/*
  * 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
 * libgme demuxer
 */
 
 #include <gme/gme.h>
 #include "libavutil/avstring.h"
 #include "libavutil/eval.h"
 #include "libavutil/opt.h"
 #include "avformat.h"
 #include "internal.h"
 
 typedef struct GMEContext {
     const AVClass *class;
     Music_Emu *music_emu;
     gme_info_t *info;   ///< selected track
 
     /* options */
     int track_index;
     int sample_rate;
     int64_t max_size;
 } GMEContext;
 
 #define OFFSET(x) offsetof(GMEContext, x)
 #define A AV_OPT_FLAG_AUDIO_PARAM
 #define D AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
     {"track_index", "set track that should be played",        OFFSET(track_index), AV_OPT_TYPE_INT,   {.i64 = 0},                0,    INT_MAX,  A|D},
     {"sample_rate", "set sample rate",                        OFFSET(sample_rate), AV_OPT_TYPE_INT,   {.i64 = 44100},            1000, 999999,   A|D},
     {"max_size",    "set max file size supported (in bytes)", OFFSET(max_size),    AV_OPT_TYPE_INT64, {.i64 = 50 * 1024 * 1024}, 0,    SIZE_MAX, A|D},
     {NULL}
 };
 
 static void add_meta(AVFormatContext *s, const char *name, const char *value)
 {
     if (value && value[0])
         av_dict_set(&s->metadata, name, value, 0);
 }
 
 static int load_metadata(AVFormatContext *s)
 {
     GMEContext *gme = s->priv_data;
     gme_info_t *info = gme->info;
     char buf[30];
 
     add_meta(s, "system",       info->system);
     add_meta(s, "game",         info->game);
     add_meta(s, "song",         info->song);
     add_meta(s, "author",       info->author);
     add_meta(s, "copyright",    info->copyright);
     add_meta(s, "comment",      info->comment);
     add_meta(s, "dumper",       info->dumper);
 
     snprintf(buf, sizeof(buf), "%d", (int)gme_track_count(gme->music_emu));
     add_meta(s, "tracks", buf);
 
     return 0;
 }
 
 #define AUDIO_PKT_SIZE 512
 
 static int read_header_gme(AVFormatContext *s)
 {
     AVStream *st;
     AVIOContext *pb = s->pb;
     GMEContext *gme = s->priv_data;
     int64_t sz = avio_size(pb);
     char *buf;
     char dummy;
 
     if (sz < 0) {
         av_log(s, AV_LOG_WARNING, "Could not determine file size\n");
         sz = gme->max_size;
     } else if (gme->max_size && sz > gme->max_size) {
         sz = gme->max_size;
     }
 
     buf = av_malloc(sz);
     if (!buf)
         return AVERROR(ENOMEM);
     sz = avio_read(pb, buf, sz);
 
     // Data left means our buffer (the max_size option) is too small
     if (avio_read(pb, &dummy, 1) == 1) {
         av_log(s, AV_LOG_ERROR, "File size is larger than max_size option "
                "value %"PRIi64", consider increasing the max_size option\n",
                gme->max_size);
         return AVERROR_BUFFER_TOO_SMALL;
     }
 
     if (gme_open_data(buf, sz, &gme->music_emu, gme->sample_rate)) {
         av_freep(&buf);
         return AVERROR_INVALIDDATA;
     }
     av_freep(&buf);
 
     if (gme_track_info(gme->music_emu, &gme->info, gme->track_index))
         return AVERROR_STREAM_NOT_FOUND;
 
     if (gme_start_track(gme->music_emu, gme->track_index))
         return AVERROR_UNKNOWN;
 
     load_metadata(s);
 
     st = avformat_new_stream(s, NULL);
     if (!st)
         return AVERROR(ENOMEM);
     avpriv_set_pts_info(st, 64, 1, 1000);
     if (st->duration > 0)
         st->duration = gme->info->length;

     st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
     st->codecpar->codec_id    = AV_NE(AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE);
     st->codecpar->channels    = 2;
     st->codecpar->sample_rate = gme->sample_rate;

 
     return 0;
 }
 
 static int read_packet_gme(AVFormatContext *s, AVPacket *pkt)
 {
     GMEContext *gme = s->priv_data;
     int n_samples = AUDIO_PKT_SIZE / 2;
     int ret;
 
     if (gme_track_ended(gme->music_emu))
         return AVERROR_EOF;
 
     if ((ret = av_new_packet(pkt, AUDIO_PKT_SIZE)) < 0)
         return ret;
 
     if (gme_play(gme->music_emu, n_samples, (short *)pkt->data))
         return AVERROR_EXTERNAL;
     pkt->size = AUDIO_PKT_SIZE;
 
     return 0;
 }
 
 static int read_close_gme(AVFormatContext *s)
 {
     GMEContext *gme = s->priv_data;
     gme_free_info(gme->info);
     gme_delete(gme->music_emu);
     return 0;
 }
 
 static int read_seek_gme(AVFormatContext *s, int stream_idx, int64_t ts, int flags)
 {
     GMEContext *gme = s->priv_data;
     if (!gme_seek(gme->music_emu, (int)ts))
         return AVERROR_EXTERNAL;
     return 0;
 }
 

 static int probe_gme(const AVProbeData *p)

 {
     // Reads 4 bytes - returns "" if unknown format.
     if (gme_identify_header(p->buf)[0]) {
         if (p->buf_size < 16384)

             return AVPROBE_SCORE_MAX / 4 ;

         else
             return AVPROBE_SCORE_MAX / 2;
     }
     return 0;
 }
 
 static const AVClass class_gme = {
     .class_name = "Game Music Emu demuxer",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 AVInputFormat ff_libgme_demuxer = {
     .name           = "libgme",
     .long_name      = NULL_IF_CONFIG_SMALL("Game Music Emu demuxer"),
     .priv_data_size = sizeof(GMEContext),
     .read_probe     = probe_gme,
     .read_header    = read_header_gme,
     .read_packet    = read_packet_gme,
     .read_close     = read_close_gme,
     .read_seek      = read_seek_gme,
     .priv_class     = &class_gme,
 };