#include "terrain.h"
#include "terrain_page.h"
#include "glincl.h"
#include "util/loading/resource_manager.h"
#include "debug.h"
#include <math.h>
#ifdef HAVE_SDL_SDL_IMAGE_H
#include <SDL/SDL_image.h>
#else
#include <SDL_image.h>
#endif

bool validateSize( int _s )
{
  _s-=1;
  int s = 16;
  while ( s <= _s )
  {
    if (s == _s )
      return true;
    s*=2;
  }
  return false;
}
void Terrain::build()
{

  printf("SHOULD GET LOADED :)\n");

  ResourceManager *MANAGER = ResourceManager::getInstance();
  std::string full = MANAGER->getFullName( heightmapSource );
  SDL_Surface *tmpData = IMG_Load( full.c_str() );
  if ( !tmpData )
  {
    PRINT(0)( "I' sorry, I can't load %s\n", full.c_str() );
    return;
  }
  if ( !validateSize( tmpData->h ) || !validateSize( tmpData->w ) )
  {
    PRINT(0)( "The size of the elevation map must be 2^n+1x2^m+1. and at least 17x17" );
    return;
  }
  if ( tmpData->format->BytesPerPixel != 1 )
  {
    PRINT(0)( "The elevetation map must be an 8bit image not %d",
              tmpData->format->BytesPerPixel*8 );
    return;
  }
  PRINTF(2)( "Loaded the elevation map\n" );
  heightfield.height = tmpData->h;
  heightfield.width = tmpData->w;
  heightfield.pitch = tmpData->pitch;
  int dataSize = heightfield.pitch*heightfield.height;
  heightfield.data = new Uint8[dataSize];
  memcpy( heightfield.data, tmpData->pixels, sizeof(Uint8)*dataSize );
  SDL_FreeSurface( tmpData );
  pagesX = (heightfield.width/(pageSize-1) );
  pagesZ = (heightfield.height/(pageSize-1) );


  pages = new pTerrainPage[pagesX*pagesZ];
  for ( int x = 0; x < pagesX; ++x )
    for ( int z = 0; z < pagesZ; ++z )
      pages[z*pagesX+x] = createPage( x, z );
  //Inform each page about its neighbors.
  for ( int x = 0; x < pagesX; ++x )
    for ( int z = 0; z < pagesZ; ++z )
      pages[z*pagesX+x]->setNeighbors(
        x > 0 			? getPage( x-1, z+0 ) : NULL,
        x < pagesX-1	? getPage( x+1, z+0 ) : NULL,
        z < pagesZ-1	? getPage( x+0, z+1 ) : NULL,
        z > 0 			? getPage( x+0, z-1 ) : NULL );

  root = createQuadTree( 0, 0, pagesX, pagesZ );

  for ( unsigned int i = 0; i < layers.size(); ++i )
  {
    determineLayerVisibility( i );
  }
  activePages = NULL;
}

pTerrainQuad Terrain::createQuadTree( int _x0, int _z0, int _x1, int _z1, int _depth )
{
  int _x01 = (_x1+_x0)/2; int _z01 = (_z1+_z0)/2;
  pTerrainQuad node;
  if ( _x1-_x0 == 1 )
  {
    node = getPage( _x0, _z0 );
    node->setChildren( NULL, NULL, NULL, NULL );
  }
  else
  {
    node = new TerrainQuad( this, _x0, _z0, _x1, _z1 );
    node->setChildren(
      createQuadTree( _x0, _z0, _x01, _z01, _depth+1 ),
      createQuadTree( _x01, _z0, _x1, _z01, _depth+1 ),
      createQuadTree( _x0, _z01, _x01, _z1, _depth+1 ),
      createQuadTree( _x01, _z01, _x1, _z1, _depth+1 ) );
  }
  node->calculateBounds();
  return node;
}

