/*
 * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/HttpParser.java,v 1.13 2005/01/11 13:57:06 oglueck Exp $
 * $Revision: 533405 $
 * $Date: 2007-04-28 20:19:29 +0200 (Sat, 28 Apr 2007) $
 *
 * ====================================================================
 *
 *  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.commons.httpclient;

import java.io.IOException;
import java.io.InputStream;
import java.io.ByteArrayOutputStream;
import java.util.ArrayList;

import org.apache.commons.httpclient.util.EncodingUtil;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

A utility class for parsing http header values according to
RFC-2616 Section 4 and 19.3.
Author:
Michael Becke, Oleg Kalnichevski
Since:
2.0beta1/**
 * A utility class for parsing http header values according to
 * RFC-2616 Section 4 and 19.3.
 * 
 * @author Michael Becke
 * @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
 * 
 * @since 2.0beta1
 */
public class HttpParser {

    
Log object for this class. /** Log object for this class. */
    private static final Log LOG = LogFactory.getLog(HttpParser.class);
    
    
Constructor for HttpParser.
/**
     * Constructor for HttpParser.
     */
    private HttpParser() { }

    
Return byte array from an (unchunked) input stream.
Stop reading when "\n" terminator encountered 
If the stream ends before the line terminator is found,
the last part of the string will still be returned. 
If no input data available, null is returned.
Params:
inputStream – the stream to read from
Throws:
IOException – if an I/O problem occurs
Returns:
a byte array from the stream/**
     * Return byte array from an (unchunked) input stream.
     * Stop reading when <tt>"\n"</tt> terminator encountered 
     * If the stream ends before the line terminator is found,
     * the last part of the string will still be returned. 
     * If no input data available, <code>null</code> is returned.
     *
     * @param inputStream the stream to read from
     *
     * @throws IOException if an I/O problem occurs
     * @return a byte array from the stream
     */
    public static byte[] readRawLine(InputStream inputStream) throws IOException {
        LOG.trace("enter HttpParser.readRawLine()");

        ByteArrayOutputStream buf = new ByteArrayOutputStream();
        int ch;
        while ((ch = inputStream.read()) >= 0) {
            buf.write(ch);
            if (ch == '\n') { // be tolerant (RFC-2616 Section 19.3)
                break;
            }
        }
        if (buf.size() == 0) {
            return null;
        }
        return buf.toByteArray();
    }

    
Read up to "\n" from an (unchunked) input stream.
If the stream ends before the line terminator is found,
the last part of the string will still be returned.
If no input data available, null is returned.
Params:
inputStream – the stream to read from
charset – charset of HTTP protocol elements
Throws:
IOException – if an I/O problem occurs
Returns:
a line from the stream
Since:
3.0/**
     * Read up to <tt>"\n"</tt> from an (unchunked) input stream.
     * If the stream ends before the line terminator is found,
     * the last part of the string will still be returned.
     * If no input data available, <code>null</code> is returned.
     *
     * @param inputStream the stream to read from
     * @param charset charset of HTTP protocol elements
     *
     * @throws IOException if an I/O problem occurs
     * @return a line from the stream
     * 
     * @since 3.0
     */
    public static String readLine(InputStream inputStream, String charset) throws IOException {
        LOG.trace("enter HttpParser.readLine(InputStream, String)");
        byte[] rawdata = readRawLine(inputStream);
        if (rawdata == null) {
            return null;
        }
        // strip CR and LF from the end
        int len = rawdata.length;
        int offset = 0;
        if (len > 0) {
            if (rawdata[len - 1] == '\n') {
                offset++;
                if (len > 1) {
                    if (rawdata[len - 2] == '\r') {
                        offset++;
                    }
                }
            }
        }
        final String result =
            EncodingUtil.getString(rawdata, 0, len - offset, charset);
        if (Wire.HEADER_WIRE.enabled()) {
            String logoutput = result;
            if (offset == 2)
                logoutput = result + "\r\n";
            else if (offset == 1)
                logoutput = result + "\n";
            Wire.HEADER_WIRE.input(logoutput);
        }
        return result;
    }

