/*
  * Apple HTTP Live Streaming Protocol Handler
  * Copyright (c) 2010 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
  */
 
 /**
  * @file
  * Apple HTTP Live Streaming Protocol Handler
  * http://tools.ietf.org/html/draft-pantos-http-live-streaming
  */
 
 #include "libavutil/avstring.h"

 #include "libavutil/time.h"

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

 #include "url.h"

 #include "version.h"

 
 /*
  * An apple http stream consists of a playlist with media segment files,
  * played sequentially. There may be several playlists with the same
  * video content, in different bandwidth variants, that are played in

  * parallel (preferably only one bandwidth variant at a time). In this case,

  * the user supplied the url to a main playlist that only lists the variant
  * playlists.
  *
  * If the main playlist doesn't point at any variants, we still create
  * one anonymous toplevel variant for this, to maintain the structure.
  */
 
 struct segment {

     int64_t duration;

     char url[MAX_URL_SIZE];
 };
 
 struct variant {
     int bandwidth;
     char url[MAX_URL_SIZE];
 };
 

 typedef struct HLSContext {

     char playlisturl[MAX_URL_SIZE];

     int64_t target_duration;

     int start_seq_no;
     int finished;
     int n_segments;
     struct segment **segments;
     int n_variants;
     struct variant **variants;
     int cur_seq_no;
     URLContext *seg_hd;
     int64_t last_load_time;

 } HLSContext;

 
 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
 {
     int len = ff_get_line(s, buf, maxlen);

     while (len > 0 && av_isspace(buf[len - 1]))

         buf[--len] = '\0';
     return len;
 }
 

 static void free_segment_list(HLSContext *s)

 {
     int i;
     for (i = 0; i < s->n_segments; i++)

         av_freep(&s->segments[i]);

     av_freep(&s->segments);
     s->n_segments = 0;
 }
 

 static void free_variant_list(HLSContext *s)

 {
     int i;
     for (i = 0; i < s->n_variants; i++)

         av_freep(&s->variants[i]);

     av_freep(&s->variants);
     s->n_variants = 0;
 }
 
 struct variant_info {
     char bandwidth[20];
 };
 
 static void handle_variant_args(struct variant_info *info, const char *key,
                                 int key_len, char **dest, int *dest_len)
 {
     if (!strncmp(key, "BANDWIDTH=", key_len)) {
         *dest     =        info->bandwidth;
         *dest_len = sizeof(info->bandwidth);
     }
 }
 
 static int parse_playlist(URLContext *h, const char *url)
 {

     HLSContext *s = h->priv_data;

     AVIOContext *in;

     int ret = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
     int64_t duration = 0;

     char line[1024];
     const char *ptr;
 

     if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
                           &h->interrupt_callback, NULL)) < 0)

         return ret;
 
     read_chomp_line(in, line, sizeof(line));

     if (strcmp(line, "#EXTM3U")) {
         ret = AVERROR_INVALIDDATA;
         goto fail;
     }

 
     free_segment_list(s);
     s->finished = 0;

     while (!avio_feof(in)) {

         read_chomp_line(in, line, sizeof(line));
         if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
             struct variant_info info = {{0}};
             is_variant = 1;
             ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
                                &info);
             bandwidth = atoi(info.bandwidth);
         } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {

             s->target_duration = atoi(ptr) * AV_TIME_BASE;

         } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
             s->start_seq_no = atoi(ptr);
         } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
             s->finished = 1;
         } else if (av_strstart(line, "#EXTINF:", &ptr)) {
             is_segment = 1;

             duration = atof(ptr) * AV_TIME_BASE;

         } else if (av_strstart(line, "#", NULL)) {
             continue;
         } else if (line[0]) {
             if (is_segment) {
                 struct segment *seg = av_malloc(sizeof(struct segment));
                 if (!seg) {
                     ret = AVERROR(ENOMEM);
                     goto fail;
                 }
                 seg->duration = duration;

                 ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);

                 dynarray_add(&s->segments, &s->n_segments, seg);
                 is_segment = 0;
             } else if (is_variant) {
                 struct variant *var = av_malloc(sizeof(struct variant));
                 if (!var) {
                     ret = AVERROR(ENOMEM);
                     goto fail;
                 }
                 var->bandwidth = bandwidth;

                 ff_make_absolute_url(var->url, sizeof(var->url), url, line);

                 dynarray_add(&s->variants, &s->n_variants, var);
                 is_variant = 0;
             }
         }
     }

     s->last_load_time = av_gettime_relative();

 
 fail:
     avio_close(in);
     return ret;
 }
 

 static int hls_close(URLContext *h)

