(*
 * Copyright 2003-2011 Savonet team
 *
 * This file is part of Ocaml-vorbis.
 *
 * Ocaml-vorbis is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Ocaml-vorbis 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Ocaml-vorbis; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *)

let check = Vorbis.Decoder.check_packet

let buflen = 1024

let decoder os =
  let decoder = ref None in
  let packet1 = ref None in
  let packet2 = ref None in
  let packet3 = ref None in
  let os = ref os in
  let init () = 
    match !decoder with
      | None -> 
         let packet1 =
           match !packet1 with
             | None ->
                let p = Ogg.Stream.get_packet !os in
                packet1 := Some p; p
             | Some p -> p
         in
         let packet2 = 
           match !packet2 with
             | None -> 
                let p = Ogg.Stream.get_packet !os in
                packet2 := Some p; p
             | Some p -> p
         in
         let packet3 = 
           match !packet3 with
             | None ->
                 let p = Ogg.Stream.get_packet !os in
                 packet3 := Some p; p
             | Some p -> p
         in
         let d = Vorbis.Decoder.init packet1 packet2 packet3 in
         let info = Vorbis.Decoder.info d in
         (* This buffer is created once. The call to Array.sub
          * below makes a fresh array out of it to pass to
          * liquidsoap. *)
         let chan _ = Array.make buflen 0. in
         let buf = Array.init info.Vorbis.audio_channels chan in
         let meta =  Vorbis.Decoder.comments d in
         decoder := Some (d,info,buf,meta);
         d,info,buf,meta
      | Some d -> d
  in
  let info () = 
    let (_,info,_,meta) = init () in
    { Ogg_demuxer.
       channels = info.Vorbis.audio_channels;
       sample_rate = info.Vorbis.audio_samplerate },meta
  in
  let restart new_os = 
    os := new_os;
    let (d,_,_,_) = init () in
    Vorbis.Decoder.restart d
  in
  let decode feed =
    let decoder,_,buf,_ = init () in 
    try
      let ret = Vorbis.Decoder.decode_pcm decoder !os buf 0 buflen in
      feed (Array.map (fun x -> Array.sub x 0 ret) buf)
    with
      (* Apparently, we should hide this one.. *)
      | Vorbis.False -> raise Ogg.Not_enough_data
  in
  Ogg_demuxer.Audio
    { Ogg_demuxer.
       name = "vorbis";
       info = info;
       decode = decode;
       restart = restart;
       samples_of_granulepos = (fun x -> x) }

let register () = 
  Hashtbl.add Ogg_demuxer.ogg_decoders "vorbis" (check,decoder)
