/*
  * RedSpark demuxer
  * Copyright (c) 2013 James Almer
  *
  * 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 "libavcodec/bytestream.h"
 #include "libavutil/intreadwrite.h"
 #include "avformat.h"
 #include "avio.h"
 #include "internal.h"
 
 #define HEADER_SIZE 4096
 
 typedef struct RedSparkContext {
     int         samples_count;
 } RedSparkContext;
 
 static int redspark_probe(AVProbeData *p)
 {
     uint32_t key, data;
     uint8_t header[8];
 
     /* Decrypt first 8 bytes of the header */
     data = AV_RB32(p->buf);
     data = data ^ (key = data ^ 0x52656453);
     AV_WB32(header, data);
     key = (key << 11) | (key >> 21);
 
     data = AV_RB32(p->buf + 4) ^ (((key << 3) | (key >> 29)) + key);
     AV_WB32(header + 4, data);
 
     if (AV_RB64(header) == AV_RB64("RedSpark"))
         return AVPROBE_SCORE_MAX;
 
     return 0;
 }
 
 static int redspark_read_header(AVFormatContext *s)
 {
     AVIOContext *pb = s->pb;
     RedSparkContext *redspark = s->priv_data;
     AVCodecContext *codec;
     GetByteContext gbc;

     int i, coef_off, ret = 0;

     uint32_t key, data;
     uint8_t *header, *pbc;
     AVStream *st;
 
     st = avformat_new_stream(s, NULL);
     if (!st)
         return AVERROR(ENOMEM);
     codec = st->codec;
 

     header = av_malloc(HEADER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);

     if (!header)
         return AVERROR(ENOMEM);
     pbc = header;
 
     /* Decrypt header */
     data = avio_rb32(pb);
     data = data ^ (key = data ^ 0x52656453);
     bytestream_put_be32(&pbc, data);
     key = (key << 11) | (key >> 21);
 
     for (i = 4; i < HEADER_SIZE; i += 4) {
         data = avio_rb32(pb) ^ (key = ((key << 3) | (key >> 29)) + key);
         bytestream_put_be32(&pbc, data);
     }
 
     codec->codec_id    = AV_CODEC_ID_ADPCM_THP;
     codec->codec_type  = AVMEDIA_TYPE_AUDIO;
 
     bytestream2_init(&gbc, header, HEADER_SIZE);
     bytestream2_seek(&gbc, 0x3c, SEEK_SET);
     codec->sample_rate = bytestream2_get_be32u(&gbc);
     if (codec->sample_rate <= 0 || codec->sample_rate > 96000) {
         av_log(s, AV_LOG_ERROR, "Invalid sample rate: %d\n", codec->sample_rate);

         ret = AVERROR_INVALIDDATA;
         goto fail;

     }
 
     st->duration = bytestream2_get_be32u(&gbc) * 14;
     redspark->samples_count = 0;
     bytestream2_skipu(&gbc, 10);
     codec->channels = bytestream2_get_byteu(&gbc);

     if (!codec->channels) {
         ret = AVERROR_INVALIDDATA;
         goto fail;
     }

 
     coef_off = 0x54 + codec->channels * 8;
     if (bytestream2_get_byteu(&gbc)) // Loop flag
         coef_off += 16;
 

     if (coef_off + codec->channels * (32 + 14) > HEADER_SIZE) {
         ret = AVERROR_INVALIDDATA;
         goto fail;
     }
 

     if (ff_alloc_extradata(codec, 32 * codec->channels)) {

         ret = AVERROR(ENOMEM);
         goto fail;
     }

 
     /* Get the ADPCM table */
     bytestream2_seek(&gbc, coef_off, SEEK_SET);
     for (i = 0; i < codec->channels; i++) {

         if (bytestream2_get_bufferu(&gbc, codec->extradata + i * 32, 32) != 32) {
             ret = AVERROR_INVALIDDATA;
             goto fail;
         }

         bytestream2_skipu(&gbc, 14);
     }
 
     avpriv_set_pts_info(st, 64, 1, codec->sample_rate);
 

 fail:
     av_free(header);
 
     return ret;

 }
 
 static int redspark_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     AVCodecContext *codec = s->streams[0]->codec;
     RedSparkContext *redspark = s->priv_data;
     uint32_t size = 8 * codec->channels;
     int ret;
 
     if (url_feof(s->pb) || redspark->samples_count == s->streams[0]->duration)
         return AVERROR_EOF;
 
     ret = av_get_packet(s->pb, pkt, size);
     if (ret != size) {
         av_free_packet(pkt);
         return AVERROR(EIO);
     }
 
     pkt->duration = 14;
     redspark->samples_count += pkt->duration;
     pkt->stream_index = 0;
 
     return ret;
 }
 
 AVInputFormat ff_redspark_demuxer = {
     .name           =   "redspark",
     .long_name      =   NULL_IF_CONFIG_SMALL("RedSpark"),
     .priv_data_size =   sizeof(RedSparkContext),
     .read_probe     =   redspark_probe,
     .read_header    =   redspark_read_header,
     .read_packet    =   redspark_read_packet,
     .extensions     =   "rsd",
 };