/**
 * 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.felix.karaf.features.internal;

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

/**
 * Utility class to parse a standard OSGi header with paths.
 *
 * @author <a href="mailto:dev@geronimo.apache.org">Apache Geronimo Project</a>
 * @version $Rev: 786132 $, $Date: 2009-06-18 17:47:58 +0200 (Thu, 18 Jun 2009) $
 */
public final class HeaderParser  {

    // Private constructor for static final class
    private HeaderParser() {
    }

    /**
     * Parse a given OSGi header into a list of paths
     *
     * @param header the OSGi header to parse
     * @return the list of paths extracted from this header
     */
    public static List<PathElement> parseHeader(String header) {
        List<PathElement> elements = new ArrayList<PathElement>();
        if (header == null || header.trim().length() == 0) {
            return elements;
        }
        String[] clauses = parseDelimitedString(header, ",");
        for (String clause : clauses) {
            String[] tokens = clause.split(";");
            if (tokens.length < 1) {
                throw new IllegalArgumentException("Invalid header clause: " + clause);
            }
            PathElement elem = new PathElement(tokens[0].trim());
            elements.add(elem);
            for (int i = 1; i < tokens.length; i++) {
                int pos = tokens[i].indexOf('=');
                if (pos != -1) {
                    if (pos > 0 && tokens[i].charAt(pos - 1) == ':') {
                        String name = tokens[i].substring(0, pos - 1).trim();
                        String value = tokens[i].substring(pos + 1).trim();
                        if (value.startsWith("\"") && value.endsWith("\"")) {
                            value = value.substring(1, value.length() - 1);
                        }
                        elem.addDirective(name, value);
                    } else {
                        String name = tokens[i].substring(0, pos).trim();
                        String value = tokens[i].substring(pos + 1).trim();
                        if (value.startsWith("\"") && value.endsWith("\"")) {
                            value = value.substring(1, value.length() - 1);
                        }
                        elem.addAttribute(name, value);
                    }
                } else {
                    elem = new PathElement(tokens[i].trim());
                    elements.add(elem);
                }
            }
        }
        return elements;
    }

    /**
     * Parses delimited string and returns an array containing the tokens. This
     * parser obeys quotes, so the delimiter character will be ignored if it is
     * inside of a quote. This method assumes that the quote character is not
     * included in the set of delimiter characters.
     * @param value the delimited string to parse.
     * @param delim the characters delimiting the tokens.
     * @return an array of string tokens or null if there were no tokens.
    **/
    public static String[] parseDelimitedString(String value, String delim)
    {
        if (value == null)
        {
           value = "";
        }

        List list = new ArrayList();

        int CHAR = 1;
        int DELIMITER = 2;
        int STARTQUOTE = 4;
        int ENDQUOTE = 8;

        StringBuffer sb = new StringBuffer();

        int expecting = (CHAR | DELIMITER | STARTQUOTE);

        for (int i = 0; i < value.length(); i++)
        {
            char c = value.charAt(i);

            boolean isDelimiter = (delim.indexOf(c) >= 0);
            boolean isQuote = (c == '"');

            if (isDelimiter && ((expecting & DELIMITER) > 0))
            {
                list.add(sb.toString().trim());
                sb.delete(0, sb.length());
                expecting = (CHAR | DELIMITER | STARTQUOTE);
            }
            else if (isQuote && ((expecting & STARTQUOTE) > 0))
            {
                sb.append(c);
                expecting = CHAR | ENDQUOTE;
            }
            else if (isQuote && ((expecting & ENDQUOTE) > 0))
            {
                sb.append(c);
                expecting = (CHAR | STARTQUOTE | DELIMITER);
            }
            else if ((expecting & CHAR) > 0)
            {
                sb.append(c);
            }
            else
            {
                throw new IllegalArgumentException("Invalid delimited string: " + value);
            }
        }

        if (sb.length() > 0)
        {
            list.add(sb.toString().trim());
        }

        return (String[]) list.toArray(new String[list.size()]);
    }

    public static class PathElement {

        private String path;
        private Map<String, String> attributes;
        private Map<String, String> directives;

        public PathElement(String path) {
            this.path = path;
            this.attributes = new HashMap<String, String>();
            this.directives = new HashMap<String, String>();
        }

        public String getName() {
            return this.path;
        }

        public Map<String, String> getAttributes() {
            return attributes;
        }

        public String getAttribute(String name) {
            return attributes.get(name);
        }

        public void addAttribute(String name, String value) {
            attributes.put(name, value);
        }

        public Map<String, String> getDirectives() {
            return directives;
        }

        public String getDirective(String name) {
            return directives.get(name);
        }

        public void addDirective(String name, String value) {
            directives.put(name, value);
        }

        public String toString() {
            StringBuilder sb = new StringBuilder(this.path);
            for (Map.Entry<String,String> directive : this.directives.entrySet()) {
                sb.append(";").append(directive.getKey()).append(":=").append(directive.getValue());
            }
            for (Map.Entry<String,String> attribute : this.attributes.entrySet()) {
                sb.append(";").append(attribute.getKey()).append("=").append(attribute.getValue());
            }
            return sb.toString(); 
        }

    }
}
