/*
    SDL_image:  An example image loading library for use with SDL
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/

/* This is a XCF image file loading framework */

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>

#include "SDL_endian.h"
#include "SDL_image.h"

#ifdef LOAD_XCF

#if DEBUG
static char prop_names [][30] = {
  "end",
  "colormap",
  "active_layer",
  "active_channel",
  "selection",
  "floating_selection",
  "opacity",
  "mode",
  "visible",
  "linked",
  "preserve_transparency",
  "apply_mask",
  "edit_mask",
  "show_mask",
  "show_masked",
  "offsets",
  "color",
  "compression",
  "guides",
  "resolution",
  "tattoo",
  "parasites",
  "unit",
  "paths",
  "user_unit"
};
#endif


typedef enum
{
  PROP_END = 0,
  PROP_COLORMAP = 1,
  PROP_ACTIVE_LAYER = 2,
  PROP_ACTIVE_CHANNEL = 3,
  PROP_SELECTION = 4,
  PROP_FLOATING_SELECTION = 5,
  PROP_OPACITY = 6,
  PROP_MODE = 7,
  PROP_VISIBLE = 8,
  PROP_LINKED = 9,
  PROP_PRESERVE_TRANSPARENCY = 10,
  PROP_APPLY_MASK = 11,
  PROP_EDIT_MASK = 12,
  PROP_SHOW_MASK = 13,
  PROP_SHOW_MASKED = 14,
  PROP_OFFSETS = 15,
  PROP_COLOR = 16,
  PROP_COMPRESSION = 17,
  PROP_GUIDES = 18,
  PROP_RESOLUTION = 19,
  PROP_TATTOO = 20,
  PROP_PARASITES = 21,
  PROP_UNIT = 22,
  PROP_PATHS = 23,
  PROP_USER_UNIT = 24
} xcf_prop_type;

typedef enum {
  COMPR_NONE    = 0,
  COMPR_RLE     = 1,
  COMPR_ZLIB    = 2,
  COMPR_FRACTAL = 3
} xcf_compr_type;

typedef enum {
  IMAGE_RGB       = 0,
  IMAGE_GREYSCALE = 1,
  IMAGE_INDEXED   = 2
} xcf_image_type;

typedef struct {
  Uint32 id;
  Uint32 length;
  union {
    struct {
      Uint32 num;
      char * cmap;
    } colormap; // 1
    struct {
      Uint32 drawable_offset;
    } floating_selection; // 5
    Sint32 opacity;
    Sint32 mode;
    int    visible;
    int    linked;
    int    preserve_transparency;
    int    apply_mask;
    int    show_mask;
    struct {
      Sint32 x;
      Sint32 y;
    } offset;
    unsigned char color [3];
    Uint8 compression;
    struct {
      Sint32 x;
      Sint32 y;
    } resolution;
    struct {
      char * name;
      Uint32 flags;
      Uint32 size;
      char * data;
    } parasite;
  } data;
} xcf_prop;

typedef struct {
  char   sign [14];
  Uint32 width;
  Uint32 height;
  Sint32 image_type;
  xcf_prop * properties;

  Uint32 * layer_file_offsets;
  Uint32 * channel_file_offsets;

  xcf_compr_type compr;
  Uint32         cm_num;
  unsigned char * cm_map;
} xcf_header;

typedef struct {
  Uint32 width;
  Uint32 height;
  Sint32 layer_type;
  char * name;
  xcf_prop * properties;

  Uint32 hierarchy_file_offset;
  Uint32 layer_mask_offset;

  Uint32 offset_x;
  Uint32 offset_y;
  int visible;
} xcf_layer;

typedef struct {
  Uint32 width;
  Uint32 height;
  char * name;
  xcf_prop * properties;

  Uint32 hierarchy_file_offset;

  Uint32 color;
  Uint32 opacity;
  int selection;
  int visible;
} xcf_channel;

typedef struct {
  Uint32 width;
  Uint32 height;
  Uint32 bpp;

