/*
  * Copyright (c) 2012 Nicolas George
  *
  * 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 "libavutil/avstring.h"
 #include "avformat.h"
 #include "internal.h"
 
 typedef struct {
     char *url;
     int64_t start_time;
     int64_t duration;
 } ConcatFile;
 
 typedef struct {
     ConcatFile *files;
     ConcatFile *cur_file;
     unsigned nb_files;
     AVFormatContext *avf;
 } ConcatContext;
 
 static int concat_probe(AVProbeData *probe)
 {
     return 0;
 }
 
 static char *get_keyword(uint8_t **cursor)
 {
     char *ret = *cursor += strspn(*cursor, SPACE_CHARS);
     *cursor += strcspn(*cursor, SPACE_CHARS);
     if (**cursor) {
         *((*cursor)++) = 0;
         *cursor += strspn(*cursor, SPACE_CHARS);
     }
     return ret;
 }
 
 #define FAIL(retcode) do { ret = (retcode); goto fail; } while(0)
 
 static int add_file(AVFormatContext *avf, char *filename, ConcatFile **rfile,
                     unsigned *nb_files_alloc)
 {
     ConcatContext *cat = avf->priv_data;
     ConcatFile *file;
     char *url;
     size_t url_len;
 
     url_len = strlen(avf->filename) + strlen(filename) + 16;
     if (!(url = av_malloc(url_len)))
         return AVERROR(ENOMEM);
     ff_make_absolute_url(url, url_len, avf->filename, filename);
     av_free(filename);
 
     if (cat->nb_files >= *nb_files_alloc) {

         size_t n = FFMAX(*nb_files_alloc * 2, 16);

         ConcatFile *new_files;
         if (n <= cat->nb_files || n > SIZE_MAX / sizeof(*cat->files) ||
             !(new_files = av_realloc(cat->files, n * sizeof(*cat->files))))

             return AVERROR(ENOMEM);

         cat->files = new_files;

         *nb_files_alloc = n;
     }
 
     file = &cat->files[cat->nb_files++];
     memset(file, 0, sizeof(*file));
     *rfile = file;
 
     file->url        = url;
     file->start_time = AV_NOPTS_VALUE;
     file->duration   = AV_NOPTS_VALUE;
 
     return 0;
 }
 
 static int open_file(AVFormatContext *avf, unsigned fileno)
 {
     ConcatContext *cat = avf->priv_data;
     ConcatFile *file = &cat->files[fileno];
     int ret;
 
     if ((ret = avformat_open_input(&cat->avf, file->url, NULL, NULL)) < 0 ||
         (ret = avformat_find_stream_info(cat->avf, NULL)) < 0) {
         av_log(avf, AV_LOG_ERROR, "Impossible to open '%s'\n", file->url);
         return ret;
     }
     cat->cur_file = file;
     if (file->start_time == AV_NOPTS_VALUE)
         file->start_time = !fileno ? 0 :
                            cat->files[fileno - 1].start_time +
                            cat->files[fileno - 1].duration;
     return 0;
 }
 
 static int concat_read_close(AVFormatContext *avf)
 {
     ConcatContext *cat = avf->priv_data;
     unsigned i;
 
     if (cat->avf)
         avformat_close_input(&cat->avf);
     for (i = 0; i < cat->nb_files; i++)
         av_freep(&cat->files[i].url);
     av_freep(&cat->files);
     return 0;
 }
 
 static int concat_read_header(AVFormatContext *avf)
 {
     ConcatContext *cat = avf->priv_data;
     uint8_t buf[4096];
     uint8_t *cursor, *keyword;
     int ret, line = 0, i;
     unsigned nb_files_alloc = 0;
     ConcatFile *file = NULL;
     AVStream *st, *source_st;
 
     while (1) {
         if ((ret = ff_get_line(avf->pb, buf, sizeof(buf))) <= 0)
             break;
         line++;
         cursor = buf;
         keyword = get_keyword(&cursor);
         if (!*keyword || *keyword == '#')
             continue;
 
         if (!strcmp(keyword, "file")) {
             char *filename = av_get_token((const char **)&cursor, SPACE_CHARS);
             if (!filename) {
                 av_log(avf, AV_LOG_ERROR, "Line %d: filename required\n", line);
                 FAIL(AVERROR_INVALIDDATA);
             }
             if ((ret = add_file(avf, filename, &file, &nb_files_alloc)) < 0)
                 FAIL(ret);
         } else {
             av_log(avf, AV_LOG_ERROR, "Line %d: unknown keyword '%s'\n",
                    line, keyword);
             FAIL(AVERROR_INVALIDDATA);
         }
     }
     if (ret < 0)
         FAIL(ret);
 
     if ((ret = open_file(avf, 0)) < 0)
         FAIL(ret);
     for (i = 0; i < cat->avf->nb_streams; i++) {
         if (!(st = avformat_new_stream(avf, NULL)))
             FAIL(AVERROR(ENOMEM));
         source_st = cat->avf->streams[i];
         if ((ret = avcodec_copy_context(st->codec, source_st->codec)) < 0)
             FAIL(ret);
         st->r_frame_rate        = source_st->r_frame_rate;
         st->avg_frame_rate      = source_st->avg_frame_rate;
         st->time_base           = source_st->time_base;
         st->sample_aspect_ratio = source_st->sample_aspect_ratio;
     }
 
     return 0;
 
 fail:
     concat_read_close(avf);
     return ret;
 }
 
 static int open_next_file(AVFormatContext *avf)
 {
     ConcatContext *cat = avf->priv_data;
     unsigned fileno = cat->cur_file - cat->files;
 
     if (cat->cur_file->duration == AV_NOPTS_VALUE)
         cat->cur_file->duration = cat->avf->duration;
 
     if (++fileno >= cat->nb_files)
         return AVERROR_EOF;
     avformat_close_input(&cat->avf);
     return open_file(avf, fileno);
 }
 
 static int concat_read_packet(AVFormatContext *avf, AVPacket *pkt)
 {
     ConcatContext *cat = avf->priv_data;
     int ret;
     int64_t delta;
 
     while (1) {
         if ((ret = av_read_frame(cat->avf, pkt)) != AVERROR_EOF ||
             (ret = open_next_file(avf)) < 0)
             break;
     }
     delta = av_rescale_q(cat->cur_file->start_time - cat->avf->start_time,
                          AV_TIME_BASE_Q,
                          cat->avf->streams[pkt->stream_index]->time_base);
     if (pkt->pts != AV_NOPTS_VALUE)
         pkt->pts += delta;
     if (pkt->dts != AV_NOPTS_VALUE)
         pkt->dts += delta;
     return ret;
 }
 
 AVInputFormat ff_concat_demuxer = {
     .name           = "concat",
     .long_name      = NULL_IF_CONFIG_SMALL("Virtual concatenation script"),
     .priv_data_size = sizeof(ConcatContext),
     .read_probe     = concat_probe,
     .read_header    = concat_read_header,
     .read_packet    = concat_read_packet,
     .read_close     = concat_read_close,
 };