/* The GIMP -- an image manipulation program
 * Copyright (C) 1999 Andy Thomas alt@gimp.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include <gtk/gtk.h>

#include "apptypes.h"

#include "gimppreviewcache.h"


#define MAX_CACHE_PREVIEWS 5

#undef PREVIEW_CACHE_DEBUG


typedef struct _PreviewCache 
{
  TempBuf *preview;
  gint     width;
  gint     height;
} PreviewCache;

typedef struct _PreviewNearest 
{
  PreviewCache *pc;
  gint          width;
  gint          height;
} PreviewNearest;


static gint 
preview_cache_compare (gconstpointer  a,
		       gconstpointer  b)
{
  PreviewCache *pc1 = (PreviewCache *) a;
  PreviewCache *pc2 = (PreviewCache *) b;

  if (pc1->width > pc2->width && pc1->height > pc2->height)
    return -1;

  return 1;
}

static void
preview_cache_find_exact (gpointer data, 
			  gpointer udata)
{
  PreviewCache   *pc       = (PreviewCache *) data;
  PreviewNearest *pNearest = (PreviewNearest *) udata;

/*   g_print ("this value w,h [%d,%d]\n",pc->width,pc->height); */

/*   if (pNearest->pc) */
/*       g_print ("current nearest value w,h [%d,%d]\n",
                 pNearest->pc->width,pNearest->pc->height); */

  if (pNearest->pc)
    return;

  if(pc->width == pNearest->width &&
     pc->height == pNearest->height)
    {
      /* Ok we could make the preview out of this one...
       * If we already have it are these bigger dimensions? 
       */
      pNearest->pc = pc;

      return;
    }
}

static void
preview_cache_find_biggest (gpointer data, 
			    gpointer udata)
{
  PreviewCache   *pc       = (PreviewCache *) data;
  PreviewNearest *pNearest = (PreviewNearest *) udata;

/*   g_print ("this value w,h [%d,%d]\n",pc->width,pc->height); */

/*   if (pNearest->pc) */
/*       g_print ("current nearest value w,h [%d,%d]\n",
                 pNearest->pc->width,pNearest->pc->height); */
  
  if (pc->width >= pNearest->width &&
      pc->height >= pNearest->height)
    {
      /* Ok we could make the preview out of this one...
       * If we already have it are these bigger dimensions? 
       */
      if (pNearest->pc)
	{
	  if (pNearest->pc->width > pc->width &&
	      pNearest->pc->height > pc->height)
	    return;
	}
      pNearest->pc = pc;
    }
}

static void
preview_cache_remove_smallest (GSList **plist)
{
  GSList       *list;
  PreviewCache *smallest = NULL;
  
/*   g_print ("Removing smallest\n"); */

  for (list = *plist; list; list = g_slist_next (list))
    {
      if (!smallest)
	{
	  smallest = list->data;
/* 	  g_print ("init smallest  %d,%d\n",
	            smallest->width,smallest->height); */
	}
      else
	{
	  PreviewCache *pcthis = list->data;

/* 	  g_print ("Checking %d,%d\n",pcthis->width,pcthis->height); */
	  if ((smallest->height * smallest->width) >=
	      (pcthis->height * pcthis->width))
	    {
	      smallest = pcthis;
/* 	      g_print ("smallest now  %d,%d\n",
                      smallest->width,smallest->height); */
	    }
	}
    } 

  if (*plist && smallest)
    *plist = g_slist_remove (*plist, smallest);
/*   g_print ("removed %d,%d\n",smallest->width,smallest->height); */
/*   g_print ("removed smallest\n"); */
}

static void
preview_cache_invalidate (gpointer data, 
			  gpointer udata)
{
  PreviewCache *pc = (PreviewCache *) data;

  temp_buf_free (pc->preview);
  g_free(pc);
}

static void
preview_cache_print (GSList *plist)
{
#ifdef PREVIEW_CACHE_DEBUG  
  GSList       *list;
  PreviewCache *pc;

  g_print ("preview cache dump:\n");

  for (list = plist; list; list = g_slist_next (list))
    {
      pc = (PreviewCache *) list->data;

      g_print ("\tvalue w,h [%d,%d] => %p\n", 
	       pc->width, pc->height, pc->preview);
    }
#endif  /* PREVIEW_CACHE_DEBUG */
}

void
gimp_preview_cache_invalidate (GSList **plist)
{
/*   g_print ("gimp_preview_cache_invalidate\n"); */
  preview_cache_print (*plist);

  g_slist_foreach (*plist, preview_cache_invalidate, NULL);
  *plist = NULL;
}

void 
gimp_preview_cache_add (GSList  **plist,
			TempBuf  *buf)
{
  PreviewCache *pc;

/*   g_print ("gimp_preview_cache_add %d %d\n",buf->width,buf->height); */
  preview_cache_print (*plist);

  if (g_slist_length (*plist) > MAX_CACHE_PREVIEWS)
    {
      /* Remove the smallest */
      preview_cache_remove_smallest(plist);
    }

  pc = g_new0(PreviewCache,1);
  pc->preview = buf; 
  pc->width   = buf->width;
  pc->height  = buf->height;

