//-----------------------------------------------------------------------------
//
// VTFCreate - Convert images to VTF with DXT compression
// Based on VTFConv by Darkimmortal and various DevIL tutorials
//
// @Author ALHat
// @Date 7.4.2012
// @Version 1.0
//
//-----------------------------------------------------------------------------

// DevIL core
#include <IL/il.h>

// fopen, ftell, fwrite, fseek
// also included by il.h but I won't rely on that
#include <stdio.h>

// strcmp
#include <string.h>

// malloc & free
#include <stdlib.h>

int main(int argc, char **argv)
{
   // DevIL handle for the current image
   ILuint   ImgId;
   
   // Size of the compressed image data
   ILuint   DXTCSize;
   
   // type of compression to use
   ILenum   DXType;
   
   // the compressed image data
   ILubyte   *compressedData;
   
   // the uncompressed image data
   ILubyte *data;
   
   // pointer used during repair of image file
   FILE * pFile;
   
   long int uncompressedSize;
   long int fileSize;

   // check for the correct number of arguments, else print usage info
   if (argc < 3 || argc > 4)
   {
      fprintf(stderr, "Usage: vtfconv <file> <destination> [<DXT[1,3,5]>]\n");
      return 1;
   }

   // Check if the shared lib's version matches the executable's version.
   if (ilGetInteger(IL_VERSION_NUM) < IL_VERSION)
   {
      printf("DevIL version is different...exiting!\n");
      return 2;
   }
   
   // check if the user specified a compression type; use DXT1 as default
   if (argc == 4)
   {
      if(strcmp(argv[3], "DXT3") == 0) DXType = IL_DXT3;
      else if(strcmp(argv[3], "DXT5") == 0) DXType = IL_DXT5;
      else DXType = IL_DXT1;
   }
   else
   {
      DXType = IL_DXT1;
   }
   
   // Initialize DevIL core.
   ilInit();

   // Generate the main image name to use.
   ilGenImages(1, &ImgId);

   // Bind this image name.
   ilBindImage(ImgId);

   // allow overwriting existing files
   ilEnable(IL_FILE_OVERWRITE);
   
   // set the application wide compression type
   // not sure if this actually has any effect on VTFs
   ilSetInteger(IL_DXTC_FORMAT, DXType);
   
   // set the VTF specific compression type
   ilSetInteger(IL_VTF_COMP, DXType);

   // Loads the image specified by File into the image named by ImgId.
   if (!ilLoadImage(argv[1]))
   {
      printf("Could not open file...exiting.\n");
      return 3;
   }
   
   // Try and save the file; if no error occurs we're done.
   if(ilSave(IL_VTF,argv[2]) == IL_TRUE) return 0;
   
   /* If the file could not be saved without error we'll try to repair
    * it. As of April 2012 DevIL 1.7.8-10 manages to create the file
    * header but dies when trying to write the image data. */
   
   // first open the file in read mode for some checks
   pFile = fopen(argv[2],"r");
   
   // if no file was created at there's nothing to fix here, we failed.
   if(pFile == NULL)
   {
      // TODO write image header ourselves?
      printf("DevIL did not even create a stump for %s; aborting.\n",argv[2]);
      return 4;
   }
   
   // get the file size of the stump
   fseek(pFile,0L, SEEK_END);
   fileSize = ftell(pFile);
   fclose(pFile);
   
   /* VTF headers are 80 bytes long. If has a different size it's
    * probably not a valid VTF header. We failed. */
   if(fileSize != 80)
   {
      // TODO write image header ourselves?
      printf("DevIL did not create a properly sized VTF header; aborting.\n");
      remove(argv[2]);
      return 5;
   }
   
   /* OK so we probably have a valid VTF header. Next steps are to compress
    * the image data and append it to the header without relying on DevIL */
   
   /* calculate the memory needed for the source image data and allocate it
    * formula is height*width for the number of pixels and that times 3 because
    * we have three components per pixel (RGB, BGR, etc.). Make that four if
    * you want an alpha channel, I guess. */
   uncompressedSize = ilGetInteger(IL_IMAGE_WIDTH) *ilGetInteger(IL_IMAGE_HEIGHT) * 3 * sizeof(unsigned char);
   data = (ILubyte*) malloc(uncompressedSize);
   
   // get the image data from the source image
   ilCopyPixels(0, 0, 0, ilGetInteger(IL_IMAGE_WIDTH), ilGetInteger(IL_IMAGE_HEIGHT), 1, IL_RGB, IL_UNSIGNED_BYTE, data);
   
   // compress the data from the source image
   compressedData = ilCompressDXT(data,ilGetInteger(IL_IMAGE_WIDTH),ilGetInteger(IL_IMAGE_HEIGHT),1,DXType,&DXTCSize);
   
   // open the destination file for appending, write the data and close the file
   pFile = fopen(argv[2],"a");
   fwrite(compressedData,DXTCSize,1,pFile);
   fclose(pFile);
   
   // done! now some cleanup.
   ilDeleteImages(1, &ImgId);
   free(data); data = NULL;
   free(compressedData); compressedData = NULL;

   return 0;
}