/*
 * @(#)Request.java	1.4 10/01/12
 * 
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 * 
 * -Redistribution in binary form must reproduce the above copyright notice, 
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may 
 * be used to endorse or promote products derived from this software without 
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL 
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST 
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, 
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY 
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, 
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * 
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */

import java.net.*;
import java.nio.*;
import java.nio.charset.*;
import java.util.regex.*;

/**
 * An encapsulation of the request received.
 * <P>
 * The static method parse() is responsible for creating this
 * object.
 *
 * @author Mark Reinhold
 * @author Brad R. Wetmore
 * @version 1.4, 10/01/12
 */
class Request {

    /**
     * A helper class for parsing HTTP command actions.
     */
    static class Action {

	private String name;
	private Action(String name) { this.name = name; }
	public String toString() { return name; }

	static Action GET = new Action("GET");
	static Action PUT = new Action("PUT");
	static Action POST = new Action("POST");
	static Action HEAD = new Action("HEAD");

	static Action parse(String s) {
	    if (s.equals("GET"))
		return GET;
	    if (s.equals("PUT"))
		return PUT;
	    if (s.equals("POST"))
		return POST;
	    if (s.equals("HEAD"))
		return HEAD;
	    throw new IllegalArgumentException(s);
	}
    }

    private Action action;
    private String version;
    private URI uri;

    Action action() { return action; }
    String version() { return version; }
    URI uri() { return uri; }

    private Request(Action a, String v, URI u) {
	action = a;
	version = v;
	uri = u;
    }

    public String toString() {
	return (action + " " + version + " " + uri);
    }

    static boolean isComplete(ByteBuffer bb) {
	int p = bb.position() - 4;
	if (p < 0)
	    return false;
	return (((bb.get(p + 0) == '\r') &&
		 (bb.get(p + 1) == '\n') &&
		 (bb.get(p + 2) == '\r') &&
		 (bb.get(p + 3) == '\n')));
    }

    private static Charset ascii = Charset.forName("US-ASCII");

    /*
     * The expected message format is first compiled into a pattern,
     * and is then compared against the inbound character buffer to
     * determine if there is a match.  This convienently tokenizes
     * our request into usable pieces.
     *
     * This uses Matcher "expression capture groups" to tokenize
     * requests like:
     *
     *     GET /dir/file HTTP/1.1
     *     Host: hostname
     *
     * into:
     *
     *     group[1] = "GET"
     *     group[2] = "/dir/file"
     *     group[3] = "1.1"
     *     group[4] = "hostname"
     *
     * The text in between the parens are used to captured the regexp text.
     */
    private static Pattern requestPattern
	= Pattern.compile("\\A([A-Z]+) +([^ ]+) +HTTP/([0-9\\.]+)$"
			  + ".*^Host: ([^ ]+)$.*\r\n\r\n\\z",
			  Pattern.MULTILINE | Pattern.DOTALL);

    static Request parse(ByteBuffer bb) throws MalformedRequestException {

	CharBuffer cb = ascii.decode(bb);
	Matcher m = requestPattern.matcher(cb);
	if (!m.matches())
	    throw new MalformedRequestException();
	Action a;
	try {
	    a = Action.parse(m.group(1));
	} catch (IllegalArgumentException x) {
	    throw new MalformedRequestException();
	}
	URI u;
	try {
	    u = new URI("http://"
			+ m.group(4)
			+ m.group(2));
	} catch (URISyntaxException x) {
	    throw new MalformedRequestException();
	}
	return new Request(a, m.group(3), u);
    }
}
