//----------------------------------------------------------------------------//
//                                                                            //
// ozz-animation is hosted at http://github.com/guillaumeblanc/ozz-animation  //
// and distributed under the MIT License (MIT).                               //
//                                                                            //
// Copyright (c) Guillaume Blanc                                              //
//                                                                            //
// Permission is hereby granted, free of charge, to any person obtaining a    //
// copy of this software and associated documentation files (the "Software"), //
// to deal in the Software without restriction, including without limitation  //
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//                                                                            //
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//                                                                            //
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//                                                                            //
//----------------------------------------------------------------------------//

#include "ozz/animation/offline/raw_animation_utils.h"

#include <algorithm>
#include <limits>

namespace ozz {
namespace animation {
namespace offline {

// Translation interpolation method.
// This must be the same Lerp as the one used by the sampling job.
math::Float3 LerpTranslation(const math::Float3& _a, const math::Float3& _b,
                             float _alpha) {
  return math::Lerp(_a, _b, _alpha);
}

// Rotation interpolation method.
// This must be the same Lerp as the one used by the sampling job.
// The goal is to take the shortest path between _a and _b. This code replicates
// this behavior that is actually not done at runtime, but when building the
// animation.
math::Quaternion LerpRotation(const math::Quaternion& _a,
                              const math::Quaternion& _b, float _alpha) {
  // Finds the shortest path. This is done by the AnimationBuilder for runtime
  // animations.
  const float dot = _a.x * _b.x + _a.y * _b.y + _a.z * _b.z + _a.w * _b.w;
  return math::NLerp(_a, dot < 0.f ? -_b : _b, _alpha);  // _b an -_b are the
                                                         // same rotation.
}

// Scale interpolation method.
// This must be the same Lerp as the one used by the sampling job.
math::Float3 LerpScale(const math::Float3& _a, const math::Float3& _b,
                       float _alpha) {
  return math::Lerp(_a, _b, _alpha);
}

namespace {

// The next functions are used to sample a RawAnimation. This feature is not
// part of ozz sdk, as RawAnimation is a intermediate format used to build the
// runtime animation.

// Less comparator, used by search algorithm to walk through track sorted
// keyframes
template <typename _Key>
bool Less(const _Key& _left, const _Key& _right) {
  return _left.time < _right.time;
}

// Samples a component (translation, rotation or scale) of a track.
template <typename _Track, typename _Lerp>
typename _Track::value_type::Value SampleComponent(const _Track& _track,
                                                   const _Lerp& _lerp,
                                                   float _time) {
  if (_track.size() == 0) {
    // Return identity if there's no key for this track.
    return _Track::value_type::identity();
  } else if (_time <= _track.front().time) {
    // Returns the first keyframe if _time is before the first keyframe.
    return _track.front().value;
  } else if (_time >= _track.back().time) {
    // Returns the last keyframe if _time is before the last keyframe.
    return _track.back().value;
  } else {
    // Needs to interpolate the 2 keyframes before and after _time.
    assert(_track.size() >= 2);
    // First find the 2 keys.
    const typename _Track::value_type cmp = {_time,
                                             _Track::value_type::identity()};
    typename _Track::const_pointer it =
        std::lower_bound(array_begin(_track), array_end(_track), cmp,
                         Less<typename _Track::value_type>);
    assert(it > array_begin(_track) && it < array_end(_track));

    // Then interpolate them at t = _time.
    const typename _Track::const_reference right = it[0];
    const typename _Track::const_reference left = it[-1];
    const float alpha = (_time - left.time) / (right.time - left.time);
    return _lerp(left.value, right.value, alpha);
  }
}

void SampleTrack_NoValidate(const RawAnimation::JointTrack& _track, float _time,
                            ozz::math::Transform* _transform) {
  _transform->translation =
      SampleComponent(_track.translations, LerpTranslation, _time);
  _transform->rotation = SampleComponent(_track.rotations, LerpRotation, _time);
  _transform->scale = SampleComponent(_track.scales, LerpScale, _time);
}
}  // namespace

bool SampleTrack(const RawAnimation::JointTrack& _track, float _time,
                 ozz::math::Transform* _transform) {
  if (!_track.Validate(std::numeric_limits<float>::infinity())) {
    return false;
  }

  SampleTrack_NoValidate(_track, _time, _transform);
  return true;
}

bool SampleAnimation(const RawAnimation& _animation, float _time,
                     const span<ozz::math::Transform>& _transforms) {
  if (!_animation.Validate()) {
    return false;
  }
  if (_animation.tracks.size() > _transforms.size()) {
    return false;
  }

  for (size_t i = 0; i < _animation.tracks.size(); ++i) {
    SampleTrack_NoValidate(_animation.tracks[i], _time, _transforms.begin() + i);
  }
  return true;
}

FixedRateSamplingTime::FixedRateSamplingTime(float _duration, float _frequency)
    : duration_(_duration),
      period_(1.f / _frequency),
      num_keys_(static_cast<size_t>(std::ceil(1.f + _duration * _frequency))) {}

}  // namespace offline
}  // namespace animation
}  // namespace ozz