#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <png.h>
#include <setjmp.h>

#ifdef _WIN32
# include <Evil.h>
#endif

#include "evas_common_private.h"
#include "evas_private.h"

#define PNG_BYTES_TO_CHECK 4

typedef struct _Evas_PNG_Info Evas_PNG_Info;
struct _Evas_PNG_Info
{
   unsigned char *map;
   size_t length;
   size_t position;
};

typedef struct _Evas_Loader_Internal Evas_Loader_Internal;
struct _Evas_Loader_Internal
{
   Eina_File *f;
   Evas_Image_Load_Opts *opts;
};

static const Evas_Colorspace cspace_grey[2] = {
   EVAS_COLORSPACE_GRY8,
   EVAS_COLORSPACE_ARGB8888
};

static const Evas_Colorspace cspace_grey_alpha[2] = {
   EVAS_COLORSPACE_AGRY88,
   EVAS_COLORSPACE_ARGB8888
};

static void
_evas_image_png_read(png_structp png_ptr, png_bytep out, png_size_t count)
{
   Evas_PNG_Info *epi = png_get_io_ptr(png_ptr);

   if (!epi) return;
   if (epi->position == epi->length) return;

   if (epi->position + count > epi->length) count = epi->length - epi->position;
   memcpy(out, epi->map + epi->position, count);
   epi->position += count;
}

static void *
evas_image_load_file_open_png(Eina_File *f, Eina_Stringshare *key EINA_UNUSED,
                              Evas_Image_Load_Opts *opts,
                              Evas_Image_Animated *animated EINA_UNUSED,
                              int *error)
{
   Evas_Loader_Internal *loader;

   loader = calloc(1, sizeof (Evas_Loader_Internal));
   if (!loader)
     {
        *error = EVAS_LOAD_ERROR_RESOURCE_ALLOCATION_FAILED;
        return NULL;
     }

   loader->f = f;
   loader->opts = opts;
   return loader;
}

static void
evas_image_load_file_close_png(void *loader_data)
{
   free(loader_data);
}

static Eina_Bool
evas_image_load_file_head_png(void *loader_data,
                              Evas_Image_Property *prop,
                              int *error)
{
   Evas_Loader_Internal *loader = loader_data;
   Evas_Image_Load_Opts *opts;
   Eina_File *f;

   Evas_PNG_Info epi;
   png_structp png_ptr = NULL;
   png_infop info_ptr = NULL;
   png_uint_32 w32, h32;
   int bit_depth, color_type, interlace_type;
   volatile char hasa;
   volatile Eina_Bool r = EINA_FALSE;

   opts = loader->opts;
   f = loader->f;

   hasa = 0;
   epi.map = eina_file_map_all(f, EINA_FILE_RANDOM);
   if (!epi.map)
     {
        *error = EVAS_LOAD_ERROR_CORRUPT_FILE;
        goto close_file;
     }
   epi.length = eina_file_size_get(f);
   epi.position = 0;

   if (epi.length < PNG_BYTES_TO_CHECK)
     {
	*error = EVAS_LOAD_ERROR_UNKNOWN_FORMAT;
	goto close_file;
     }

   if (png_sig_cmp(epi.map, 0, PNG_BYTES_TO_CHECK))
     {
	*error = EVAS_LOAD_ERROR_UNKNOWN_FORMAT;
	goto close_file;
     }

   png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
   if (!png_ptr)
     {
	*error = EVAS_LOAD_ERROR_RESOURCE_ALLOCATION_FAILED;
	goto close_file;
     }

   info_ptr = png_create_info_struct(png_ptr);
   if (!info_ptr)
     {
	*error = EVAS_LOAD_ERROR_RESOURCE_ALLOCATION_FAILED;
	goto close_file;
     }

   png_set_read_fn(png_ptr, &epi, _evas_image_png_read);

   if (setjmp(png_jmpbuf(png_ptr)))
     {
	*error = EVAS_LOAD_ERROR_CORRUPT_FILE;
	goto close_file;
     }

   png_read_info(png_ptr, info_ptr);
   png_get_IHDR(png_ptr, info_ptr, (png_uint_32 *) (&w32),
		(png_uint_32 *) (&h32), &bit_depth, &color_type,
		&interlace_type, NULL, NULL);
   if ((w32 < 1) || (h32 < 1) || (w32 > IMG_MAX_SIZE) || (h32 > IMG_MAX_SIZE) ||
       IMG_TOO_BIG(w32, h32))
     {
	if (IMG_TOO_BIG(w32, h32))
	  *error = EVAS_LOAD_ERROR_RESOURCE_ALLOCATION_FAILED;
	else
	  *error = EVAS_LOAD_ERROR_GENERIC;
	goto close_file;
     }

