#ifndef _TEX_DECODE_H
#define _TEX_DECODE_H

#include <cstdint>
#include <vector>

#include "tex.h"

// all credit to Ioncannon
// copied/pasted from https://bitbucket.org/Ioncannon/ffxiv-explorer/src/9330429c1540cf35f947fe7321739d857f4f31a7/src/com/fragmenterworks/ffxivextract/helpers/ImageDecoding.java

struct Colour
{
  uint8_t r, g, b, a;

  Colour( int r, int g, int b, int a )
  {
    this->r = r;
    this->g = g;
    this->b = b;
    this->a = a;
  }

  uint32_t getRGB()
  {
    return ( a << 24 ) | ( r << 16 ) | ( g << 8 ) | ( b << 0 );
  }
};

struct ImageHeader
{
  uint32_t height;
  uint32_t width;
};

struct Image
{
  uint32_t height, width;
  std::vector< std::vector< uint32_t > > data;

  Image()
  {

  }

  Image( int height, int width )
  {
    this->height = height;
    this->width = width;
  }

  Image( char* buf )
  {
    height = *reinterpret_cast< uint32_t* >( buf + 0 );
    width = *reinterpret_cast< uint32_t* >( buf + 4 );
    data.resize( *reinterpret_cast< uint32_t* >( buf + 8 ) );

    auto offset = 12;
    for( auto y = 0; y < data.size(); ++y )
    {
      auto row = *reinterpret_cast< uint32_t* >( buf + offset );
      auto entries = *reinterpret_cast< uint32_t* >( buf + offset + 4 );
      data[ y ].resize( entries );
      offset += 8;

      for( auto x = 0; x < entries; ++x )
        data[ y ][ x ] = *reinterpret_cast< uint32_t* >( buf + offset + ( x * 4 ) );
      offset += entries * 4;
    }
  }

  void toFile( const std::string& path )
  {
    std::ofstream out( path.c_str(), std::ios::trunc );
    out.close();
    out.open( path, std::ios::binary | std::ios::app );

    out.write( reinterpret_cast< char* >( &height ), 4 ); // 0
    out.write( reinterpret_cast< char* >( &width ), 4 );  // 4

    auto size = data.size();
    out.write( reinterpret_cast< char* >( &size ), 4 );   // 8

    for( auto y = 0; y < data.size(); ++y )
    {
      out.write( reinterpret_cast< char* >( &y ), 4 );
      auto entries = data[ y ].size();
      out.write( reinterpret_cast< char* >( &entries ), 4 );
      for( auto x = 0; x < data[ y ].size(); ++x )
      {
        out.write( reinterpret_cast< char* >( &data[ y ][ x ] ), 4 );
      }
    }
    out.close();
  }

  void setRGB( unsigned int x, unsigned int y, uint32_t colour )
  {
    if( data.size() <= y )
      data.resize( y + 1 );
    if( data[ y ].size() <= x )
      data[ y ].resize( x + 1 );
    data[ y ][ x ] = colour;
  }

};