pTerrainPage Terrain::createPage( int _xOffset, int _zOffset ) const
{
  pTerrainPage newPage = new TerrainPage( const_cast<Terrain*>( this ), _xOffset, _zOffset );
  newPage->setScale( scale );
  newPage->setPosition( Vector( scale.x*_xOffset, 0.0f, scale.z*_zOffset ) );
  newPage->calculateErrors();
  return newPage;
}

void Terrain::addLevelFourPage( int _numVertices, Vertex *_vertices,
                                int _numIndices, unsigned short *_indices )
{
  assert( indices ); assert( vertices );
  BufferInfo bi = buffers[current];
  if ( ( MAX_VERTICES < _numVertices+bi.numVertices ) ||
       ( MAX_INDICES < _numIndices+bi.numIndices+2 ) )
  {
    //So, we need the next vb and ib. Lets put the old into vram...
    glBindBufferARB( GL_ARRAY_BUFFER_ARB, bi.vbIdentifier );
    glBufferDataARB( GL_ARRAY_BUFFER_ARB, MAX_VERTICES*sizeof( Vertex ),
                     vertices, GL_DYNAMIC_DRAW_ARB );
    glBindBufferARB( GL_ELEMENT_ARRAY_BUFFER_ARB, bi.ibIdentifier );
    glBufferDataARB( GL_ELEMENT_ARRAY_BUFFER_ARB, MAX_INDICES*sizeof( short ),
                     indices, GL_DYNAMIC_DRAW_ARB );
    BufferInfo newInfo;
    broker->acquire( newInfo.vbIdentifier, newInfo.ibIdentifier );
    current++;
    buffers.push_back( newInfo );
    bi = newInfo;
  }
  //For the vertex data, a simple copy operation is sufficient...
  memcpy( &vertices[bi.numVertices], _vertices,
          _numVertices*sizeof( Vertex ) );
  //The indices need to be updated with an offset :(
  unsigned short *dst= &indices[bi.numIndices];
  unsigned short offset = bi.numVertices;
  unsigned short *src= _indices;
  unsigned short *end= src+_numIndices;
  bi.numVertices+=_numVertices;
  if ( bi.numIndices )
  {
    dst[0] = *(dst-1);
    dst[1] = *src+offset;
    dst+=2; bi.numIndices+=2;
  }
  while ( src < end )
  {
    *dst= *src+offset;
    dst++;
    src++;
  }
  bi.numIndices+=_numIndices;
  buffers[current] = bi;
}

void Terrain::determineVisiblePages( pTerrainQuad _node )
{
  switch( _node->cull() )
  {
    case Frustum::INTERSECT:
      if ( !_node->isChildless() )
      {
        pTerrainQuad *children = _node->getChildren();
        for ( int i = 0; i < 4; ++i, ++children )
          determineVisiblePages( *children );
      }
      else
      {
        showPages( _node->getXOffset(),
                   _node->getZOffset(), 1, 1 );
      }
      break;
    case Frustum::INSIDE:
      showPages( _node->getXOffset(),
                 _node->getZOffset(),
                 _node->getWidth() ,
                 _node->getHeight() );
      break;
    case Frustum::OUTSIDE:
      break;
  }
}

