// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/base/wall_clock_time_source.h"

#include "base/logging.h"
#include "base/time/default_tick_clock.h"

namespace media {

WallClockTimeSource::WallClockTimeSource()
    : tick_clock_(new base::DefaultTickClock()),
      ticking_(false),
      playback_rate_(1.0) {
}

WallClockTimeSource::~WallClockTimeSource() {
}

void WallClockTimeSource::StartTicking() {
  DVLOG(1) << __FUNCTION__;
  base::AutoLock auto_lock(lock_);
  DCHECK(!ticking_);
  ticking_ = true;
  reference_wall_ticks_ = tick_clock_->NowTicks();
}

void WallClockTimeSource::StopTicking() {
  DVLOG(1) << __FUNCTION__;
  base::AutoLock auto_lock(lock_);
  DCHECK(ticking_);
  base_time_ = CurrentMediaTime_Locked();
  ticking_ = false;
  reference_wall_ticks_ = tick_clock_->NowTicks();
}

void WallClockTimeSource::SetPlaybackRate(double playback_rate) {
  DVLOG(1) << __FUNCTION__ << "(" << playback_rate << ")";
  base::AutoLock auto_lock(lock_);
  // Estimate current media time using old rate to use as a new base time for
  // the new rate.
  if (ticking_) {
    base_time_ = CurrentMediaTime_Locked();
    reference_wall_ticks_ = tick_clock_->NowTicks();
  }

  playback_rate_ = playback_rate;
}

void WallClockTimeSource::SetMediaTime(base::TimeDelta time) {
  DVLOG(1) << __FUNCTION__ << "(" << time.InMicroseconds() << ")";
  base::AutoLock auto_lock(lock_);
  CHECK(!ticking_);
  base_time_ = time;
}

base::TimeDelta WallClockTimeSource::CurrentMediaTime() {
  base::AutoLock auto_lock(lock_);
  return CurrentMediaTime_Locked();
}

base::TimeTicks WallClockTimeSource::GetWallClockTime(base::TimeDelta time) {
  base::AutoLock auto_lock(lock_);
  if (!ticking_ || playback_rate_ == 0.0)
    return base::TimeTicks();

  // See notes about |time| values less than |base_time_| in TimeSource header.
  return reference_wall_ticks_ +
         base::TimeDelta::FromMicroseconds(
             (time - base_time_).InMicroseconds() / playback_rate_);
}

void WallClockTimeSource::SetTickClockForTesting(
    scoped_ptr<base::TickClock> tick_clock) {
  tick_clock_.swap(tick_clock);
}

base::TimeDelta WallClockTimeSource::CurrentMediaTime_Locked() {
  lock_.AssertAcquired();
  if (!ticking_ || playback_rate_ == 0.0)
    return base_time_;

  base::TimeTicks now = tick_clock_->NowTicks();
  return base_time_ +
         base::TimeDelta::FromMicroseconds(
             (now - reference_wall_ticks_).InMicroseconds() * playback_rate_);
}

}  // namespace media