// File: example3.cpp - Demonstrates how to use crnlib's simple block compression
// API's to manually pack images to DXTn compressed .DDS files. This example isn't multithreaded
// so it's not going to be fast.
// Also note that this sample only demonstrates traditional/vanilla 4x4 DXTn block compression (not CRN).

// See Copyright Notice and license at the end of inc/crnlib.h
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <algorithm>

#if !defined(_WIN32)
#include <libgen.h>
#endif

// CRN transcoder library.
#include "crnlib.h"
// .DDS file format definitions.
#include "dds_defs.h"

#include "crn_core.h"
#include "crn_strutils.h"
#include "crn_file_utils.h"

// stb_image, for loading/saving image files.
#ifdef _MSC_VER
#pragma warning(disable : 4244)  // conversion from 'int' to 'uint8', possible loss of data
#pragma warning(disable : 4100)  // unreferenced formal parameter
#pragma warning(disable : 4127)  // conditional expression is constant
#endif

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

using namespace crnlib;

typedef unsigned int uint;

const uint cDXTBlockSize = 4;

static int print_usage() {
  printf("Description: Simple .DDS DXTn block compression using crnlib.\n");
  printf("Copyright (c) 2010-2016 Binomial LLC\n");
  printf("Usage: example3 [source_file] [options]\n");
  printf("\n");
  printf("Note: This simple example is not multithreaded, so it's not going to be\n");
  printf("particularly fast.\n");
  printf("\n");
  printf("Supported source image formats:\n");
  printf("Baseline JPEG, PNG, BMP, TGA, PSD, and HDR\n");
  printf("\nOptions:\n");
  printf("-out filename - Force output filename (always use .DDS extension).\n");
  printf("-nonsrgb - Input is not sRGB: disables gamma filtering, perceptual metrics.\n");
  printf("-pixelformat X - Output DXTn format. Supported formats:\n");
  printf("DXT1, DXT3, DXT5, DXN_XY (ATI 3DC), DXN_YX (ATI 3DC), DXT5A (ATN1N)\n");
  printf("If no output pixel format is specified, this example uses either DXT1 or DXT5.\n");
  printf("-dxtquality X - DXTn quality: superfast, fast, normal, better, uber (default)\n");
  printf("-setalphatoluma - Set alpha channel to luma before compression.\n");
  printf("-converttoluma - Set RGB to luma before compression.\n");
  return EXIT_FAILURE;
}

static int error(const char* pMsg, ...) {
  va_list args;
  va_start(args, pMsg);
  char buf[512];
  crnlib_vsnprintf(buf, sizeof(buf), pMsg, args);
  va_end(args);
  printf("%s", buf);
  return EXIT_FAILURE;
}

int main(int argc, char* argv[]) {
  printf("example3 - Version v%u.%02u Built " __DATE__ ", " __TIME__ "\n", CRNLIB_VERSION / 100, CRNLIB_VERSION % 100);

  if (argc < 2)
    return print_usage();

  // Parse command line options
  const char* pSrc_filename = argv[1];
  char out_filename[FILENAME_MAX] = {'\0'};
  crn_format fmt = cCRNFmtInvalid;
  bool srgb_colorspace = true;
  crn_dxt_quality dxt_quality = cCRNDXTQualityUber;  // best quality, but slowest
  bool set_alpha_to_luma = false;
  bool convert_to_luma = false;

  for (int i = 2; i < argc; i++) {
    if (argv[i][0] == '/')
      argv[i][0] = '-';

    if (!crnlib_stricmp(argv[i], "-out")) {
      if (++i >= argc)
        return error("Expected output filename!");

      strcpy_safe(out_filename, sizeof(out_filename), argv[i]);
    } else if (!crnlib_stricmp(argv[i], "-nonsrgb"))
      srgb_colorspace = false;
    else if (!crnlib_stricmp(argv[i], "-pixelformat")) {
      if (++i >= argc)
        return error("Expected pixel format!");

