// Copyright (c) 2011 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 "ui/gfx/animation/linear_animation.h"

#include <math.h>
#include <stdint.h>

#include <algorithm>

#include "base/command_line.h"
#include "base/cxx17_backports.h"
#include "base/strings/string_number_conversions.h"
#include "ui/gfx/animation/animation_container.h"
#include "ui/gfx/animation/animation_delegate.h"
#include "ui/gfx/switches.h"

namespace gfx {

static base::TimeDelta CalculateInterval(int frame_rate) {
  int timer_interval = 1000000 / frame_rate;
  if (timer_interval < 10000)
    timer_interval = 10000;
  return base::Microseconds(timer_interval);
}

const int LinearAnimation::kDefaultFrameRate = 60;

LinearAnimation::LinearAnimation(AnimationDelegate* delegate, int frame_rate)
    : LinearAnimation({}, frame_rate, delegate) {}

LinearAnimation::LinearAnimation(base::TimeDelta duration,
                                 int frame_rate,
                                 AnimationDelegate* delegate)
    : Animation(CalculateInterval(frame_rate)), state_(0.0), in_end_(false) {
  set_delegate(delegate);
  SetDuration(duration);
}

double LinearAnimation::GetCurrentValue() const {
  // Default is linear relationship, subclass to adapt.
  return state_;
}

void LinearAnimation::SetCurrentValue(double new_value) {
  new_value = base::clamp(new_value, 0.0, 1.0);
  const base::TimeDelta time_delta = duration_ * (new_value - state_);
  SetStartTime(start_time() - time_delta);
  state_ = new_value;
}

void LinearAnimation::End() {
  if (!is_animating())
    return;

  // NOTE: We don't use AutoReset here as Stop may end up deleting us (by way
  // of the delegate).
  in_end_ = true;
  Stop();
}

void LinearAnimation::SetDuration(base::TimeDelta duration) {
  static const double duration_scale_factor = []() {
    base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
    double animation_duration_scale;
    return (base::StringToDouble(command_line->GetSwitchValueASCII(
                                     switches::kAnimationDurationScale),
                                 &animation_duration_scale) &&
            (animation_duration_scale >= 0.0))
               ? animation_duration_scale
               : 1.0;
  }();
  duration_ = std::max(duration * duration_scale_factor, timer_interval());
  if (is_animating())
    SetStartTime(container()->last_tick_time());
}

void LinearAnimation::Step(base::TimeTicks time_now) {
  state_ = std::min((time_now - start_time()) / duration_, 1.0);

  AnimateToState(state_);

  if (delegate())
    delegate()->AnimationProgressed(this);

  if (state_ == 1.0)
    Stop();
}

void LinearAnimation::AnimationStarted() {
  state_ = 0.0;
}

void LinearAnimation::AnimationStopped() {
  if (!in_end_)
    return;

  in_end_ = false;
  // Set state_ to ensure we send ended to delegate and not canceled.
  state_ = 1;
  AnimateToState(1.0);
}

bool LinearAnimation::ShouldSendCanceledFromStop() {
  return state_ != 1;
}

}  // namespace gfx