/*
  * Copyright (c) 2019 James Almer <jamrial@gmail.com>
  *
  * 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
  */
 

 #include "bsf.h"

 #include "bsf_internal.h"

 #include "cbs.h"
 #include "cbs_av1.h"
 
 typedef struct AV1FMergeContext {
     CodedBitstreamContext *cbc;
     CodedBitstreamFragment frag[2];
     AVPacket *pkt, *in;
     int idx;
 } AV1FMergeContext;
 
 static void av1_frame_merge_flush(AVBSFContext *bsf)
 {
     AV1FMergeContext *ctx = bsf->priv_data;
 
     ff_cbs_fragment_reset(ctx->cbc, &ctx->frag[0]);
     ff_cbs_fragment_reset(ctx->cbc, &ctx->frag[1]);
     av_packet_unref(ctx->in);
     av_packet_unref(ctx->pkt);
 }
 
 static int av1_frame_merge_filter(AVBSFContext *bsf, AVPacket *out)
 {
     AV1FMergeContext *ctx = bsf->priv_data;
     CodedBitstreamFragment *frag = &ctx->frag[ctx->idx], *tu = &ctx->frag[!ctx->idx];
     AVPacket *in = ctx->in, *buffer_pkt = ctx->pkt;
     int err, i;
 
     err = ff_bsf_get_packet_ref(bsf, in);
     if (err < 0) {
         if (err == AVERROR_EOF && tu->nb_units > 0)
             goto eof;
         return err;
     }
 
     err = ff_cbs_read_packet(ctx->cbc, frag, in);
     if (err < 0) {
         av_log(bsf, AV_LOG_ERROR, "Failed to read packet.\n");
         goto fail;
     }
 
     if (frag->nb_units == 0) {
         av_log(bsf, AV_LOG_ERROR, "No OBU in packet.\n");
         err = AVERROR_INVALIDDATA;
         goto fail;
     }
 
     if (tu->nb_units == 0 && frag->units[0].type != AV1_OBU_TEMPORAL_DELIMITER) {
         av_log(bsf, AV_LOG_ERROR, "Missing Temporal Delimiter.\n");
         err = AVERROR_INVALIDDATA;
         goto fail;
     }
 
     for (i = 1; i < frag->nb_units; i++) {
         if (frag->units[i].type == AV1_OBU_TEMPORAL_DELIMITER) {
             av_log(bsf, AV_LOG_ERROR, "Temporal Delimiter in the middle of a packet.\n");
             err = AVERROR_INVALIDDATA;
             goto fail;
         }
     }
 
     if (tu->nb_units > 0 && frag->units[0].type == AV1_OBU_TEMPORAL_DELIMITER) {
 eof:
         err = ff_cbs_write_packet(ctx->cbc, buffer_pkt, tu);
         if (err < 0) {
             av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
             goto fail;
         }
         av_packet_move_ref(out, buffer_pkt);
 
         // Swap fragment index, to avoid copying fragment references.
         ctx->idx = !ctx->idx;
     } else {
         for (i = 0; i < frag->nb_units; i++) {
             err = ff_cbs_insert_unit_content(ctx->cbc, tu, -1, frag->units[i].type,
                                              frag->units[i].content, frag->units[i].content_ref);
             if (err < 0)
                 goto fail;
         }
 
         err = AVERROR(EAGAIN);
     }
 
     // Buffer packets with timestamps. There should be at most one per TU, be it split or not.
     if (!buffer_pkt->data && in->pts != AV_NOPTS_VALUE)
         av_packet_move_ref(buffer_pkt, in);
     else
         av_packet_unref(in);
 
     ff_cbs_fragment_reset(ctx->cbc, &ctx->frag[ctx->idx]);
 
 fail:
     if (err < 0 && err != AVERROR(EAGAIN))
         av1_frame_merge_flush(bsf);
 
     return err;
 }
 
 static int av1_frame_merge_init(AVBSFContext *bsf)
 {
     AV1FMergeContext *ctx = bsf->priv_data;
 
     ctx->in  = av_packet_alloc();
     ctx->pkt = av_packet_alloc();
     if (!ctx->in || !ctx->pkt)
         return AVERROR(ENOMEM);
 
     return ff_cbs_init(&ctx->cbc, AV_CODEC_ID_AV1, bsf);
 }
 
 static void av1_frame_merge_close(AVBSFContext *bsf)
 {
     AV1FMergeContext *ctx = bsf->priv_data;
 
     ff_cbs_fragment_free(ctx->cbc, &ctx->frag[0]);
     ff_cbs_fragment_free(ctx->cbc, &ctx->frag[1]);
     av_packet_free(&ctx->in);
     av_packet_free(&ctx->pkt);
     ff_cbs_close(&ctx->cbc);
 }
 
 static const enum AVCodecID av1_frame_merge_codec_ids[] = {
     AV_CODEC_ID_AV1, AV_CODEC_ID_NONE,
 };
 
 const AVBitStreamFilter ff_av1_frame_merge_bsf = {
     .name           = "av1_frame_merge",
     .priv_data_size = sizeof(AV1FMergeContext),
     .init           = av1_frame_merge_init,
     .flush          = av1_frame_merge_flush,
     .close          = av1_frame_merge_close,
     .filter         = av1_frame_merge_filter,
     .codec_ids      = av1_frame_merge_codec_ids,
 };