module Exercise06 where

import Data.List (transpose)

import Effects ( addEffects, clip, addGain ) 
import Types

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

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

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

triPeriod :: Signal
triPeriod d 
  | d < 0.5 = 4*d-1
  | otherwise = -4*d+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 ad semitone duration = adsr ad duration fpshift
  where t = 1 / f semitone
        fpshift = \x -> fp (x / t) -- a new signal with the right periode
        fp = \x -> signal (x - 1 - fromInteger (floor (x - 1)))  -- repeat the input signal within the duration

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

mix :: [SampledSignal] -> SampledSignal
mix xs = let l = length xs 
             sg = map sum (transpose xs) in map (\a -> (a::Double) / fromIntegral l) sg


{-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)

harmonica :: Oscillator 
harmonica =  osc sawPeriod (0.98, 0.89, 0.02, 0.83)

electronic :: Oscillator 
electronic = osc sawPeriod (0.98, 0.02, 8, 0.83)

eightBit :: Oscillator 
eightBit = osc sqwPeriod (0.01, 0.09, 0.01, 0.01)

-- you can add more effects here
chorusEffect :: DSPEffect 
chorusEffect s = [x  + 0.75 * delay x | x <- s]
  where delay x = harmonica (-92) 0.3 x

flanger :: DSPEffect 
flanger s = [x + 0.75 * delay x | x <- s]
  where delay x = 0.1 * eightBit (-160) 0.1 x

amplitude :: DSPEffect 
amplitude s = [1.8 * x | x <- s]

noise :: DSPEffect 
noise s = [3 * (x ** 2) - 2 * (x ** 3) | x <- s]

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


{-MCCOMMENT: stack run synth star.mid star.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 [bass, electronic]
    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 [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 = addEffects [chorusEffect, addGain 1, noise, flanger] audioNoEffects
{-TTEW-}