/*
  * 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 "libavutil/opt.h"

 #include "libavutil/parseutils.h"

 #include "avformat.h"
 #include "internal.h"

 #include "url.h"

 
 typedef struct {
     char *url;
     int64_t start_time;
     int64_t duration;
 } ConcatFile;
 
 typedef struct {

     AVClass *class;

     ConcatFile *files;
     ConcatFile *cur_file;
     unsigned nb_files;
     AVFormatContext *avf;

     int safe;

     int seekable;

 } ConcatContext;
 
 static int concat_probe(AVProbeData *probe)
 {

     return memcmp(probe->buf, "ffconcat version 1.0", 20) ?
            0 : AVPROBE_SCORE_MAX;

 }
 
 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;
 }
 

 static int safe_filename(const char *f)
 {
     const char *start = f;
 
     for (; *f; f++) {
         /* A-Za-z0-9_- */
         if (!((unsigned)((*f | 32) - 'a') < 26 ||
               (unsigned)(*f - '0') < 10 || *f == '_' || *f == '-')) {
             if (f == start)
                 return 0;
             else if (*f == '/')
                 start = f + 1;
             else if (*f != '.')
                 return 0;
         }
     }
     return 1;
 }
 

 #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 = NULL;

     size_t url_len;

     int ret;

     if (cat->safe > 0 && !safe_filename(filename)) {
         av_log(avf, AV_LOG_ERROR, "Unsafe file name '%s'\n", filename);

         FAIL(AVERROR(EPERM));

     }

     url_len = strlen(avf->filename) + strlen(filename) + 16;
     if (!(url = av_malloc(url_len)))

         FAIL(AVERROR(ENOMEM));

     ff_make_absolute_url(url, url_len, avf->filename, filename);

     av_freep(&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))))

             FAIL(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;

 
 fail:
     av_free(url);
     av_free(filename);
     return ret;

 }
 
 static int open_file(AVFormatContext *avf, unsigned fileno)
 {
     ConcatContext *cat = avf->priv_data;
     ConcatFile *file = &cat->files[fileno];
     int ret;
 

     if (cat->avf)
         avformat_close_input(&cat->avf);

 
     cat->avf = avformat_alloc_context();
     if (!cat->avf)
         return AVERROR(ENOMEM);
 
     cat->avf->interrupt_callback = avf->interrupt_callback;

     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);

         avformat_close_input(&cat->avf);

         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;

     int64_t time = 0;

 
     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 if (!strcmp(keyword, "duration")) {
             char *dur_str = get_keyword(&cursor);
             int64_t dur;
             if (!file) {
                 av_log(avf, AV_LOG_ERROR, "Line %d: duration without file\n",
                        line);
                 FAIL(AVERROR_INVALIDDATA);
             }
             if ((ret = av_parse_time(&dur, dur_str, 1)) < 0) {
                 av_log(avf, AV_LOG_ERROR, "Line %d: invalid duration '%s'\n",
                        line, dur_str);
                 FAIL(ret);
             }
             file->duration = dur;

         } else if (!strcmp(keyword, "ffconcat")) {
             char *ver_kw  = get_keyword(&cursor);
             char *ver_val = get_keyword(&cursor);
             if (strcmp(ver_kw, "version") || strcmp(ver_val, "1.0")) {
                 av_log(avf, AV_LOG_ERROR, "Line %d: invalid version\n", line);
                 FAIL(AVERROR_INVALIDDATA);
             }
             if (cat->safe < 0)
                 cat->safe = 1;

         } else {
             av_log(avf, AV_LOG_ERROR, "Line %d: unknown keyword '%s'\n",
                    line, keyword);
             FAIL(AVERROR_INVALIDDATA);
         }
     }
     if (ret < 0)
         FAIL(ret);

     if (!cat->nb_files)
         FAIL(AVERROR_INVALIDDATA);

     for (i = 0; i < cat->nb_files; i++) {
         if (cat->files[i].start_time == AV_NOPTS_VALUE)
             cat->files[i].start_time = time;
         else
             time = cat->files[i].start_time;
         if (cat->files[i].duration == AV_NOPTS_VALUE)
             break;
         time += cat->files[i].duration;
     }

     if (i == cat->nb_files) {

         avf->duration = time;

         cat->seekable = 1;
     }

     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;
     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;
     }

     if (ret < 0)
         return ret;
 