  Uint32 * level_file_offsets;
} xcf_hierarchy;

typedef struct {
  Uint32 width;
  Uint32 height;

  Uint32 * tile_file_offsets;
} xcf_level;

typedef unsigned char * xcf_tile;

typedef unsigned char * (* load_tile_type) (SDL_RWops *, Uint32, int, int, int);


/* See if an image is contained in a data source */
int IMG_isXCF(SDL_RWops *src)
{
	int start;
	int is_XCF;
	char magic[14];

	if ( !src )
		return 0;
	start = SDL_RWtell(src);
	is_XCF = 0;
	if ( SDL_RWread(src, magic, sizeof(magic), 1) ) {
		if (strncmp(magic, "gimp xcf ", 9) == 0) {
			is_XCF = 1;
		}
	}
	SDL_RWseek(src, start, SEEK_SET);
	return(is_XCF);
}

static char * read_string (SDL_RWops * src) {
  Uint32 tmp;
  char * data;

  tmp = SDL_ReadBE32 (src);
  if (tmp > 0) {
    data = (char *) malloc (sizeof (char) * tmp);
    SDL_RWread (src, data, tmp, 1);
  }
  else {
    data = NULL;
  }

  return data;
}


static Uint32 Swap32 (Uint32 v) {
  return
    ((v & 0x000000FF) << 16)
    |  ((v & 0x0000FF00))
    |  ((v & 0x00FF0000) >> 16)
    |  ((v & 0xFF000000));
}

void xcf_read_property (SDL_RWops * src, xcf_prop * prop) {
  prop->id = SDL_ReadBE32 (src);
  prop->length = SDL_ReadBE32 (src);

#if DEBUG
  printf ("%.8X: %s: %d\n", SDL_RWtell (src), prop->id < 25 ? prop_names [prop->id] : "unknown", prop->length);
#endif

  switch (prop->id) {
  case PROP_COLORMAP:
    prop->data.colormap.num = SDL_ReadBE32 (src);
    prop->data.colormap.cmap = (char *) malloc (sizeof (char) * prop->data.colormap.num * 3);
    SDL_RWread (src, prop->data.colormap.cmap, prop->data.colormap.num*3, 1);
    break;

  case PROP_OFFSETS:
    prop->data.offset.x = SDL_ReadBE32 (src);
    prop->data.offset.y = SDL_ReadBE32 (src);
    break;
  case PROP_OPACITY:
    prop->data.opacity = SDL_ReadBE32 (src);
    break;
  case PROP_COMPRESSION:
  case PROP_COLOR:
    SDL_RWread (src, &prop->data, prop->length, 1);
    break;
  case PROP_VISIBLE:
    prop->data.visible = SDL_ReadBE32 (src);
    break;
  default:
    //    SDL_RWread (src, &prop->data, prop->length, 1);
    SDL_RWseek (src, prop->length, SEEK_CUR);
  }
}

void free_xcf_header (xcf_header * h) {
  if (h->cm_num)
    free (h->cm_map);

  free (h);
}

xcf_header * read_xcf_header (SDL_RWops * src) {
  xcf_header * h;
  xcf_prop prop;

  h = (xcf_header *) malloc (sizeof (xcf_header));
  SDL_RWread (src, h->sign, 14, 1);
  h->width       = SDL_ReadBE32 (src);
  h->height      = SDL_ReadBE32 (src);
  h->image_type  = SDL_ReadBE32 (src);

  h->properties = NULL;
  h->compr      = COMPR_NONE;
  h->cm_num = 0;
  h->cm_map = NULL;