   if (opts->emile.region.w > 0 && opts->emile.region.h > 0)
     {
        if (((int) w32 < opts->emile.region.x + opts->emile.region.w) ||
            ((int) h32 < opts->emile.region.y + opts->emile.region.h))
          {
             *error = EVAS_LOAD_ERROR_GENERIC;
             goto close_file;
          }
        if(opts->emile.scale_down_by > 1)
          {
             prop->w = opts->emile.region.w / opts->emile.scale_down_by;
             prop->h = opts->emile.region.h / opts->emile.scale_down_by;
          }
        else
          {
             prop->w = opts->emile.region.w;
             prop->h = opts->emile.region.h;
          }
     }
   else if (opts->emile.scale_down_by > 1)
     {
        prop->w = (int) w32 / opts->emile.scale_down_by;
        prop->h = (int) h32 / opts->emile.scale_down_by;
        if ((prop->w < 1) || (prop->h < 1))
          {
             *error = EVAS_LOAD_ERROR_GENERIC;
             goto close_file;
          }
     }
   else
     {
        prop->w = (int) w32;
        prop->h = (int) h32;
     }
   if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) hasa = 1;
   switch (color_type)
     {
      case PNG_COLOR_TYPE_RGB_ALPHA:
         hasa = 1;
         break;
      case PNG_COLOR_TYPE_GRAY_ALPHA:
         hasa = 1;
         prop->cspaces = cspace_grey_alpha;
         break;
      case PNG_COLOR_TYPE_GRAY:
         if (!hasa) prop->cspaces = cspace_grey;
         break;
     }
   if (hasa) prop->alpha = 1;

   *error = EVAS_LOAD_ERROR_NONE;
   r = EINA_TRUE;

 close_file:
   if (png_ptr) png_destroy_read_struct(&png_ptr,
                                        info_ptr ? &info_ptr : NULL,
                                        NULL);
   if (epi.map) eina_file_map_free(f, epi. map);

   return r;
}

static Eina_Bool
evas_image_load_file_data_png(void *loader_data,
                              Evas_Image_Property *prop,
                              void *pixels,
                              int *error)
{
   Evas_Loader_Internal *loader = loader_data;
   Evas_Image_Load_Opts *opts;
   Eina_File *f;

   unsigned char *surface;
   png_structp png_ptr = NULL;
   png_infop info_ptr = NULL;
   Evas_PNG_Info epi;
   png_uint_32 w32, h32;
   unsigned int pack_offset;
   int w, h;
   int bit_depth, color_type, interlace_type;
   volatile char hasa;
   char passes;
   int i, j, p, k;
   volatile int scale_ratio = 1;
   volatile int region_set = 0;
   int image_w = 0, image_h = 0;
   volatile Eina_Bool r = EINA_FALSE;

   opts = loader->opts;
   f = loader->f;

   hasa = 0;

   epi.map = eina_file_map_all(f, EINA_FILE_SEQUENTIAL);
   if (!epi.map)
     {
        *error = EVAS_LOAD_ERROR_CORRUPT_FILE;
        goto close_file;
     }
   epi.length = eina_file_size_get(f);
   epi.position = 0;

   if (epi.length < PNG_BYTES_TO_CHECK)
     {
        *error = EVAS_LOAD_ERROR_UNKNOWN_FORMAT;
        goto close_file;
     }

   /* if we havent read the header before, set the header data */
   if (png_sig_cmp(epi.map, 0, PNG_BYTES_TO_CHECK))
     {
        *error = EVAS_LOAD_ERROR_UNKNOWN_FORMAT;
	goto close_file;
     }
   png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
   if (!png_ptr)
     {
	*error = EVAS_LOAD_ERROR_RESOURCE_ALLOCATION_FAILED;
	goto close_file;
     }

   info_ptr = png_create_info_struct(png_ptr);
   if (!info_ptr)
     {
	png_destroy_read_struct(&png_ptr, NULL, NULL);
	*error = EVAS_LOAD_ERROR_RESOURCE_ALLOCATION_FAILED;
	goto close_file;
     }

   png_set_read_fn(png_ptr, &epi, _evas_image_png_read);

   if (setjmp(png_jmpbuf(png_ptr)))
     {
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
	*error = EVAS_LOAD_ERROR_CORRUPT_FILE;
	goto close_file;
     }

   png_read_info(png_ptr, info_ptr);
   png_get_IHDR(png_ptr, info_ptr, (png_uint_32 *) (&w32),
		(png_uint_32 *) (&h32), &bit_depth, &color_type,
		&interlace_type, NULL, NULL);
   image_w = w32;
   image_h = h32;
   if (opts->emile.scale_down_by > 1)
     {
        scale_ratio = opts->emile.scale_down_by;
        w32 /= scale_ratio;
        h32 /= scale_ratio;
     }

