/*
  * LRC lyrics file format decoder
  * Copyright (c) 2014 StarBrilliant <m13253@hotmail.com>
  *
  * 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 <inttypes.h>
 #include <stdint.h>
 #include <string.h>
 
 #include "avformat.h"
 #include "internal.h"
 #include "lrc.h"
 #include "metadata.h"
 #include "subtitles.h"
 #include "libavutil/bprint.h"
 #include "libavutil/dict.h"
 
 typedef struct LRCContext {
     FFDemuxSubtitlesQueue q;
     int64_t ts_offset; // offset metadata item
 } LRCContext;
 
 static int64_t find_header(const char *p)
 {
     int64_t offset = 0;
     while(p[offset] == ' ' || p[offset] == '\t') {
         offset++;
     }
     if(p[offset] == '[' && p[offset + 1] >= 'a' && p[offset + 1] <= 'z') {
         return offset;
     } else {
         return -1;
     }
 }
 
 static int64_t count_ts(const char *p)
 {
     int64_t offset = 0;
     int in_brackets = 0;
 
     for(;;) {
         if(p[offset] == ' ' || p[offset] == '\t') {
             offset++;
         } else if(p[offset] == '[') {
             offset++;
             in_brackets++;
         } else if (p[offset] == ']' && in_brackets) {
             offset++;
             in_brackets--;
         } else if(in_brackets &&
                  (p[offset] == ':' || p[offset] == '.' || p[offset] == '-' ||
                  (p[offset] >= '0' && p[offset] <= '9'))) {
             offset++;
         } else {
             break;
         }
     }
     return offset;
 }
 
 static int64_t read_ts(const char *p, int64_t *start)
 {
     int64_t offset = 0;
     uint64_t mm, ss, cs;
 
     while(p[offset] == ' ' || p[offset] == '\t') {
         offset++;
     }
     if(p[offset] != '[') {
         return 0;
     }
     if(sscanf(p, "[-%"SCNu64":%"SCNu64".%"SCNu64"]", &mm, &ss, &cs) == 3) {
         /* Just in case negative pts, players may drop it but we won't. */
         *start = -(int64_t) (mm*60000 + ss*1000 + cs*10);
     } else if(sscanf(p, "[%"SCNu64":%"SCNu64".%"SCNu64"]", &mm, &ss, &cs) == 3) {
         *start = mm*60000 + ss*1000 + cs*10;
     } else {
         return 0;
     }
     do {
         offset++;
     } while(p[offset] && p[offset-1] != ']');
     return offset;
 }
 
 static int64_t read_line(AVBPrint *buf, AVIOContext *pb)
 {
     int64_t pos = avio_tell(pb);
 
     av_bprint_clear(buf);

     while(!avio_feof(pb)) {

         int c = avio_r8(pb);
         if(c != '\r') {
             av_bprint_chars(buf, c, 1);
         }
         if(c == '\n') {
             break;
         }
     }
     return pos;
 }
 
 static int lrc_probe(AVProbeData *p)
 {
     int64_t offset = 0;
     int64_t mm;
     uint64_t ss, cs;
     const AVMetadataConv *metadata_item;
 
     if(!memcmp(p->buf, "\xef\xbb\xbf", 3)) { // Skip UTF-8 BOM header
         offset += 3;
     }
     while(p->buf[offset] == '\n' || p->buf[offset] == '\r') {
         offset++;
     }
     if(p->buf[offset] != '[') {
         return 0;
     }
     offset++;
     // Common metadata item but not exist in ff_lrc_metadata_conv
     if(!memcmp(p->buf + offset, "offset:", 7)) {
         return 40;
     }
     if(sscanf(p->buf + offset, "%"SCNd64":%"SCNu64".%"SCNu64"]",
               &mm, &ss, &cs) == 3) {
         return 50;
     }
     // Metadata items exist in ff_lrc_metadata_conv
     for(metadata_item = ff_lrc_metadata_conv;
         metadata_item->native; metadata_item++) {
         size_t metadata_item_len = strlen(metadata_item->native);
         if(p->buf[offset + metadata_item_len] == ':' &&
            !memcmp(p->buf + offset, metadata_item->native, metadata_item_len)) {
             return 40;
         }
     }
     return 5; // Give it 5 scores since it starts with a bracket
 }
 
 static int lrc_read_header(AVFormatContext *s)
 {
     LRCContext *lrc = s->priv_data;
     AVBPrint line;
     AVStream *st;
 
     st = avformat_new_stream(s, NULL);
     if(!st) {
         return AVERROR(ENOMEM);
     }
     avpriv_set_pts_info(st, 64, 1, 1000);
     lrc->ts_offset = 0;

     st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
     st->codecpar->codec_id   = AV_CODEC_ID_TEXT;

     av_bprint_init(&line, 0, AV_BPRINT_SIZE_UNLIMITED);
 

     while(!avio_feof(s->pb)) {

         int64_t pos = read_line(&line, s->pb);
         int64_t header_offset = find_header(line.str);
         if(header_offset >= 0) {
             char *comma_offset = strchr(line.str, ':');
             if(comma_offset) {
                 char *right_bracket_offset = strchr(line.str, ']');
                 if(!right_bracket_offset) {
                     continue;
                 }
 
                 *right_bracket_offset = *comma_offset = '\0';
                 if(strcmp(line.str + 1, "offset") ||
                    sscanf(comma_offset + 1, "%"SCNd64, &lrc->ts_offset) != 1) {
                     av_dict_set(&s->metadata, line.str + 1, comma_offset + 1, 0);
                 }
                 *comma_offset = ':';
                 *right_bracket_offset = ']';
             }
 
         } else {
             AVPacket *sub;
             int64_t ts_start = AV_NOPTS_VALUE;
             int64_t ts_stroffset = 0;
             int64_t ts_stroffset_incr = 0;
             int64_t ts_strlength = count_ts(line.str);
 
             while((ts_stroffset_incr = read_ts(line.str + ts_stroffset,
                                                &ts_start)) != 0) {
                 ts_stroffset += ts_stroffset_incr;
                 sub = ff_subtitles_queue_insert(&lrc->q, line.str + ts_strlength,
                                                 line.len - ts_strlength, 0);
                 if(!sub) {
                     return AVERROR(ENOMEM);
                 }
                 sub->pos = pos;
                 sub->pts = ts_start - lrc->ts_offset;
                 sub->duration = -1;
             }
         }
     }

     ff_subtitles_queue_finalize(s, &lrc->q);

     ff_metadata_conv_ctx(s, NULL, ff_lrc_metadata_conv);
     return 0;
 }
 
 static int lrc_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     LRCContext *lrc = s->priv_data;
     return ff_subtitles_queue_read_packet(&lrc->q, pkt);
 }
 
 static int lrc_read_seek(AVFormatContext *s, int stream_index,
                          int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
 {
     LRCContext *lrc = s->priv_data;
     return ff_subtitles_queue_seek(&lrc->q, s, stream_index,
                                    min_ts, ts, max_ts, flags);
 }
 
 static int lrc_read_close(AVFormatContext *s)
 {
     LRCContext *lrc = s->priv_data;
     ff_subtitles_queue_clean(&lrc->q);
     return 0;
 }
 
 AVInputFormat ff_lrc_demuxer = {
     .name           = "lrc",
     .long_name      = NULL_IF_CONFIG_SMALL("LRC lyrics"),
     .priv_data_size = sizeof (LRCContext),
     .read_probe     = lrc_probe,
     .read_header    = lrc_read_header,
     .read_packet    = lrc_read_packet,
     .read_close     = lrc_read_close,
     .read_seek2     = lrc_read_seek
 };