// Copyright 2013 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 <algorithm>
#include <cmath>
#include <limits>

#include "base/logging.h"
#include "cc/animation/transform_operation.h"
#include "ui/gfx/box_f.h"
#include "ui/gfx/vector3d_f.h"

namespace {
const SkMScalar kAngleEpsilon = 1e-4f;
}

namespace cc {

bool TransformOperation::IsIdentity() const {
  return matrix.IsIdentity();
}

static bool IsOperationIdentity(const TransformOperation* operation) {
  return !operation || operation->IsIdentity();
}

static bool ShareSameAxis(const TransformOperation* from,
                          const TransformOperation* to,
                          SkMScalar* axis_x,
                          SkMScalar* axis_y,
                          SkMScalar* axis_z,
                          SkMScalar* angle_from) {
  if (IsOperationIdentity(from) && IsOperationIdentity(to))
    return false;

  if (IsOperationIdentity(from) && !IsOperationIdentity(to)) {
    *axis_x = to->rotate.axis.x;
    *axis_y = to->rotate.axis.y;
    *axis_z = to->rotate.axis.z;
    *angle_from = 0;
    return true;
  }

  if (!IsOperationIdentity(from) && IsOperationIdentity(to)) {
    *axis_x = from->rotate.axis.x;
    *axis_y = from->rotate.axis.y;
    *axis_z = from->rotate.axis.z;
    *angle_from = from->rotate.angle;
    return true;
  }

  SkMScalar length_2 = from->rotate.axis.x * from->rotate.axis.x +
                       from->rotate.axis.y * from->rotate.axis.y +
                       from->rotate.axis.z * from->rotate.axis.z;
  SkMScalar other_length_2 = to->rotate.axis.x * to->rotate.axis.x +
                             to->rotate.axis.y * to->rotate.axis.y +
                             to->rotate.axis.z * to->rotate.axis.z;

  if (length_2 <= kAngleEpsilon || other_length_2 <= kAngleEpsilon)
    return false;

  SkMScalar dot = to->rotate.axis.x * from->rotate.axis.x +
                  to->rotate.axis.y * from->rotate.axis.y +
                  to->rotate.axis.z * from->rotate.axis.z;
  SkMScalar error =
      std::abs(SK_MScalar1 - (dot * dot) / (length_2 * other_length_2));
  bool result = error < kAngleEpsilon;
  if (result) {
    *axis_x = to->rotate.axis.x;
    *axis_y = to->rotate.axis.y;
    *axis_z = to->rotate.axis.z;
    // If the axes are pointing in opposite directions, we need to reverse
    // the angle.
    *angle_from = dot > 0 ? from->rotate.angle : -from->rotate.angle;
  }
  return result;
}

static SkMScalar BlendSkMScalars(SkMScalar from,
                                 SkMScalar to,
                                 SkMScalar progress) {
  return from * (1 - progress) + to * progress;
}

bool TransformOperation::BlendTransformOperations(
    const TransformOperation* from,
    const TransformOperation* to,
    SkMScalar progress,
    gfx::Transform* result) {
  if (IsOperationIdentity(from) && IsOperationIdentity(to))
    return true;

  TransformOperation::Type interpolation_type =
      TransformOperation::TransformOperationIdentity;
  if (IsOperationIdentity(to))
    interpolation_type = from->type;
  else
    interpolation_type = to->type;

