/*
 * OpenH264 video decoder
 * Copyright (C) 2016 Martin Storsjo
 *
 * 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 <wels/codec_api.h>
#include <wels/codec_ver.h>

#include "libavutil/common.h"
#include "libavutil/fifo.h"
#include "libavutil/imgutils.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"

#include "avcodec.h"
#include "internal.h"
#include "libopenh264.h"

typedef struct SVCContext {
    ISVCDecoder *decoder;
    AVBSFContext *bsf;
    AVFifoBuffer *packet_fifo;
    AVPacket pkt_filtered;
} SVCContext;

static av_cold int svc_decode_close(AVCodecContext *avctx)
{
    SVCContext *s = avctx->priv_data;
    AVPacket pkt;

    if (s->decoder)
        WelsDestroyDecoder(s->decoder);

    while (s->packet_fifo && av_fifo_size(s->packet_fifo) >= sizeof(pkt)) {
        av_fifo_generic_read(s->packet_fifo, &pkt, sizeof(pkt), NULL);
        av_packet_unref(&pkt);
    }

    av_bsf_free(&s->bsf);
    av_packet_unref(&s->pkt_filtered);
    av_fifo_free(s->packet_fifo);

    return 0;
}

static av_cold int svc_decode_init(AVCodecContext *avctx)
{
    SVCContext *s = avctx->priv_data;
    SDecodingParam param = { 0 };
    int err;
    int log_level;
    WelsTraceCallback callback_function;

    if ((err = ff_libopenh264_check_version(avctx)) < 0)
        return err;

    s->packet_fifo = av_fifo_alloc(sizeof(AVPacket));
    if (!s->packet_fifo)
        return AVERROR(ENOMEM);

    if (WelsCreateDecoder(&s->decoder)) {
        av_log(avctx, AV_LOG_ERROR, "Unable to create decoder\n");
        return AVERROR_UNKNOWN;
    }

    // Pass all libopenh264 messages to our callback, to allow ourselves to filter them.
    log_level = WELS_LOG_DETAIL;
    callback_function = ff_libopenh264_trace_callback;
    (*s->decoder)->SetOption(s->decoder, DECODER_OPTION_TRACE_LEVEL, &log_level);
    (*s->decoder)->SetOption(s->decoder, DECODER_OPTION_TRACE_CALLBACK, (void *)&callback_function);
    (*s->decoder)->SetOption(s->decoder, DECODER_OPTION_TRACE_CALLBACK_CONTEXT, (void *)&avctx);

#if !OPENH264_VER_AT_LEAST(1, 6)
    param.eOutputColorFormat = videoFormatI420;
#endif
    param.eEcActiveIdc       = ERROR_CON_DISABLE;
    param.sVideoProperty.eVideoBsType = VIDEO_BITSTREAM_DEFAULT;

    if ((*s->decoder)->Initialize(s->decoder, &param) != cmResultSuccess) {
        av_log(avctx, AV_LOG_ERROR, "Initialize failed\n");
        return AVERROR_UNKNOWN;
    }

    avctx->pix_fmt = AV_PIX_FMT_YUV420P;

    return 0;
}

static int init_bsf(AVCodecContext *avctx)
{
    SVCContext *s = avctx->priv_data;
    const AVBitStreamFilter *filter;
    int ret;

    if (s->bsf)
        return 0;

    // If the input stream already is annex b, this BSF only passes the
    // packets through unchanged.
    filter = av_bsf_get_by_name("h264_mp4toannexb");
    if (!filter)
        return AVERROR_BSF_NOT_FOUND;

    ret = av_bsf_alloc(filter, &s->bsf);
    if (ret < 0)
        return ret;

    ret = avcodec_parameters_from_context(s->bsf->par_in, avctx);
    if (ret < 0)
        return ret;

    s->bsf->time_base_in = avctx->time_base;

    ret = av_bsf_init(s->bsf);
    if (ret < 0)
        return ret;

    return ret;
}

static int svc_decode_frame(AVCodecContext *avctx, void *data,
                            int *got_frame, AVPacket *avpkt)
{
    SVCContext *s = avctx->priv_data;
    SBufferInfo info = { 0 };
    uint8_t* ptrs[3];
    int linesize[3];
    AVFrame *avframe = data;
    int ret;
    DECODING_STATE state;

