/*
 * Copyright 2006-2009 Wyona
 *
 *  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.wyona.org/licenses/APACHE-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.wyona.yanel.core.util;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;

import javax.servlet.http.HttpServletRequest;

import org.apache.log4j.Logger;

/**
 * TODO:
 * create Request class which extends javax.servlet.http.HttpServletRequest
 * and override the getParameter(...) method.
 *
 */
public class HttpServletRequestHelper  {
    public static String form_encoding = "UTF-8";
    public static String container_encoding = "ISO-8859-1";
    
    private static Logger log = Logger.getLogger(HttpServletRequestHelper.class);

    public static String getParameter(HttpServletRequest req, String name) {
        return getParameterValue(req, req.getParameter(name));
    }

    public static String getParameterValue(HttpServletRequest req, String value) {
        if ("POST".equals(req.getMethod())) {
            final String request_body_encoding = req.getCharacterEncoding();
            if (log.isDebugEnabled()) log.debug("request_body_encoding: "+request_body_encoding);
            if (request_body_encoding != null) {
                if (value == null) {
                    return value;
                }
                try {
                    value = new String(value.getBytes(request_body_encoding), container_encoding);
                } catch (UnsupportedEncodingException uee) {
                    throw new RuntimeException(uee.toString(), uee);
                }
            }
        }
        if (value == null) {
            return value;
        }
        // Form and container encoding are equal, skip expensive value decoding
        if (container_encoding.equals(form_encoding)) {
            return value;
        }
        try {
            byte[] bytes = value.getBytes(container_encoding);
            return new String(bytes, form_encoding);
        } catch (UnsupportedEncodingException uee) {
            throw new RuntimeException(uee.toString(), uee);
        }
    }

    /**
     * Decode an URI that was part of an URL path.
     *
     * Algorithm: If the 1st character of the URI is the escape character,
     *  replace all occurrences of this character by '%' and decode as Percent-Encoded URI.
     */
    public static String decodeURIinURLpath(final char escapeCharacter, final String URLpathPart) {
        final char firstCharacter = URLpathPart.charAt(0);
        if (firstCharacter != escapeCharacter) {
            return URLpathPart;
        }
        final String decodedURLpathPart = URLpathPart.substring(1).replace(escapeCharacter, '%');
        final String encodedURL = decodedURLpathPart.replaceAll("\\+", "%2B");
        try {
            return URLDecoder.decode(encodedURL, "UTF-8");
        } catch (UnsupportedEncodingException uee) {
            throw new RuntimeException(uee); // this should never happen, as UTF-8 encoding should be always available
        }
    }

}