  // Just read, don't save
  do {
    xcf_read_property (src, &prop);
    if (prop.id == PROP_COMPRESSION)
      h->compr = prop.data.compression;
    else if (prop.id == PROP_COLORMAP) {
      // unused var: int i;

      h->cm_num = prop.data.colormap.num;
      h->cm_map = (unsigned char *) malloc (sizeof (unsigned char) * 3 * h->cm_num);
      memcpy (h->cm_map, prop.data.colormap.cmap, 3*sizeof (char)*h->cm_num);
      free (prop.data.colormap.cmap);
    }
  } while (prop.id != PROP_END);

  return h;
}

void free_xcf_layer (xcf_layer * l) {
  free (l->name);
  free (l);
}

xcf_layer * read_xcf_layer (SDL_RWops * src) {
  xcf_layer * l;
  xcf_prop    prop;

  l = (xcf_layer *) malloc (sizeof (xcf_layer));
  l->width  = SDL_ReadBE32 (src);
  l->height = SDL_ReadBE32 (src);
  l->layer_type = SDL_ReadBE32 (src);

  l->name = read_string (src);

  do {
    xcf_read_property (src, &prop);
    if (prop.id == PROP_OFFSETS) {
      l->offset_x = prop.data.offset.x;
      l->offset_y = prop.data.offset.y;
    } else if (prop.id == PROP_VISIBLE) {
      l->visible = prop.data.visible ? 1 : 0;
    }
  } while (prop.id != PROP_END);

  l->hierarchy_file_offset = SDL_ReadBE32 (src);
  l->layer_mask_offset     = SDL_ReadBE32 (src);

  return l;
}

void free_xcf_channel (xcf_channel * c) {
  free (c->name);
  free (c);
}

xcf_channel * read_xcf_channel (SDL_RWops * src) {
  xcf_channel * l;
  xcf_prop    prop;

  l = (xcf_channel *) malloc (sizeof (xcf_channel));
  l->width  = SDL_ReadBE32 (src);
  l->height = SDL_ReadBE32 (src);

  l->name = read_string (src);

  l->selection = 0;
  do {
    xcf_read_property (src, &prop);
    switch (prop.id) {
    case PROP_OPACITY:
      l->opacity = prop.data.opacity << 24;
      break;
    case PROP_COLOR:
      l->color = ((Uint32) prop.data.color[0] << 16)
	| ((Uint32) prop.data.color[1] << 8)
	| ((Uint32) prop.data.color[2]);
      break;
    case PROP_SELECTION:
      l->selection = 1;
      break;
    case PROP_VISIBLE:
      l->visible = prop.data.visible ? 1 : 0;
      break;
    default:
        ;
    }
  } while (prop.id != PROP_END);

  l->hierarchy_file_offset = SDL_ReadBE32 (src);

  return l;
}

void free_xcf_hierarchy (xcf_hierarchy * h) {
  free (h->level_file_offsets);
  free (h);
}

xcf_hierarchy * read_xcf_hierarchy (SDL_RWops * src) {
  xcf_hierarchy * h;
  int i;

  h = (xcf_hierarchy *) malloc (sizeof (xcf_hierarchy));
  h->width  = SDL_ReadBE32 (src);
  h->height = SDL_ReadBE32 (src);
  h->bpp    = SDL_ReadBE32 (src);

  h->level_file_offsets = NULL;
  i = 0;
  do {
    h->level_file_offsets = (Uint32 *) realloc (h->level_file_offsets, sizeof (Uint32) * (i+1));
    h->level_file_offsets [i] = SDL_ReadBE32 (src);
  } while (h->level_file_offsets [i++]);

  return h;
}

void free_xcf_level (xcf_level * l) {
  free (l->tile_file_offsets);
  free (l);
}

xcf_level * read_xcf_level (SDL_RWops * src) {
  xcf_level * l;
  int i;

  l = (xcf_level *) malloc (sizeof (xcf_level));
  l->width  = SDL_ReadBE32 (src);
  l->height = SDL_ReadBE32 (src);

