/*
 * Copyright (C) 2018, Google LLC.
 * 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.internal.transport.parser;

import static java.util.Arrays.asList;
import static java.util.Collections.emptySet;
import static java.util.Collections.unmodifiableSet;
import static java.util.stream.Collectors.toSet;

import java.util.Set;

import org.eclipse.jgit.annotations.NonNull;

/**
 * In a push, the client sends a list of commands. The first command
 * is special, as it can include a list of capabilities at its end.
 * <p>
 * For example:
 * "oid oid name\0cap1 cap cap3"
 * <p>
 * Not to be confused with {@link FirstWant}, nor with the first line
 * of the reference advertisement parsed by
 * {@code BasePackConnection.readAdvertisedRefs}.
 * <p>
 * This class parses the inputted command line and holds the results:
 * the actual command line and the capabilities.
 */
public final class FirstCommand {
	private final String line;
	private final Set<String> capabilities;

	/**
	 * Parse the first line of a receive-pack request.
	 *
	 * @param line
	 *            line from the client.
	 * @return an instance of FirstCommand with capabilities parsed out
	 */
	@NonNull
	public static FirstCommand fromLine(String line) {
		int nul = line.indexOf('\0');
		if (nul < 0) {
			return new FirstCommand(line, emptySet());
		}
		Set<String> opts =
				asList(line.substring(nul + 1).split(" ")) //$NON-NLS-1$
					.stream()
					.collect(toSet());
		return new FirstCommand(line.substring(0, nul), unmodifiableSet(opts));
	}

	private FirstCommand(String line, Set<String> capabilities) {
		this.line = line;
		this.capabilities = capabilities;
	}

	/** @return non-capabilities part of the line. */
	@NonNull
	public String getLine() {
		return line;
	}

	/** @return capabilities parsed from the line, as an immutable set. */
	@NonNull
	public Set<String> getCapabilities() {
		return capabilities;
	}
}