void DecompressBlockDTX1( int x, const int y, const int width, const int color0, const int color1, const int txl1,
                          const int txl2, Image& img )
{
  float temp = ( ( color0 >> 11 ) * 255.0f ) + 16.0f;
  const float r0 = ( ( ( temp / 32.0f ) + temp ) / 32.0f );
  temp = ( ( ( color0 & 0x07E0 ) >> 5 ) * 255.0f ) + 32.0f;
  const float g0 = ( ( ( temp / 64.0f ) + temp ) / 64.0f );
  temp = ( ( color0 & 0x001F ) * 255.0f ) + 16.0f;
  const float b0 = ( ( ( temp / 32.0f ) + temp ) / 32.0f );
  temp = ( ( color1 >> 11 ) * 255.0f ) + 16.0f;
  const float r1 = ( ( ( temp / 32.0f ) + temp ) / 32.0f );
  temp = ( ( ( color1 & 0x07E0 ) >> 5 ) * 255.0f ) + 32.0f;
  const float g1 = ( ( ( temp / 64.0f ) + temp ) / 64.0f );
  temp = ( ( color1 & 0x001F ) * 255.0f ) + 16.0f;
  const float b1 = ( ( ( temp / 32.0f ) + temp ) / 32.0f );
  for( int j = 0; j < 4; j++ )
  {
    for( int i = 0; i < 4; i++ )
    {
      // Color FinalColor;
      const int d = ( 4 * j ) + i;
      int positionCode;
      if( ( d * 2 ) >= 16 )
      {
        positionCode = ( txl2 >> ( ( d * 2 ) % 16 ) ) & 0x03;
      }
      else
      {
        positionCode = ( txl1 >> ( d * 2 ) ) & 0x03;
      }
      float fr, fg, fb, fa;
      if( color0 > color1 )
      {
        switch( positionCode )
        {
          case 0:
          {
            fr = r0;
            fg = g0;
            fb = b0;
            fa = 0;
            break;
          }
          case 1:
          {
            fr = r1;
            fg = g1;
            fb = b1;
            fa = 0;
            break;
          }
          case 2:
          {
            fr = ( ( 2.0f * ( float ) r0 ) + ( float ) r1 ) / 3.0f;
            fg = ( ( 2.0f * ( float ) g0 ) + ( float ) g1 ) / 3.0f;
            fb = ( ( 2.0f * ( float ) b0 ) + ( float ) b1 ) / 3.0f;
            fa = 0;
            break;
          }
          case 3:
          {
            fr = ( ( float ) r0 + ( 2.0f * ( float ) r1 ) ) / 3.0f;
            fg = ( ( float ) g0 + ( 2.0f * ( float ) g1 ) ) / 3.0f;
            fb = ( ( float ) b0 + ( 2.0f * ( float ) b1 ) ) / 3.0f;
            fa = 0;
            break;
          }
          default:
          {
            fr = 0;
            fg = 0;
            fb = 0;
            fa = 0;
          }
        }
      }
      else
      {
        switch( positionCode )
        {
          case 0:
          {
            fr = r0;
            fg = g0;
            fb = b0;
            fa = 0xff;
            break;
          }
          case 1:
          {
            fr = r1;
            fg = g1;
            fb = b1;
            fa = 0xff;
            break;
          }
          case 2:
          {
            fr = ( ( float ) r0 + ( float ) r1 ) / 2.0f;
            fg = ( ( float ) g0 + ( float ) g1 ) / 2.0f;
            fb = ( ( float ) b0 + ( float ) b1 ) / 2.0f;
            fa = 0xff;
            break;
          }
          case 3:
          {
            fr = 0;
            fg = 0;
            fb = 0;
            fa = 0xff;
            break;
          }
          default:
          {
            fr = 0;
            fg = 0;
            fb = 0;
            fa = 0;
          }
        }
      }
      if( ( x + i ) < width )
      {
        int alpha = 0;
        if( ( fr == fg ) && ( fr == fb ) && ( fr == 0 ) )
        {
          alpha = 0xff;
        }
        img.setRGB( x + i, y + j, Colour( ( int ) fr, ( int ) fg, ( int ) fb, 255 - alpha ).getRGB() );
      }
    }
  }
}

Image DecodeTexDXT1( const TEX_FILE& tex, uint32_t offset, uint32_t targetHeight, uint32_t targetWidth,
                     uint32_t compressedHeight, uint32_t compressedWidth )
{
  if( offset > tex.data.size() )
    throw std::runtime_error( "Unable to decode TEX file " + tex.name + ": offset too large" );
  else if( tex.data.size() < ( ( targetHeight * targetWidth ) / 2 ) )
    throw std::runtime_error( "Unable to decode TEX file " + tex.name + ": data too small" );

  std::vector< char > ret;
  auto data = tex.data.data() + offset;
  int pos = 0;

  Image img( targetHeight, targetWidth );

  for( int y = 0; y < compressedHeight; y++ )
  {
    for( int x = 0; x < compressedWidth; x++ )
    {
      const int t0 = *reinterpret_cast< const uint16_t* >( data + pos + 0 ) & 0xffff;
      const int t1 = *reinterpret_cast< const uint16_t* >( data + pos + 2 ) & 0xffff;
      const int t2 = *reinterpret_cast< const uint16_t* >( data + pos + 4 ) & 0xffff;
      const int t3 = *reinterpret_cast< const uint16_t* >( data + pos + 6 ) & 0xffff;

      pos += 8;
      DecompressBlockDTX1( x * 4, y * 4, targetWidth, t0, t1, t2, t3, img );
    }
  }
  return img;
}

#endif