/*
 * Copyright (c) 2012, grossmann
 * 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 the jo-widgets.org 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 jo-widgets.org 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.
 */

package org.jowidgets.i18n.api;

import java.util.Iterator;
import java.util.Locale;
import java.util.ServiceLoader;

import org.jowidgets.classloading.api.SharedClassLoader;

public final class LocaleHolder {

    private static ILocaleHolder instance;

    private LocaleHolder() {}

    /**
     * The the instance of the value holder. The previously used instance will be overridden.
     * 
     * @param localeProvider The locale provider to set
     */
    public static void setInstance(final ILocaleHolder localeProvider) {
        instance = localeProvider;
    }

    /**
     * @return The user locale of the currently set LocaleHolder
     */
    public static Locale getUserLocale() {
        return getInstance().getUserLocale();
    }

    /**
     * Sets the user locale on the currently set LocaleHolder
     * 
     * @param userLocale The locale to set, may be null
     */
    public static void setUserLocale(final Locale userLocale) {
        getInstance().setUserLocale(userLocale);
    }

    /**
     * Clears the user locale on the currently set LocaleHolder
     */
    public static void clearUserLocale() {
        getInstance().clearUserLocale();
    }

    /**
     * Gets the instance of the currently set value holder. If no value holder was injected before, an
     * default implementation will be returned
     * 
     * @return The currently set value holder
     */
    public static synchronized ILocaleHolder getInstance() {
        if (instance == null) {
            final ServiceLoader<ILocaleHolder> loader = ServiceLoader.load(
                    ILocaleHolder.class,
                    SharedClassLoader.getCompositeClassLoader());
            final Iterator<ILocaleHolder> iterator = loader.iterator();

            if (!iterator.hasNext()) {
                instance = new DefaultUserLocaleProvider();
            }
            else {
                instance = iterator.next();
                if (iterator.hasNext()) {
                    throw new IllegalStateException("More than one implementation found for '"
                        + ILocaleHolder.class.getName()
                        + "'");
                }
            }

        }
        return instance;
    }

    private static final class DefaultUserLocaleProvider implements ILocaleHolder {

        private Locale userLocale;

        @Override
        public Locale getUserLocale() {
            if (userLocale != null) {
                return userLocale;
            }
            else {
                return Locale.getDefault();
            }
        }

        @Override
        public void setUserLocale(final Locale userLocale) {
            this.userLocale = userLocale;
        }

        @Override
        public void clearUserLocale() {
            this.userLocale = null;
        }

    }

}