    
Read up to "\n" from an (unchunked) input stream.
If the stream ends before the line terminator is found,
the last part of the string will still be returned.
If no input data available, null is returned
Params:
inputStream – the stream to read from
Throws:
IOException – if an I/O problem occurs
Returns:
a line from the stream
Deprecated:
use #readLine(InputStream, String)/**
     * Read up to <tt>"\n"</tt> from an (unchunked) input stream.
     * If the stream ends before the line terminator is found,
     * the last part of the string will still be returned.
     * If no input data available, <code>null</code> is returned
     *
     * @param inputStream the stream to read from
     *
     * @throws IOException if an I/O problem occurs
     * @return a line from the stream
     * 
     * @deprecated use #readLine(InputStream, String)
     */

    public static String readLine(InputStream inputStream) throws IOException {
        LOG.trace("enter HttpParser.readLine(InputStream)");
        return readLine(inputStream, "US-ASCII");
    }
    
    
Parses headers from the given stream.  Headers with the same name are not
combined.
Params:
is – the stream to read headers from
charset – the charset to use for reading the data
Throws:
IOException – if an IO error occurs while reading from the stream
HttpException – if there is an error parsing a header value
Returns:
an array of headers in the order in which they were parsed
Since:
3.0/**
     * Parses headers from the given stream.  Headers with the same name are not
     * combined.
     * 
     * @param is the stream to read headers from
     * @param charset the charset to use for reading the data
     * 
     * @return an array of headers in the order in which they were parsed
     * 
     * @throws IOException if an IO error occurs while reading from the stream
     * @throws HttpException if there is an error parsing a header value
     * 
     * @since 3.0
     */
    public static Header[] parseHeaders(InputStream is, String charset) throws IOException, HttpException {
        LOG.trace("enter HeaderParser.parseHeaders(InputStream, String)");

        ArrayList headers = new ArrayList();
        String name = null;
        StringBuffer value = null;
        for (; ;) {
            String line = HttpParser.readLine(is, charset);
            if ((line == null) || (line.trim().length() < 1)) {
                break;
            }

            // Parse the header name and value
            // Check for folded headers first
            // Detect LWS-char see HTTP/1.0 or HTTP/1.1 Section 2.2
            // discussion on folded headers
            if ((line.charAt(0) == ' ') || (line.charAt(0) == '\t')) {
                // we have continuation folded header
                // so append value
                if (value != null) {
                    value.append(' ');
                    value.append(line.trim());
                }
            } else {
                // make sure we save the previous name,value pair if present
                if (name != null) {
                    headers.add(new Header(name, value.toString()));
                }

                // Otherwise we should have normal HTTP header line
                // Parse the header name and value
                int colon = line.indexOf(":");
                if (colon < 0) {
                    throw new ProtocolException("Unable to parse header: " + line);
                }
                name = line.substring(0, colon).trim();
                value = new StringBuffer(line.substring(colon + 1).trim());
            }

        }

        // make sure we save the last name,value pair if present
        if (name != null) {
            headers.add(new Header(name, value.toString()));
        }
        
        return (Header[]) headers.toArray(new Header[headers.size()]);    
    }

    
Parses headers from the given stream.  Headers with the same name are not
combined.
Params:
is – the stream to read headers from
Throws:
IOException – if an IO error occurs while reading from the stream
HttpException – if there is an error parsing a header value
Returns:
an array of headers in the order in which they were parsed
Deprecated:
use #parseHeaders(InputStream, String)/**
     * Parses headers from the given stream.  Headers with the same name are not
     * combined.
     * 
     * @param is the stream to read headers from
     * 
     * @return an array of headers in the order in which they were parsed
     * 
     * @throws IOException if an IO error occurs while reading from the stream
     * @throws HttpException if there is an error parsing a header value
     * 
     * @deprecated use #parseHeaders(InputStream, String)
     */
    public static Header[] parseHeaders(InputStream is) throws IOException, HttpException {
        LOG.trace("enter HeaderParser.parseHeaders(InputStream, String)");
        return parseHeaders(is, "US-ASCII");
    }
}