/*
  * Apple HTTP Live Streaming demuxer
  * 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 demuxer
  * http://tools.ietf.org/html/draft-pantos-http-live-streaming
  */
 
 #include "libavutil/avstring.h"

 #include "libavutil/intreadwrite.h"
 #include "libavutil/opt.h"

 #include "libavutil/dict.h"

 #include "avformat.h"
 #include "internal.h"
 #include <unistd.h>

 #include "avio_internal.h"

 #include "url.h"

 
 #define INITIAL_BUFFER_SIZE 32768

 
 /*
  * 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 (preferrably 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.
  */
 

 enum KeyType {
     KEY_NONE,
     KEY_AES_128,
 };
 

 struct segment {
     int duration;
     char url[MAX_URL_SIZE];

     char key[MAX_URL_SIZE];
     enum KeyType key_type;
     uint8_t iv[16];

 };
 
 /*
  * Each variant has its own demuxer. If it currently is active,

  * it has an open AVIOContext too, and potentially an AVPacket

  * containing the next packet from this stream.
  */
 struct variant {
     int bandwidth;
     char url[MAX_URL_SIZE];

     AVIOContext pb;
     uint8_t* read_buffer;
     URLContext *input;
     AVFormatContext *parent;
     int index;

     AVFormatContext *ctx;
     AVPacket pkt;
     int stream_offset;
 

     int finished;
     int target_duration;

     int start_seq_no;
     int n_segments;
     struct segment **segments;

     int needed, cur_needed;
     int cur_seq_no;
     int64_t last_load_time;

 
     char key_url[MAX_URL_SIZE];
     uint8_t key[16];

 };
 
 typedef struct AppleHTTPContext {
     int n_variants;
     struct variant **variants;
     int cur_seq_no;

     int end_of_segment;
     int first_packet;

 } AppleHTTPContext;
 

 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)

 {
     int len = ff_get_line(s, buf, maxlen);
     while (len > 0 && isspace(buf[len - 1]))
         buf[--len] = '\0';
     return len;
 }
 
 static void free_segment_list(struct variant *var)
 {
     int i;
     for (i = 0; i < var->n_segments; i++)
         av_free(var->segments[i]);
     av_freep(&var->segments);
     var->n_segments = 0;
 }
 
 static void free_variant_list(AppleHTTPContext *c)
 {
     int i;
     for (i = 0; i < c->n_variants; i++) {
         struct variant *var = c->variants[i];
         free_segment_list(var);
         av_free_packet(&var->pkt);

         av_free(var->pb.buffer);
         if (var->input)

             ffurl_close(var->input);

         if (var->ctx) {
             var->ctx->pb = NULL;
             av_close_input_file(var->ctx);
         }
         av_free(var);
     }
     av_freep(&c->variants);
     c->n_variants = 0;
 }
 
 /*
  * Used to reset a statically allocated AVPacket to a clean slate,
  * containing no data.
  */
 static void reset_packet(AVPacket *pkt)
 {
     av_init_packet(pkt);
     pkt->data = NULL;
 }
 
 static struct variant *new_variant(AppleHTTPContext *c, int bandwidth,
                                    const char *url, const char *base)
 {
     struct variant *var = av_mallocz(sizeof(struct variant));
     if (!var)
         return NULL;
     reset_packet(&var->pkt);
     var->bandwidth = bandwidth;

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

     dynarray_add(&c->variants, &c->n_variants, var);
     return var;
 }
 
 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);
     }
 }
 

 struct key_info {
      char uri[MAX_URL_SIZE];
      char method[10];
      char iv[35];
 };
 
 static void handle_key_args(struct key_info *info, const char *key,
                             int key_len, char **dest, int *dest_len)
 {
     if (!strncmp(key, "METHOD=", key_len)) {
         *dest     =        info->method;
         *dest_len = sizeof(info->method);
     } else if (!strncmp(key, "URI=", key_len)) {
         *dest     =        info->uri;
         *dest_len = sizeof(info->uri);
     } else if (!strncmp(key, "IV=", key_len)) {
         *dest     =        info->iv;
         *dest_len = sizeof(info->iv);
     }
 }
 

 static int parse_playlist(AppleHTTPContext *c, const char *url,

                           struct variant *var, AVIOContext *in)

