/*
    * Copyright (C) 2016, Google Inc. 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.junit.time;
  
  import java.time.Duration;
  import java.util.concurrent.TimeUnit;
  
  import org.eclipse.jgit.util.time.MonotonicClock;
  import org.eclipse.jgit.util.time.ProposedTimestamp;
  
  /**
   * Fake {@link org.eclipse.jgit.util.time.MonotonicClock} for testing code that
   * uses Clock.
   *
   * @since 4.6
   */
  public class MonotonicFakeClock implements MonotonicClock {
  	private long now = TimeUnit.SECONDS.toMicros(42);
  
  	/**
  	 * Advance the time returned by future calls to {@link #propose()}.
  	 *
  	 * @param add
  	 *            amount of time to add; must be {@code > 0}.
  	 * @param unit
  	 *            unit of {@code add}.
  	 */
  	public void tick(long add, TimeUnit unit) {
  		if (add <= 0) {
  			throw new IllegalArgumentException();
  		}
  		now += unit.toMillis(add);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public ProposedTimestamp propose() {
  		long t = now++;
  		return new ProposedTimestamp() {
  			@Override
  			public long read(TimeUnit unit) {
  				return unit.convert(t, TimeUnit.MILLISECONDS);
  			}
  
  			@Override
  			public void blockUntil(Duration maxWait) {
  				// Nothing to do, since fake time does not go backwards.
  			}
  		};
  	}
  }