/*
 * Copyright (C) 2018, Google LLC. and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
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.

For example:
"oid oid name\0cap1 cap cap3"
 Not to be confused with FirstWant, nor with the first line of the reference advertisement parsed by BasePackConnection.readAdvertisedRefs. 

This class parses the inputted command line and holds the results:
the actual command line and the capabilities.
/**
 * 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.
Params:
line – 
           line from the client.
Returns:
an instance of FirstCommand with capabilities parsed out/**
	 * 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;
	}

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

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