--
-- Copyright Michael Orlitzky
--
-- http://michael.orlitzky.com/
--
-- This program 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 3 of the License, or
-- (at your option) any later version.
--
-- This program 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.
--
-- http://www.fsf.org/licensing/licenses/gpl.html
--

module Tnef.File where

import Data.Binary
import qualified Data.Binary.Get as BinaryGet
import qualified Data.Binary.Put as BinaryPut
import Data.Int (Int64)
import Tnef.Attachment
import Tnef.Object


-- A TNEF "file" has a signature at the top which should be the same
-- for all TNEF files. There's also a "key," which probably does
-- something, and looks to be unique. After that, there's a variable
-- number of objects (whose structure can be seen in TnefObject). The
-- "total bytes" thing is not part of the file. I'm just using it to
-- keep track of the bytes read for now (to make sure it equals the
-- size of the file when we're done).
data TnefFile = TnefFile { signature    :: Word32,
                           key          :: Word16,
                           first_object :: TnefObject,
                           total_bytes  :: Int64 }


-- Magicest of numbers
-- Important: Int doesn't guarantee 32 bits, so we
-- need to use the Integer type here.
tnef_signature :: Integer
tnef_signature = 0x223e9f78                  



instance Show TnefFile where
    show x = "Signature: " ++ (show (signature x)) ++ " (Correct: " ++ (show tnef_signature) ++ ")\n" ++
             "Key: " ++ (show (key x)) ++ "\n" ++
             concat (map show (get_object_list x)) -- Show the objects, one at a time


-- Recursively collect an array of objects. It dies
-- on the last one, which has no next_object property.
-- Help?
get_object_list :: TnefFile -> [TnefObject]
get_object_list x = get_successive_objects (first_object x)


get_successive_objects :: TnefObject -> [TnefObject]
get_successive_objects Nil = [Nil]
get_successive_objects x = (x : (get_successive_objects (next_object x)))


instance Binary TnefFile where
    put _ = do BinaryPut.putWord8 0
    get = do
      signature_word    <- BinaryGet.getWord32host
      key_word          <- BinaryGet.getWord16host
      first_object_word <- get :: Get TnefObject
      total_bytes_word  <- BinaryGet.bytesRead
      return (TnefFile { signature      = signature_word,
                         key            = key_word,
                         first_object   = first_object_word,
                         total_bytes    = total_bytes_word })


write_tnef_file :: TnefFile -> [IO ()]
write_tnef_file x = do
  let objects = get_object_list x
  let attachments = get_attachment_list objects
  map write_attachment attachments