[components] Closes mozilla-mobile/android-components#3584: Api for s…

…upporting language switching.

android-components/.buildconfig.yml

@@ -256,6 +256,10 @@ projects:
     path: components/support/rustlog
     description: 'A bridge allowing log messages from Rust code to be sent to the log system in support-base'
     publish: true
+  support-locale:
+    path: components/support/locale
+    description: 'A component to allow apps to change the system defined language by their custom one'
+    publish: true
   lib-crash:
     path: components/lib/crash
     description: 'A generic crash reporter library that can report crashes to multiple services.'

android-components/components/support/base/src/main/res/values/strings.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<resources>
+    <string name="mozac_support_base_locale_preference_key_locale" translatable="false">mozac_support_base_locale_preference_key_locale</string>
+</resources>

android-components/components/support/locale/README.md

@@ -0,0 +1,19 @@
+# [Android Components](../../../README.md) > Support > Locale
+
+A component to allow apps to change the system defined language by their custom one.
+
+## Usage
+
+### Setting up the dependency
+
+Use Gradle to download the library from [maven.mozilla.org](https://maven.mozilla.org/) ([Setup repository](../../../README.md#maven-repository)):
+
+```Groovy
+implementation "org.mozilla.components:support-locale:{latest-version}"
+```
+
+## License
+
+    This Source Code Form is subject to the terms of the Mozilla Public
+    License, v. 2.0. If a copy of the MPL was not distributed with this
+    file, You can obtain one at http://mozilla.org/MPL/2.0/

android-components/components/support/locale/build.gradle

@@ -0,0 +1,42 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+
+android {
+    compileSdkVersion config.compileSdkVersion
+
+    defaultConfig {
+        minSdkVersion config.minSdkVersion
+        targetSdkVersion config.targetSdkVersion
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+}
+
+dependencies {
+    implementation Dependencies.kotlin_stdlib
+    implementation Dependencies.androidx_core
+    implementation Dependencies.androidx_core_ktx
+
+    implementation project(':support-base')
+    implementation project(':support-utils')
+
+    testImplementation project(':support-test')
+    testImplementation Dependencies.androidx_test_core
+    testImplementation Dependencies.androidx_test_junit
+    testImplementation Dependencies.testing_robolectric
+    testImplementation Dependencies.testing_mockito
+}
+
+apply from: '../../../publish.gradle'
+ext.configurePublish(config.componentsGroupId, archivesBaseName, project.ext.description)

android-components/components/support/locale/gradle.properties

@@ -0,0 +1,2 @@
+# TODO remove
+android.enableUnitTestBinaryResources=false

android-components/components/support/locale/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

android-components/components/support/locale/src/main/AndroidManifest.xml

@@ -0,0 +1,5 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="mozilla.components.support.locale" />

android-components/components/support/locale/src/main/java/mozilla/components/support/locale/Extensions.kt

@@ -0,0 +1,22 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package mozilla.components.support.locale
+
+import java.util.Locale
+
+fun String.toLocale(): Locale {
+    val index: Int = if (contains('-')) {
+        indexOf('-')
+    } else {
+        indexOf('_')
+    }
+    return if (index != -1) {
+        val langCode = substring(0, index)
+        val countryCode = substring(index + 1)
+        Locale(langCode, countryCode)
+    } else {
+        Locale(this)
+    }
+}

android-components/components/support/locale/src/main/java/mozilla/components/support/locale/LocaleAwareAppCompatActivity.kt

@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package mozilla.components.support.locale
+
+import android.content.Context
+import androidx.appcompat.app.AppCompatActivity
+
+/**
+ * Base activity for apps that want to customized the system defined language by their own.
+ */
+open class LocaleAwareAppCompatActivity : AppCompatActivity() {
+    override fun attachBaseContext(base: Context) {
+        val context = LocaleManager.updateResources(base)
+        super.attachBaseContext(context)
+    }
+}

android-components/components/support/locale/src/main/java/mozilla/components/support/locale/LocaleAwareApplication.kt

@@ -0,0 +1,25 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package mozilla.components.support.locale
+
+import android.app.Application
+import android.content.Context
+import android.content.res.Configuration
+
+/**
+ * Base application for apps that want to customized the system defined language by their own.
+ */
+open class LocaleAwareApplication : Application() {
+
+    override fun attachBaseContext(base: Context) {
+        val context = LocaleManager.updateResources(base)
+        super.attachBaseContext(context)
+    }
+
+    override fun onConfigurationChanged(config: Configuration) {
+        super.onConfigurationChanged(config)
+        LocaleManager.updateResources(this)
+    }
+}

android-components/components/support/locale/src/main/java/mozilla/components/support/locale/LocaleManager.kt

