FoxMagiskModuleManager/app/src/main/java/com/fox2code/mmm/compat/CompatConfigHelper.java

package com.fox2code.mmm.compat;

import android.content.Context;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.os.Build;
import android.os.LocaleList;

import java.util.Locale;

/**
 * I will probably outsource this to a separate library later
 */
final class CompatConfigHelper {
    // ENGLISH like this is an unnatural local, as it doesn't precise the country
    // All english locales settable by the user precise the country (Ex: en-US)
    private static final Locale englishLocale = Locale.ENGLISH;
    private static final Object englishLocales =
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.N ?
            new LocaleList(englishLocale) : null;

    private final Context context;
    private Object userLocales;
    private Locale userLocale;

    CompatConfigHelper(Context context) {
        this.context = context;
    }

    void checkResourcesOverrides(boolean forceEnglish,
                                 Boolean nightModeOverride) {
        this.checkResourcesOverrides(
                this.context.getTheme(),
                forceEnglish, nightModeOverride);
    }

    void checkResourcesOverrides(Resources.Theme theme, boolean forceEnglish,
                                 Boolean nightModeOverride) {
        Resources res = theme.getResources();
        if (this.checkResourcesOverrides(res.getConfiguration(),
                forceEnglish, nightModeOverride)) {
            res.updateConfiguration(
                    res.getConfiguration(),
                    res.getDisplayMetrics());
        }
    }

    boolean checkResourcesOverrides(Configuration conf, boolean forceEnglish,
                                 Boolean nightModeOverride) {
        Locale current = conf.locale;
        boolean didChange = false;
        boolean wasForceEnglish = englishLocale.equals(current);
        if (forceEnglish != wasForceEnglish) {
            didChange = true;
            if (forceEnglish) {
                this.userLocale = conf.locale;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                    this.userLocales = conf.getLocales();
                }
                conf.locale = englishLocale;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                    conf.setLocales((LocaleList) englishLocales);
                }
            } else {
                conf.locale = this.userLocale;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                    conf.setLocales((LocaleList) this.userLocales);
                }
            }
        }
        int nightMode = conf.uiMode & Configuration.UI_MODE_NIGHT_MASK;
        int sysNightMode = Resources.getSystem()
                .getConfiguration().uiMode & Configuration.UI_MODE_NIGHT_MASK;
        if (nightModeOverride == null ? sysNightMode != nightMode :
                nightMode != (nightModeOverride ?
                        Configuration.UI_MODE_NIGHT_YES : Configuration.UI_MODE_NIGHT_NO)) {
            didChange = true;
            nightMode = nightModeOverride == null ? sysNightMode : nightModeOverride ?
                    Configuration.UI_MODE_NIGHT_YES : Configuration.UI_MODE_NIGHT_NO;
            conf.uiMode = nightMode | (conf.uiMode & ~Configuration.UI_MODE_NIGHT_MASK);
        }
        if (!forceEnglish && !wasForceEnglish) {
            this.userLocale = null;
            this.userLocales = null;
        }
        return didChange;
    }

    public Locale getUserLocale() {
        // Only use cached value if force english
        Locale locale = this.context.getResources().getConfiguration().locale;
        return englishLocale.equals(locale) ? this.userLocale : locale;
    }
}