{-# LANGUAGE Arrows #-}

module RMCA.Translator.Note where

import Data.Ratio
import FRP.Yampa
import RMCA.Global.Clock
import RMCA.Semantics
import RMCA.Translator.Message

messageToNote :: Message -> Note
messageToNote (NoteOn _ p s) = Note { notePch = p
                                    , noteStr = s
                                    , noteDur = 1 % 4
                                    , noteOrn = noOrn
                                    }
messageToNote m = error $ "In messageToNote: the message "
                  ++ show m ++ " is not a note message"

-- noteToMessage gives a pair of two time-stamped messages. The one on
-- the left is a note message, the other a note off.
noteToMessages :: LTempo
               -> SampleRate
               -> Int -- Channel number
               -> (Frames,Note) -- Note to convert
               -> [(Frames,Message)]
noteToMessages layTempo sr chan =
  proc (t,n@Note { noteDur = d }) -> do
    nm <- noteOnToMessage chan -< n
    let dt :: Double
        dt = fromRational (d * toRational (tempoToQNoteIvl layTempo))
        dn :: Int
        dn = floor $ dt * fromIntegral sr
    returnA -< [(t,nm),(t + dn,switchOnOff nm)]

noteOnToMessage :: Int -> Note -> Message
noteOnToMessage c Note { notePch = p
                       , noteStr = s
                       } = NoteOn (makeChannel c) p s