void Terrain::tick( float _dt )
{
  for ( unsigned int i = 0; i < buffers.size(); ++i )
    broker->release( buffers[i].vbIdentifier, buffers[i].ibIdentifier );
  buffers.clear();
  pTerrainPage page = NULL;
  //Extract the frustum planes out of the modelview matrix.
  frustum->extractPlanes();
  // Lets see which pages are visible.
  determineVisiblePages( root );
  int wantedLeft, wantedRight, wantedBottom, wantedTop, minLOD;
  pTerrainPage neighbor = NULL;
  page = activePages;
  bool dirty;
  current = 0;
  BufferInfo bi;
  broker->acquire( bi.vbIdentifier, bi.ibIdentifier );
  buffers.push_back( bi );
  int dirtyRounds = 0;
  do
  {
    dirtyRounds++;
    dirty = false;
    page = activePages;
    while ( page )
    {
      if ( !page->isActive() )
      {
        pTerrainPage tmp = page;
        page = tmp->getNext();
        tmp->setVisibility( false );
        continue;
      }
      wantedLeft = wantedRight = wantedBottom = wantedTop = page->getWantedLOD();
      if ( ( neighbor = page->getLeft() ) && ( neighbor->isActive() ) )
        wantedLeft = neighbor->getWantedLOD();
      if ( ( neighbor = page->getRight() ) && ( neighbor->isActive() ) )
        wantedRight = neighbor->getWantedLOD();
      if ( ( neighbor = page->getTop() ) && ( neighbor->isActive() ) )
        wantedTop = neighbor->getWantedLOD();
      if ( ( neighbor = page->getBottom() ) && ( neighbor->isActive() ) )
        wantedBottom = neighbor->getWantedLOD();

      minLOD = std::min( std::min( wantedBottom, wantedTop ),
                         std::min( wantedLeft, wantedRight ) );
      if ( minLOD < page->getWantedLOD()-1 )
      {
        page->setWantedLOD( minLOD+1 );
        dirty = true;
      }
      page = page->getNext();
    }
  }
  while ( dirty );

  page = activePages;
  while ( page )
  {
    assert( page->isActive() );
    page->updateTesselation();
    page = page->getNext();
  }
  //If there is some data in the buffer, we need to upload the data
  //into the vram...
  if ( buffers[current].numIndices != 0 )
  {
    BufferInfo bi = buffers[current];
    glBindBufferARB( GL_ARRAY_BUFFER_ARB, bi.vbIdentifier );
    glBufferDataARB( GL_ARRAY_BUFFER_ARB, MAX_VERTICES*sizeof( Vertex ),
                     vertices, GL_DYNAMIC_DRAW_ARB );
    glBindBufferARB( GL_ELEMENT_ARRAY_BUFFER_ARB, bi.ibIdentifier );
    glBufferDataARB( GL_ELEMENT_ARRAY_BUFFER_ARB, MAX_INDICES*sizeof( short ),
                     indices, GL_DYNAMIC_DRAW_ARB );
  }
}

void Terrain::draw( )
{
  pTerrainPage page = NULL;
  glGetError();
  /*pTerrainPage page = NULL;
  frustum->extractPlanes();*/
  Plane far = frustum->getPlane( Frustum::FAR );
  //Due to some reason, the OpenGL implementors chose the plane equation
  //to an array of doubles. So we will make them happy.
  double farPlane[] = { far.n.x, far.n.y, far.n.z, far.k };
  glEnable( GL_CLIP_PLANE0 );
  glClipPlane( GL_CLIP_PLANE0, farPlane );
  glPushAttrib( GL_ALL_ATTRIB_BITS );
  glPushClientAttrib( GL_CLIENT_VERTEX_ARRAY_BIT );
  /*
   * Enable texture and vertex arrays for the first and the second texture
   * units and disable the normal arrays.
   */
  glClientActiveTextureARB( GL_TEXTURE0_ARB );
  glEnableClientState( GL_VERTEX_ARRAY );
  glEnableClientState( GL_TEXTURE_COORD_ARRAY );
  glDisableClientState( GL_NORMAL_ARRAY );

  glClientActiveTextureARB( GL_TEXTURE1_ARB );
  glEnableClientState( GL_VERTEX_ARRAY );
  glEnableClientState( GL_TEXTURE_COORD_ARRAY );
  glDisableClientState( GL_NORMAL_ARRAY );
  glDisable( GL_CULL_FACE );
  glDisable( GL_LIGHTING );
  glColor3f( 1.0f, 1.0f, 1.0f );
  //glPolygonMode( GL_FRONT_AND_BACK, GL_LINE );
  cullCount = 0;
  glEnable( GL_BLEND );
  glDepthFunc( GL_LEQUAL );
  glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
  for ( unsigned int i = 0; i < layers.size(); ++i )
  {
    LayerInfo* layer= layers[i];
    page = activePages;

