[Panlingual] Use feature flag to switch opt-in on/off

- Currently per app language use opt-out by default. This change is to
   add a new idea to have a way to change opt-out to opt-in, and let
   user be able to use LocaleConfig.xml to control the feature more
   precise.
 - If app does not support locale picker or there is no locale provided, remove entries' UI.

Bug: b/231396734
Bug: b/230688538
Test: local
Change-Id: I2661fffab804a2816744711130b26aa2ec47f820

src/com/android/settings/applications/AppLocaleUtil.java

@@ -18,11 +18,14 @@ package com.android.settings.applications;
 
 import android.annotation.NonNull;
 import android.app.ActivityManager;
+import android.app.LocaleConfig;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
+import android.os.LocaleList;
+import android.util.FeatureFlagUtils;
 import android.util.Log;
 
 import com.android.settings.R;
@@ -46,12 +49,17 @@ public class AppLocaleUtil {
         boolean isDisallowedPackage = isDisallowedPackage(context, packageName);
         boolean hasLauncherEntry = hasLauncherEntry(packageName, infos);
         boolean isSignedWithPlatformKey = isSignedWithPlatformKey(context, packageName);
+        boolean isAppLocaleSupported = isAppLocaleSupported(context, packageName);
         Log.i(TAG, "Can display preference - [" + packageName + "] :"
                 + " isDisallowedPackage : " + isDisallowedPackage
                 + " / isSignedWithPlatformKey : " + isSignedWithPlatformKey
-                + " / hasLauncherEntry : " + hasLauncherEntry);
+                + " / hasLauncherEntry : " + hasLauncherEntry
+                + " / isAppLocaleSupported : " + isAppLocaleSupported);
 
-        return !isDisallowedPackage && !isSignedWithPlatformKey && hasLauncherEntry;
+        return !isDisallowedPackage
+                && !isSignedWithPlatformKey
+                && hasLauncherEntry
+                && isAppLocaleSupported;
     }
 
     private static boolean isDisallowedPackage(Context context, String packageName) {
@@ -86,4 +94,61 @@ public class AppLocaleUtil {
         return infos.stream()
                 .anyMatch(info -> info.activityInfo.packageName.equals(packageName));
     }
+
+    /**
+     * Check the function of per app language is supported by current application.
+     */
+    public static boolean isAppLocaleSupported(Context context, String packageName) {
+        if (getPackageLocales(context, packageName) != null) {
+            return true;
+        }
+
+        if (FeatureFlagUtils.isEnabled(
+                context, FeatureFlagUtils.SETTINGS_APP_LOCALE_OPT_IN_ENABLED)) {
+            return false;
+        }
+
+        return getAssetLocales(context, packageName).length > 0;
+    }
+
+    /**
+     * Get locales fron AssetManager.
+     */
+    public static String[] getAssetLocales(Context context, String packageName) {
+        try {
+            PackageManager packageManager = context.getPackageManager();
+            String[] locales = packageManager.getResourcesForApplication(
+                    packageManager.getPackageInfo(packageName, PackageManager.MATCH_ALL)
+                            .applicationInfo).getAssets().getNonSystemLocales();
+            if (locales == null) {
+                Log.i(TAG, "[" + packageName + "] locales are null.");
+            }
+            if (locales.length <= 0) {
+                Log.i(TAG, "[" + packageName + "] locales length is 0.");
+                return new String[0];
+            }
+            String locale = locales[0];
+            Log.i(TAG, "First asset locale - [" + packageName + "] " + locale);
+            return locales;
+        } catch (PackageManager.NameNotFoundException e) {
+            Log.w(TAG, "Can not found the package name : " + packageName + " / " + e);
+        }
+        return new String[0];
+    }
+
+    /**
+     * Get locales from LocaleConfig.
+     */
+    public static LocaleList getPackageLocales(Context context, String packageName) {
+        try {
+            LocaleConfig localeConfig =
+                    new LocaleConfig(context.createPackageContext(packageName, 0));
+            if (localeConfig.getStatus() == LocaleConfig.STATUS_SUCCESS) {
+                return localeConfig.getSupportedLocales();
+            }
+        } catch (PackageManager.NameNotFoundException e) {
+            Log.w(TAG, "Can not found the package name : " + packageName + " / " + e);
+        }
+        return null;
+    }
 }