/*

  * Simon & Schuster Interactive VAG (de)muxer

  *
  * Copyright (C) 2020 Zane van Iperen (zane@zanevaniperen.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 "avformat.h"
 #include "internal.h"

 #include "rawenc.h"

 #include "libavutil/intreadwrite.h"
 
 #define KVAG_TAG            MKTAG('K', 'V', 'A', 'G')
 #define KVAG_HEADER_SIZE    14
 #define KVAG_MAX_READ_SIZE  4096
 
 typedef struct KVAGHeader {
     uint32_t    magic;
     uint32_t    data_size;
     uint32_t    sample_rate;
     uint16_t    stereo;
 } KVAGHeader;
 

 #if CONFIG_KVAG_DEMUXER

 static int kvag_probe(const AVProbeData *p)
 {
     if (AV_RL32(p->buf) != KVAG_TAG)
         return 0;
 
     return AVPROBE_SCORE_EXTENSION + 1;
 }
 
 static int kvag_read_header(AVFormatContext *s)
 {
     int ret;
     AVStream *st;
     KVAGHeader hdr;
     AVCodecParameters *par;
     uint8_t buf[KVAG_HEADER_SIZE];
 
     if (!(st = avformat_new_stream(s, NULL)))
         return AVERROR(ENOMEM);
 
     if ((ret = avio_read(s->pb, buf, KVAG_HEADER_SIZE)) < 0)
         return ret;
     else if (ret != KVAG_HEADER_SIZE)
         return AVERROR(EIO);
 
     hdr.magic                   = AV_RL32(buf +  0);
     hdr.data_size               = AV_RL32(buf +  4);
     hdr.sample_rate             = AV_RL32(buf +  8);
     hdr.stereo                  = AV_RL16(buf + 12);
 
     par                         = st->codecpar;
     par->codec_type             = AVMEDIA_TYPE_AUDIO;
     par->codec_id               = AV_CODEC_ID_ADPCM_IMA_SSI;
     par->format                 = AV_SAMPLE_FMT_S16;
 
     if (hdr.stereo) {
         par->channel_layout     = AV_CH_LAYOUT_STEREO;
         par->channels           = 2;
     } else {
         par->channel_layout     = AV_CH_LAYOUT_MONO;
         par->channels           = 1;
     }
 
     par->sample_rate            = hdr.sample_rate;
     par->bits_per_coded_sample  = 4;
     par->bits_per_raw_sample    = 16;
     par->block_align            = 1;
     par->bit_rate               = par->channels *
                                   par->sample_rate *
                                   par->bits_per_coded_sample;
 
     avpriv_set_pts_info(st, 64, 1, par->sample_rate);
     st->start_time              = 0;
     st->duration                = hdr.data_size *
                                   (8 / par->bits_per_coded_sample) /
                                   par->channels;
 
     return 0;
 }
 
 static int kvag_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     int ret;
     AVCodecParameters *par = s->streams[0]->codecpar;
 
     if ((ret = av_get_packet(s->pb, pkt, KVAG_MAX_READ_SIZE)) < 0)
         return ret;
 
     pkt->flags          &= ~AV_PKT_FLAG_CORRUPT;
     pkt->stream_index   = 0;
     pkt->duration       = ret * (8 / par->bits_per_coded_sample) / par->channels;
 
     return 0;
 }
 
 AVInputFormat ff_kvag_demuxer = {
     .name           = "kvag",
     .long_name      = NULL_IF_CONFIG_SMALL("Simon & Schuster Interactive VAG"),
     .read_probe     = kvag_probe,
     .read_header    = kvag_read_header,
     .read_packet    = kvag_read_packet
 };

 #endif
 
 #if CONFIG_KVAG_MUXER
 static int kvag_write_init(AVFormatContext *s)
 {
     AVCodecParameters *par;
 
     if (s->nb_streams != 1) {
         av_log(s, AV_LOG_ERROR, "KVAG files have exactly one stream\n");
         return AVERROR(EINVAL);
     }
 
     par = s->streams[0]->codecpar;
 
     if (par->codec_id != AV_CODEC_ID_ADPCM_IMA_SSI) {
         av_log(s, AV_LOG_ERROR, "%s codec not supported\n",
                avcodec_get_name(par->codec_id));
         return AVERROR(EINVAL);
     }
 
     if (par->channels > 2) {
         av_log(s, AV_LOG_ERROR, "KVAG files only support up to 2 channels\n");
         return AVERROR(EINVAL);
     }
 
     if (!(s->pb->seekable & AVIO_SEEKABLE_NORMAL)) {
         av_log(s, AV_LOG_WARNING, "Stream not seekable, unable to write output file\n");
         return AVERROR(EINVAL);
     }
 
     return 0;
 }
 
 static int kvag_write_header(AVFormatContext *s)
 {
     uint8_t buf[KVAG_HEADER_SIZE];
     AVCodecParameters *par = s->streams[0]->codecpar;
 
     AV_WL32(buf +  0, KVAG_TAG);
     AV_WL32(buf +  4, 0); /* Data size, we fix this up later. */
     AV_WL32(buf +  8, par->sample_rate);
     AV_WL16(buf + 12, par->channels == 2);
 
     avio_write(s->pb, buf, sizeof(buf));
     return 0;
 }
 
 static int kvag_write_trailer(AVFormatContext *s)
 {
     int64_t file_size, data_size;
 
     file_size = avio_tell(s->pb);
     data_size = file_size - KVAG_HEADER_SIZE;
     if (data_size < UINT32_MAX) {
         avio_seek(s->pb, 4, SEEK_SET);
         avio_wl32(s->pb, (uint32_t)data_size);
         avio_seek(s->pb, file_size, SEEK_SET);
     } else {
         av_log(s, AV_LOG_WARNING,
                "Filesize %"PRId64" invalid for KVAG, output file will be broken\n",
                file_size);
     }
 
     return 0;
 }
 
 AVOutputFormat ff_kvag_muxer = {
     .name           = "kvag",
     .long_name      = NULL_IF_CONFIG_SMALL("Simon & Schuster Interactive VAG"),
     .extensions     = "vag",
     .audio_codec    = AV_CODEC_ID_ADPCM_IMA_SSI,
     .video_codec    = AV_CODEC_ID_NONE,
     .init           = kvag_write_init,
     .write_header   = kvag_write_header,
     .write_packet   = ff_raw_write_packet,
     .write_trailer  = kvag_write_trailer
 };
 #endif