/*
  * SSA/ASS muxer
  * Copyright (c) 2008 Michael Niedermayer
  *
  * 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"

 #include "libavutil/opt.h"
 

 typedef struct DialogueLine {
     int readorder;
     char *line;
     struct DialogueLine *prev, *next;
 } DialogueLine;
 

 typedef struct ASSContext {

     const AVClass *class;

     int expected_readorder;
     DialogueLine *dialogue_cache;
     DialogueLine *last_added_dialogue;
     int cache_size;

     int ssa_mode;

     int ignore_readorder;

     uint8_t *trailer;
     size_t trailer_size;

 } ASSContext;

 
 static int write_header(AVFormatContext *s)
 {
     ASSContext *ass = s->priv_data;

     AVCodecParameters *par = s->streams[0]->codecpar;

     if (s->nb_streams != 1 || par->codec_id != AV_CODEC_ID_ASS) {

         av_log(s, AV_LOG_ERROR, "Exactly one ASS/SSA stream is needed.\n");

         return AVERROR(EINVAL);

     }

     avpriv_set_pts_info(s->streams[0], 64, 1, 100);

     if (par->extradata_size > 0) {
         size_t header_size = par->extradata_size;
         uint8_t *trailer = strstr(par->extradata, "\n[Events]");

 
         if (trailer)
             trailer = strstr(trailer, "Format:");
         if (trailer)
             trailer = strstr(trailer, "\n");
 
         if (trailer++) {

             header_size = (trailer - par->extradata);
             ass->trailer_size = par->extradata_size - header_size;

             if (ass->trailer_size)
                 ass->trailer = trailer;
         }
 

         avio_write(s->pb, par->extradata, header_size);
         if (par->extradata[header_size - 1] != '\n')

             avio_write(s->pb, "\r\n", 2);

         ass->ssa_mode = !strstr(par->extradata, "\n[V4+ Styles]");
         if (!strstr(par->extradata, "\n[Events]"))

             avio_printf(s->pb, "[Events]\r\nFormat: %s, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text\r\n",
                         ass->ssa_mode ? "Marked" : "Layer");

     }

     avio_flush(s->pb);

 
     return 0;
 }
 

 static void purge_dialogues(AVFormatContext *s, int force)
 {
     int n = 0;
     ASSContext *ass = s->priv_data;
     DialogueLine *dialogue = ass->dialogue_cache;
 
     while (dialogue && (dialogue->readorder == ass->expected_readorder || force)) {
         DialogueLine *next = dialogue->next;
         if (dialogue->readorder != ass->expected_readorder) {
             av_log(s, AV_LOG_WARNING, "ReadOrder gap found between %d and %d\n",
                    ass->expected_readorder, dialogue->readorder);
             ass->expected_readorder = dialogue->readorder;
         }
         avio_printf(s->pb, "Dialogue: %s\r\n", dialogue->line);
         if (dialogue == ass->last_added_dialogue)
             ass->last_added_dialogue = next;

         av_freep(&dialogue->line);

         av_free(dialogue);
         if (next)
             next->prev = NULL;
         dialogue = ass->dialogue_cache = next;
         ass->expected_readorder++;
         n++;
     }
     ass->cache_size -= n;
     if (n > 1)
         av_log(s, AV_LOG_DEBUG, "wrote %d ASS lines, cached dialogues: %d, waiting for event id %d\n",
                n, ass->cache_size, ass->expected_readorder);
 }
 
 static void insert_dialogue(ASSContext *ass, DialogueLine *dialogue)
 {
     DialogueLine *cur, *next = NULL, *prev = NULL;
 
     /* from the last added to the end of the list */
     if (ass->last_added_dialogue) {
         for (cur = ass->last_added_dialogue; cur; cur = cur->next) {
             if (cur->readorder > dialogue->readorder)
                 break;
             prev = cur;
             next = cur->next;
         }
     }
 
