeffb8a754ecb12b77eddac3452ed74
+  channel: master