/*
  * Copyright (c) 2015, Vignesh Venkatasubramanian
  *
  * 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 WebM Chunk Muxer
  * The chunk muxer enables writing WebM Live chunks where there is a header
  * chunk, followed by data chunks where each Cluster is written out as a Chunk.
  */
 
 #include <float.h>
 #include <time.h>
 
 #include "avformat.h"
 #include "avio.h"

 #include "avio_internal.h"

 #include "internal.h"
 
 #include "libavutil/avassert.h"
 #include "libavutil/log.h"
 #include "libavutil/opt.h"
 #include "libavutil/avstring.h"
 #include "libavutil/parseutils.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/time.h"
 #include "libavutil/time_internal.h"
 #include "libavutil/timestamp.h"
 

 #define MAX_FILENAME_SIZE 1024
 

 typedef struct WebMChunkContext {
     const AVClass *class;
     int chunk_start_index;
     char *header_filename;
     int chunk_duration;
     int chunk_index;

     char *http_method;

     uint64_t duration_written;
     int prev_pts;
     AVOutputFormat *oformat;
     AVFormatContext *avf;
 } WebMChunkContext;
 
 static int chunk_mux_init(AVFormatContext *s)
 {
     WebMChunkContext *wc = s->priv_data;
     AVFormatContext *oc;
     int ret;
 
     ret = avformat_alloc_output_context2(&wc->avf, wc->oformat, NULL, NULL);
     if (ret < 0)
         return ret;
     oc = wc->avf;
 
     oc->interrupt_callback = s->interrupt_callback;
     oc->max_delay          = s->max_delay;
     av_dict_copy(&oc->metadata, s->metadata, 0);
 
     *(const AVClass**)oc->priv_data = oc->oformat->priv_class;
     av_opt_set_defaults(oc->priv_data);
     av_opt_set_int(oc->priv_data, "dash", 1, 0);
     av_opt_set_int(oc->priv_data, "cluster_time_limit", wc->chunk_duration, 0);
     av_opt_set_int(oc->priv_data, "live", 1, 0);
 
     oc->streams = s->streams;
     oc->nb_streams = s->nb_streams;
 
     return 0;
 }
 

 static int get_chunk_filename(AVFormatContext *s, int is_header, char *filename)

 {
     WebMChunkContext *wc = s->priv_data;
     AVFormatContext *oc = wc->avf;

     if (!filename) {
         return AVERROR(EINVAL);
     }

     if (is_header) {
         if (!wc->header_filename) {

             av_log(oc, AV_LOG_ERROR, "No header filename provided\n");

             return AVERROR(EINVAL);
         }

         av_strlcpy(filename, wc->header_filename, strlen(wc->header_filename) + 1);

     } else {

         if (av_get_frame_filename(filename, MAX_FILENAME_SIZE,
                                   s->filename, wc->chunk_index - 1) < 0) {

             av_log(oc, AV_LOG_ERROR, "Invalid chunk filename template '%s'\n", s->filename);
             return AVERROR(EINVAL);
         }
     }
     return 0;
 }
 
 static int webm_chunk_write_header(AVFormatContext *s)
 {
     WebMChunkContext *wc = s->priv_data;
     AVFormatContext *oc = NULL;
     int ret;

     int i;

     AVDictionary *options = NULL;

 
     // DASH Streams can only have either one track per file.
     if (s->nb_streams != 1) { return AVERROR_INVALIDDATA; }
 
     wc->chunk_index = wc->chunk_start_index;
     wc->oformat = av_guess_format("webm", s->filename, "video/webm");
     if (!wc->oformat)
         return AVERROR_MUXER_NOT_FOUND;
 
     ret = chunk_mux_init(s);
     if (ret < 0)
         return ret;
     oc = wc->avf;

     ret = get_chunk_filename(s, 1, oc->filename);
     if (ret < 0)

         return ret;

     if (wc->http_method)
         av_dict_set(&options, "method", wc->http_method, 0);
     ret = s->io_open(s, &oc->pb, oc->filename, AVIO_FLAG_WRITE, &options);
     av_dict_free(&options);

     if (ret < 0)
         return ret;
 
     oc->pb->seekable = 0;
     ret = oc->oformat->write_header(oc);
     if (ret < 0)
         return ret;

     ff_format_io_close(s, &oc->pb);

     for (i = 0; i < s->nb_streams; i++) {
         // ms precision is the de-facto standard timescale for mkv files.
         avpriv_set_pts_info(s->streams[i], 64, 1, 1000);
     }

     return 0;
 }
 
 static int chunk_start(AVFormatContext *s)
 {
     WebMChunkContext *wc = s->priv_data;
     AVFormatContext *oc = wc->avf;
     int ret;
 

     ret = avio_open_dyn_buf(&oc->pb);

     if (ret < 0)
         return ret;
     wc->chunk_index++;
     return 0;
 }
 
 static int chunk_end(AVFormatContext *s)
 {
     WebMChunkContext *wc = s->priv_data;
     AVFormatContext *oc = wc->avf;
     int ret;

     int buffer_size;
     uint8_t *buffer;
     AVIOContext *pb;
     char filename[MAX_FILENAME_SIZE];