  l->tile_file_offsets = NULL;
  i = 0;
  do {
    l->tile_file_offsets = (Uint32 *) realloc (l->tile_file_offsets, sizeof (Uint32) * (i+1));
    l->tile_file_offsets [i] = SDL_ReadBE32 (src);
  } while (l->tile_file_offsets [i++]);

  return l;
}

void free_xcf_tile (unsigned char * t) {
  free (t);
}

unsigned char * load_xcf_tile_none (SDL_RWops * src, Uint32 len, int bpp, int x, int y) {
  unsigned char * load;

  load = (unsigned char *) malloc (len); // expect this is okay
  SDL_RWread (src, load, len, 1);

  return load;
}

unsigned char * load_xcf_tile_rle (SDL_RWops * src, Uint32 len, int bpp, int x, int y) {
  unsigned char * load, * t, * data, * d;
  Uint32 reallen;
  int i, size, count, j, length;
  unsigned char val;

  t = load = (unsigned char *) malloc (len);
  reallen = SDL_RWread (src, t, 1, len);

  data = (unsigned char *) malloc (x*y*bpp);
  for (i = 0; i < bpp; i++) {
    d    = data + i;
    size = x*y;
    count = 0;
 
    while (size > 0) {
      val = *t++;

      length = val;
      if (length >= 128) {
	length = 255 - (length - 1);
	if (length == 128) {
	  length = (*t << 8) + t[1];
	  t += 2;
	}

	count += length;
	size -= length;

	while (length-- > 0) {
	  *d = *t++;
	  d += bpp;
	}
      }
      else {
	length += 1;
	if (length == 128) {
	  length = (*t << 8) + t[1];
	  t += 2;
	}

	count += length;
	size -= length;

	val = *t++;

	for (j = 0; j < length; j++) {
	  *d = val;
	  d += bpp;
	}
      }
    }
  }

  free (load);
  return (data);
}

static Uint32 rgb2grey (Uint32 a) {
  Uint8 l;
  l = 0.2990 * ((a && 0x00FF0000) >> 16)
    + 0.5870 * ((a && 0x0000FF00) >>  8)
    + 0.1140 * ((a && 0x000000FF));

  return (l << 16) | (l << 8) | l;
}

void create_channel_surface (SDL_Surface * surf, xcf_image_type itype, Uint32 color, Uint32 opacity) {
  Uint32 c = 0;

  switch (itype) {
  case IMAGE_RGB:
  case IMAGE_INDEXED:
    c = opacity | color;
    break;
  case IMAGE_GREYSCALE:
    c = opacity | rgb2grey (color);
    break;
  }
  SDL_FillRect (surf, NULL, c);
}

int do_layer_surface (SDL_Surface * surface, SDL_RWops * src, xcf_header * head, xcf_layer * layer, load_tile_type load_tile) {
  xcf_hierarchy * hierarchy;
  xcf_level     * level;
  unsigned char * tile;
  Uint8  * p8;
  Uint16 * p16;
  Uint32 * p;
  int x, y, tx, ty, ox, oy, i, j;
  Uint32 *row;

  SDL_RWseek (src, layer->hierarchy_file_offset, SEEK_SET);
  hierarchy = read_xcf_hierarchy (src);

  level = NULL;
  for (i = 0; hierarchy->level_file_offsets [i]; i++) {
    SDL_RWseek (src, hierarchy->level_file_offsets [i], SEEK_SET);
    level = read_xcf_level (src);

    ty = tx = 0;
    for (j = 0; level->tile_file_offsets [j]; j++) {
      SDL_RWseek (src, level->tile_file_offsets [j], SEEK_SET);
      ox = tx+64 > level->width ? level->width % 64 : 64;
      oy = ty+64 > level->height ? level->height % 64 : 64;

      if (level->tile_file_offsets [j+1]) {
	tile = load_tile
	  (src,
	   level->tile_file_offsets [j+1] - level->tile_file_offsets [j],
	   hierarchy->bpp,
	   ox, oy);
      }
      else {
	tile = load_tile
	  (src,
	   ox*oy*6,
	   hierarchy->bpp,
	   ox, oy);
      }