   if ((opts->emile.region.w > 0 && opts->emile.region.h > 0) &&
       (opts->emile.region.w != image_w || opts->emile.region.h != image_h))
     {
        w32 = opts->emile.region.w / scale_ratio;
        h32 = opts->emile.region.h / scale_ratio;
        region_set = 1;
     }

   if (prop->w != w32 ||
       prop->h != h32)
     {
      *error = EVAS_LOAD_ERROR_GENERIC;
      goto close_file;
     }

   surface = pixels;
   if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
     {
        /* expand transparency entry -> alpha channel if present */
        png_set_tRNS_to_alpha(png_ptr);
        hasa = 1;
     }
   if (color_type == PNG_COLOR_TYPE_RGB_ALPHA) hasa = 1;
   if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA) hasa = 1;
   if (hasa) prop->alpha = 1;

   /* Prep for transformations...  ultimately we want ARGB */
   /* expand palette -> RGB if necessary */
   if (color_type == PNG_COLOR_TYPE_PALETTE) png_set_palette_to_rgb(png_ptr);
   /* expand gray (w/reduced bits) -> 8-bit RGB if necessary */
   if ((color_type == PNG_COLOR_TYPE_GRAY) ||
       (color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
     {
        if (prop->cspace == EVAS_COLORSPACE_ARGB8888)
          png_set_gray_to_rgb(png_ptr);
	if (bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
     }
   /* reduce 16bit color -> 8bit color if necessary */
   if (bit_depth > 8) png_set_strip_16(png_ptr);
   /* pack all pixels to byte boundaries */
   png_set_packing(png_ptr);

   w = w32;
   h = h32;

   switch (prop->cspace)
     {
      case EVAS_COLORSPACE_ARGB8888:
         /* we want ARGB */
#ifdef WORDS_BIGENDIAN
         png_set_swap_alpha(png_ptr);
         if (!hasa) png_set_filler(png_ptr, 0xff, PNG_FILLER_BEFORE);
#else
         png_set_bgr(png_ptr);
         if (!hasa) png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
#endif
         pack_offset = sizeof(DATA32);
         break;
      case EVAS_COLORSPACE_AGRY88:
         /* we want AGRY */
#ifdef WORDS_BIGENDIAN
         png_set_swap_alpha(png_ptr);
         if (!hasa) png_set_filler(png_ptr, 0xff, PNG_FILLER_BEFORE);
#else
         if (!hasa) png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
#endif
         pack_offset = sizeof(DATA16);
         break;
      case EVAS_COLORSPACE_GRY8: pack_offset = sizeof(DATA8); break;
      default: abort();
     }

   passes = png_set_interlace_handling(png_ptr);

   /* we read image line by line if scale down was set */
   if (scale_ratio == 1 && region_set == 0)
     {
        for (p = 0; p < passes; p++)
          {
             for (i = 0; i < h; i++)
               png_read_row(png_ptr, surface + (i * w * pack_offset), NULL);
          }
        png_read_end(png_ptr, info_ptr);
     }
   else
     {
        unsigned char *src_ptr;
        unsigned char *dst_ptr = surface;
        int skip_row = 0, region_x = 0, region_y = 0;

        if (region_set)
          {
             region_x = opts->emile.region.x;
             region_y = opts->emile.region.y;
          }

        if (passes == 1)
          {
             int line_size = (image_w * pack_offset) - (region_x * pack_offset);
             unsigned char *tmp_line = (unsigned char *) alloca(image_w * pack_offset);
             //accumulate pixel color here.
             unsigned short *interp_buf = (unsigned short *) alloca(line_size * sizeof(unsigned short));
             unsigned short *pbuf;

             for (skip_row = 0; skip_row < region_y; skip_row++)
               png_read_row(png_ptr, tmp_line, NULL);

             png_read_row(png_ptr, tmp_line, NULL);
             src_ptr = tmp_line + (region_x * pack_offset);

             //The first pixel, of the first line
             for (k = 0; k < (int) pack_offset; k++)
               dst_ptr[k] = src_ptr[k];

             dst_ptr += pack_offset;
             src_ptr += (scale_ratio * pack_offset);

             for (j = 1; j < w; j++)
               {
                  //rgba
                  interp_buf[0] = 0;
                  interp_buf[1] = 0;
                  interp_buf[2] = 0;
                  interp_buf[3] = 0;

                  //horizontal interpolation.
                  for (p = 0; p < scale_ratio; p++)
                    {
                       for (k = 0; k < (int) pack_offset; k++)
                         interp_buf[k] += src_ptr[k - (int)(p * pack_offset)];
                    }
                  for (k = 0; k < (int) pack_offset; k++)
                    dst_ptr[k] = (interp_buf[k] / scale_ratio);

                  dst_ptr += pack_offset;
                  src_ptr += (scale_ratio * pack_offset);
               }