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

     enum KeyType key_type = KEY_NONE;
     uint8_t iv[16] = "";
     int has_iv = 0;
     char key[MAX_URL_SIZE];

     char line[1024];
     const char *ptr;
     int close_in = 0;
 
     if (!in) {
         close_in = 1;

         if ((ret = avio_open(&in, url, AVIO_FLAG_READ)) < 0)

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

     if (var) {

         free_segment_list(var);

         var->finished = 0;
     }

     while (!url_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-KEY:", &ptr)) {
             struct key_info info = {{0}};
             ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_key_args,
                                &info);
             key_type = KEY_NONE;
             has_iv = 0;
             if (!strcmp(info.method, "AES-128"))
                 key_type = KEY_AES_128;
             if (!strncmp(info.iv, "0x", 2) || !strncmp(info.iv, "0X", 2)) {
                 ff_hex_to_data(iv, info.iv + 2);
                 has_iv = 1;
             }
             av_strlcpy(key, info.uri, sizeof(key));

         } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {

             if (!var) {
                 var = new_variant(c, 0, url, NULL);
                 if (!var) {
                     ret = AVERROR(ENOMEM);
                     goto fail;
                 }
             }
             var->target_duration = atoi(ptr);

         } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
             if (!var) {
                 var = new_variant(c, 0, url, NULL);
                 if (!var) {
                     ret = AVERROR(ENOMEM);
                     goto fail;
                 }
             }
             var->start_seq_no = atoi(ptr);
         } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {

             if (var)
                 var->finished = 1;

         } else if (av_strstart(line, "#EXTINF:", &ptr)) {
             is_segment = 1;
             duration   = atoi(ptr);
         } else if (av_strstart(line, "#", NULL)) {
             continue;
         } else if (line[0]) {
             if (is_variant) {
                 if (!new_variant(c, bandwidth, line, url)) {
                     ret = AVERROR(ENOMEM);
                     goto fail;
                 }
                 is_variant = 0;
                 bandwidth  = 0;
             }
             if (is_segment) {
                 struct segment *seg;
                 if (!var) {
                     var = new_variant(c, 0, url, NULL);
                     if (!var) {
                         ret = AVERROR(ENOMEM);
                         goto fail;
                     }
                 }
                 seg = av_malloc(sizeof(struct segment));
                 if (!seg) {
                     ret = AVERROR(ENOMEM);
                     goto fail;
                 }
                 seg->duration = duration;

                 seg->key_type = key_type;
                 if (has_iv) {
                     memcpy(seg->iv, iv, sizeof(iv));
                 } else {
                     int seq = var->start_seq_no + var->n_segments;
                     memset(seg->iv, 0, sizeof(seg->iv));
                     AV_WB32(seg->iv + 12, seq);
                 }
                 ff_make_absolute_url(seg->key, sizeof(seg->key), url, key);

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

                 dynarray_add(&var->segments, &var->n_segments, seg);
                 is_segment = 0;
             }
         }
     }

     if (var)
         var->last_load_time = av_gettime();

 
 fail:
     if (close_in)

         avio_close(in);

