tasks/src/main/java/org/tasks/locale/Locale.java

package org.tasks.locale;

import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Dialog;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.os.Build;
import android.preference.PreferenceManager;
import android.support.v4.text.TextUtilsCompat;
import android.view.ContextThemeWrapper;
import android.view.View;
import android.view.ViewParent;

import com.google.common.base.Strings;

import org.tasks.R;

import java.text.NumberFormat;

import static com.todoroo.andlib.utility.AndroidUtilities.atLeastJellybeanMR1;

public class Locale {

    private static Locale DEFAULT = new Locale(java.util.Locale.getDefault(), null, -1);
    private static Locale INSTANCE;

    public static Locale getInstance(Context context) {
        if (INSTANCE == null) {
            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
            String language = prefs.getString(context.getString(R.string.p_language), null);
            int directionOverride = Integer.parseInt(prefs.getString(context.getString(R.string.p_layout_direction), "-1"));
            INSTANCE = new Locale(DEFAULT.getLocale(), language, directionOverride);
            java.util.Locale.setDefault(INSTANCE.getLocale());
        }

        return getInstance();
    }

    public static Locale getInstance() {
        return INSTANCE == null ? DEFAULT : INSTANCE;
    }

    private static final int[] sDialogButtons = new int[] { android.R.id.button1, android.R.id.button2, android.R.id.button3 };
    private static final char LEFT_TO_RIGHT_MARK = '\u200e';
    private static final char RIGHT_TO_LEFT_MARK = '\u200f';

    private static java.util.Locale localeFromString(String locale) {
        if (Strings.isNullOrEmpty(locale)) {
            return null;
        }

        String[] split = locale.split("-");
        if (split.length == 1) {
            return new java.util.Locale(split[0]);
        } else if (split.length == 2) {
            return new java.util.Locale(split[0], split[1]);
        }
        throw new RuntimeException();
    }

    private final java.util.Locale deviceLocale;
    private final java.util.Locale appLocale;
    private final int appDirectionality;
    private final char appDirectionalityMark;
    private final String languageOverride;
    private final int directionOverride;
    private final boolean hasUserOverrides;

    public Locale(java.util.Locale deviceLocale, String languageOverride, int directionOverride) {
        this.deviceLocale = deviceLocale;
        this.languageOverride = languageOverride;
        this.directionOverride = directionOverride;

        java.util.Locale override = localeFromString(languageOverride);
        if (override != null) {
            appLocale = override;
        } else {
            appLocale = deviceLocale;
        }

        if (directionOverride == View.LAYOUT_DIRECTION_LTR || directionOverride == View.LAYOUT_DIRECTION_RTL) {
            appDirectionality = directionOverride;
        } else  {
            appDirectionality = TextUtilsCompat.getLayoutDirectionFromLocale(appLocale);
        }
        appDirectionalityMark = appDirectionality == View.LAYOUT_DIRECTION_RTL ? RIGHT_TO_LEFT_MARK : LEFT_TO_RIGHT_MARK;
        int deviceDirectionality = TextUtilsCompat.getLayoutDirectionFromLocale(deviceLocale);
        hasUserOverrides = !(deviceLocale.equals(appLocale) && appDirectionality == deviceDirectionality) && atLeastJellybeanMR1();
    }

    public java.util.Locale getLocale() {
        return appLocale;
    }

    public char getDirectionalityMark() {
        return appDirectionalityMark;
    }

    public int getDirectionality() {
        return appDirectionality;
    }

    public String getLanguageOverride() {
        return languageOverride;
    }

    @SuppressLint("NewApi")
    public Context createConfigurationContext(Context context) {
        return hasUserOverrides
                ? context.createConfigurationContext(getLocaleConfiguration())
                : context;
    }

    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
    private Configuration getLocaleConfiguration() {
        Configuration configuration = new Configuration();
        configuration.locale = getLocale();
        final int layoutDirection = 1 + appDirectionality;
        configuration.screenLayout = (configuration.screenLayout&~Configuration.SCREENLAYOUT_LAYOUTDIR_MASK)|
                (layoutDirection << Configuration.SCREENLAYOUT_LAYOUTDIR_SHIFT);
        return configuration;
    }

    @SuppressLint("NewApi")
    public void applyOverrideConfiguration(ContextThemeWrapper wrapper) {
        if (hasUserOverrides) {
            wrapper.applyOverrideConfiguration(getLocaleConfiguration());
        }
    }

    public Locale withLanguage(String language) {
        return new Locale(deviceLocale, language, directionOverride);
    }

    public Locale withDirectionality(int directionality) {
        return new Locale(deviceLocale, languageOverride, directionality);
    }

    public String getDisplayName() {
        java.util.Locale locale = getLocale();
        return locale.getDisplayName(locale);
    }

    public String formatNumber(int number) {
        return NumberFormat.getNumberInstance(appLocale).format(number);
    }

    public String formatPercentage(int percentage) {
        return NumberFormat.getPercentInstance(appLocale).format(percentage / 100.0);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Locale locale = (Locale) o;

        return languageOverride != null ? languageOverride.equals(locale.languageOverride) : locale.languageOverride == null;
    }

    @Override
    public int hashCode() {
        return languageOverride != null ? languageOverride.hashCode() : 0;
    }

    @Override
    public String toString() {
        return "Locale{" +
                "deviceLocale=" + deviceLocale +
                ", appLocale=" + appLocale +
                ", appDirectionality=" + appDirectionality +
                ", languageOverride='" + languageOverride + '\'' +
                ", directionOverride=" + directionOverride +
                ", hasUserOverrides=" + hasUserOverrides +
                '}';
    }

    @SuppressLint("NewApi")
    public void applyDirectionality(Dialog dialog) {
        if (hasUserOverrides) {
            dialog.findViewById(android.R.id.content).setLayoutDirection(appDirectionality);
            for (int id : sDialogButtons) {
                ViewParent parent = dialog.findViewById(id).getParent();
                ((View) parent).setLayoutDirection(appDirectionality);
            }
        }
    }
}