    glActiveTextureARB( GL_TEXTURE1_ARB );
    glClientActiveTextureARB( GL_TEXTURE1_ARB );
    if ( layer->detail )
    {
      //glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND );
      glEnable( GL_TEXTURE_2D );
      glBindTexture( GL_TEXTURE_2D, layer->detail->getTexture() );
      glMatrixMode( GL_TEXTURE );
      glLoadIdentity();
      glScalef( layer->repeatX, layer->repeatZ, 1.0f );
    }
    else
    {
      glDisable( GL_TEXTURE_2D );
    }
    glEnable( GL_CULL_FACE );
    glCullFace( GL_BACK );
    glClientActiveTextureARB( GL_TEXTURE0_ARB );
    glActiveTextureARB( GL_TEXTURE0_ARB );
    glEnable( GL_TEXTURE_2D );
    if ( layer->alpha )
    {
      //glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND );
      glBindTexture( GL_TEXTURE_2D, layer->alpha->getTexture() );
    }
    else
    {

      glBindTexture( GL_TEXTURE_2D, lightmap->getTexture() );
    }
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );

    for ( unsigned j = 0; j < buffers.size(); ++j )
    {
      BufferInfo bi = buffers[j];
      glBindBufferARB( GL_ARRAY_BUFFER_ARB, bi.vbIdentifier );
      glClientActiveTextureARB( GL_TEXTURE0_ARB );
      glInterleavedArrays( GL_T2F_V3F, 0, NULL );

      glClientActiveTextureARB( GL_TEXTURE1_ARB );
      glInterleavedArrays( GL_T2F_V3F, 0, NULL );

      glBindBufferARB( GL_ELEMENT_ARRAY_BUFFER_ARB,
                       bi.ibIdentifier );

      glDrawElements( GL_TRIANGLE_STRIP, bi.numIndices,
                      GL_UNSIGNED_SHORT, NULL );
    }
    while ( page )
    {
      if ( page->hasMaterial( i ) )
        page->draw();
      page = page->getNext();
    }
  }
  glClientActiveTextureARB( GL_TEXTURE1_ARB );
  glActiveTextureARB( GL_TEXTURE1_ARB );
  glDisable( GL_TEXTURE_2D );
  glActiveTextureARB( GL_TEXTURE0_ARB );
  glEnable( GL_LIGHTING );
  glMatrixMode( GL_TEXTURE );
  glLoadIdentity();
  glPopAttrib();
  glPopClientAttrib();
  glCullFace( GL_FRONT );
  glDisable( GL_CLIP_PLANE0 );
}

inline Uint8 getAlpha( const SDL_Surface *_s, int _x, int _y )
{
  int bpp = _s->format->BytesPerPixel;
  Uint8 *p = (Uint8 *)_s->pixels + _y*_s->pitch + _x * bpp;
  Uint32 pixel = 0;
  switch( bpp )
  {
    case 1:
      pixel = *p;
      break;
    case 2:
      if ( SDL_BYTEORDER == SDL_BIG_ENDIAN )
        pixel = p[0] << 8 | p[1];
      else
        pixel = *(Uint16 *)p;
      break;
    case 3:
      if( SDL_BYTEORDER == SDL_BIG_ENDIAN )
        pixel = p[0] << 16 | p[1] << 8 | p[2];
      else
        pixel = p[0] | p[1] << 8 | p[2] << 16;
      break;
    case 4:
      pixel = *(Uint32 *)p;
      break;
    default:
      return 255; /* shouldn't happen, but avoids warnings */
  }
  Uint8 r,g,b,a;
  SDL_GetRGBA( pixel, _s->format, &r, &g, &b, &a );
  return a;
}