     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;
 }
 

 static void rescale_interval(AVRational tb_in, AVRational tb_out,
                              int64_t *min_ts, int64_t *ts, int64_t *max_ts)
 {
     *ts     = av_rescale_q    (*    ts, tb_in, tb_out);
     *min_ts = av_rescale_q_rnd(*min_ts, tb_in, tb_out,
                                AV_ROUND_UP   | AV_ROUND_PASS_MINMAX);
     *max_ts = av_rescale_q_rnd(*max_ts, tb_in, tb_out,
                                AV_ROUND_DOWN | AV_ROUND_PASS_MINMAX);
 }
 
 static int try_seek(AVFormatContext *avf, int stream,
                     int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     ConcatContext *cat = avf->priv_data;
     int64_t t0 = cat->cur_file->start_time - cat->avf->start_time;
 
     ts -= t0;
     min_ts = min_ts == INT64_MIN ? INT64_MIN : min_ts - t0;
     max_ts = max_ts == INT64_MAX ? INT64_MAX : max_ts - t0;
     if (stream >= 0) {
         if (stream >= cat->avf->nb_streams)
             return AVERROR(EIO);
         rescale_interval(AV_TIME_BASE_Q, cat->avf->streams[stream]->time_base,
                          &min_ts, &ts, &max_ts);
     }
     return avformat_seek_file(cat->avf, stream, min_ts, ts, max_ts, flags);
 }
 
 static int real_seek(AVFormatContext *avf, int stream,
                      int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     ConcatContext *cat = avf->priv_data;
     int ret, left, right;
 
     if (stream >= 0) {
         if (stream >= avf->nb_streams)
             return AVERROR(EINVAL);
         rescale_interval(avf->streams[stream]->time_base, AV_TIME_BASE_Q,
                          &min_ts, &ts, &max_ts);
     }
 
     left  = 0;
     right = cat->nb_files;
     while (right - left > 1) {
         int mid = (left + right) / 2;
         if (ts < cat->files[mid].start_time)
             right = mid;
         else
             left  = mid;
     }
 
     if ((ret = open_file(avf, left)) < 0)
         return ret;
 
     ret = try_seek(avf, stream, min_ts, ts, max_ts, flags);

     if (ret < 0 &&

         left < cat->nb_files - 1 &&
         cat->files[left + 1].start_time < max_ts) {
         if ((ret = open_file(avf, left + 1)) < 0)
             return ret;
         ret = try_seek(avf, stream, min_ts, ts, max_ts, flags);
     }
     return ret;
 }
 
 static int concat_seek(AVFormatContext *avf, int stream,
                        int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     ConcatContext *cat = avf->priv_data;
     ConcatFile *cur_file_saved = cat->cur_file;
     AVFormatContext *cur_avf_saved = cat->avf;
     int ret;
 
     if (!cat->seekable)
         return AVERROR(ESPIPE); /* XXX: can we use it? */
     if (flags & (AVSEEK_FLAG_BYTE | AVSEEK_FLAG_FRAME))
         return AVERROR(ENOSYS);
     cat->avf = NULL;
     if ((ret = real_seek(avf, stream, min_ts, ts, max_ts, flags)) < 0) {
         if (cat->avf)
             avformat_close_input(&cat->avf);
         cat->avf      = cur_avf_saved;
         cat->cur_file = cur_file_saved;
     } else {
         avformat_close_input(&cur_avf_saved);
     }
     return ret;
 }
 

 #define OFFSET(x) offsetof(ConcatContext, x)
 #define DEC AV_OPT_FLAG_DECODING_PARAM
 
 static const AVOption options[] = {
     { "safe", "enable safe mode",
       OFFSET(safe), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, DEC },
     { NULL }
 };
 
 static const AVClass concat_class = {
     .class_name = "concat demuxer",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 

 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,

     .read_seek2     = concat_seek,

     .priv_class     = &concat_class,

 };