     return ret;
 }
 

 static int open_input(struct variant *var)
 {
     struct segment *seg = var->segments[var->cur_seq_no - var->start_seq_no];
     if (seg->key_type == KEY_NONE) {
         return ffurl_open(&var->input, seg->url, AVIO_FLAG_READ);
     } else if (seg->key_type == KEY_AES_128) {
         char iv[33], key[33], url[MAX_URL_SIZE];
         int ret;
         if (strcmp(seg->key, var->key_url)) {
             URLContext *uc;
             if (ffurl_open(&uc, seg->key, AVIO_FLAG_READ) == 0) {
                 if (ffurl_read_complete(uc, var->key, sizeof(var->key))
                     != sizeof(var->key)) {
                     av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
                            seg->key);
                 }
                 ffurl_close(uc);
             } else {
                 av_log(NULL, AV_LOG_ERROR, "Unable to open key file %s\n",
                        seg->key);
             }
             av_strlcpy(var->key_url, seg->key, sizeof(var->key_url));
         }
         ff_data_to_hex(iv, seg->iv, sizeof(seg->iv), 0);
         ff_data_to_hex(key, var->key, sizeof(var->key), 0);
         iv[32] = key[32] = '\0';
         if (strstr(seg->url, "://"))
             snprintf(url, sizeof(url), "crypto+%s", seg->url);
         else
             snprintf(url, sizeof(url), "crypto:%s", seg->url);
         if ((ret = ffurl_alloc(&var->input, url, AVIO_FLAG_READ)) < 0)
             return ret;
         av_set_string3(var->input->priv_data, "key", key, 0, NULL);
         av_set_string3(var->input->priv_data, "iv", iv, 0, NULL);
         if ((ret = ffurl_connect(var->input)) < 0) {
             ffurl_close(var->input);
             var->input = NULL;
             return ret;
         }
         return 0;
     }
     return AVERROR(ENOSYS);
 }
 

 static int read_data(void *opaque, uint8_t *buf, int buf_size)
 {
     struct variant *v = opaque;
     AppleHTTPContext *c = v->parent->priv_data;
     int ret, i;
 
 restart:
     if (!v->input) {
 reload:
         /* If this is a live stream and target_duration has elapsed since
          * the last playlist reload, reload the variant playlists now. */
         if (!v->finished &&
             av_gettime() - v->last_load_time >= v->target_duration*1000000 &&
             (ret = parse_playlist(c, v->url, v, NULL)) < 0)
                 return ret;
         if (v->cur_seq_no < v->start_seq_no) {
             av_log(NULL, AV_LOG_WARNING,
                    "skipping %d segments ahead, expired from playlists\n",
                    v->start_seq_no - v->cur_seq_no);
             v->cur_seq_no = v->start_seq_no;
         }
         if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
             if (v->finished)
                 return AVERROR_EOF;
             while (av_gettime() - v->last_load_time <
                    v->target_duration*1000000) {
                 if (url_interrupt_cb())
                     return AVERROR_EXIT;
                 usleep(100*1000);
             }
             /* Enough time has elapsed since the last reload */
             goto reload;
         }
 

         ret = open_input(v);

         if (ret < 0)
             return ret;
     }

     ret = ffurl_read(v->input, buf, buf_size);

     if (ret > 0)
         return ret;
     if (ret < 0 && ret != AVERROR_EOF)
         return ret;

     ffurl_close(v->input);

     v->input = NULL;
     v->cur_seq_no++;
 
     c->end_of_segment = 1;
     c->cur_seq_no = v->cur_seq_no;
 

     if (v->ctx) {
         v->needed = 0;
         for (i = v->stream_offset; i < v->stream_offset + v->ctx->nb_streams;
              i++) {
             if (v->parent->streams[i]->discard < AVDISCARD_ALL)
                 v->needed = 1;
         }