@@ -0,0 +1,109 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package mozilla.components.support.locale
+
+import android.content.Context
+import android.content.SharedPreferences
+import android.content.res.Configuration
+import androidx.appcompat.app.AppCompatActivity
+import mozilla.components.support.base.R
+import mozilla.components.support.base.log.logger.Logger
+import java.util.Locale
+
+/**
+ * Helper for apps that want to change locale defined by the system.
+ */
+object LocaleManager {
+    private val logger = Logger("LocaleManager")
+
+    /**
+     * Change the system defined locale to the indicated in the [language] parameter.
+     * This new [language] will be stored and will be the new current locale returned by [getCurrentLocale].
+     *
+     * After calling this function, to visualize the locale changes you have to make sure all your visible activities
+     * get recreated. If your app is using the single activity approach, this will be trivial just call
+     * [AppCompatActivity.recreate]. On the other hand, if you have multiple activity this could be tricky, one
+     * alternative could be restarting your application process see https://github.com/JakeWharton/ProcessPhoenix
+     * @return A new Context object for whose resources are adjusted to match the new [language].
+     */
+    fun setNewLocale(context: Context, language: String): Context {
+        Storage.save(context, language)
+        return updateResources(context)
+    }
+
+    /**
+     * The latest stored locale saved by [setNewLocale].
+     */
+    fun getCurrentLocale(context: Context): Locale? {
+        var currentLocale: Locale? = null
+
+        if (currentLocale == null) {
+            val locale = Storage.getLocale(context)
+            if (locale != null) {
+                currentLocale = locale.toLocale()
+            }
+        }
+        return currentLocale
+    }
+
+    internal fun updateResources(baseContext: Context): Context {
+        val locale = getCurrentLocale(baseContext)
+        return if (locale != null) {
+            updateSystemLocale(locale)
+            updateConfiguration(baseContext, locale)
+        } else {
+            baseContext
+        }
+    }
+
+    private fun updateConfiguration(context: Context, locale: Locale): Context {
+        val configuration = Configuration(context.resources.configuration)
+        configuration.setLocale(locale)
+        configuration.setLayoutDirection(locale)
+        return context.createConfigurationContext(configuration)
+    }
+
+    private fun updateSystemLocale(locale: Locale) {
+        Locale.setDefault(locale)
+    }
+
+    internal fun clear(context: Context) {
+        Storage.clear(context)
+    }
+
+    private object Storage {
+        private const val PREFERENCE_FILE = "mozac_support_base_locale_manager_preference"
+        private var currentLocal: String? = null
+
+        fun getLocale(context: Context): String? {
+            return if (currentLocal == null) {
+                val settings = getSharedPreferences(context)
+                val key = context.getString(R.string.mozac_support_base_locale_preference_key_locale)
+                currentLocal = settings.getString(key, null)
+                currentLocal
+            } else {
+                currentLocal
+            }
+        }
+
+        @Synchronized
+        fun save(context: Context, localeCode: String) {
+            val settings = getSharedPreferences(context)
+            val key = context.getString(R.string.mozac_support_base_locale_preference_key_locale)
+            settings.edit().putString(key, localeCode).apply()
+            currentLocal = localeCode
+        }
+
+        fun clear(context: Context) {
+            val settings = getSharedPreferences(context)
+            settings.edit().clear().apply()
+            currentLocal = null
+        }
+
+        private fun getSharedPreferences(context: Context): SharedPreferences {
+            return context.getSharedPreferences(PREFERENCE_FILE, Context.MODE_PRIVATE)
+        }
+    }
+}

android-components/components/support/locale/src/test/java/mozilla/components/support/locale/LocaleManagerTest.kt

@@ -0,0 +1,51 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package mozilla.components.support.locale
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import mozilla.components.support.test.robolectric.testContext
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotEquals
+import org.junit.Assert.assertNull
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.util.Locale
+
+@RunWith(AndroidJUnit4::class)
+class LocaleManagerTest {
+
+    @Before
+    fun setup() {
+        LocaleManager.clear(testContext)
+        Locale.setDefault("en_US".toLocale())
+    }
+
+    @Test
+    fun `changing the language to Spanish must change the system locale to Spanish and change the configurations`() {
+
+        var currentLocale = LocaleManager.getCurrentLocale(testContext)
+
+        assertNull(currentLocale)
+
+        val newContext = LocaleManager.setNewLocale(testContext, "es")
+
+        assertNotEquals(testContext, newContext)
+
+        currentLocale = LocaleManager.getCurrentLocale(testContext)
+
+        assertEquals(currentLocale, "es".toLocale())
+        assertEquals(currentLocale, Locale.getDefault())
+    }
+
+    @Test
+    fun `when calling updateResources with none current language must not change the system locale neither change configurations`() {
+        val previousSystemLocale = Locale.getDefault()
+        val context = LocaleManager.updateResources(testContext)
+
+        assertEquals(testContext, context)
+        assertEquals(previousSystemLocale, Locale.getDefault())
+    }
+}