module Exercise06 where

import Data.List

import Effects
import Types

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

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

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

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 at_de_su_re semitone duration = adsr at_de_su_re duration (signal . norm)
  where
    frequency = f semitone
    norm x = (x*frequency) - fromIntegral (floor (x*frequency))

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

mix :: [SampledSignal] -> SampledSignal
mix xss = foldr (mAdd . (\xs -> [x/fromIntegral len | x<-xs])) [] xss
  where
    len = length xss

mAdd :: Fractional a => [a] -> [a] -> [a]
mAdd [] ys = ys
mAdd xs [] = xs
mAdd (x:xs) (y:ys) = (x+y) : mAdd xs ys

{-WETT-}

-- 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)

-- you can add more effects here
lowCut :: Double -> DSPEffect
lowCut d = map (\sample -> if abs sample < d then 0 else sample)

echo :: Int -> DSPEffect 
echo d xs = [x+y | (x,y)<-zip xs (drop d (xs++[0.0 | x<-[1..d]]))]

smooth :: DSPEffect 
smooth xs = [(a+b+c+d)/4 | ((a,b),(c,d))<-zip (zip xs (drop 1 (xs++[0.0]))) (zip (drop 2 (xs++[0.0,0.0])) (drop 3 (xs++[0.0,0.0,0.0])))]

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

{-MCCOMMENT run:
  stack run synth mid/wwyamc.mid wwyamc.wav-}

-- 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 [piano, bass, lead, piano, bass]
    audioTracks = zipWith playNotes instrs tracks
    audioNoEffects = mixTracks audioTracks [0.8, 0.7]
    -- 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 [smooth, smooth, smooth, smooth, smooth, addGain 1.8, clip 0.8, echo 69200] 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-}