/*
    * $Header: /home/cvs/jakarta-commons/httpclient/src/java/org/apache/commons/httpclient/HttpParser.java,v 1.7.2.1 2004/02/22 18:21:13 olegk Exp $
    * $Revision: 1.7.2.1 $
    * $Date: 2004/02/22 18:21:13 $
    *
    * ====================================================================
    *
    *  Copyright 1999-2004 The Apache Software Foundation
    *
   *  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.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/>.
   *
   * [Additional notices, if required by prior licensing conditions]
   *
   */
  
  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.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /***
   * A utility class for parsing http header values.
   * 
   * @author Michael Becke
   * @author <a href="mailto:oleg@ural.ru">Oleg Kalnichevski</a>
   * 
   * @since 2.0beta1
   */
  public class HttpParser {
  
      /*** Log object for this class. */
      private static final Log LOG = LogFactory.getLog(HttpParser.class);
      
      /***
       * Constructor for HttpParser.
       */
      private HttpParser() { }
  
      /***
       * 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') {
                  break;
              }
          }
          if (buf.size() == 0) {
              return null;
          }
          return buf.toByteArray();
      }
  
      /***
       * 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
       */
 
     public static String readLine(InputStream inputStream) throws IOException {
         LOG.trace("enter HttpParser.readLine()");
         byte[] rawdata = readRawLine(inputStream);
         if (rawdata == null) {
             return null;
         }
         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++;
                     }
                 }
             }
         }
         return HttpConstants.getString(rawdata, 0, len - offset);
     }
 
     /***
      * 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
      */
     public static Header[] parseHeaders(InputStream is) throws IOException, HttpException {
         LOG.trace("enter HeaderParser.parseHeaders(HttpConnection, HeaderGroup)");
 
         ArrayList headers = new ArrayList();
         String name = null;
         StringBuffer value = null;
         for (; ;) {
             String line = HttpParser.readLine(is);
             if ((line == null) || (line.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 HttpException("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()]);    
     }
     
 }