     }
     if (!v->needed) {
         av_log(v->parent, AV_LOG_INFO, "No longer receiving variant %d\n",
                v->index);
         return AVERROR_EOF;
     }
     goto restart;
 }
 

 static int applehttp_read_header(AVFormatContext *s, AVFormatParameters *ap)
 {
     AppleHTTPContext *c = s->priv_data;
     int ret = 0, i, j, stream_offset = 0;
 
     if ((ret = parse_playlist(c, s->filename, NULL, s->pb)) < 0)
         goto fail;
 
     if (c->n_variants == 0) {
         av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
         ret = AVERROR_EOF;
         goto fail;
     }
     /* If the playlist only contained variants, parse each individual
      * variant playlist. */
     if (c->n_variants > 1 || c->variants[0]->n_segments == 0) {
         for (i = 0; i < c->n_variants; i++) {
             struct variant *v = c->variants[i];
             if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
                 goto fail;
         }
     }
 
     if (c->variants[0]->n_segments == 0) {
         av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
         ret = AVERROR_EOF;
         goto fail;
     }
 
     /* If this isn't a live stream, calculate the total duration of the
      * stream. */

     if (c->variants[0]->finished) {

         int64_t duration = 0;

         for (i = 0; i < c->variants[0]->n_segments; i++)
             duration += c->variants[0]->segments[i]->duration;
         s->duration = duration * AV_TIME_BASE;
     }
 
     /* Open the demuxer for each variant */
     for (i = 0; i < c->n_variants; i++) {
         struct variant *v = c->variants[i];

         AVInputFormat *in_fmt = NULL;

         char bitrate_str[20];

         if (v->n_segments == 0)
             continue;

         if (!(v->ctx = avformat_alloc_context())) {
             ret = AVERROR(ENOMEM);
             goto fail;
         }
 

         v->index  = i;
         v->needed = 1;
         v->parent = s;
 
         /* If this is a live stream with more than 3 segments, start at the
          * third last segment. */
         v->cur_seq_no = v->start_seq_no;
         if (!v->finished && v->n_segments > 3)
             v->cur_seq_no = v->start_seq_no + v->n_segments - 3;
 
         v->read_buffer = av_malloc(INITIAL_BUFFER_SIZE);
         ffio_init_context(&v->pb, v->read_buffer, INITIAL_BUFFER_SIZE, 0, v,
                           read_data, NULL, NULL);
         v->pb.seekable = 0;
         ret = av_probe_input_buffer(&v->pb, &in_fmt, v->segments[0]->url,
                                     NULL, 0, 0);
         if (ret < 0)
             goto fail;

         v->ctx->pb       = &v->pb;
         ret = avformat_open_input(&v->ctx, v->segments[0]->url, in_fmt, NULL);

         if (ret < 0)
             goto fail;
         v->stream_offset = stream_offset;

         snprintf(bitrate_str, sizeof(bitrate_str), "%d", v->bandwidth);

         /* Create new AVStreams for each stream in this variant */
         for (j = 0; j < v->ctx->nb_streams; j++) {
             AVStream *st = av_new_stream(s, i);
             if (!st) {
                 ret = AVERROR(ENOMEM);
                 goto fail;
             }
             avcodec_copy_context(st->codec, v->ctx->streams[j]->codec);

             if (v->bandwidth)

                 av_dict_set(&st->metadata, "variant_bitrate", bitrate_str,

                                  0);

         }
         stream_offset += v->ctx->nb_streams;
     }
 

     c->first_packet = 1;

 
     return 0;
 fail:
     free_variant_list(c);
     return ret;
 }
 

 static int recheck_discard_flags(AVFormatContext *s, int first)

 {

     AppleHTTPContext *c = s->priv_data;
     int i, changed = 0;

     /* Check if any new streams are needed */
     for (i = 0; i < c->n_variants; i++)
         c->variants[i]->cur_needed = 0;;
 
     for (i = 0; i < s->nb_streams; i++) {
         AVStream *st = s->streams[i];
         struct variant *var = c->variants[s->streams[i]->id];
         if (st->discard < AVDISCARD_ALL)
             var->cur_needed = 1;

