import Codec.Midi ( exportFile, importFile )
import Codec.Midi
import Data.Audio ( Audio(Audio) )
import Data.Array.Unboxed ( listArray, elems )
import Data.Int ( Int32 )
import Data.Maybe ( fromMaybe )
import System.IO (FilePath)

outMain :: FilePath -> IO ()
outMain path = do
  let track0 = [(0,  NoteOn 0 60 80),
            (24, NoteOff 0 60 0),
            (0,  TrackEnd)]

  let track1 = [(0,  NoteOn 0 64 80),
            (24, NoteOn 0 64 0),
            (0,  TrackEnd)]

  let myMidi = Midi { fileType = MultiTrack,
                      timeDiv = TicksPerBeat 24,
                      tracks = [track0, track1] }

  exportFile path myMidi

inMain :: FilePath -> IO ()
inMain path = do
  maybeAudio <- importFile path
  case maybeAudio :: Either String (Midi) of
    Left s -> putStrLn $ "wav decoding error: " ++ s
    Right (Midi fileType timeDiv tracks) -> do
      putStrLn $ "fileType = " ++ show fileType
      putStrLn $ "timeDiv: " ++ show timeDiv

main = do
  putStrLn $ "* Outputting the sound to "++"sample.mid"
  outMain "sample.mid"
  putStrLn $ "* Printing the content of "++"sample.mid"
  inMain "sample.mid"