void Terrain::determineLayerVisibility( int _layer )
{
  LayerInfo * layer = layers[_layer];
  if ( !layer->alpha )
  {
    int numPages = pagesX*pagesZ;
    for ( int i = 0; i < numPages; ++i )
      pages[i]->setLayerVisibility( _layer, LV_FULL );

    return;
  }
  SDL_Surface *alpha = const_cast<SDL_Surface*>( layer->alpha->getStoredImage() );
  SDL_LockSurface( alpha );
  float du = ( (float)alpha->w)/pagesX;
  float dv = ( (float)alpha->h)/pagesZ;
  float u = 0.0f, v = 0.0f;
  for ( int pageX = 0; pageX < pagesX; ++pageX )
  {
    v = 0.0f;
    for ( int pageZ = 0; pageZ < pagesZ; ++pageZ )
    {
      bool full = true; bool has = false;
      for ( int x = 0; x < (int)PAGE_SIZE; ++x )
      {
        for ( int z = 0; z < (int)PAGE_SIZE; ++z )
        {
          Uint8 a = getAlpha( alpha, (int)u, (int)v );
          if ( a )
            has = true;
          if ( a < 255 )
            full = false;
        }
      }
      LayerVisibility lv;
      if ( has )
      {
        if ( full )
          lv = LV_FULL;
        else
          lv = LV_PARTIAL;
      }
      else
      {
        lv = LV_NO;
      }
      getPage( pageX, pageZ )->setLayerVisibility( _layer, lv );
      v+= dv;
    }
    u+= du;
  }
  SDL_UnlockSurface( alpha );
}

void Terrain::getAltitude( Vector& _alt, Vector& _normal )
{
  float xScaled = _alt.x / scale.x, zScaled = _alt.z / scale.z;
  //The offset on the map
  int xOff =  (int)xScaled, zOff = (int)zScaled;
  //The interpolation values.
  float u = xScaled-xOff, v = zScaled-zOff;

  float dX = scale.x / ( pageSize-1 );
  float dZ = scale.z / ( pageSize-1 );

  //If u is bigger than v, we are on the lower triangle...
  if ( u > v )
  {

    float alt[] = {
                    getAltitude( xOff+0, zOff+0 )*scale.y,
                    getAltitude( xOff+1, zOff+0 )*scale.y,
                    getAltitude( xOff+1, zOff+1 )*scale.y };
    _alt.y = (1.0f-u-v)*alt[0]+u*alt[1]+v*alt[2];

    //Since we know about the directions of some x and z-coordinates,
    //not the whole cross products needs to be calculated. Grab yourself
    //pen and paper :)
    _normal.x =  dZ*( alt[0] - alt[1] );
    _normal.y =  dZ*dX;
    _normal.z = -dX*( alt[2] - alt[1] );
  }
  else
  {
    float alt[] = {
                    getAltitude( xOff+0, zOff+0 )*scale.y,
                    getAltitude( xOff+0, zOff+1 )*scale.y,
                    getAltitude( xOff+1, zOff+1 )*scale.y };
    _alt.y = (1.0f-u-v)*alt[0]+v*alt[1]+u*alt[2];
    //Since we know about the directions of some x and z-coordinates,
    //not the whole cross products needs to be calculated. Grab yourself
    //pen and paper :)
    _normal.x = -dZ*( alt[2] - alt[1] );
    _normal.y =  dZ*dX;
    _normal.z =  dX*( alt[0] - alt[1] );
  }
}

void Terrain::showPages( int _x0, int _z0, int _width, int _height )
{
  for ( int x = 0; x < _width; ++x )
  {
    for ( int z = 0; z < _height; ++z )
    {
      pTerrainPage page = getPage( _x0+x, _z0+z );
      page->setVisibility( true );
      page->chooseLOD();

    }
  }
}