     }

     for (i = 0; i < c->n_variants; i++) {
         struct variant *v = c->variants[i];
         if (v->cur_needed && !v->needed) {
             v->needed = 1;
             changed = 1;
             v->cur_seq_no = c->cur_seq_no;
             v->pb.eof_reached = 0;
             av_log(s, AV_LOG_INFO, "Now receiving variant %d\n", i);
         } else if (first && !v->cur_needed && v->needed) {
             if (v->input)

                 ffurl_close(v->input);

             v->input = NULL;
             v->needed = 0;
             changed = 1;
             av_log(s, AV_LOG_INFO, "No longer receiving variant %d\n", i);

         }
     }

     return changed;

 }
 
 static int applehttp_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     AppleHTTPContext *c = s->priv_data;

     int ret, i, minvariant = -1;

     if (c->first_packet) {
         recheck_discard_flags(s, 1);
         c->first_packet = 0;

     }

 start:

     c->end_of_segment = 0;

     for (i = 0; i < c->n_variants; i++) {
         struct variant *var = c->variants[i];
         /* Make sure we've got one buffered packet from each open variant
          * stream */

         if (var->needed && !var->pkt.data) {

             ret = av_read_frame(var->ctx, &var->pkt);
             if (ret < 0) {

                 if (!url_feof(&var->pb))

                     return ret;
                 reset_packet(&var->pkt);
             }
         }
         /* Check if this stream has the packet with the lowest dts */
         if (var->pkt.data) {
             if (minvariant < 0 ||
                 var->pkt.dts < c->variants[minvariant]->pkt.dts)
                 minvariant = i;
         }
     }

     if (c->end_of_segment) {
         if (recheck_discard_flags(s, 0))
             goto start;
     }

     /* If we got a packet, return it */
     if (minvariant >= 0) {
         *pkt = c->variants[minvariant]->pkt;
         pkt->stream_index += c->variants[minvariant]->stream_offset;
         reset_packet(&c->variants[minvariant]->pkt);
         return 0;
     }

     return AVERROR_EOF;

 }
 
 static int applehttp_close(AVFormatContext *s)
 {
     AppleHTTPContext *c = s->priv_data;
 
     free_variant_list(c);
     return 0;
 }
 
 static int applehttp_read_seek(AVFormatContext *s, int stream_index,
                                int64_t timestamp, int flags)
 {
     AppleHTTPContext *c = s->priv_data;

     int i, j, ret;

     if ((flags & AVSEEK_FLAG_BYTE) || !c->variants[0]->finished)

         return AVERROR(ENOSYS);
 

     timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
                                s->streams[stream_index]->time_base.den :
                                AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
                                AV_ROUND_DOWN : AV_ROUND_UP);
     ret = AVERROR(EIO);

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

         /* Reset reading */

         struct variant *var = c->variants[i];

         int64_t pos = 0;

         if (var->input) {

             ffurl_close(var->input);

             var->input = NULL;

         }
         av_free_packet(&var->pkt);
         reset_packet(&var->pkt);

         var->pb.eof_reached = 0;

         /* Locate the segment that contains the target timestamp */
         for (j = 0; j < var->n_segments; j++) {
             if (timestamp >= pos &&
                 timestamp < pos + var->segments[j]->duration) {
                 var->cur_seq_no = var->start_seq_no + j;
                 ret = 0;
                 break;
             }
             pos += var->segments[j]->duration;

         }
     }

     return ret;

 }
 
 static int applehttp_probe(AVProbeData *p)
 {
     /* Require #EXTM3U at the start, and either one of the ones below
      * somewhere for a proper match. */
     if (strncmp(p->buf, "#EXTM3U", 7))
         return 0;
     if (strstr(p->buf, "#EXT-X-STREAM-INF:")     ||
         strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
         strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
         return AVPROBE_SCORE_MAX;
     return 0;
 }
 

 AVInputFormat ff_applehttp_demuxer = {

     "applehttp",
     NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
     sizeof(AppleHTTPContext),
     applehttp_probe,
     applehttp_read_header,
     applehttp_read_packet,
     applehttp_close,
     applehttp_read_seek,
 };