             //next lines
             for (i = 1; i < h; i++)
               {
                  memset(interp_buf, 0x00, line_size * sizeof(unsigned short));

                  //vertical interpolation.
                  for (j = 0; j < scale_ratio; j++)
                    {
                       png_read_row(png_ptr, tmp_line, NULL);
                       src_ptr = tmp_line + (region_x * pack_offset);

                      for (p = 0; p < line_size; ++p)
                         interp_buf[p] += src_ptr[p];
                    }

                  for (p = 0; p < line_size; ++p)
                    interp_buf[p] /= scale_ratio;

                  pbuf = interp_buf;

                  //The first pixel of the current line
                  for (k = 0; k < (int) pack_offset; k++)
                    dst_ptr[k] = pbuf[k];

                  dst_ptr += pack_offset;
                  pbuf += scale_ratio * pack_offset;

                  for (j = 1; j < w; j++)
                    {
                       //horizontal interpolation.
                       for (p = 1; p < scale_ratio; ++p)
                         {
                            for (k = 0; k < (int) pack_offset; k++)
                              pbuf[k] += pbuf[k - (int)(p * pack_offset)];
                         }
                       for (k = 0; k < (int) pack_offset; k++)
                         dst_ptr[k] = (pbuf[k] / scale_ratio);

                       dst_ptr += pack_offset;
                       pbuf += (scale_ratio * pack_offset);
                    }
               }

             for (skip_row = region_y + h * scale_ratio; skip_row < image_h; skip_row++)
               png_read_row(png_ptr, tmp_line, NULL);
          }
        else
          {
             //TODO: Scale-down interpolation for multi-pass?

             unsigned char *pixels2 = malloc(image_w * image_h * pack_offset);

             if (pixels2)
               {
                  for (p = 0; p < passes; p++)
                    {
                       for (i = 0; i < image_h; i++)
                         png_read_row(png_ptr, pixels2 + (i * image_w * pack_offset), NULL);
                    }

                  src_ptr = pixels2 + (region_y * image_w * pack_offset) + region_x * pack_offset;

                  //general case: 4 bytes pixel.
                  if (pack_offset == sizeof(DATA32))
                    {
                       DATA32 *dst_ptr = (DATA32 *) surface;
                       DATA32 *src_ptr2 = (DATA32 *) src_ptr;

                       for (i = 0; i < h; i++)
                         {
                            for (j = 0; j < w; j++)
                              {
                                 *dst_ptr = *src_ptr2;
                                 ++dst_ptr;
                                 src_ptr2 += scale_ratio;
                              }
                            src_ptr2 += scale_ratio * image_w;
                         }
                    }
                  else
                    {
                       unsigned char *dst_ptr = surface;

                       for (i = 0; i < h; i++)
                         {
                            for (j = 0; j < w; j++)
                              {
                                 for (k = 0; k < (int)pack_offset; k++)
                                   dst_ptr[k] = src_ptr[k + scale_ratio * j * pack_offset];
                                 dst_ptr += pack_offset;
                              }
                            src_ptr += scale_ratio * image_w * pack_offset;
                         }
                    }
                  free(pixels2);
               }
          }
     }

   prop->premul = EINA_TRUE;

   *error = EVAS_LOAD_ERROR_NONE;
   r = EINA_TRUE;

 close_file:
   if (png_ptr) png_destroy_read_struct(&png_ptr,
                                        info_ptr ? &info_ptr : NULL,
                                        NULL);
   if (epi.map) eina_file_map_free(f, epi.map);
   return r;
}

static Evas_Image_Load_Func evas_image_load_png_func =
{
  evas_image_load_file_open_png,
  evas_image_load_file_close_png,
  evas_image_load_file_head_png,
  evas_image_load_file_data_png,
  NULL,
  EINA_TRUE,
  EINA_FALSE
};

static int
module_open(Evas_Module *em)
{
   if (!em) return 0;
   em->functions = (void *)(&evas_image_load_png_func);
   return 1;
}

static void
module_close(Evas_Module *em EINA_UNUSED)
{
}

static Evas_Module_Api evas_modapi =
{
   EVAS_MODULE_API_VERSION,
   "png",
   "none",
   {
     module_open,
     module_close
   }
};

EVAS_MODULE_DEFINE(EVAS_MODULE_TYPE_IMAGE_LOADER, image_loader, png);

#ifndef EVAS_STATIC_BUILD_PNG
EVAS_EINA_MODULE_DEFINE(image_loader, png);
#endif