/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 package org.apache.myfaces.application;

 import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.Collections;

 import java.util.HashSet;

 import java.util.List;

 import java.util.Locale;

 import java.util.Set;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.ConcurrentMap;

 /**

  * <p>Operations to assist when working with a {@link Locale}.</p>

  *

  * <p>This class tries to handle {@code null} input gracefully.

  * An exception will not be thrown for a {@code null} input.

  * Each method documents its behaviour in more detail.</p>

  *

  * NOTE: This a copy of commons lang LocaleUtils, to use it inside MyFaces 

  *

  * @since 2.2

  * @version $Id$

  */

 class _LocaleUtils

 {

     /** Concurrent map of language locales by country. */

     private static final ConcurrentMap<String, List<Locale>> LANGUAGES_BY_COUNTRY =

             new ConcurrentHashMap<String, List<Locale>>();

     /** Concurrent map of country locales by language. */

     private static final ConcurrentMap<String, List<Locale>> COUNTRIES_BY_LANGUAGE =

             new ConcurrentHashMap<String, List<Locale>>();

     /**

      * <p>{@code _LocaleUtils} instances should NOT be constructed in standard programming.

      * Instead, the class should be used as {@code _LocaleUtils.toLocale("en_GB");}.</p>

      *

      * <p>This constructor is public to permit tools that require a JavaBean instance

      * to operate.</p>

      */

     public _LocaleUtils()

     {

         super();

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Converts a String to a Locale.</p>

      *

      * <p>This method takes the string format of a locale and creates the

      * locale object from it.</p>

      *

      * <pre>

      *   _LocaleUtils.toLocale("en")         = new Locale("en", "")

      *   _LocaleUtils.toLocale("en_GB")      = new Locale("en", "GB")

      *   _LocaleUtils.toLocale("en_GB_xxx")  = new Locale("en", "GB", "xxx")   (#)

      * </pre>

      *

      * <p>(#) The behaviour of the JDK variant constructor changed between JDK1.3 and JDK1.4.

      * In JDK1.3, the constructor upper cases the variant, in JDK1.4, it doesn't.

      * Thus, the result from getVariant() may vary depending on your JDK.</p>

      *

      * <p>This method validates the input strictly.

      * The language code must be lowercase.

      * The country code must be uppercase.

      * The separator must be an underscore.

      * The length must be correct.

      * </p>

      *

      * @param str  the locale String to convert, null returns null

      * @return a Locale, null if null input

      * @throws IllegalArgumentException if the string is an invalid format

      */

     public static Locale toLocale(String str)

     {

         if (str == null)

         {

             return null;

         }

         int len = str.length();

         if (len != 2 && len != 5 && len < 7)

         {

             throw new IllegalArgumentException("Invalid locale format: " + str);

         }

         char ch0 = str.charAt(0);

         char ch1 = str.charAt(1);

         if (ch0 < 'a' || ch0 > 'z' || ch1 < 'a' || ch1 > 'z')

         {

             throw new IllegalArgumentException("Invalid locale format: " + str);

         }

         if (len == 2)

         {

             return new Locale(str, "");

         }

         else

         {

             if (str.charAt(2) != '_')

             {

                 throw new IllegalArgumentException("Invalid locale format: " + str);

             }

             char ch3 = str.charAt(3);

             if (ch3 == '_')

             {

                 return new Locale(str.substring(0, 2), "", str.substring(4));

             }

             char ch4 = str.charAt(4);

             if (ch3 < 'A' || ch3 > 'Z' || ch4 < 'A' || ch4 > 'Z')

             {

                 throw new IllegalArgumentException("Invalid locale format: " + str);

             }

             if (len == 5)

             {

                 return new Locale(str.substring(0, 2), str.substring(3, 5));

             }

             else

             {

                 if (str.charAt(5) != '_')

                 {

                     throw new IllegalArgumentException("Invalid locale format: " + str);

                 }

                 return new Locale(str.substring(0, 2), str.substring(3, 5), str.substring(6));

             }

         }

     }

     /**

      * Same as toLocale(), but return null when it cannot derive a valid Locale object.

      * 

      * @param str

      * @return 

      */

     public static Locale deriveLocale(String str)

     {

         if (str == null)

         {

             return null;

         }

         int len = str.length();

         if (len != 2 && len != 5 && len < 7)

         {

             return null;

         }

         char ch0 = str.charAt(0);

         char ch1 = str.charAt(1);

         if (ch0 < 'a' || ch0 > 'z' || ch1 < 'a' || ch1 > 'z')

         {

             return null;

         }

         if (len == 2)

         {

             return new Locale(str, "");

         }

         else

         {

             if (str.charAt(2) != '_')

             {

                 return null;

             }

             char ch3 = str.charAt(3);

             if (ch3 == '_')

             {

                 return new Locale(str.substring(0, 2), "", str.substring(4));

             }

             char ch4 = str.charAt(4);

             if (ch3 < 'A' || ch3 > 'Z' || ch4 < 'A' || ch4 > 'Z')

             {

                 return null;

             }

             if (len == 5)

             {

                 return new Locale(str.substring(0, 2), str.substring(3, 5));

             }

             else

             {

                 if (str.charAt(5) != '_')

                 {

                     return null;

                 }

                 return new Locale(str.substring(0, 2), str.substring(3, 5), str.substring(6));

             }

         }

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Obtains the list of locales to search through when performing

      * a locale search.</p>

      *

      * <pre>

      * localeLookupList(Locale("fr","CA","xxx"))

      *   = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr")]

      * </pre>

      *

      * @param locale  the locale to start from

      * @return the unmodifiable list of Locale objects, 0 being locale, not null

      */

     public static List<Locale> localeLookupList(Locale locale)

     {

         return localeLookupList(locale, locale);

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Obtains the list of locales to search through when performing

      * a locale search.</p>

      *

      * <pre>

      * localeLookupList(Locale("fr", "CA", "xxx"), Locale("en"))

      *   = [Locale("fr","CA","xxx"), Locale("fr","CA"), Locale("fr"), Locale("en"]

      * </pre>

      *

      * <p>The result list begins with the most specific locale, then the

      * next more general and so on, finishing with the default locale.

