/*
 * Copyright (C) 2008-2010, Google Inc.
 * Copyright (C) 2008-2009, Robin Rosenberg <robin.rosenberg@dewire.com>
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions 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 the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.transport;

import java.io.IOException;
import java.io.InputStream;

import org.eclipse.jgit.errors.PackProtocolException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.MutableObjectId;
import org.eclipse.jgit.util.IO;
import org.eclipse.jgit.util.RawParseUtils;

class PacketLineIn {
	static final String END = new String("") /* must not string pool */;

	static enum AckNackResult {
		/** NAK */
		NAK,
		/** ACK */
		ACK,
		/** ACK + continue */
		ACK_CONTINUE,
		/** ACK + common */
		ACK_COMMON,
		/** ACK + ready */
		ACK_READY;
	}

	private final InputStream in;

	private final byte[] lineBuffer;

	PacketLineIn(final InputStream i) {
		in = i;
		lineBuffer = new byte[SideBandOutputStream.SMALL_BUF];
	}

	AckNackResult readACK(final MutableObjectId returnedId) throws IOException {
		final String line = readString();
		if (line.length() == 0)
			throw new PackProtocolException("Expected ACK/NAK, found EOF");
		if ("NAK".equals(line))
			return AckNackResult.NAK;
		if (line.startsWith("ACK ")) {
			returnedId.fromString(line.substring(4, 44));
			if (line.length() == 44)
				return AckNackResult.ACK;

			final String arg = line.substring(44);
			if (arg.equals(" continue"))
				return AckNackResult.ACK_CONTINUE;
			else if (arg.equals(" common"))
				return AckNackResult.ACK_COMMON;
			else if (arg.equals(" ready"))
				return AckNackResult.ACK_READY;
		}
		throw new PackProtocolException("Expected ACK/NAK, got: " + line);
	}

	String readString() throws IOException {
		int len = readLength();
		if (len == 0)
			return END;

		len -= 4; // length header (4 bytes)
		if (len == 0)
			return "";

		final byte[] raw = new byte[len];
		IO.readFully(in, raw, 0, len);
		if (raw[len - 1] == '\n')
			len--;
		return RawParseUtils.decode(Constants.CHARSET, raw, 0, len);
	}

	String readStringRaw() throws IOException {
		int len = readLength();
		if (len == 0)
			return END;

		len -= 4; // length header (4 bytes)

		byte[] raw;
		if (len <= lineBuffer.length)
			raw = lineBuffer;
		else
			raw = new byte[len];

		IO.readFully(in, raw, 0, len);
		return RawParseUtils.decode(Constants.CHARSET, raw, 0, len);
	}

	int readLength() throws IOException {
		IO.readFully(in, lineBuffer, 0, 4);
		try {
			final int len = RawParseUtils.parseHexInt16(lineBuffer, 0);
			if (len != 0 && len < 4)
				throw new ArrayIndexOutOfBoundsException();
			return len;
		} catch (ArrayIndexOutOfBoundsException err) {
			throw new IOException("Invalid packet line header: "
					+ (char) lineBuffer[0] + (char) lineBuffer[1]
					+ (char) lineBuffer[2] + (char) lineBuffer[3]);
		}
	}
}