/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/auth/AuthChallengeParser.java,v 1.10 2004/05/13 04:02:00 mbecke Exp $
 * $Revision: 1.10 $
 * $Date: 2004/05/13 04:02:00 $
 *
 * ====================================================================
 *
 *  Copyright 2002-2004 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient.auth;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.util.ParameterParser;

/**
 * This class provides utility methods for parsing HTTP www and proxy authentication 
 * challenges.
 * 
 * @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
 * 
 * @since 2.0beta1
 */
public final class AuthChallengeParser {
    /** 
     * Extracts authentication scheme from the given authentication 
     * challenge.
     *
     * @param challengeStr the authentication challenge string
     * @return authentication scheme
     * 
     * @throws MalformedChallengeException when the authentication challenge string
     *  is malformed
     * 
     * @since 2.0beta1
     */
    public static String extractScheme(final String challengeStr) 
      throws MalformedChallengeException {
        if (challengeStr == null) {
            throw new IllegalArgumentException("Challenge may not be null"); 
        }
        int idx = challengeStr.indexOf(' ');
        String s = null; 
        if (idx == -1) {
            s = challengeStr;
        } else {
            s = challengeStr.substring(0, idx);
        }
        if (s.equals("")) {
            throw new MalformedChallengeException("Invalid challenge: " + challengeStr);
        }
        return s.toLowerCase();
    }

    /** 
     * Extracts a map of challenge parameters from an authentication challenge.
     * Keys in the map are lower-cased
     *
     * @param challengeStr the authentication challenge string
     * @return a map of authentication challenge parameters
     * @throws MalformedChallengeException when the authentication challenge string
     *  is malformed
     * 
     * @since 2.0beta1
     */
    public static Map extractParams(final String challengeStr)
      throws MalformedChallengeException {
        if (challengeStr == null) {
            throw new IllegalArgumentException("Challenge may not be null"); 
        }
        int idx = challengeStr.indexOf(' ');
        if (idx == -1) {
            throw new MalformedChallengeException("Invalid challenge: " + challengeStr);
        }
        Map map = new HashMap();
        ParameterParser parser = new ParameterParser();
        List params = parser.parse(
            challengeStr.substring(idx + 1, challengeStr.length()), ',');
        for (int i = 0; i < params.size(); i++) {
            NameValuePair param = (NameValuePair) params.get(i);
            map.put(param.getName().toLowerCase(), param.getValue());
        }
        return map;
    }

    /** 
     * Extracts a map of challenges ordered by authentication scheme name
     *
     * @param headers the array of authorization challenges
     * @return a map of authorization challenges
     * 
     * @throws MalformedChallengeException if any of challenge strings
     *  is malformed
     * 
     * @since 3.0
     */
    public static Map parseChallenges(final Header[] headers)
      throws MalformedChallengeException {
        if (headers == null) {
            throw new IllegalArgumentException("Array of challenges may not be null");
        }
        String challenge = null;
        Map challengemap = new HashMap(headers.length); 
        for (int i = 0; i < headers.length; i++) {
            challenge = headers[i].getValue();
            String s = AuthChallengeParser.extractScheme(challenge);
            challengemap.put(s, challenge);
        }
        return challengemap;
   }
}