      uint f;
      for (f = 0; f < cCRNFmtTotal; f++) {
        crn_format actual_fmt = crn_get_fundamental_dxt_format(static_cast<crn_format>(f));
        if (!crnlib_stricmp(argv[i], crn_get_format_string(actual_fmt))) {
          fmt = actual_fmt;
          break;
        }
      }
      if (f == cCRNFmtTotal)
        return error("Unrecognized pixel format: %s\n", argv[i]);
    } else if (!crnlib_stricmp(argv[i], "-dxtquality")) {
      if (++i >= argc)
        return error("Expected DXTn quality!\n");

      uint q;
      for (q = 0; q < cCRNDXTQualityTotal; q++) {
        if (!crnlib_stricmp(argv[i], crn_get_dxt_quality_string(static_cast<crn_dxt_quality>(q)))) {
          dxt_quality = static_cast<crn_dxt_quality>(q);
          break;
        }
      }
      if (q == cCRNDXTQualityTotal)
        return error("Unrecognized DXTn quality: %s\n", argv[i]);
    } else if (!crnlib_stricmp(argv[i], "-setalphatoluma"))
      set_alpha_to_luma = true;
    else if (!crnlib_stricmp(argv[i], "-converttoluma"))
      convert_to_luma = true;
    else
      return error("Invalid option: %s\n", argv[i]);
  }

  // Split the source filename into its various components.
  dynamic_string drive, dir, fname, ext;
  if (!file_utils::split_path(pSrc_filename, &drive, &dir, &fname, &ext))
    return error("Invalid source filename!\n");

  // Load the source image into memory.
  printf("Loading source file: %s\n", pSrc_filename);
  int width, height, actual_comps;
  crn_uint32* pSrc_image = (crn_uint32*)stbi_load(pSrc_filename, &width, &height, &actual_comps, 4);
  if (!pSrc_image)
    return error("Unable to read source file\n");

  if (fmt == cCRNFmtInvalid) {
    // Format not specified - automatically choose the DXTn format.
    fmt = (actual_comps > 3) ? cCRNFmtDXT5 : cCRNFmtDXT1;
  }

  if ((fmt == cCRNFmtDXT5A) && (actual_comps <= 3))
    set_alpha_to_luma = true;

  if ((set_alpha_to_luma) || (convert_to_luma)) {
    for (int i = 0; i < width * height; i++) {
      crn_uint32 r = pSrc_image[i] & 0xFF, g = (pSrc_image[i] >> 8) & 0xFF, b = (pSrc_image[i] >> 16) & 0xFF;
      // Compute CCIR 601 luma.
      crn_uint32 y = (19595U * r + 38470U * g + 7471U * b + 32768) >> 16U;
      crn_uint32 a = (pSrc_image[i] >> 24) & 0xFF;
      if (set_alpha_to_luma)
        a = y;
      if (convert_to_luma) {
        r = y;
        g = y;
        b = y;
      }
      pSrc_image[i] = r | (g << 8) | (b << 16) | (a << 24);
    }
  }

  printf("Source Dimensions: %ux%u, Actual Components: %u\n", width, height, actual_comps);

  const uint num_blocks_x = (width + cDXTBlockSize - 1) / cDXTBlockSize;
  const uint num_blocks_y = (height + cDXTBlockSize - 1) / cDXTBlockSize;
  const uint bytes_per_block = crn_get_bytes_per_dxt_block(fmt);
  const uint total_compressed_size = num_blocks_x * num_blocks_y * bytes_per_block;

  printf("Block Dimensions: %ux%u, BytesPerBlock: %u, Total Compressed Size: %u\n", num_blocks_x, num_blocks_y, bytes_per_block, total_compressed_size);

  void* pCompressed_data = malloc(total_compressed_size);
  if (!pCompressed_data) {
    stbi_image_free(pSrc_image);
    return error("Out of memory!");
  }

  crn_comp_params comp_params;
  comp_params.m_format = fmt;
  comp_params.m_dxt_quality = dxt_quality;
  comp_params.set_flag(cCRNCompFlagPerceptual, srgb_colorspace);
  comp_params.set_flag(cCRNCompFlagDXT1AForTransparency, actual_comps > 3);

  crn_block_compressor_context_t pContext = crn_create_block_compressor(comp_params);

  printf("Compressing to %s:     ", crn_get_format_string(fmt));

  int prev_percentage_complete = -1;
  for (crn_uint32 block_y = 0; block_y < num_blocks_y; block_y++) {
    for (crn_uint32 block_x = 0; block_x < num_blocks_x; block_x++) {
      crn_uint32 pixels[cDXTBlockSize * cDXTBlockSize];

