/* this belongs to the WebRaveler package */
package webraveler.io;

import java.io.*;

import webraveler.http.HTTPMessage;


/**
 * InputStream that decodes Chunked encoding
 *
 * @author The Web Raveler Development Squad
 * @version 1.0
 */
 
public class ChunkedInputStream extends InputStream{
    /* instance variables */
    InputStream input;
    int bytesLeft= -1;
    boolean closed= false;

    /* constructors */
    /**
     *
     */
    public ChunkedInputStream(InputStream input){
	this.input = input;
    }

    /* instance methods */
    
    /**
     * Reads a byte from the input stream
     *
     * @return an int representing the byte read
     */
    public int read() throws IOException{
	if(closed) return -1;
	if( bytesLeft > 0 ){ //read from chunk
	    bytesLeft--;
	    return input.read();
	} else { //new chunk, so read its length
	    String line;
	    if( bytesLeft == 0) //first line, no extra crlf
		HTTPMessage.readLine(input);
	    line= HTTPMessage.readLine(input);
	    try{
		int c= line.indexOf(' ');
		if(c < 0) c= line.indexOf('\r');
		if(c < 0) c= line.indexOf('\n');
		if(c < 0) c= line.length();
		bytesLeft= Integer.parseInt(line.substring(0,c), 16);
	    } catch(NumberFormatException e){
		throw new IOException("Bad Transfer Encoding");
	    }
	    if( bytesLeft == 0 ) {//we found the terminating chunk
		closed= true;
		while( (line= HTTPMessage.readLine(input)) != null
			&& line.length() > 0); //clear trailers
	    }
	    return read();
	}
    }

    /**
     * Closes the input streams
     */
    public void close() throws IOException{
    }	
}