      * The list will never contain the same locale twice.</p>

      *

      * @param locale  the locale to start from, null returns empty list

      * @param defaultLocale  the default locale to use if no other is found

      * @return the unmodifiable list of Locale objects, 0 being locale, not null

      */

     public static List<Locale> localeLookupList(Locale locale, Locale defaultLocale)

     {

         List<Locale> list = new ArrayList<Locale>(4);

         if (locale != null)

         {

             list.add(locale);

             if (locale.getVariant().length() > 0)

             {

                 list.add(new Locale(locale.getLanguage(), locale.getCountry()));

             }

             if (locale.getCountry().length() > 0)

             {

                 list.add(new Locale(locale.getLanguage(), ""));

             }

             if (!list.contains(defaultLocale))

             {

                 list.add(defaultLocale);

             }

         }

         return Collections.unmodifiableList(list);

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Obtains an unmodifiable list of installed locales.</p>

      *

      * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.

      * It is more efficient, as the JDK method must create a new array each

      * time it is called.</p>

      *

      * @return the unmodifiable list of available locales

      */

     public static List<Locale> availableLocaleList()

     {

         return SyncAvoid.AVAILABLE_LOCALE_LIST;

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Obtains an unmodifiable set of installed locales.</p>

      *

      * <p>This method is a wrapper around {@link Locale#getAvailableLocales()}.

      * It is more efficient, as the JDK method must create a new array each

      * time it is called.</p>

      *

      * @return the unmodifiable set of available locales

      */

     public static Set<Locale> availableLocaleSet()

     {

         return SyncAvoid.AVAILABLE_LOCALE_SET;

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Checks if the locale specified is in the list of available locales.</p>

      *

      * @param locale the Locale object to check if it is available

      * @return true if the locale is a known locale

      */

     public static boolean isAvailableLocale(Locale locale)

     {

         return availableLocaleList().contains(locale);

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Obtains the list of languages supported for a given country.</p>

      *

      * <p>This method takes a country code and searches to find the

      * languages available for that country. Variant locales are removed.</p>

      *

      * @param countryCode  the 2 letter country code, null returns empty

      * @return an unmodifiable List of Locale objects, not null

      */

     public static List<Locale> languagesByCountry(String countryCode)

     {

         if (countryCode == null)

         {

             return Collections.emptyList();

         }

         List<Locale> langs = LANGUAGES_BY_COUNTRY.get(countryCode);

         if (langs == null)

         {

             langs = new ArrayList<Locale>();

             List<Locale> locales = availableLocaleList();

             for (int i = 0; i < locales.size(); i++)

             {

                 Locale locale = locales.get(i);

                 if (countryCode.equals(locale.getCountry()) &&

                         locale.getVariant().length() == 0)

                 {

                     langs.add(locale);

                 }

             }

             langs = Collections.unmodifiableList(langs);

             LANGUAGES_BY_COUNTRY.putIfAbsent(countryCode, langs);

             langs = LANGUAGES_BY_COUNTRY.get(countryCode);

         }

         return langs;

     }

     //-----------------------------------------------------------------------

     /**

      * <p>Obtains the list of countries supported for a given language.</p>

      *

      * <p>This method takes a language code and searches to find the

      * countries available for that language. Variant locales are removed.</p>

      *

      * @param languageCode  the 2 letter language code, null returns empty

      * @return an unmodifiable List of Locale objects, not null

      */

     public static List<Locale> countriesByLanguage(String languageCode)

     {

         if (languageCode == null)

         {

             return Collections.emptyList();

         }

         List<Locale> countries = COUNTRIES_BY_LANGUAGE.get(languageCode);

         if (countries == null)

         {

             countries = new ArrayList<Locale>();

             List<Locale> locales = availableLocaleList();

             for (int i = 0; i < locales.size(); i++)

             {

                 Locale locale = locales.get(i);

                 if (languageCode.equals(locale.getLanguage()) &&

                         locale.getCountry().length() != 0 &&

                         locale.getVariant().length() == 0)

                 {

                     countries.add(locale);

                 }

             }

             countries = Collections.unmodifiableList(countries);

             COUNTRIES_BY_LANGUAGE.putIfAbsent(languageCode, countries);

             countries = COUNTRIES_BY_LANGUAGE.get(languageCode);

         }

         return countries;

     }

     //-----------------------------------------------------------------------

     // class to avoid synchronization

     static class SyncAvoid

     {

         /** Unmodifiable list of available locales. */

         private static final List<Locale> AVAILABLE_LOCALE_LIST;

         /** Unmodifiable set of available locales. */

         private static final Set<Locale> AVAILABLE_LOCALE_SET;

         static

         {

             List<Locale> list = new ArrayList<Locale>(Arrays.asList(Locale.getAvailableLocales()));  // extra safe

             AVAILABLE_LOCALE_LIST = Collections.unmodifiableList(list);

             AVAILABLE_LOCALE_SET = Collections.unmodifiableSet(new HashSet<Locale>(availableLocaleList()));

         }

     }

 }