/* SPDX-FileCopyrightText: 2013 Pixar
 * SPDX-FileCopyrightText: 2021 Blender Foundation
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Original code by Pixar with modifications by the Blender foundation. */

#include "internal/evaluator/patch_map.h"
#include <algorithm>

using OpenSubdiv::Far::ConstPatchParamArray;
using OpenSubdiv::Far::Index;
using OpenSubdiv::Far::PatchParam;
using OpenSubdiv::Far::PatchParamTable;
using OpenSubdiv::Far::PatchTable;

namespace blender::opensubdiv {

//
//  Inline quadtree assembly methods used by the constructor:
//

// sets all the children to point to the patch of given index
inline void PatchMap::QuadNode::SetChildren(int index)
{

  for (int i = 0; i < 4; ++i) {
    children[i].isSet = true;
    children[i].isLeaf = true;
    children[i].index = index;
  }
}

// sets the child in "quadrant" to point to the node or patch of the given index
inline void PatchMap::QuadNode::SetChild(int quadrant, int index, bool isLeaf)
{

  assert(!children[quadrant].isSet);
  children[quadrant].isSet = true;
  children[quadrant].isLeaf = isLeaf;
  children[quadrant].index = index;
}

inline void PatchMap::assignRootNode(QuadNode *node, int index)
{

  //  Assign the given index to all children of the node (all leaves)
  node->SetChildren(index);
}

inline PatchMap::QuadNode *PatchMap::assignLeafOrChildNode(QuadNode *node,
                                                           bool isLeaf,
                                                           int quadrant,
                                                           int index)
{

  //  Assign the node given if it is a leaf node, otherwise traverse
  //  the node -- creating/assigning a new child node if needed

  if (isLeaf) {
    node->SetChild(quadrant, index, true);
    return node;
  }
  if (node->children[quadrant].isSet) {
    return &_quadtree[node->children[quadrant].index];
  }

  int newChildNodeIndex = (int)_quadtree.size();
  _quadtree.emplace_back();
  node->SetChild(quadrant, newChildNodeIndex, false);
  return &_quadtree[newChildNodeIndex];
}

//
//  Constructor and initialization methods for the handles and quadtree:
//
PatchMap::PatchMap(PatchTable const &patchTable)
    : _minPatchFace(-1), _maxPatchFace(-1), _maxDepth(0)
{

  _patchesAreTriangular = patchTable.GetVaryingPatchDescriptor().GetNumControlVertices() == 3;

  if (patchTable.GetNumPatchesTotal() > 0) {
    initializeHandles(patchTable);
    initializeQuadtree(patchTable);
  }
}

void PatchMap::initializeHandles(PatchTable const &patchTable)
{

  //
  //  Populate the vector of patch Handles.  Keep track of the min and max
  //  face indices to allocate resources accordingly and limit queries:
  //
  _minPatchFace = (int)patchTable.GetPatchParamTable()[0].GetFaceId();
  _maxPatchFace = _minPatchFace;

  int numArrays = patchTable.GetNumPatchArrays();
  int numPatches = patchTable.GetNumPatchesTotal();

  _handles.resize(numPatches);

  for (int pArray = 0, handleIndex = 0; pArray < numArrays; ++pArray) {

    ConstPatchParamArray params = patchTable.GetPatchParams(pArray);

    int patchSize = patchTable.GetPatchArrayDescriptor(pArray).GetNumControlVertices();

    for (Index j = 0; j < patchTable.GetNumPatches(pArray); ++j, ++handleIndex) {

      Handle &h = _handles[handleIndex];

      h.arrayIndex = pArray;
      h.patchIndex = handleIndex;
      h.vertIndex = j * patchSize;

      int patchFaceId = params[j].GetFaceId();
      _minPatchFace = std::min(_minPatchFace, patchFaceId);
      _maxPatchFace = std::max(_maxPatchFace, patchFaceId);
    }
  }
}

void PatchMap::initializeQuadtree(PatchTable const &patchTable)
{

  //
  //  Reserve quadtree nodes for the worst case and prune later.  Set the
  //  initial size to accomodate the root node of each patch face:
  //
  int nPatchFaces = (_maxPatchFace - _minPatchFace) + 1;

  int nHandles = int(_handles.size());

  _quadtree.reserve(nPatchFaces + nHandles);
  _quadtree.resize(nPatchFaces);

  PatchParamTable const &params = patchTable.GetPatchParamTable();

  for (int handle = 0; handle < nHandles; ++handle) {

    PatchParam const &param = params[handle];

    int depth = param.GetDepth();
    int rootDepth = param.NonQuadRoot();

    _maxDepth = std::max(_maxDepth, depth);

    QuadNode *node = &_quadtree[param.GetFaceId() - _minPatchFace];

    if (depth == rootDepth) {
      assignRootNode(node, handle);
      continue;
    }

    if (!_patchesAreTriangular) {
      //  Use the UV bits of the PatchParam directly for quad patches:
      int u = param.GetU();
      int v = param.GetV();

      for (int j = rootDepth + 1; j <= depth; ++j) {
        int uBit = (u >> (depth - j)) & 1;
        int vBit = (v >> (depth - j)) & 1;

        int quadrant = (vBit << 1) | uBit;

        node = assignLeafOrChildNode(node, (j == depth), quadrant, handle);
      }
    }
    else {
      //  Use an interior UV point of triangles to identify quadrants:
      double u = 0.25;
      double v = 0.25;
      param.UnnormalizeTriangle(u, v);

      double median = 0.5;
      bool triRotated = false;

      for (int j = rootDepth + 1; j <= depth; ++j, median *= 0.5) {
        int quadrant = transformUVToTriQuadrant(median, u, v, triRotated);

        node = assignLeafOrChildNode(node, (j == depth), quadrant, handle);
      }
    }
  }

  //  Swap the Node vector with a copy to reduce worst case memory allocation:
  QuadTree tmpTree = _quadtree;
  _quadtree.swap(tmpTree);
}

}  // namespace blender::opensubdiv
