/*
 * Copyright (c) 2001 Matthew Feldt. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided the copyright notice above is
 * retained.
 *
 * THIS SOFTWARE IS PROVIDED ''AS IS'' AND WITHOUT ANY EXPRESSED OR
 * IMPLIED WARRANTIES.
 */

/**
 * HttpClient.java
 *
 * Java Examples In A Nutshell Copyright (c) 2000 David Flanagan
 * Exercise 5-2:
 * Modify the HttpClient program of Example 5-4 so that it uses a newer version
 * of the HTTP protocol. To do this, you have to send a somewhat more
 * complicated GET request to the web server. Use the HttpMirror program of
 * Example 5-5 to find what form this request should take. HTTP Versions 1.0
 * and later add a version number to the GET request and follow the GET line
 * with a number of header lines followed by a blank line that serves to
 * terminate the request.
 *
 * For this excercise the only header you need to include is the User-Agent line,
 * which should identify the web client that you are using. Since you are writing
 * your own web client, you give it any name you like! Be sure to follow
 * your GET request and User-Agent header with a blank line, or the web server
 * will keep waiting for more headers and will never respond to your request.
 * Whe you get this program working, you should notice that web servers
 * respond differently to requests from it than they did to requests from the
 * original HttpClient program. When a client requests data using HTTP 1.0 or 1.1,
 * the server sends a version number, a status code, and a number of reponse
 * header lines before it sends the actual requested file.
 *
 * @author Matthew Feldt <developer@feldt.com>
 * @version 1.0, 03/02/2001 17:30
 */

package com.feldt.examples.net;
import java.io.*;
import java.net.*;

public class HttpClient {
	public static void get(String in, OutputStream out) throws Exception {
		String protocol, local, host, filename;
		int port;

		// use the URL class to parse the input
		URL url = new URL(in);
		protocol = url.getProtocol();
		if (! protocol.equals("http")) // only support http
			throw new IllegalArgumentException("Only support HTTP protocol.");

		if ((host = url.getHost()) == null)
			throw new IllegalArgumentException("Invalid host specified.");

		// if no port, use the default HTTP port
		if ((port = url.getPort()) == -1) port = 80;

		// if no filename, request root directory index
		if((filename = url.getFile()) == "") filename = "/";

		// open a network socket
		Socket socket = new Socket(host, port);

		// get input and output streams from the socket
		InputStream from = socket.getInputStream();
		PrintWriter to = new PrintWriter(socket.getOutputStream());

		// send the HTTP GET v1.0 commands to the web server
		to.print("GET " + filename + " HTTP/1.0\n");
		/* Host header required for HTTP/1.1
		if ((local = InetAddress.getLocalHost().getHostName()) == null)
			local = "unknown";
		to.print("Host: " + local + "\n");
		*/
		to.print("User-Agent: none\n\n");
		to.flush();

		// read server response and write it to the specified output stream
		byte[] buf = new byte[4096];
		int bytes_read;
		while((bytes_read = from.read(buf)) != -1)
			out.write(buf, 0, bytes_read);

		// close the server and file streams
		socket.close();
		out.close();
	}

	static class Test {
		public static void main(String[] args) {
			final String usage = "Usage: java HttpClient <URL> [<filename>]";
			OutputStream out;

			try {
				// verify command line
				if ((args.length != 1) && (args.length != 2)) {
					System.err.println(usage);
					System.exit(-1);
				}

				// determine output stream
				if (args.length == 2) out = new FileOutputStream(args[1]);
				else out = System.out;

				// get the url
				HttpClient.get(args[0], out);
			} catch (Exception e) {
				System.err.println(e);
				System.err.println(usage);
			}
		}
	}
}