/*

 * 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 *input;

    CodedBitstreamContext *output;

    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->frag[0]);

    ff_cbs_fragment_reset(&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->input, 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->output, 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(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)

     * or any packet if buffer_pkt is empty. The latter is needed to

     * passthrough positions in case there are no timestamps like with

     * the raw OBU demuxer. */

    if (!buffer_pkt->data ||

        in->pts != AV_NOPTS_VALUE && buffer_pkt->pts == AV_NOPTS_VALUE) {

        av_packet_unref(buffer_pkt);

        av_packet_move_ref(buffer_pkt, in);

    } else

        av_packet_unref(in);

    ff_cbs_fragment_reset(&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;

    int err;

    ctx->in  = av_packet_alloc();

    ctx->pkt = av_packet_alloc();

    if (!ctx->in || !ctx->pkt)

        return AVERROR(ENOMEM);

    err =  ff_cbs_init(&ctx->input, AV_CODEC_ID_AV1, bsf);

    if (err < 0)

        return err;

    return ff_cbs_init(&ctx->output, AV_CODEC_ID_AV1, bsf);

}

static void av1_frame_merge_close(AVBSFContext *bsf)

{

    AV1FMergeContext *ctx = bsf->priv_data;

    ff_cbs_fragment_free(&ctx->frag[0]);

    ff_cbs_fragment_free(&ctx->frag[1]);

    av_packet_free(&ctx->in);

    av_packet_free(&ctx->pkt);

    ff_cbs_close(&ctx->input);

    ff_cbs_close(&ctx->output);

}

static const enum AVCodecID av1_frame_merge_codec_ids[] = {

    AV_CODEC_ID_AV1, AV_CODEC_ID_NONE,

};

const FFBitStreamFilter ff_av1_frame_merge_bsf = {

    .p.name         = "av1_frame_merge",

    .p.codec_ids    = av1_frame_merge_codec_ids,

    .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,

};