/*
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/** \file
 * \ingroup imbuf
 */

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

#include "BLI_linklist.h"
#include "BLI_listbase.h" /* Needed due to import of BLO_readfile.h */
#include "BLI_utildefines.h"

#include "BLO_blend_defs.h"
#include "BLO_readfile.h"

#include "BKE_icons.h"
#include "BKE_idtype.h"
#include "BKE_main.h"

#include "DNA_ID.h" /* For preview images... */

#include "IMB_imbuf.h"
#include "IMB_imbuf_types.h"
#include "IMB_thumbs.h"

#include "MEM_guardedalloc.h"

ImBuf *IMB_thumb_load_blend(const char *blen_path, const char *blen_group, const char *blen_id)
{
  ImBuf *ima = NULL;

  if (blen_group && blen_id) {
    LinkNode *ln, *names, *lp, *previews = NULL;
    BlendFileReadReport bf_reports = {.reports = NULL};
    struct BlendHandle *libfiledata = BLO_blendhandle_from_file(blen_path, &bf_reports);
    int idcode = BKE_idtype_idcode_from_name(blen_group);
    int i, nprevs, nnames;

    if (libfiledata == NULL) {
      return ima;
    }

    /* Note: we should handle all previews for a same group at once, would avoid reopening
     * `.blend` file for each and every ID. However, this adds some complexity,
     * so keep it for later. */
    names = BLO_blendhandle_get_datablock_names(libfiledata, idcode, false, &nnames);
    previews = BLO_blendhandle_get_previews(libfiledata, idcode, &nprevs);

    BLO_blendhandle_close(libfiledata);

    if (!previews || (nnames != nprevs)) {
      if (previews != 0) {
        /* No previews at all is not a bug! */
        printf("%s: error, found %d items, %d previews\n", __func__, nnames, nprevs);
      }
      BLI_linklist_free(previews, BKE_previewimg_freefunc);
      BLI_linklist_freeN(names);
      return ima;
    }

    for (i = 0, ln = names, lp = previews; i < nnames; i++, ln = ln->next, lp = lp->next) {
      const char *blockname = ln->link;
      PreviewImage *img = lp->link;

      if (STREQ(blockname, blen_id)) {
        if (img) {
          ima = BKE_previewimg_to_imbuf(img, ICON_SIZE_PREVIEW);
        }
        break;
      }
    }

    BLI_linklist_free(previews, BKE_previewimg_freefunc);
    BLI_linklist_freeN(names);
  }
  else {
    BlendThumbnail *data;

    data = BLO_thumbnail_from_file(blen_path);
    ima = BKE_main_thumbnail_to_imbuf(NULL, data);

    if (data) {
      MEM_freeN(data);
    }
  }

  return ima;
}