module Exercise06 where

import Data.List
import Effects
import Types

sinPeriod :: Signal
sinPeriod x = sin (2 * pi * x)

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

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

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

silence :: Signal
silence = undefined

-- 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 signal params semitone duration = adsr params duration (\s -> signal $ s * f semitone - (fromIntegral . floor) (s * f semitone))

adsr :: ADSR -> Seconds -> Signal -> Signal
adsr (attack, decay, sustain, release) duration signal seconds
  | seconds <= attack = seconds / attack * signal seconds
  | seconds <= attack + decay = (1 + (sustain -1) * (seconds - attack) / decay) * signal seconds
  | seconds <= duration - release = sustain * signal seconds
  | otherwise = sustain / release * (duration - seconds) * signal seconds

mix :: [SampledSignal] -> SampledSignal
mix ss = foldr (zipWith (+) . map (/ (fromIntegral . length) ss) . (\xs -> xs ++ replicate (maxi - length xs) 0)) (replicate maxi 0) ss
  where
    maxi = maximum (map length ss)

{-WETT-}

{-MCCOMMENT 
  compile with stack run synth .\mid\song_of_storms_organ.mid .\mid\song_of_storms_organ.wav
-}

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

lead :: Oscillator
lead = osc sqwPeriod (0.01, 0.2, 0.3, 0.1)

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

organ :: Oscillator
organ = osc (sawNPeriod 3) (0.1, 0.05, 0.7, 0.05)

--returns the nth partial sum of the Fourier series that converges to the sawtooth wave
sawNPeriod :: Int -> Signal
sawNPeriod n x = (-2 / pi) * sum (take n (snd $ mapAccumL (\a b -> (a + 1, sin b / a)) 1 (iterate (* 2) (2 * pi * x)))) 

-- you can add more effects here

-- 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 [organ, piano]
    audioTracks = zipWith playNotes instrs tracks
    audioNoEffects = mixTracks audioTracks [0.8, 0.05]
    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, addGain 4] 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-}