/* The GIMP -- an image manipulation program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * 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 <glib.h>

#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>

#ifdef G_OS_WIN32
#include <process.h>		/* For _getpid() */
#endif
 
#include "appenv.h"
#include "drawable.h"
#include "gdisplay.h"
#include "general.h"
#include "gimprc.h"
#include "paint_funcs.h"
#include "temp_buf.h"

#include "libgimp/gimpcolorspace.h"

static unsigned char *   temp_buf_allocate (unsigned int);
static void              temp_buf_to_color (TempBuf *, TempBuf *);
static void              temp_buf_to_gray  (TempBuf *, TempBuf *);


/*  Memory management  */

static unsigned char *
temp_buf_allocate (unsigned int size)
{
  unsigned char *data;

  data = (unsigned char *) g_malloc (size);

  return data;
}


/*  The conversion routines  */

static void
temp_buf_to_color (TempBuf *src_buf, 
		   TempBuf *dest_buf)
{
  unsigned char *src;
  unsigned char *dest;
  long num_bytes;

  src = temp_buf_data (src_buf);
  dest = temp_buf_data (dest_buf);

  num_bytes = src_buf->width * src_buf->height;

  while (num_bytes--)
    {
      unsigned char tmpch;
      *dest++ = *src++;  /* alpha channel */
      *dest++ = tmpch = *src++;
      *dest++ = tmpch;
      *dest++ = tmpch;
    }
}


static void
temp_buf_to_gray (TempBuf *src_buf, 
		  TempBuf *dest_buf)
{
  unsigned char *src;
  unsigned char *dest;
  long  num_bytes;
  float pix;

  src = temp_buf_data (src_buf);
  dest = temp_buf_data (dest_buf);

  num_bytes = src_buf->width * src_buf->height;

  while (num_bytes--)
    {
      *dest++ = *src++;  /* alpha channel */

      pix = INTENSITY (*src++, *src++, *src++);

      *dest++ = (unsigned char) pix;
    }
}


TempBuf *
temp_buf_new (int width, 
	      int height, 
	      int bytes, 
	      int x, 
	      int y, 
	      unsigned char *col)
{
  long i;
  int  j;
  unsigned char * data;
  TempBuf * temp;

  temp = (TempBuf *) g_malloc (sizeof (TempBuf));

  temp->width  = width;
  temp->height = height;
  temp->bytes  = bytes;
  temp->x      = x;
  temp->y      = y;
  temp->swapped = FALSE;
  temp->filename = NULL;

  temp->data = data = temp_buf_allocate (width * height * bytes);

  /*  initialize the data  */
  if (col)
    {
      /* First check if we can save a lot of work */
      if (bytes == 1)
        {
          memset (data, *col, width * height);
        }
      else if ((bytes == 3) && (col[1] == *col) && (*col == col[2]))
        {
          memset (data, *col, width * height * 3);
        }
      else if ((bytes == 4) && (col[1] == *col) && (*col == col[2]) && (col[2] == col[3]))
        {
          memset (data, *col, (width * height) << 2);
        }
      else
        {
          /* No, we cannot */
          unsigned char * dptr;
          /* Fill the first row */
          dptr = data;
          for (i = width - 1; i >= 0; --i)
            {
              unsigned char * init;
              j = bytes;
              init = col;
              while (j--)
                *dptr++ = *init++;
            }
          /* Now copy from it (we set bytes to bytesperrow now) */
          bytes *= width;
          while (--height)
            {
              memcpy (dptr, data, bytes);
              dptr += bytes;
            }
        }
    }

  return temp;
}


TempBuf *
temp_buf_copy (TempBuf *src, 
	       TempBuf *dest)
{
  TempBuf * new;
  long length;

  if (!src)
    {
      g_message ("trying to copy a temp buf which is NULL.");
      return dest;
    }

  if (!dest)
    new = temp_buf_new (src->width, src->height, src->bytes, 0, 0, NULL);
  else
    {
      new = dest;
      if (dest->width != src->width || dest->height != src->height)
	g_message ("In temp_buf_copy, the widths or heights don't match.");
      /*  The temp buf is smart, and can translate between color and gray  */
      /*  (only necessary if not we allocated it */
      if (src->bytes != new->bytes)
        {
          if (src->bytes == 4)  /* RGB color */
	    temp_buf_to_gray (src, new);
          else if (src->bytes == 2) /* grayscale */
	    temp_buf_to_color (src, new);
          else
	    g_message ("Cannot convert from indexed color.");
	  return new;
        }
    }

  /* make the copy */
  length = src->width * src->height * src->bytes;
  memcpy (temp_buf_data (new), temp_buf_data (src), length);

  return new;
}


TempBuf *
temp_buf_resize (TempBuf *buf, 
		 int      bytes, 
		 int      x, 
		 int      y, 
		 int      w, 
		 int      h)
{
  int size;

