#include "PipelineMerger.hpp"
#include "RenderItemMatcher.hpp"
#include "RenderItemMergeFunction.hpp"


/*  FIXME: Use math.h constants.  */
const double PipelineMerger::e(2.71828182845904523536);
const double PipelineMerger::s(0.5);


void
PipelineMerger::mergePipelines (
const Pipeline                  &a,
const Pipeline                  &b,
Pipeline                        &out,
RenderItemMatcher::MatchResults &results,
RenderItemMergeFunction         &mergeFunction,
float                           ratio
)
{
  const double x = (ratio - 0.5) * 20;
  const double sigmoid = 1.0 / (1.0 + e - s * x);
  const double invratio = 1.0 - ratio;

  out.textureWrap = (ratio < 0.5) ? a.textureWrap : b.textureWrap;

  out.screenDecay = lerp (b.screenDecay, a.screenDecay, ratio);

  out.drawables.clear();
  out.compositeDrawables.clear();

  for (std::vector<RenderItem*>::const_iterator pos = a.drawables.begin();
       pos != a.drawables.end();
       ++pos)
  {
    (*pos)->masterAlpha = invratio;
    out.drawables.push_back (*pos);
  }

  for (std::vector<RenderItem*>::const_iterator pos = b.drawables.begin();
       pos != b.drawables.end();
       ++pos)
  {
    (*pos)->masterAlpha = ratio;
    out.drawables.push_back (*pos);
  }

  if (ratio < 0.5) {
    const double local_ratio = (invratio - 0.5) * 2;

    for (std::vector<RenderItem*>::const_iterator pos = a.compositeDrawables.begin();
         pos != a.compositeDrawables.end();
         ++pos)
    {
      (*pos)->masterAlpha = local_ratio;
      out.compositeDrawables.push_back (*pos);
    }
  } else {
    const double local_ratio = (ratio - 0.5) * 2;

    for (std::vector<RenderItem*>::const_iterator pos = b.compositeDrawables.begin();
         pos != b.compositeDrawables.end();
         ++pos)
    {
      (*pos)->masterAlpha = local_ratio;
      out.compositeDrawables.push_back (*pos);
    }
  }

  /*
  for (RenderItemMatchList::iterator pos = results.matches.begin();
       pos != results.matches.end();
       ++pos)
  {
    RenderItem * itemA = pos->first;
    RenderItem * itemB = pos->second;

    RenderItem * itemC = mergeFunction(itemA, itemB, ratio);

    if (itemC == 0) {
      itemA->masterAlpha = ratio;
      out.drawables.push_back (itemA);
      itemB->masterAlpha = invratio;
      out.drawables.push_back (itemB);
    } else
      out.drawables.push_back (itemC);
  }


  for (std::vector<RenderItem*>::const_iterator pos = results.unmatchedLeft.begin();
       pos != results.unmatchedLeft.end();
       ++pos)
  {
    (*pos)->masterAlpha = invratio;
    out.drawables.push_back (*pos);
  }

  for (std::vector<RenderItem*>::const_iterator pos = results.unmatchedRight.begin();
       pos != results.unmatchedRight.end();
       ++pos)
  {
    (*pos)->masterAlpha = ratio;
    out.drawables.push_back (*pos);
  }
  */

  if (a.staticPerPixel  &&  b.staticPerPixel) {
    out.staticPerPixel = true;
    for (int x = 0;  x < a.gx;  x++)
    {
      for (int y = 0;  y < a.gy;  y++)
      {
        out.x_mesh[x][y]  = a.x_mesh[x][y] * invratio + b.x_mesh[x][y] * ratio;
      }
    }
    for (int x = 0;  x < a.gx;  x++)
    {
      for (int y = 0;  y < a.gy;  y++)
      {
        out.y_mesh[x][y]  = a.y_mesh[x][y] * invratio + b.y_mesh[x][y] * ratio;
      }
    }
  }

  if (ratio < 0.5)
  {
    out.compositeShader = a.compositeShader;
    out.warpShader = a.warpShader;
  }
  else
  {
    out.compositeShader = b.compositeShader;
    out.warpShader = b.warpShader;
  }
}