/*
 *  Copyright 1999-2004 The Apache Software Foundation
 *
 *  Licensed 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.tomcat.util.http;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Locale;
import java.util.StringTokenizer;
import java.util.Vector;

/**
 * Util to process the "Accept-Language" header. Used by facade to implement
 * getLocale() and by StaticInterceptor.
 *
 * Not optimized - it's very slow.
 * 
 * @author James Duncan Davidson [duncan@eng.sun.com]
 * @author James Todd [gonzo@eng.sun.com]
 * @author Jason Hunter [jch@eng.sun.com]
 * @author Harish Prabandham
 * @author costin@eng.sun.com
 */
public class AcceptLanguage {

    public static Locale getLocale(String acceptLanguage) {
	if( acceptLanguage == null ) return Locale.getDefault();

        Hashtable languages = new Hashtable();
        Vector quality=new Vector();
        processAcceptLanguage(acceptLanguage, languages,quality);

        if (languages.size() == 0) return Locale.getDefault();

        Vector l = new Vector();
        extractLocales( languages,quality, l);

        return (Locale)l.elementAt(0);
    }

    public static Enumeration getLocales(String acceptLanguage) {
    	// Short circuit with an empty enumeration if null header
        if (acceptLanguage == null) {
            Vector v = new Vector();
            v.addElement(Locale.getDefault());
            return v.elements();
        }
	
        Hashtable languages = new Hashtable();
        Vector quality=new Vector();
    	processAcceptLanguage(acceptLanguage, languages , quality);

        if (languages.size() == 0) {
            Vector v = new Vector();
            v.addElement(Locale.getDefault());
            return v.elements();
        }
    	Vector l = new Vector();
    	extractLocales( languages, quality , l);
    	return l.elements();
    }

    private static void processAcceptLanguage( String acceptLanguage,
					      Hashtable languages, Vector q)
    {
        StringTokenizer languageTokenizer =
            new StringTokenizer(acceptLanguage, ",");

        while (languageTokenizer.hasMoreTokens()) {
            String language = languageTokenizer.nextToken().trim();
            int qValueIndex = language.indexOf(';');
            int qIndex = language.indexOf('q');
            int equalIndex = language.indexOf('=');
            Double qValue = new Double(1);

            if (qValueIndex > -1 &&
                    qValueIndex < qIndex &&
                    qIndex < equalIndex) {
    	        String qValueStr = language.substring(qValueIndex + 1);
                language = language.substring(0, qValueIndex);
                qValueStr = qValueStr.trim().toLowerCase();
                qValueIndex = qValueStr.indexOf('=');
                qValue = new Double(0);
                if (qValueStr.startsWith("q") &&
                    qValueIndex > -1) {
                    qValueStr = qValueStr.substring(qValueIndex + 1);
                    try {
                        qValue = new Double(qValueStr.trim());
                    } catch (NumberFormatException nfe) {
                    }
                }
            }

            // XXX
            // may need to handle "*" at some point in time

            if (! language.equals("*")) {
                String key = qValue.toString();
                Vector v;
                if (languages.containsKey(key)) {
                    v = (Vector)languages.get(key) ;
                } else {
                    v= new Vector();
                    q.addElement(qValue);
                }
                v.addElement(language);
                languages.put(key, v);
            }
        }
    }

    private static void extractLocales(Hashtable languages, Vector q,Vector l)
    {
        // XXX We will need to order by q value Vector in the Future ?
        Enumeration e = q.elements();
        while (e.hasMoreElements()) {
            Vector v =
                (Vector)languages.get(((Double)e.nextElement()).toString());
            Enumeration le = v.elements();
            while (le.hasMoreElements()) {
    	        String language = (String)le.nextElement();
	        	String country = "";
        		int countryIndex = language.indexOf("-");
                if (countryIndex > -1) {
                    country = language.substring(countryIndex + 1).trim();
                    language = language.substring(0, countryIndex).trim();
                }
                l.addElement(new Locale(language, country));
            }
        }
    }


}