type oogg64 = (int * int * int * int);;
type oogg32 = (int * int);;

type serialNo = oogg32;;
type granulePos = oogg64 option;;
type checksum = oogg32;;
type sequenceNo = oogg32;;

(* raw byte streams *)
type stream = IO.input;;
type outStream = unit IO.output;;

(*
 * an oogg Page record
 *) 
type rawPage = 
  { continued : bool ;
    bos : bool ;
    eos : bool ;
    last_packet_complete : bool ;
    granulepos : granulePos ;
    serialno : serialNo ;
    sequenceno : sequenceNo ;
    checksum : checksum ;
    packet_sizes : int list ;
    raw_data : string list ;
  };;

(* media types *)
type mediaType = Skeleton | CMML | Vorbis | Theora | Unknown;;

type page = 
  { raw : rawPage ;
    time : float option; 
    identity : mediaType
  };;

type rawPageStream  = rawPage Stream.t;;

type pageStream = page Stream.t;;

(* the type of a media stream *)
type mediaStream =
  { stream_serialno : serialNo ;
    stream_pages : rawPageStream ;
    stream_type : mediaType ;
    stream_time : (granulePos -> float option) 
  };;

let oogg32_to_int64 (a, b) =
    Int64.add (Int64.of_int b) (Int64.shift_left (Int64.of_int a) 16);; 

let oogg64_to_int64 (a,b,c,d) =
  if (a,b,c,d) = (65535, 65535, 65535, 65535) then -1L else
  Int64.add 
    (oogg32_to_int64 (c,d)) 
    (Int64.shift_left (oogg32_to_int64 (a,b)) 32);;

let int64_to_oogg32 value =
    (Int64.to_int (Int64.shift_right value 16),
    Int64.to_int (Int64.logand value (Int64.of_int 0xFFFF)));;

let int64_to_oogg64 value =
  let mask = Int64.of_int 0xFFFF in
  (Int64.to_int (Int64.shift_right value 48),
   Int64.to_int (Int64.logand (Int64.shift_right value 32) mask),
   Int64.to_int (Int64.logand (Int64.shift_right value 16) mask),
   Int64.to_int (Int64.logand value mask));;

let oogg64_to_float (a,b,c,d) = 
  if (a,b,c,d) = (65535, 65535, 65535, 65535) then -1.0 else
  float_of_int a *. (256. ** 6.) +.
  float_of_int b *. (256. ** 4.) +.
  float_of_int c *. (256. ** 2.) +.
  float_of_int d;;

let oogg32_to_string value = Int64.to_string (oogg32_to_int64 value);;

let print_oogg32 value = 
  print_string (oogg32_to_string value)

let print_oogg64 (a,b,c,d) =
  if a > 0 then
    Printf.printf "%x%04x%04x%04x" a b c d
  else if b > 0 then
    Printf.printf "%x%04x%04x" b c d
  else if c > 0 then
    Printf.printf "%x%04x" c d
  else
    Printf.printf "%x" d;;

let print_granulepos gp = match gp with
  | None -> Printf.printf "None"
  | Some gp -> print_oogg64 gp;;

let print_mediaType t = print_string (match t with
  | Skeleton -> "Skeleton"
  | CMML     -> "CMML"
  | Vorbis   -> "Vorbis"
  | Theora   -> "Theora"
  | Unknown  -> "Unknown!");;

type packet = 
  { p_data : string ;
    mutable p_granulepos : granulePos ;
    mutable p_time : float option ;
    p_pageno : int ;
    p_serialno : serialNo ;
    p_continued : bool ;
    p_continues : bool ;
    p_page_seq : sequenceNo ;
    p_identity : mediaType ;
    p_bos : bool ;
    p_eos : bool 
  };;

type packetStream = packet Stream.t;;

let read_ui32 stream =
  let b = IO.read_ui16 stream in
  let a = IO.read_ui16 stream in
  Int64.add (Int64.shift_left (Int64.of_int a) 16) (Int64.of_int b);;

let mask = Int64.of_int 0xFFFF
  
let write_ui32 stream value =
  let a = Int64.to_int (Int64.shift_right value 16) in
  let b = Int64.to_int (Int64.logand value mask) in
  IO.write_ui16 stream b;
  IO.write_ui16 stream a;;

let read_oogg64 stream = 
    (IO.read_ui16 stream, IO.read_ui16 stream, IO.read_ui16 stream,
        IO.read_ui16 stream);;

let write_oogg64 stream (a, b, c, d) = 
    IO.write_ui16 stream d; IO.write_ui16 stream c; 
    IO.write_ui16 stream b; IO.write_ui16 stream a;;

let read_oogg32 stream = 
    (IO.read_ui16 stream, IO.read_ui16 stream);;

let write_oogg32 stream (a, b) =
    IO.write_ui16 stream b; IO.write_ui16 stream a;;

let read_granulepos stream =
  let gp = read_oogg64 stream in 
  if gp = (0xFFFF,0xFFFF,0xFFFF,0xFFFF) then None else Some gp;;

let write_granulepos stream gp = match gp with
  | None -> write_oogg64 stream (0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF)
  | Some gp -> write_oogg64 stream gp;;

let extract_be_int32 str pos = 
  let substr = IO.input_string (String.sub str pos 4) in
  let a = IO.read_byte substr in
  let b = IO.read_byte substr in
  let c = IO.read_byte substr in
  let d = IO.read_byte substr in
  let e = (a lsl 8) + b in
  let f = (c lsl 8) + d in
  Int64.add (Int64.shift_left (Int64.of_int e) 16) (Int64.of_int f);;

let extract_le_int32 str pos = 
  let substr = IO.input_string (String.sub str pos 4) in
  let d = IO.read_byte substr in
  let c = IO.read_byte substr in
  let b = IO.read_byte substr in
  let a = IO.read_byte substr in
  let e = (a lsl 8) + b in
  let f = (c lsl 8) + d in
  Int64.add (Int64.shift_left (Int64.of_int e) 16) (Int64.of_int f);;

let extract_le_int64 str pos = 
  let a = extract_le_int32 str pos in
  let b = extract_le_int32 str (pos + 4) in
  Int64.add (Int64.shift_left a 32) b;;
 
let extract_int8 str pos = 
  let substr = IO.input_string (String.sub str pos 1) in
  IO.read_byte substr;;

let extract_le_oogg64 str pos =
  let substr = IO.input_string (String.sub str pos 8) in read_oogg64 substr;;