     /* from the beginning to the last one added */
     if (!prev) {
         next = ass->dialogue_cache;
         for (cur = next; cur != ass->last_added_dialogue; cur = cur->next) {
             if (cur->readorder > dialogue->readorder)
                 break;
             prev = cur;
             next = cur->next;
         }
     }
 
     if (prev) {
         prev->next = dialogue;
         dialogue->prev = prev;
     } else {
         dialogue->prev = ass->dialogue_cache;
         ass->dialogue_cache = dialogue;
     }
     if (next) {
         next->prev = dialogue;
         dialogue->next = next;
     }
     ass->cache_size++;
     ass->last_added_dialogue = dialogue;
 }
 

 static int write_packet(AVFormatContext *s, AVPacket *pkt)
 {

     ASSContext *ass = s->priv_data;
 

     long int layer;
     char *p = pkt->data;
     int64_t start = pkt->pts;
     int64_t end   = start + pkt->duration;
     int hh1, mm1, ss1, ms1;
     int hh2, mm2, ss2, ms2;
     DialogueLine *dialogue = av_mallocz(sizeof(*dialogue));
 
     if (!dialogue)
         return AVERROR(ENOMEM);
 
     dialogue->readorder = strtol(p, &p, 10);
     if (dialogue->readorder < ass->expected_readorder)
         av_log(s, AV_LOG_WARNING, "Unexpected ReadOrder %d\n",
                dialogue->readorder);
     if (*p == ',')
         p++;
 
     if (ass->ssa_mode && !strncmp(p, "Marked=", 7))
         p += 7;
 
     layer = strtol(p, &p, 10);
     if (*p == ',')
         p++;
     hh1 = (int)(start / 360000);    mm1 = (int)(start / 6000) % 60;
     hh2 = (int)(end   / 360000);    mm2 = (int)(end   / 6000) % 60;
     ss1 = (int)(start / 100) % 60;  ms1 = (int)(start % 100);
     ss2 = (int)(end   / 100) % 60;  ms2 = (int)(end   % 100);
     if (hh1 > 9) hh1 = 9, mm1 = 59, ss1 = 59, ms1 = 99;
     if (hh2 > 9) hh2 = 9, mm2 = 59, ss2 = 59, ms2 = 99;
 
     dialogue->line = av_asprintf("%s%ld,%d:%02d:%02d.%02d,%d:%02d:%02d.%02d,%s",
                                  ass->ssa_mode ? "Marked=" : "",
                                  layer, hh1, mm1, ss1, ms1, hh2, mm2, ss2, ms2, p);
     if (!dialogue->line) {
         av_free(dialogue);
         return AVERROR(ENOMEM);
     }
     insert_dialogue(ass, dialogue);
     purge_dialogues(s, ass->ignore_readorder);

     return 0;
 }
 
 static int write_trailer(AVFormatContext *s)
 {

     ASSContext *ass = s->priv_data;
 

     purge_dialogues(s, 1);

 
     if (ass->trailer) {
         avio_write(s->pb, ass->trailer, ass->trailer_size);
     }
 

     return 0;
 }
 

 #define OFFSET(x) offsetof(ASSContext, x)
 #define E AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {

     { "ignore_readorder", "write events immediately, even if they're out-of-order", OFFSET(ignore_readorder), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },

     { NULL },
 };
 
 static const AVClass ass_class = {
     .class_name = "ass muxer",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 

 AVOutputFormat ff_ass_muxer = {

     .name           = "ass",

     .long_name      = NULL_IF_CONFIG_SMALL("SSA (SubStation Alpha) subtitle"),

     .mime_type      = "text/x-ass",

     .extensions     = "ass,ssa",
     .priv_data_size = sizeof(ASSContext),

     .subtitle_codec = AV_CODEC_ID_ASS,

     .write_header   = write_header,
     .write_packet   = write_packet,
     .write_trailer  = write_trailer,

     .flags          = AVFMT_GLOBALHEADER | AVFMT_NOTIMESTAMPS | AVFMT_TS_NONSTRICT,

     .priv_class     = &ass_class,

 };