  /*  calculate the requested size  */
  size = w * h * bytes;

  /*  First, configure the canvas buffer  */
  if (!buf)
    buf = temp_buf_new (w, h, bytes, x, y, NULL);
  else
    {
      if (size != (buf->width * buf->height * buf->bytes))
      {
	/*  Make sure the temp buf is unswapped  */
	temp_buf_unswap (buf);

	/*  Reallocate the data for it  */
	buf->data = g_realloc (buf->data, size);
      }

      /*  Make sure the temp buf fields are valid  */
      buf->x = x;
      buf->y = y;
      buf->width = w;
      buf->height = h;
      buf->bytes = bytes;
    }

  return buf;
}


TempBuf *
temp_buf_copy_area (TempBuf *src, 
		    TempBuf *dest, 
		    int      x, 
		    int      y, 
		    int      w, 
		    int      h, 
		    int      border)
{
  TempBuf * new;
  PixelRegion srcR, destR;
  unsigned char empty[MAX_CHANNELS] = { 0, 0, 0, 0 };
  int x1, y1, x2, y2;

  if (!src)
    {
      g_message ("trying to copy a temp buf which is NULL.");
      return dest;
    }

  /*  some bounds checking  */
  x1 = CLAMP (x, 0, src->width);
  y1 = CLAMP (y, 0, src->height);
  x2 = CLAMP (x + w, 0, src->width);
  y2 = CLAMP (y + h, 0, src->height);

  if (!(x2 - x1) || !(y2 - y1))
    return dest;

  x = x1 - border;
  y = y1 - border;
  w = (x2 - x1) + border * 2;
  h = (y2 - y1) + border * 2;

  if (!dest)
    new = temp_buf_new (w, h, src->bytes, x, y, empty);
  else
    {
      new = dest;
      if (dest->bytes != src->bytes)
	g_message ("In temp_buf_copy_area, the widths or heights or bytes don't match.");
    }

  /*  Set the offsets for the dest  */
  new->x = src->x + x;
  new->y = src->y + y;

  /*  Copy the region  */
  srcR.bytes = src->bytes;
  srcR.w = (x2 - x1);
  srcR.h = (y2 - y1);
  srcR.rowstride = src->bytes * src->width;
  srcR.data = temp_buf_data (src) + y1 * srcR.rowstride + x1 * srcR.bytes;

  destR.rowstride = new->bytes * new->width;
  destR.data = temp_buf_data (new) + (y1 - y) * destR.rowstride + (x1 - x) * srcR.bytes;

  copy_region (&srcR, &destR);

  return new;
}


void
temp_buf_free (TempBuf *temp_buf)
{
  if (temp_buf->data)
    g_free (temp_buf->data);

  if (temp_buf->swapped)
    temp_buf_swap_free (temp_buf);

  g_free (temp_buf);
}


unsigned char *
temp_buf_data (TempBuf *temp_buf)
{
  if (temp_buf->swapped)
    temp_buf_unswap (temp_buf);

  return temp_buf->data;
}


/******************************************************************
 *  Mask buffer functions                                         *
 ******************************************************************/


MaskBuf *
mask_buf_new (int width, 
	      int height)
{
  static unsigned char empty = 0;

  return (temp_buf_new (width, height, 1, 0, 0, &empty));
}


void
mask_buf_free (MaskBuf *mask)
{
  temp_buf_free ((TempBuf *) mask);
}


unsigned char *
mask_buf_data (MaskBuf *mask_buf)
{
  if (mask_buf->swapped)
    temp_buf_unswap (mask_buf);

  return mask_buf->data;
}


/******************************************************************
 *  temp buffer disk caching functions                            *
 ******************************************************************/

/*  NOTES:
 *  Disk caching is setup as follows:
 *    On a call to temp_buf_swap, the TempBuf parameter is stored
 *    in a temporary variable called cached_in_memory.
 *    On the next call to temp_buf_swap, if cached_in_memory is non-null,
 *    cached_in_memory is moved to disk, and the latest TempBuf parameter
 *    is stored in cached_in_memory.  This method keeps the latest TempBuf
 *    structure in memory instead of moving it directly to disk as requested.
 *    On a call to temp_buf_unswap, if cached_in_memory is non-null, it is
 *    compared against the requested TempBuf.  If they are the same, nothing
 *    must be moved in from disk since it still resides in memory.  However,
 *    if the two pointers are different, the requested TempBuf is retrieved
 *    from disk.  In the former case, cached_in_memory is set to NULL;
 *    in the latter case, cached_in_memory is left unchanged.
 *    If temp_buf_swap_free is called, cached_in_memory must be checked
 *    against the temp buf being freed.  If they are the same, then 
 *    cached_in_memory must be set to NULL;
 *
 *  In the case where memory usage is set to "stingy":
 *    temp bufs are not cached in memory at all, they go right to disk.
 */