     AVDictionary *options = NULL;

 
     if (wc->chunk_start_index == wc->chunk_index)
         return 0;
     // Flush the cluster in WebM muxer.
     oc->oformat->write_packet(oc, NULL);

     buffer_size = avio_close_dyn_buf(oc->pb, &buffer);
     ret = get_chunk_filename(s, 0, filename);

     if (ret < 0)

         goto fail;

     if (wc->http_method)
         av_dict_set(&options, "method", wc->http_method, 0);
     ret = s->io_open(s, &pb, filename, AVIO_FLAG_WRITE, &options);

     if (ret < 0)
         goto fail;
     avio_write(pb, buffer, buffer_size);

     ff_format_io_close(s, &pb);

     oc->pb = NULL;
 fail:

     av_dict_free(&options);

     av_free(buffer);
     return (ret < 0) ? ret : 0;

 }
 
 static int webm_chunk_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
     WebMChunkContext *wc = s->priv_data;
     AVFormatContext *oc = wc->avf;
     AVStream *st = s->streams[pkt->stream_index];
     int ret;
 

     if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {

         wc->duration_written += av_rescale_q(pkt->pts - wc->prev_pts,
                                              st->time_base,
                                              (AVRational) {1, 1000});
         wc->prev_pts = pkt->pts;
     }
 
     // For video, a new chunk is started only on key frames. For audio, a new
     // chunk is started based on chunk_duration.

     if ((st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&

          (pkt->flags & AV_PKT_FLAG_KEY)) ||

         (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&

          (pkt->pts == 0 || wc->duration_written >= wc->chunk_duration))) {
         wc->duration_written = 0;
         if ((ret = chunk_end(s)) < 0 || (ret = chunk_start(s)) < 0) {
             goto fail;
         }
     }
 
     ret = oc->oformat->write_packet(oc, pkt);
     if (ret < 0)
         goto fail;
 
 fail:
     if (ret < 0) {
         oc->streams = NULL;
         oc->nb_streams = 0;
         avformat_free_context(oc);
     }
 
     return ret;
 }
 
 static int webm_chunk_write_trailer(AVFormatContext *s)
 {
     WebMChunkContext *wc = s->priv_data;
     AVFormatContext *oc = wc->avf;
     oc->oformat->write_trailer(oc);
     chunk_end(s);
     oc->streams = NULL;
     oc->nb_streams = 0;
     avformat_free_context(oc);
     return 0;
 }
 
 #define OFFSET(x) offsetof(WebMChunkContext, x)
 static const AVOption options[] = {
     { "chunk_start_index",  "start index of the chunk", OFFSET(chunk_start_index), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
     { "header", "filename of the header where the initialization data will be written", OFFSET(header_filename), AV_OPT_TYPE_STRING, { 0 }, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
     { "audio_chunk_duration", "duration of each chunk in milliseconds", OFFSET(chunk_duration), AV_OPT_TYPE_INT, {.i64 = 5000}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },

     { "method", "set the HTTP method", OFFSET(http_method), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0, AV_OPT_FLAG_ENCODING_PARAM },

     { NULL },
 };
 
 #if CONFIG_WEBM_CHUNK_MUXER
 static const AVClass webm_chunk_class = {
     .class_name = "WebM Chunk Muxer",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 AVOutputFormat ff_webm_chunk_muxer = {
     .name           = "webm_chunk",
     .long_name      = NULL_IF_CONFIG_SMALL("WebM Chunk Muxer"),
     .mime_type      = "video/webm",
     .extensions     = "chk",
     .flags          = AVFMT_NOFILE | AVFMT_GLOBALHEADER | AVFMT_NEEDNUMBER |

                       AVFMT_TS_NONSTRICT,

     .priv_data_size = sizeof(WebMChunkContext),
     .write_header   = webm_chunk_write_header,
     .write_packet   = webm_chunk_write_packet,
     .write_trailer  = webm_chunk_write_trailer,
     .priv_class     = &webm_chunk_class,
 };
 #endif