      p8  = tile;
      p16 = (Uint16 *) p8;
      p   = (Uint32 *) p8;
      for (y=ty; y < ty+oy; y++) {
	row = (Uint32 *)((Uint8 *)surface->pixels + y*surface->pitch + tx*4);
	switch (hierarchy->bpp) {
	case 4:
	  for (x=tx; x < tx+ox; x++)
	    *row++ = Swap32 (*p++);
	  break;
	case 3:
	  for (x=tx; x < tx+ox; x++) {
	    *row = 0xFF000000;
	    *row |= ((Uint32) *(p8++) << 16);
	    *row |= ((Uint32) *(p8++) << 8);
	    *row |= ((Uint32) *(p8++) << 0);
	    row++;
	  }
	  break;
	case 2: // Indexed/Greyscale + Alpha
	  switch (head->image_type) {
	  case IMAGE_INDEXED:
	    for (x=tx; x < tx+ox; x++) {
	      *row =  ((Uint32) (head->cm_map [*p8*3])     << 16);
	      *row |= ((Uint32) (head->cm_map [*p8*3+1])   << 8);
	      *row |= ((Uint32) (head->cm_map [*p8++*3+2]) << 0);
	      *row |= ((Uint32) *p8++ << 24);;
	      row++;
	    }
	    break;
	  case IMAGE_GREYSCALE:
	    for (x=tx; x < tx+ox; x++) {
	      *row = ((Uint32) *p8 << 16);
	      *row |= ((Uint32) *p8 << 8);
	      *row |= ((Uint32) *p8++ << 0);
	      *row |= ((Uint32) *p8++ << 24);;
	      row++;
	    }
	    break;	    
	  default:
	    fprintf (stderr, "Unknown Gimp image type (%d)\n", head->image_type);
	    return 1;
	  }
	  break;
	case 1: // Indexed/Greyscale
	  switch (head->image_type) {
	  case IMAGE_INDEXED:
	    for (x = tx; x < tx+ox; x++) {
	      *row++ = 0xFF000000
		| ((Uint32) (head->cm_map [*p8*3]) << 16)
		| ((Uint32) (head->cm_map [*p8*3+1]) << 8)
		| ((Uint32) (head->cm_map [*p8*3+2]) << 0);
	      p8++;
	    }
	    break;
	  case IMAGE_GREYSCALE:
	    for (x=tx; x < tx+ox; x++) {
	      *row++ = 0xFF000000
		| (((Uint32) (*p8)) << 16)
		| (((Uint32) (*p8)) << 8)
		| (((Uint32) (*p8)) << 0);
			++p8;
	    }
	    break;	    
	  default:
	    fprintf (stderr, "Unknown Gimp image type (%d)\n", head->image_type);
	    return 1;
	  }
	  break;
	}
      }
      tx += 64;
      if (tx >= level->width) {
	tx = 0;
	ty += 64;
      }
      if (ty >= level->height) {
	break;
      }

      free_xcf_tile (tile);
    }
    free_xcf_level (level);
  }

  free_xcf_hierarchy (hierarchy);
  
  return 0;
}

SDL_Surface *IMG_LoadXCF_RW(SDL_RWops *src)
{
  int start;
  const char *error = NULL;
  SDL_Surface *surface, *lays;
  xcf_header * head;
  xcf_layer  * layer;
  xcf_channel ** channel;
  int chnls, i, offsets;
  Uint32 offset, fp;

  unsigned char * (* load_tile) (SDL_RWops *, Uint32, int, int, int);

  if ( !src ) {
    /* The error message has been set in SDL_RWFromFile */
    return NULL;
  }
  start = SDL_RWtell(src);