 {

     HLSContext *s = h->priv_data;

 
     free_segment_list(s);
     free_variant_list(s);
     ffurl_close(s->seg_hd);
     return 0;
 }
 

 static int hls_open(URLContext *h, const char *uri, int flags)

 {

     HLSContext *s = h->priv_data;

     int ret, i;
     const char *nested_url;
 

     if (flags & AVIO_FLAG_WRITE)

         return AVERROR(ENOSYS);

 
     h->is_streamed = 1;
 

     if (av_strstart(uri, "hls+", &nested_url)) {

         av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));

     } else if (av_strstart(uri, "hls://", &nested_url)) {
         av_log(h, AV_LOG_ERROR,
                "No nested protocol specified. Specify e.g. hls+http://%s\n",
                nested_url);
         ret = AVERROR(EINVAL);
         goto fail;

     } else {

         av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);

         ret = AVERROR(EINVAL);
         goto fail;
     }

     av_log(h, AV_LOG_WARNING,
            "Using the hls protocol is discouraged, please try using the "
            "hls demuxer instead. The hls demuxer should be more complete "
            "and work as well as the protocol implementation. (If not, "
            "please report it.) To use the demuxer, simply use %s as url.\n",
            s->playlisturl);

 
     if ((ret = parse_playlist(h, s->playlisturl)) < 0)
         goto fail;
 
     if (s->n_segments == 0 && s->n_variants > 0) {
         int max_bandwidth = 0, maxvar = -1;
         for (i = 0; i < s->n_variants; i++) {
             if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
                 max_bandwidth = s->variants[i]->bandwidth;
                 maxvar = i;
             }
         }
         av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
                    sizeof(s->playlisturl));
         if ((ret = parse_playlist(h, s->playlisturl)) < 0)
             goto fail;
     }
 
     if (s->n_segments == 0) {

         av_log(h, AV_LOG_WARNING, "Empty playlist\n");

         ret = AVERROR(EIO);
         goto fail;
     }
     s->cur_seq_no = s->start_seq_no;
     if (!s->finished && s->n_segments >= 3)
         s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
 
     return 0;
 
 fail:

     hls_close(h);

     return ret;
 }
 

 static int hls_read(URLContext *h, uint8_t *buf, int size)

 {

     HLSContext *s = h->priv_data;

     const char *url;
     int ret;

     int64_t reload_interval;

 
 start:
     if (s->seg_hd) {

         ret = ffurl_read(s->seg_hd, buf, size);

         if (ret > 0)
             return ret;
     }
     if (s->seg_hd) {

         ffurl_close(s->seg_hd);

         s->seg_hd = NULL;
         s->cur_seq_no++;
     }

     reload_interval = s->n_segments > 0 ?
                       s->segments[s->n_segments - 1]->duration :
                       s->target_duration;

 retry:
     if (!s->finished) {

         int64_t now = av_gettime_relative();

         if (now - s->last_load_time >= reload_interval) {

             if ((ret = parse_playlist(h, s->playlisturl)) < 0)
                 return ret;

             /* If we need to reload the playlist again below (if
              * there's still no more segments), switch to a reload
              * interval of half the target duration. */

             reload_interval = s->target_duration / 2;

         }

     }
     if (s->cur_seq_no < s->start_seq_no) {

         av_log(h, AV_LOG_WARNING,

                "skipping %d segments ahead, expired from playlist\n",
                s->start_seq_no - s->cur_seq_no);
         s->cur_seq_no = s->start_seq_no;
     }
     if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
         if (s->finished)
             return AVERROR_EOF;

         while (av_gettime_relative() - s->last_load_time < reload_interval) {

             if (ff_check_interrupt(&h->interrupt_callback))

                 return AVERROR_EXIT;

             av_usleep(100*1000);

         }
         goto retry;
     }
     url = s->segments[s->cur_seq_no - s->start_seq_no]->url,

     av_log(h, AV_LOG_DEBUG, "opening %s\n", url);

     ret = ffurl_open(&s->seg_hd, url, AVIO_FLAG_READ,

                      &h->interrupt_callback, NULL);

     if (ret < 0) {

         if (ff_check_interrupt(&h->interrupt_callback))

             return AVERROR_EXIT;

         av_log(h, AV_LOG_WARNING, "Unable to open %s\n", url);

         s->cur_seq_no++;
         goto retry;
     }
     goto start;
 }
 

 URLProtocol ff_hls_protocol = {
     .name           = "hls",

     .url_open       = hls_open,
     .url_read       = hls_read,
     .url_close      = hls_close,

     .flags          = URL_PROTOCOL_FLAG_NESTED_SCHEME,

     .priv_data_size = sizeof(HLSContext),

 };