/*
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * 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.http.impl.cookie;

import java.util.ArrayList;
import java.util.BitSet;
import java.util.List;

import org.apache.http.HeaderElement;
import org.apache.http.NameValuePair;
import org.apache.http.ParseException;
import org.apache.http.annotation.Immutable;
import org.apache.http.message.BasicHeaderElement;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.message.ParserCursor;
import org.apache.http.message.TokenParser;
import org.apache.http.util.Args;
import org.apache.http.util.CharArrayBuffer;

/**
 *
 * @since 4.0
 */
@Immutable
public class NetscapeDraftHeaderParser {

    public final static NetscapeDraftHeaderParser DEFAULT = new NetscapeDraftHeaderParser();

    private final static char PARAM_DELIMITER                = ';';

    // IMPORTANT!
    // These private static variables must be treated as immutable and never exposed outside this class
    private static final BitSet TOKEN_DELIMS = TokenParser.INIT_BITSET('=', PARAM_DELIMITER);
    private static final BitSet VALUE_DELIMS = TokenParser.INIT_BITSET(PARAM_DELIMITER);

    private final TokenParser tokenParser;

    public NetscapeDraftHeaderParser() {
        super();
        this.tokenParser = TokenParser.INSTANCE;
    }

    public HeaderElement parseHeader(
            final CharArrayBuffer buffer,
            final ParserCursor cursor) throws ParseException {
        Args.notNull(buffer, "Char array buffer");
        Args.notNull(cursor, "Parser cursor");
        final NameValuePair nvp = parseNameValuePair(buffer, cursor);
        final List<NameValuePair> params = new ArrayList<NameValuePair>();
        while (!cursor.atEnd()) {
            final NameValuePair param = parseNameValuePair(buffer, cursor);
            params.add(param);
        }
        return new BasicHeaderElement(
                nvp.getName(),
                nvp.getValue(), params.toArray(new NameValuePair[params.size()]));
    }

    private NameValuePair parseNameValuePair(
            final CharArrayBuffer buffer, final ParserCursor cursor) {
        final String name = tokenParser.parseToken(buffer, cursor, TOKEN_DELIMS);
        if (cursor.atEnd()) {
            return new BasicNameValuePair(name, null);
        }
        final int delim = buffer.charAt(cursor.getPos());
        cursor.updatePos(cursor.getPos() + 1);
        if (delim != '=') {
            return new BasicNameValuePair(name, null);
        }
        final String value = tokenParser.parseToken(buffer, cursor, VALUE_DELIMS);
        if (!cursor.atEnd()) {
            cursor.updatePos(cursor.getPos() + 1);
        }
        return new BasicNameValuePair(name, value);
    }

}