/*  a static counter for generating unique filenames  */
static int swap_index = 0;

/*  a static pointer which keeps track of the last request for a swapped buffer  */
static TempBuf * cached_in_memory = NULL;


static char *
generate_unique_filename (void)
{
  pid_t pid;
  pid = getpid ();
  return g_strdup_printf ("%s" G_DIR_SEPARATOR_S "gimp%d.%d",
			  temp_path, (int) pid, swap_index++);
}


void
temp_buf_swap (TempBuf *buf)
{
  TempBuf * swap;
  char * filename;
  struct stat stat_buf;
  int err;
  FILE * fp;

  if (!buf || buf->swapped)
    return;

  /*  Set the swapped flag  */
  buf->swapped = TRUE;

  if (stingy_memory_use)
    swap = buf;
  else
    {
      swap = cached_in_memory;
      cached_in_memory = buf;
    }

  /*  For the case where there is no temp buf ready to be moved to disk, return  */
  if (!swap)
    return;

  /*  Get a unique filename for caching the data to a UNIX file  */
  filename = generate_unique_filename ();

  /*  Check if generated filename is valid  */
  err = stat (filename, &stat_buf);
  if (!err)
    {
      if (stat_buf.st_mode & S_IFDIR)
	{
	  g_message ("Error in temp buf caching: \"%s\" is a directory (cannot overwrite)", filename);
	  g_free (filename);
	  return;
	}
    }

  /*  Open file for overwrite  */
  if ((fp = fopen (filename, "wb")))
    {
      size_t blocks_written;
      blocks_written = fwrite (swap->data, swap->width * swap->height * swap->bytes, 1, fp);
      /* Check whether all bytes were written and fclose() was able to flush its buffers */
      if ((0 != fclose (fp)) || (1 != blocks_written))
        {
          (void) unlink (filename);
          perror ("Write error on temp buf");
          g_message ("Cannot write \"%s\"", filename);
          g_free (filename);
          return;
        }
    }
  else
    {
      (void) unlink (filename);
      perror ("Error in temp buf caching");
      g_message ("Cannot write \"%s\"", filename);
      g_free (filename);
      return;
    }
  /*  Finally, free the buffer's data  */
  g_free (swap->data);
  swap->data = NULL;

  swap->filename = filename;
}


void
temp_buf_unswap (TempBuf *buf)
{
  struct stat stat_buf;
  FILE * fp;
  gboolean succ = FALSE;

  if (!buf || !buf->swapped)
    return;

  /*  Set the swapped flag  */
  buf->swapped = FALSE;

  /*  If the requested temp buf is still in memory, simply return  */
  if (cached_in_memory == buf)
    {
      cached_in_memory = NULL;
      return;
    }

  /*  Allocate memory for the buffer's data  */
  buf->data   = temp_buf_allocate (buf->width * buf->height * buf->bytes);

  /*  Find out if the filename of the swapped data is an existing file... */
  /*  (buf->filname HAS to be != 0 */
  if (!stat (buf->filename, &stat_buf))
    {
      if ((fp = fopen (buf->filename, "rb")))
	{
	  size_t blocks_read;
	  blocks_read = fread (buf->data, buf->width * buf->height * buf->bytes, 1, fp);
	  (void) fclose (fp);
	  if (blocks_read != 1)
            perror ("Read error on temp buf");
	  else
	    succ = TRUE;
	}
      else
	perror ("Error in temp buf caching");

      /*  Delete the swap file  */
      unlink (buf->filename);
    }
  if (!succ)
    g_message ("Error in temp buf caching: information swapped to disk was lost!");

  g_free (buf->filename);   /*  free filename  */
  buf->filename = NULL;
}


void
temp_buf_swap_free (TempBuf *buf)
{
  struct stat stat_buf;

  if (!buf->swapped)
    return;

  /*  Set the swapped flag  */
  buf->swapped = FALSE;

  /*  If the requested temp buf is cached in memory...  */
  if (cached_in_memory == buf)
    {
      cached_in_memory = NULL;
      return;
    }

  /*  Find out if the filename of the swapped data is an existing file... */
  if (!stat (buf->filename, &stat_buf))
    {
      /*  Delete the swap file  */
      unlink (buf->filename);
    }
  else
    g_message ("Error in temp buf disk swapping: information swapped to disk was lost!");

  if (buf->filename)
    g_free (buf->filename);   /*  free filename  */
  buf->filename = NULL;
}


void
swapping_free (void)
{
  if (cached_in_memory)
    temp_buf_free (cached_in_memory);
}