  switch (interpolation_type) {
  case TransformOperation::TransformOperationTranslate: {
    SkMScalar from_x = IsOperationIdentity(from) ? 0 : from->translate.x;
    SkMScalar from_y = IsOperationIdentity(from) ? 0 : from->translate.y;
    SkMScalar from_z = IsOperationIdentity(from) ? 0 : from->translate.z;
    SkMScalar to_x = IsOperationIdentity(to) ? 0 : to->translate.x;
    SkMScalar to_y = IsOperationIdentity(to) ? 0 : to->translate.y;
    SkMScalar to_z = IsOperationIdentity(to) ? 0 : to->translate.z;
    result->Translate3d(BlendSkMScalars(from_x, to_x, progress),
                        BlendSkMScalars(from_y, to_y, progress),
                        BlendSkMScalars(from_z, to_z, progress));
    break;
  }
  case TransformOperation::TransformOperationRotate: {
    SkMScalar axis_x = 0;
    SkMScalar axis_y = 0;
    SkMScalar axis_z = 1;
    SkMScalar from_angle = 0;
    SkMScalar to_angle = IsOperationIdentity(to) ? 0 : to->rotate.angle;
    if (ShareSameAxis(from, to, &axis_x, &axis_y, &axis_z, &from_angle)) {
      result->RotateAbout(gfx::Vector3dF(axis_x, axis_y, axis_z),
                          BlendSkMScalars(from_angle, to_angle, progress));
    } else {
      gfx::Transform to_matrix;
      if (!IsOperationIdentity(to))
        to_matrix = to->matrix;
      gfx::Transform from_matrix;
      if (!IsOperationIdentity(from))
        from_matrix = from->matrix;
      *result = to_matrix;
      if (!result->Blend(from_matrix, progress))
        return false;
    }
    break;
  }
  case TransformOperation::TransformOperationScale: {
    SkMScalar from_x = IsOperationIdentity(from) ? 1 : from->scale.x;
    SkMScalar from_y = IsOperationIdentity(from) ? 1 : from->scale.y;
    SkMScalar from_z = IsOperationIdentity(from) ? 1 : from->scale.z;
    SkMScalar to_x = IsOperationIdentity(to) ? 1 : to->scale.x;
    SkMScalar to_y = IsOperationIdentity(to) ? 1 : to->scale.y;
    SkMScalar to_z = IsOperationIdentity(to) ? 1 : to->scale.z;
    result->Scale3d(BlendSkMScalars(from_x, to_x, progress),
                    BlendSkMScalars(from_y, to_y, progress),
                    BlendSkMScalars(from_z, to_z, progress));
    break;
  }
  case TransformOperation::TransformOperationSkew: {
    SkMScalar from_x = IsOperationIdentity(from) ? 0 : from->skew.x;
    SkMScalar from_y = IsOperationIdentity(from) ? 0 : from->skew.y;
    SkMScalar to_x = IsOperationIdentity(to) ? 0 : to->skew.x;
    SkMScalar to_y = IsOperationIdentity(to) ? 0 : to->skew.y;
    result->SkewX(BlendSkMScalars(from_x, to_x, progress));
    result->SkewY(BlendSkMScalars(from_y, to_y, progress));
    break;
  }
  case TransformOperation::TransformOperationPerspective: {
    SkMScalar from_perspective_depth =
        IsOperationIdentity(from) ? std::numeric_limits<SkMScalar>::max()
                                  : from->perspective_depth;
    SkMScalar to_perspective_depth = IsOperationIdentity(to)
                                         ? std::numeric_limits<SkMScalar>::max()
                                         : to->perspective_depth;
    result->ApplyPerspectiveDepth(BlendSkMScalars(
        from_perspective_depth, to_perspective_depth, progress));
    break;
  }
  case TransformOperation::TransformOperationMatrix: {
    gfx::Transform to_matrix;
    if (!IsOperationIdentity(to))
      to_matrix = to->matrix;
    gfx::Transform from_matrix;
    if (!IsOperationIdentity(from))
      from_matrix = from->matrix;
    *result = to_matrix;
    if (!result->Blend(from_matrix, progress))
      return false;
    break;
  }
  case TransformOperation::TransformOperationIdentity:
    // Do nothing.
    break;
  }

  return true;
}

static void ApplyScaleToBox(float x_scale,
                            float y_scale,
                            float z_scale,
                            gfx::BoxF* box) {
  if (x_scale < 0)
    box->set_x(-box->right());
  if (y_scale < 0)
    box->set_y(-box->bottom());
  if (z_scale < 0)
    box->set_z(-box->front());
  box->Scale(std::abs(x_scale), std::abs(y_scale), std::abs(z_scale));
}

static void UnionBoxWithZeroScale(gfx::BoxF* box) {
  float min_x = std::min(box->x(), 0.f);
  float min_y = std::min(box->y(), 0.f);
  float min_z = std::min(box->z(), 0.f);
  float max_x = std::max(box->right(), 0.f);
  float max_y = std::max(box->bottom(), 0.f);
  float max_z = std::max(box->front(), 0.f);
  *box = gfx::BoxF(
      min_x, min_y, min_z, max_x - min_x, max_y - min_y, max_z - min_z);
}

