#include "AftrOpenGLIncludes.h"
#include "OVR_CAPI_GL.h"
#include "Extras/OVR_Math.h"
#include <cassert>
#include <iostream>

using namespace OVR;

struct Aftr::OculusTextureBuffer
{
   ovrSession          Session;
   ovrTextureSwapChain ColorTextureChain;
   ovrTextureSwapChain DepthTextureChain;
   GLuint              fboId;
   Sizei               texSize;

   OculusTextureBuffer( ovrSession session, Sizei size, int sampleCount ) :
      Session( session ),
      ColorTextureChain( nullptr ),
      DepthTextureChain( nullptr ),
      fboId( 0 ),
      texSize( 0, 0 )
   {
      assert( sampleCount <= 1 ); // The code doesn't currently handle MSAA textures.

      texSize = size;

      // This texture isn't necessarily going to be a render target, but it usually is.
      if( ! session ) // No HMD? A little odd.
      {
         std::cout << "ERROR: " << AFTR_FILE_LINE_STR << "No HMD found...\n";         
      }

      ovrTextureSwapChainDesc desc = {};
      desc.Type = ovrTexture_2D;
      desc.ArraySize = 1;
      desc.Width = size.w;
      desc.Height = size.h;
      desc.MipLevels = 1;
      desc.Format = OVR_FORMAT_R8G8B8A8_UNORM_SRGB;
      desc.SampleCount = sampleCount;
      desc.StaticImage = ovrFalse;

      {
         ovrResult result = ovr_CreateTextureSwapChainGL( Session, &desc, &ColorTextureChain );

         int length = 0;
         ovr_GetTextureSwapChainLength( session, ColorTextureChain, &length );

         if( OVR_SUCCESS( result ) )
         {
            for( int i = 0; i < length; ++i )
            {
               GLuint chainTexId;
               ovr_GetTextureSwapChainBufferGL( Session, ColorTextureChain, i, &chainTexId );
               glBindTexture( GL_TEXTURE_2D, chainTexId );

               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
            }
         }
      }

      desc.Format = OVR_FORMAT_D32_FLOAT;

      {
         ovrResult result = ovr_CreateTextureSwapChainGL( Session, &desc, &DepthTextureChain );

         int length = 0;
         ovr_GetTextureSwapChainLength( session, DepthTextureChain, &length );

         if( OVR_SUCCESS( result ) )
         {
            for( int i = 0; i < length; ++i )
            {
               GLuint chainTexId;
               ovr_GetTextureSwapChainBufferGL( Session, DepthTextureChain, i, &chainTexId );
               glBindTexture( GL_TEXTURE_2D, chainTexId );

               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
               glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
            }
         }
      }

      glGenFramebuffers( 1, &fboId );
   }

   ~OculusTextureBuffer()
   {
      if( ColorTextureChain )
      {
         ovr_DestroyTextureSwapChain( Session, ColorTextureChain );
         ColorTextureChain = nullptr;
      }
      if( DepthTextureChain )
      {
         ovr_DestroyTextureSwapChain( Session, DepthTextureChain );
         DepthTextureChain = nullptr;
      }
      if( fboId )
      {
         glDeleteFramebuffers( 1, &fboId );
         fboId = 0;
      }
   }

   Sizei GetSize() const
   {
      return texSize;
   }

   void SetAndClearRenderSurface()
   {
      GLuint curColorTexId;
      GLuint curDepthTexId;
      {
         int curIndex;
         ovr_GetTextureSwapChainCurrentIndex( Session, ColorTextureChain, &curIndex );
         ovr_GetTextureSwapChainBufferGL( Session, ColorTextureChain, curIndex, &curColorTexId );
      }
      {
         int curIndex;
         ovr_GetTextureSwapChainCurrentIndex( Session, DepthTextureChain, &curIndex );
         ovr_GetTextureSwapChainBufferGL( Session, DepthTextureChain, curIndex, &curDepthTexId );
      }

      glBindFramebuffer( GL_FRAMEBUFFER, fboId );
      glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, curColorTexId, 0 );
      glFramebufferTexture2D( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, curDepthTexId, 0 );

      glViewport( 0, 0, texSize.w, texSize.h );
      glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
      glEnable( GL_FRAMEBUFFER_SRGB );
   }

   void UnsetRenderSurface()
   {
      glBindFramebuffer( GL_FRAMEBUFFER, fboId );
      glFramebufferTexture2D( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 0, 0 );
      glFramebufferTexture2D( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, 0, 0 );
   }

   void Commit()
   {
      ovr_CommitTextureSwapChain( Session, ColorTextureChain );
      ovr_CommitTextureSwapChain( Session, DepthTextureChain );
   }
};