module Exercise06 where

import Data.List

import Effects
import Types
{-WETT-}
sinPeriod :: Signal
sinPeriod x = sin (x*(2*pi))

sqwPeriod :: Signal
sqwPeriod 0.5 = 0
sqwPeriod x
    |x < 0.5 = -1
    |x > 0.5 = 1

sawPeriod :: Signal
sawPeriod x = 2*x - 1

triPeriod :: Signal
triPeriod x
    |x <= 0.5 = 4*x-1
    |x > 0.5 = -4*x+3

silence :: Signal
silence = (*) 0

-- NOTE: the formula is taken from https://pages.mtu.edu/~suits/NoteFreqCalcs.html
f :: Semitone -> Hz
f n = 440.0 * (2 ** (fromInteger n / 12.0))

osc :: Signal -> ADSR -> Oscillator
osc s a t x = adsr a x (\y -> s (y*f t - fromIntegral (floor $ y * f t)))

adsr :: ADSR -> Seconds -> Signal -> Signal
adsr (a, d, s, r) t g x
  | x < a = h * x / a
  | x < (a + d) = h * (x* (s - 1) / d + ((1*(a+d)-s*a)/d))
  | x < t-r = h*s
  | x <= t = h*(x*(-s)/r + ((s*t)/r))
  | otherwise = undefined
  where
      h = g x

mix :: [SampledSignal] -> SampledSignal
mix ss = map sum $ transpose $ map (map (\ x -> x / fromIntegral (length ss))) ss

-- you can add new oscillators here
piano :: Oscillator
piano = osc sawPeriod (0.01, 0.1, 0.7, 0.2)

lead :: Oscillator
lead = osc sqwPeriod (0.25, 0.2, 0.3, 0.1)

bass :: Oscillator
bass = osc sinPeriod (0.001, 0.2, 0.9, 0.1)

tri :: Oscillator
tri = osc triPeriod (0.05, 3, 0.4, 1)

-- you can add more effects here

{-MCCOMMENT best to use with wilhelmus.mid 
stack run synth mid/wilhelmus.mid wilhelmus.wav 
(or stack run snyth "mid/"oh du froh.mid" ohdu.wav for a more seasonal variaton) -}

-- mix the signals with some volume
mixTracks :: [SampledSignal] -> [Double] -> SampledSignal
mixTracks trks vols = mix $ zipWith (\trk vol -> map (* vol) trk) trks vols

-- here we mix it all together and apply the effects
notesToSignal :: (Oscillator -> [Note] -> SampledSignal) -> [[Note]] -> SampledSignal
notesToSignal playNotes tracks = audio
  where
    -- specify the instruments of each track
    -- try the following instruments with the mario.mid file
    instrs = cycle [tri, lead, bass]
    audioTracks = zipWith playNotes instrs tracks
    audioNoEffects = mixTracks audioTracks [0.8, 0.7, 0.6]
    --audio = audioNoEffects
    -- To add effects, replace the line above by the line at the end of this comment and change the list off effects to your own effects.
    -- Note that the effects are applied from right to left, ie. the rightmost effect is applied first.
    audio = addEffects [clip 0.9, mult] audioNoEffects

    -- If you want to apply an effect only to parts of the signal, you can use the function applyEffectToInterval, as shown below.
    -- Thereby the first argument specifies the interval to which the effect should be applied in seconds.
    -- audio = applyEffectToInterval (2, 6) audioNoEffects distortion

{-TTEW-}