/**
 * 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.cxf.common.util;

import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URLDecoder;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.logging.Logger;

import org.apache.cxf.common.logging.LogUtils;

/**
 * Utility class for decoding and encoding URLs
 *
 */
public final class UrlUtils {
    
    private static final Logger LOG = LogUtils.getL7dLogger(UrlUtils.class);
    
    private static final String[] RESERVED_CHARS = {"+"};
    private static final String[] ENCODED_CHARS = {"%2b"};
    
    private UrlUtils() {
        
    }

    /**
     * Decodes using URLDecoder - use when queries or form post values are decoded
     * @param value value to decode
     * @param enc encoding
     * @return
     */
    public static String urlDecode(String value, String enc) {
        try {
            value = URLDecoder.decode(value, enc);
        } catch (UnsupportedEncodingException e) {
            LOG.warning("UTF-8 encoding can not be used to decode " + value);          
        }
        return value;
    }
    
    public static String urlDecode(String value) {
        return urlDecode(value, "UTF-8");
    }
    
    /**
     * URL path segments may contain '+' symbols which should not be decoded into ' '
     * This method replaces '+' with %2B and delegates to URLDecoder
     * @param value value to decode
     * @return
     */
    public static String pathDecode(String value) {
        // TODO: we actually need to do a proper URI analysis here according to
        // http://tools.ietf.org/html/rfc3986
        for (int i = 0; i < RESERVED_CHARS.length; i++) {
            if (value.indexOf(RESERVED_CHARS[i]) != -1) {
                value = value.replace(RESERVED_CHARS[i], ENCODED_CHARS[i]);
            }
        }
        
        return urlDecode(value);
    }
    
    
    /**
     * Create a map from String to String that represents the contents of the query
     * portion of a URL. For each x=y, x is the key and y is the value.
     * @param s the query part of the URI.
     * @return the map.
     */
    public static Map<String, String> parseQueryString(String s) {
        Map<String, String> ht = new HashMap<String, String>();
        StringTokenizer st = new StringTokenizer(s, "&");
        while (st.hasMoreTokens()) {
            String pair = st.nextToken();
            int pos = pair.indexOf('=');
            if (pos == -1) {
                ht.put(pair.toLowerCase(), "");
            } else {
                ht.put(pair.substring(0, pos).toLowerCase(),
                       pair.substring(pos + 1));
            }
        }
        return ht;
    }
    
    /**
     * Return everything in the path up to the last slash in a URI.
     * @param baseURI
     * @return the trailing 
     */
    public static String getStem(String baseURI) {
        URI uri = URI.create(baseURI);
        baseURI = uri.getRawPath();
        int idx = baseURI.lastIndexOf('/');
        if (idx != -1) {
            baseURI = baseURI.substring(0, idx);
        }
        return URI.create(baseURI).getPath();
    }
    
    
}