bool TransformOperation::BlendedBoundsForBox(const gfx::BoxF& box,
                                             const TransformOperation* from,
                                             const TransformOperation* to,
                                             SkMScalar min_progress,
                                             SkMScalar max_progress,
                                             gfx::BoxF* bounds) {
  bool is_identity_from = IsOperationIdentity(from);
  bool is_identity_to = IsOperationIdentity(to);
  if (is_identity_from && is_identity_to) {
    *bounds = box;
    return true;
  }

  TransformOperation::Type interpolation_type =
      TransformOperation::TransformOperationIdentity;
  if (is_identity_to)
    interpolation_type = from->type;
  else
    interpolation_type = to->type;

  switch (interpolation_type) {
    case TransformOperation::TransformOperationTranslate: {
      SkMScalar from_x, from_y, from_z;
      if (is_identity_from) {
        from_x = from_y = from_z = 0.0;
      } else {
        from_x = from->translate.x;
        from_y = from->translate.y;
        from_z = from->translate.z;
      }
      SkMScalar to_x, to_y, to_z;
      if (is_identity_to) {
        to_x = to_y = to_z = 0.0;
      } else {
        to_x = to->translate.x;
        to_y = to->translate.y;
        to_z = to->translate.z;
      }
      *bounds = box;
      *bounds += gfx::Vector3dF(BlendSkMScalars(from_x, to_x, min_progress),
                                BlendSkMScalars(from_y, to_y, min_progress),
                                BlendSkMScalars(from_z, to_z, min_progress));
      gfx::BoxF bounds_max = box;
      bounds_max += gfx::Vector3dF(BlendSkMScalars(from_x, to_x, max_progress),
                                   BlendSkMScalars(from_y, to_y, max_progress),
                                   BlendSkMScalars(from_z, to_z, max_progress));
      bounds->Union(bounds_max);
      return true;
    }
    case TransformOperation::TransformOperationScale: {
      SkMScalar from_x, from_y, from_z;
      if (is_identity_from) {
        from_x = from_y = from_z = 1.0;
      } else {
        from_x = from->scale.x;
        from_y = from->scale.y;
        from_z = from->scale.z;
      }
      SkMScalar to_x, to_y, to_z;
      if (is_identity_to) {
        to_x = to_y = to_z = 1.0;
      } else {
        to_x = to->scale.x;
        to_y = to->scale.y;
        to_z = to->scale.z;
      }
      *bounds = box;
      ApplyScaleToBox(
          SkMScalarToFloat(BlendSkMScalars(from_x, to_x, min_progress)),
          SkMScalarToFloat(BlendSkMScalars(from_y, to_y, min_progress)),
          SkMScalarToFloat(BlendSkMScalars(from_z, to_z, min_progress)),
          bounds);
      gfx::BoxF bounds_max = box;
      ApplyScaleToBox(
          SkMScalarToFloat(BlendSkMScalars(from_x, to_x, max_progress)),
          SkMScalarToFloat(BlendSkMScalars(from_y, to_y, max_progress)),
          SkMScalarToFloat(BlendSkMScalars(from_z, to_z, max_progress)),
          &bounds_max);
      if (!bounds->IsEmpty() && !bounds_max.IsEmpty()) {
        bounds->Union(bounds_max);
      } else if (!bounds->IsEmpty()) {
        UnionBoxWithZeroScale(bounds);
      } else if (!bounds_max.IsEmpty()) {
        UnionBoxWithZeroScale(&bounds_max);
        *bounds = bounds_max;
      }

      return true;
    }
    case TransformOperation::TransformOperationIdentity:
      *bounds = box;
      return true;
    case TransformOperation::TransformOperationRotate:
    case TransformOperation::TransformOperationSkew:
    case TransformOperation::TransformOperationPerspective:
    case TransformOperation::TransformOperationMatrix:
      return false;
  }
  NOTREACHED();
  return false;
}

}  // namespace cc