/*

  * Copyright (c) 2007 Bobby Bingham

  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
  * @file
  * FIFO buffering video filter
  */
 
 #include "avfilter.h"
 
 typedef struct BufPic {
     AVFilterBufferRef *picref;
     struct BufPic     *next;
 } BufPic;
 
 typedef struct {
     BufPic  root;
     BufPic *last;   ///< last buffered picture
 } FifoContext;
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     FifoContext *fifo = ctx->priv;
     fifo->last = &fifo->root;
 
     av_log(ctx, AV_LOG_INFO, "\n");
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     FifoContext *fifo = ctx->priv;
     BufPic *pic, *tmp;
 
     for (pic = fifo->root.next; pic; pic = tmp) {
         tmp = pic->next;
         avfilter_unref_buffer(pic->picref);
         av_free(pic);
     }
 }
 
 static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
 {
     FifoContext *fifo = inlink->dst->priv;
 
     fifo->last->next = av_mallocz(sizeof(BufPic));
     fifo->last = fifo->last->next;
     fifo->last->picref = picref;
 }
 
 static void end_frame(AVFilterLink *inlink) { }
 
 static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir) { }
 
 static int request_frame(AVFilterLink *outlink)
 {
     FifoContext *fifo = outlink->src->priv;
     BufPic *tmp;
     int ret;
 
     if (!fifo->root.next) {
         if ((ret = avfilter_request_frame(outlink->src->inputs[0]) < 0))
             return ret;
     }
 
     /* by doing this, we give ownership of the reference to the next filter,
      * so we don't have to worry about dereferencing it ourselves. */
     avfilter_start_frame(outlink, fifo->root.next->picref);
     avfilter_draw_slice (outlink, 0, outlink->h, 1);
     avfilter_end_frame  (outlink);
 
     if (fifo->last == fifo->root.next)
         fifo->last = &fifo->root;
     tmp = fifo->root.next->next;
     av_free(fifo->root.next);
     fifo->root.next = tmp;
 
     return 0;
 }
 
 AVFilter avfilter_vf_fifo = {
     .name      = "fifo",
     .description = NULL_IF_CONFIG_SMALL("Buffer input images and send them when they are requested."),
 
     .init      = init,
     .uninit    = uninit,
 
     .priv_size = sizeof(FifoContext),
 
     .inputs    = (AVFilterPad[]) {{ .name            = "default",
                                     .type            = AVMEDIA_TYPE_VIDEO,
                                     .get_video_buffer= avfilter_null_get_video_buffer,
                                     .start_frame     = start_frame,
                                     .draw_slice      = draw_slice,
                                     .end_frame       = end_frame,
                                     .rej_perms       = AV_PERM_REUSE2, },
                                   { .name = NULL}},
     .outputs   = (AVFilterPad[]) {{ .name            = "default",
                                     .type            = AVMEDIA_TYPE_VIDEO,
                                     .request_frame   = request_frame, },
                                   { .name = NULL}},
 };