// Copyright 2012 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 "cc/animation/timing_function.h"

#include <cmath>
#include <memory>

#include "base/logging.h"
#include "base/memory/ptr_util.h"

namespace cc {

TimingFunction::TimingFunction() = default;

TimingFunction::~TimingFunction() = default;

std::unique_ptr<CubicBezierTimingFunction>
CubicBezierTimingFunction::CreatePreset(EaseType ease_type) {
  // These numbers come from
  // http://www.w3.org/TR/css3-transitions/#transition-timing-function_tag.
  switch (ease_type) {
    case EaseType::EASE:
      return base::WrapUnique(
          new CubicBezierTimingFunction(ease_type, 0.25, 0.1, 0.25, 1.0));
    case EaseType::EASE_IN:
      return base::WrapUnique(
          new CubicBezierTimingFunction(ease_type, 0.42, 0.0, 1.0, 1.0));
    case EaseType::EASE_OUT:
      return base::WrapUnique(
          new CubicBezierTimingFunction(ease_type, 0.0, 0.0, 0.58, 1.0));
    case EaseType::EASE_IN_OUT:
      return base::WrapUnique(
          new CubicBezierTimingFunction(ease_type, 0.42, 0.0, 0.58, 1));
    default:
      NOTREACHED();
      return nullptr;
  }
}
std::unique_ptr<CubicBezierTimingFunction>
CubicBezierTimingFunction::Create(double x1, double y1, double x2, double y2) {
  return base::WrapUnique(
      new CubicBezierTimingFunction(EaseType::CUSTOM, x1, y1, x2, y2));
}

CubicBezierTimingFunction::CubicBezierTimingFunction(EaseType ease_type,
                                                     double x1,
                                                     double y1,
                                                     double x2,
                                                     double y2)
    : bezier_(x1, y1, x2, y2), ease_type_(ease_type) {}

CubicBezierTimingFunction::~CubicBezierTimingFunction() = default;

TimingFunction::Type CubicBezierTimingFunction::GetType() const {
  return Type::CUBIC_BEZIER;
}

float CubicBezierTimingFunction::GetValue(double x) const {
  return static_cast<float>(bezier_.Solve(x));
}

float CubicBezierTimingFunction::Velocity(double x) const {
  return static_cast<float>(bezier_.Slope(x));
}

std::unique_ptr<TimingFunction> CubicBezierTimingFunction::Clone() const {
  return base::WrapUnique(new CubicBezierTimingFunction(*this));
}

std::unique_ptr<StepsTimingFunction> StepsTimingFunction::Create(
    int steps,
    StepPosition step_position) {
  return base::WrapUnique(new StepsTimingFunction(steps, step_position));
}

StepsTimingFunction::StepsTimingFunction(int steps, StepPosition step_position)
    : steps_(steps), step_position_(step_position) {}

StepsTimingFunction::~StepsTimingFunction() = default;

TimingFunction::Type StepsTimingFunction::GetType() const {
  return Type::STEPS;
}

float StepsTimingFunction::GetValue(double t) const {
  return static_cast<float>(GetPreciseValue(t));
}

std::unique_ptr<TimingFunction> StepsTimingFunction::Clone() const {
  return base::WrapUnique(new StepsTimingFunction(*this));
}

float StepsTimingFunction::Velocity(double x) const {
  return 0.0f;
}

double StepsTimingFunction::GetPreciseValue(double t) const {
  const double steps = static_cast<double>(steps_);
  double current_step = std::floor((steps * t) + GetStepsStartOffset());
  if (t >= 0 && current_step < 0)
    current_step = 0;
  if (t <= 1 && current_step > steps)
    current_step = steps;
  return current_step / steps;
}

float StepsTimingFunction::GetStepsStartOffset() const {
  switch (step_position_) {
    case StepPosition::START:
      return 1;
    case StepPosition::MIDDLE:
      return 0.5;
    case StepPosition::END:
      return 0;
    default:
      NOTREACHED();
      return 1;
  }
}

std::unique_ptr<FramesTimingFunction> FramesTimingFunction::Create(int frames) {
  return base::WrapUnique(new FramesTimingFunction(frames));
}

FramesTimingFunction::FramesTimingFunction(int frames) : frames_(frames) {}

FramesTimingFunction::~FramesTimingFunction() = default;

TimingFunction::Type FramesTimingFunction::GetType() const {
  return Type::FRAMES;
}

float FramesTimingFunction::GetValue(double t) const {
  return static_cast<float>(GetPreciseValue(t));
}

std::unique_ptr<TimingFunction> FramesTimingFunction::Clone() const {
  return base::WrapUnique(new FramesTimingFunction(*this));
}

float FramesTimingFunction::Velocity(double x) const {
  return 0.0f;
}

double FramesTimingFunction::GetPreciseValue(double t) const {
  const double frames = static_cast<double>(frames_);
  double output_progress = std::floor(frames * t) / (frames - 1);
  if (t <= 1 && output_progress > 1)
    output_progress = 1;
  return output_progress;
}

}  // namespace cc