/* Copyright (c) 2002-2012 Croteam Ltd. All rights reserved. */

#include "Engine/StdH.h"

#include <Engine/Entities/Entity.h>
#include <Engine/Brushes/Brush.h>

#include <Engine/Templates/DynamicArray.cpp>
#include <Engine/Templates/StaticArray.cpp>
#include <Engine/Templates/StaticStackArray.cpp>
#include <Engine/Math/Geometry.inl>
#include <Engine/Math/Clipping.inl>

static CEntity *_pen;
static FLOAT3D _vHandle;
static CBrushPolygon *_pbpoNear;
static FLOAT _fNearDistance;
static FLOAT3D _vNearPoint;
static FLOATplane3D _plPlane;

class CActiveSector {
public:
  CBrushSector *as_pbsc;
  void Clear(void) {};
};

static CStaticStackArray<CActiveSector> _aas;

/* Add a sector if needed. */
static void AddSector(CBrushSector *pbsc)
{
  // if not already active and in first mip of its brush
  if ( pbsc->bsc_pbmBrushMip->IsFirstMip()
    &&!(pbsc->bsc_ulFlags&BSCF_NEARTESTED)) {
    // add it to active sectors
    _aas.Push().as_pbsc = pbsc;
    pbsc->bsc_ulFlags|=BSCF_NEARTESTED;
  }
}
/* Add all sectors of a brush. */
static void AddAllSectorsOfBrush(CBrush3D *pbr)
{
  // get first mip
  CBrushMip *pbmMip = pbr->GetFirstMip();
  // if it has no brush mip for that mip factor
  if (pbmMip==NULL) {
    // skip it
    return;
  }
  // for each sector in the brush mip
  FOREACHINDYNAMICARRAY(pbmMip->bm_abscSectors, CBrushSector, itbsc) {
    // add the sector
    AddSector(itbsc);
  }
}

void SearchThroughSectors(void)
{
  // for each active sector (sectors are added during iteration!)
  for(INDEX ias=0; ias<_aas.Count(); ias++) {
    CBrushSector *pbsc = _aas[ias].as_pbsc;
    // for each polygon in the sector
    {FOREACHINSTATICARRAY(pbsc->bsc_abpoPolygons, CBrushPolygon, itbpo) {
      CBrushPolygon &bpo = *itbpo;
      // if it is not a wall
      if (bpo.bpo_ulFlags&BPOF_PORTAL) {
        // skip it
        continue;
      }
      const FLOATplane3D &plPolygon = bpo.bpo_pbplPlane->bpl_plAbsolute;
      // find distance of the polygon plane from the handle
      FLOAT fDistance = plPolygon.PointDistance(_vHandle);
      // if it is behind the plane or further than nearest found
      if (fDistance<0.0f || fDistance>_fNearDistance) {
        // skip it
        continue;
      }
      // find projection of handle to the polygon plane
      FLOAT3D vOnPlane = plPolygon.ProjectPoint(_vHandle);
      // if it is not in the bounding box of polygon
      const FLOATaabbox3D &boxPolygon = bpo.bpo_boxBoundingBox;
      const FLOAT EPSILON = 0.01f;
      if (
        (boxPolygon.Min()(1)-EPSILON>vOnPlane(1)) ||
        (boxPolygon.Max()(1)+EPSILON<vOnPlane(1)) ||
        (boxPolygon.Min()(2)-EPSILON>vOnPlane(2)) ||
        (boxPolygon.Max()(2)+EPSILON<vOnPlane(2)) ||
        (boxPolygon.Min()(3)-EPSILON>vOnPlane(3)) ||
        (boxPolygon.Max()(3)+EPSILON<vOnPlane(3))) {
        // skip it
        continue;
      }

      // find major axes of the polygon plane
      INDEX iMajorAxis1, iMajorAxis2;
      GetMajorAxesForPlane(plPolygon, iMajorAxis1, iMajorAxis2);

      // create an intersector
      CIntersector isIntersector(_vHandle(iMajorAxis1), _vHandle(iMajorAxis2));
      // for all edges in the polygon
      FOREACHINSTATICARRAY(bpo.bpo_abpePolygonEdges, CBrushPolygonEdge, itbpePolygonEdge) {
        // get edge vertices (edge direction is irrelevant here!)
        const FLOAT3D &vVertex0 = itbpePolygonEdge->bpe_pbedEdge->bed_pbvxVertex0->bvx_vAbsolute;
        const FLOAT3D &vVertex1 = itbpePolygonEdge->bpe_pbedEdge->bed_pbvxVertex1->bvx_vAbsolute;
        // pass the edge to the intersector
        isIntersector.AddEdge(
          vVertex0(iMajorAxis1), vVertex0(iMajorAxis2),
          vVertex1(iMajorAxis1), vVertex1(iMajorAxis2));
      }

      // if the point is not inside polygon
      if (!isIntersector.IsIntersecting()) {
        // skip it
        continue;
      }

      // remember the polygon
      _pbpoNear = &bpo;
      _fNearDistance = fDistance;
      _vNearPoint = vOnPlane;
    }}

    // for each entity in the sector
    {FOREACHDSTOFSRC(pbsc->bsc_rsEntities, CEntity, en_rdSectors, pen)
      // if it is a brush
      if (pen->en_RenderType == CEntity::RT_BRUSH) {
        // get its brush
        CBrush3D &brBrush = *pen->en_pbrBrush;
        // add all sectors in the brush
        AddAllSectorsOfBrush(&brBrush);
      }
    ENDFOR}
  }
}

/* Get nearest position of nearest brush polygon to this entity if available. */
// use:
// ->bpo_pbscSector->bsc_pbmBrushMip->bm_pbrBrush->br_penEntity
// to get the entity
CBrushPolygon *CEntity::GetNearestPolygon(
  FLOAT3D &vPoint, FLOATplane3D &plPlane, FLOAT &fDistanceToEdge)
{
  _pen = this;
  // take reference point at handle of the model entity
  _vHandle = en_plPlacement.pl_PositionVector;

  // start infinitely far away
  _pbpoNear = NULL;
  _fNearDistance = UpperLimit(1.0f);

  // for each zoning sector that this entity is in
  {FOREACHSRCOFDST(en_rdSectors, CBrushSector, bsc_rsEntities, pbsc)
    // add the sector
    AddSector(pbsc);
  ENDFOR}

  // start the search
  SearchThroughSectors();

  // for each active sector
  for(INDEX ias=0; ias<_aas.Count(); ias++) {
    // mark it as inactive
    _aas[ias].as_pbsc->bsc_ulFlags&=~BSCF_NEARTESTED;
  }
  _aas.PopAll();

  // if there is some polygon found
  if( _pbpoNear!=NULL) {
    // return info
    plPlane = _pbpoNear->bpo_pbplPlane->bpl_plAbsolute;
    vPoint = _vNearPoint;
    fDistanceToEdge = _pbpoNear->GetDistanceFromEdges(_vNearPoint);
    return _pbpoNear;
  // if none is found
  } else {
    // return failure
    return NULL;
  }
}