  /* Initialize the data we will clean up when we're done */
  surface = NULL;

  head = read_xcf_header (src);

  switch (head->compr) {
  case COMPR_NONE:
    load_tile = load_xcf_tile_none;
    break;
  case COMPR_RLE:
    load_tile = load_xcf_tile_rle;
    break;
  default:
    fprintf (stderr, "Unsupported Compression.\n");
    free_xcf_header (head);
    return NULL;
  }

  /* Create the surface of the appropriate type */
  surface = SDL_AllocSurface(SDL_SWSURFACE, head->width, head->height, 32,
			     0x00FF0000,0x0000FF00,0x000000FF,0xFF000000);

  if ( surface == NULL ) {
    error = "Out of memory";
    goto done;
  }

  head->layer_file_offsets = NULL;
  offsets = 0;

  while ((offset = SDL_ReadBE32 (src))) {
    head->layer_file_offsets = (Uint32 *) realloc (head->layer_file_offsets, sizeof (Uint32) * (offsets+1));
    head->layer_file_offsets [offsets] = offset;
    offsets++;
  }
  fp = SDL_RWtell (src);
 
  lays = SDL_AllocSurface(SDL_SWSURFACE, head->width, head->height, 32,
			  0x00FF0000,0x0000FF00,0x000000FF,0xFF000000);

  if ( lays == NULL ) {
    error = "Out of memory";
    goto done;
  }

  // Blit layers backwards, because Gimp saves them highest first
  for (i = offsets; i > 0; i--) {
    SDL_Rect rs, rd;
    SDL_RWseek (src, head->layer_file_offsets [i-1], SEEK_SET);

    layer = read_xcf_layer (src);
    do_layer_surface (lays, src, head, layer, load_tile);
    rs.x = 0;
    rs.y = 0;
    rs.w = layer->width;
    rs.h = layer->height;
    rd.x = layer->offset_x;
    rd.y = layer->offset_y;
    rd.w = layer->width;
    rd.h = layer->height;

    if (layer->visible)
      SDL_BlitSurface (lays, &rs, surface, &rd);
    free_xcf_layer (layer);
  }

  SDL_FreeSurface (lays);

  SDL_RWseek (src, fp, SEEK_SET);

  // read channels
  channel = NULL;
  chnls   = 0;
  while ((offset = SDL_ReadBE32 (src))) {
    channel = (xcf_channel **) realloc (channel, sizeof (xcf_channel *) * (chnls+1));
    fp = SDL_RWtell (src);
    SDL_RWseek (src, offset, SEEK_SET);
    channel [chnls++] = (read_xcf_channel (src));
    SDL_RWseek (src, fp, SEEK_SET);    
  }

  if (chnls) {
    SDL_Surface * chs;

    chs = SDL_AllocSurface(SDL_SWSURFACE, head->width, head->height, 32,
			   0x00FF0000,0x0000FF00,0x000000FF,0xFF000000);

    if (chs == NULL) {
      error = "Out of memory";
      goto done;
    }
    for (i = 0; i < chnls; i++) {
      //      printf ("CNLBLT %i\n", i);
      if (!channel [i]->selection && channel [i]->visible) {
	create_channel_surface (chs, head->image_type, channel [i]->color, channel [i]->opacity);
	SDL_BlitSurface (chs, NULL, surface, NULL);
      }
      free_xcf_channel (channel [i]);
    }

    SDL_FreeSurface (chs);
  }

done:
  free_xcf_header (head);
  if ( error ) {
    SDL_RWseek(src, start, SEEK_SET);
    if ( surface ) {
      SDL_FreeSurface(surface);
      surface = NULL;
    }
    IMG_SetError(error);
  }

  return(surface);
}

#else

/* See if an image is contained in a data source */
int IMG_isXCF(SDL_RWops *src)
{
  return(0);
}

/* Load a XCF type image from an SDL datasource */
SDL_Surface *IMG_LoadXCF_RW(SDL_RWops *src)
{
  return(NULL);
}

#endif /* LOAD_XCF */