      // Exact block from image, clamping at the sides of non-divisible by 4 images to avoid artifacts.
      crn_uint32* pDst_pixels = pixels;
      for (uint y = 0; y < cDXTBlockSize; y++) {
        const uint actual_y = std::min(height - 1U, (block_y * cDXTBlockSize) + y);
        for (uint x = 0; x < cDXTBlockSize; x++) {
          const uint actual_x = std::min(width - 1U, (block_x * cDXTBlockSize) + x);
          *pDst_pixels++ = pSrc_image[actual_x + actual_y * width];
        }
      }

      // Compress the DXTn block.
      crn_compress_block(pContext, pixels, static_cast<crn_uint8*>(pCompressed_data) + (block_x + block_y * num_blocks_x) * bytes_per_block);
    }

    int percentage_complete = ((block_y + 1) * 100 + (num_blocks_y / 2)) / num_blocks_y;
    if (percentage_complete != prev_percentage_complete) {
      printf("\b\b\b\b%3u%%", percentage_complete);
      prev_percentage_complete = percentage_complete;
    }
  }
  printf("\n");

  // Free the block compressor.
  crn_free_block_compressor(pContext);
  pContext = NULL;

  // Now create the DDS file.
  char dst_filename[FILENAME_MAX];
  crnlib_snprintf(dst_filename, sizeof(dst_filename), "%s%s%s.dds", drive.get_ptr(), dir.get_ptr(), fname.get_ptr());
  if (out_filename[0])
    strcpy_safe(dst_filename, sizeof(dst_filename), out_filename);

  printf("Writing DDS file: %s\n", dst_filename);

  FILE* pDDS_file = NULL;
  crn_fopen(&pDDS_file, dst_filename, "wb");
  if (!pDDS_file) {
    free(pCompressed_data);
    return error("Failed creating destination file!\n");
  }

  // Write the 4-byte DDS signature (not endian safe, but whatever this is a sample).
  fwrite(&crnlib::cDDSFileSignature, sizeof(crnlib::cDDSFileSignature), 1, pDDS_file);

  // Prepare the DDS header.
  crnlib::DDSURFACEDESC2 dds_desc;
  memset(&dds_desc, 0, sizeof(dds_desc));
  dds_desc.dwSize = sizeof(dds_desc);
  dds_desc.dwFlags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH | DDSD_PIXELFORMAT;
  dds_desc.dwWidth = width;
  dds_desc.dwHeight = height;

  dds_desc.ddpfPixelFormat.dwSize = sizeof(crnlib::DDPIXELFORMAT);
  dds_desc.ddpfPixelFormat.dwFlags = DDPF_FOURCC;
  dds_desc.ddpfPixelFormat.dwFourCC = crn_get_format_fourcc(fmt);
  dds_desc.ddsCaps.dwCaps = DDSCAPS_TEXTURE;

  // Set pitch/linearsize field (some DDS readers require this field to be non-zero).
  uint bits_per_pixel = crn_get_format_bits_per_texel(fmt);
  dds_desc.lPitch = (((dds_desc.dwWidth + 3) & ~3) * ((dds_desc.dwHeight + 3) & ~3) * bits_per_pixel) >> 3;
  dds_desc.dwFlags |= DDSD_LINEARSIZE;

  // Write the DDS header to the output file.
  fwrite(&dds_desc, sizeof(dds_desc), 1, pDDS_file);

  // Write the image's compressed data to the output file.
  fwrite(pCompressed_data, total_compressed_size, 1, pDDS_file);
  free(pCompressed_data);

  stbi_image_free(pSrc_image);

  if (fclose(pDDS_file) == EOF) {
    return error("Failed writing to DDS file!\n");
  }

  return EXIT_SUCCESS;
}