  *plist = g_slist_insert_sorted (*plist, pc, preview_cache_compare);
}

TempBuf *
gimp_preview_cache_get (GSList **plist,
			gint     width,
			gint     height)
{
  PreviewNearest  pn;
  PreviewCache   *pc;

/*   g_print ("gimp_preview_cache_get %d %d\n",width,height); */
  preview_cache_print (*plist);

  pn.pc     = NULL;
  pn.width  = width;
  pn.height = height;

  g_slist_foreach (*plist, preview_cache_find_exact, &pn);

  if (pn.pc && pn.pc->preview)
    {
/*       g_print ("extact value w,h [%d,%d] => %p\n",
	           pn.pc->width,pn.pc->height,pn.pc->preview);  */
      return pn.pc->preview;
    }

  g_slist_foreach (*plist, preview_cache_find_biggest, &pn);

  if (pn.pc)
    {
      gint     pwidth;
      gint     pheight;
      gdouble  x_ratio;
      gdouble  y_ratio;
      guchar  *src_data;
      guchar  *dest_data;
      gint     loop1;
      gint     loop2;

/*       g_print ("nearest value w,h [%d,%d] => %p\n",
                   pn.pc->width,pn.pc->height,pn.pc->preview); */

/*       if(pn.pc->width == width && */
/* 	   pn.pc->height == height) */
/* 	 return pn.pc->preview; */

      if (!pn.pc->preview)
	{
	  g_error ("gimp_preview_cache_get:: Invalid cache item");
	  return NULL;
	}

      /* Make up new preview from the large one... */

      pwidth  = pn.pc->preview->width;
      pheight = pn.pc->preview->height;

      /* Now get the real one and add to cache */
/*       g_print ("Must create from large preview\n"); */
      pc = g_new0 (PreviewCache, 1);
      pc->preview = temp_buf_new (width, height, pn.pc->preview->bytes, 
				  0, 0, NULL);
      /* preview from nearest bigger one */

      if (width)
        x_ratio = (gdouble) pwidth / (gdouble) width;
      else
        x_ratio = 0.0;

      if (height)
        y_ratio = (gdouble) pheight / (gdouble) height;
      else
        y_ratio = 0.0;

      src_data = temp_buf_data(pn.pc->preview);
      dest_data = temp_buf_data(pc->preview);

/*       g_print ("x_ratio , y_ratio [%f,%f]\n",x_ratio,y_ratio); */

      for (loop1 = 0 ; loop1 < height ; loop1++)
	for (loop2 = 0 ; loop2 < width ; loop2++)
	  {
	    gint    i;
	    guchar *src_pixel;
	    guchar *dest_pixel;

	    src_pixel = src_data +
	      ((gint) (loop2 * x_ratio)) * pn.pc->preview->bytes +
	      ((gint) (loop1 * y_ratio)) * pwidth * pn.pc->preview->bytes;

	    dest_pixel = dest_data + 
	      (loop2 + loop1 * width) * pn.pc->preview->bytes;

	    for (i = 0; i < pn.pc->preview->bytes; i++)
	      *dest_pixel++ = *src_pixel++;
	  }

      pc->width  = width;
      pc->height = height;
      *plist = g_slist_insert_sorted (*plist, pc, preview_cache_compare); 
/*       g_print ("New preview created [%d,%d] => %p\n",
	           pc->width,pc->height,pc->preview);  */

      return pc->preview;
    }

/*   g_print ("gimp_preview_cache_get returning NULL\n");  */
  return NULL;
}

TempBuf *
gimp_preview_scale (TempBuf  *src,
		    gint      new_width, 
		    gint      new_height)
{
  gint     loop1;
  gint     loop2;
  gdouble  x_ratio;
  gdouble  y_ratio;
  guchar  *src_data;
  guchar  *dest_data;
  TempBuf *dest;

  /*
  g_print ("gimp_preview_scale: %d x %d -> %d x %d\n",
	   src->width, src->height, new_width, new_height);

   */

  dest = temp_buf_new (new_width,
		       new_height,
		       src->bytes, 
		       0, 0, NULL);

  src_data  = temp_buf_data (src);
  dest_data = temp_buf_data (dest);

  x_ratio = (gdouble) src->width  / (gdouble) new_width;
  y_ratio = (gdouble) src->height / (gdouble) new_height;
  
  for (loop1 = 0 ; loop1 < new_height ; loop1++)
    {
      for (loop2 = 0 ; loop2 < new_width ; loop2++)
	{
	  gint    i;
	  guchar *src_pixel;
	  guchar *dest_pixel;
	  
	  src_pixel = src_data +
	    (gint) (loop2 * x_ratio) * src->bytes +
	    (gint) (loop1 * y_ratio) * src->bytes * src->width;

	  dest_pixel = dest_data +
	    (loop2 + loop1 * new_width) * src->bytes;
	  
	  for (i = 0 ; i < src->bytes; i++)
	    *dest_pixel++ = *src_pixel++;
	}
    }

  return dest;
}