    if ((ret = init_bsf(avctx)) < 0)
        return ret;

    if (avpkt->size) {
        AVPacket input_ref = { 0 };
        if (av_fifo_space(s->packet_fifo) < sizeof(input_ref)) {
            ret = av_fifo_realloc2(s->packet_fifo,
                                   av_fifo_size(s->packet_fifo) + sizeof(input_ref));
            if (ret < 0)
                return ret;
        }

        ret = av_packet_ref(&input_ref, avpkt);
        if (ret < 0)
            return ret;
        av_fifo_generic_write(s->packet_fifo, &input_ref, sizeof(input_ref), NULL);
    }

    while (!*got_frame) {
        /* prepare the input data -- convert to Annex B if needed */
        if (s->pkt_filtered.size <= 0) {
            AVPacket input_ref;

            /* no more data */
            if (av_fifo_size(s->packet_fifo) < sizeof(AVPacket))
                return avpkt->size ? avpkt->size : 0;

            av_packet_unref(&s->pkt_filtered);

            av_fifo_generic_read(s->packet_fifo, &input_ref, sizeof(input_ref), NULL);
            ret = av_bsf_send_packet(s->bsf, &input_ref);
            if (ret < 0) {
                av_packet_unref(&input_ref);
                return ret;
            }

            ret = av_bsf_receive_packet(s->bsf, &s->pkt_filtered);
            if (ret < 0)
                av_packet_move_ref(&s->pkt_filtered, &input_ref);
            else
                av_packet_unref(&input_ref);
        }

        state = (*s->decoder)->DecodeFrame2(s->decoder, s->pkt_filtered.data, s->pkt_filtered.size, ptrs, &info);
        s->pkt_filtered.size = 0;
        if (state != dsErrorFree) {
            av_log(avctx, AV_LOG_ERROR, "DecodeFrame2 failed\n");
            return AVERROR_UNKNOWN;
        }
        if (info.iBufferStatus != 1) {
            av_log(avctx, AV_LOG_DEBUG, "No frame produced\n");
            continue;
        }

        ret = ff_set_dimensions(avctx, info.UsrData.sSystemBuffer.iWidth, info.UsrData.sSystemBuffer.iHeight);
        if (ret < 0)
            return ret;
        // The decoder doesn't (currently) support decoding into a user
        // provided buffer, so do a copy instead.
        if (ff_get_buffer(avctx, avframe, 0) < 0) {
            av_log(avctx, AV_LOG_ERROR, "Unable to allocate buffer\n");
            return AVERROR(ENOMEM);
        }

        linesize[0] = info.UsrData.sSystemBuffer.iStride[0];
        linesize[1] = linesize[2] = info.UsrData.sSystemBuffer.iStride[1];
        av_image_copy(avframe->data, avframe->linesize, (const uint8_t **) ptrs, linesize, avctx->pix_fmt, avctx->width, avctx->height);

        avframe->pts     = s->pkt_filtered.pts;
        avframe->pkt_dts = s->pkt_filtered.dts;
#if FF_API_PKT_PTS
FF_DISABLE_DEPRECATION_WARNINGS
        avframe->pkt_pts = s->pkt_filtered.pts;
FF_ENABLE_DEPRECATION_WARNINGS
#endif

        *got_frame = 1;
    }
    return avpkt->size;
}

AVCodec ff_libopenh264_decoder = {
    .name           = "libopenh264",
    .long_name      = NULL_IF_CONFIG_SMALL("OpenH264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_H264,
    .priv_data_size = sizeof(SVCContext),
    .init           = svc_decode_init,
    .decode         = svc_decode_frame,
    .close          = svc_decode_close,
    // The decoder doesn't currently support B-frames, and the decoder's API
    // doesn't support reordering/delay, but the BSF could incur delay.
    .capabilities   = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_DR1,
    .caps_internal  = FF_CODEC_CAP_SETS_PKT_DTS | FF_CODEC_CAP_INIT_THREADSAFE |
                      FF_CODEC_CAP_INIT_CLEANUP,
};
