module Exercise06 where

import Data.List

import Effects
import Types

--Signal = Seconds -> Sample
sinPeriod :: Signal
sinPeriod x = sin (x * 2 * pi)

sqwPeriod :: Signal
sqwPeriod x = if x < 0.5 then -1 else 1

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

triPeriod :: Signal
triPeriod x = if x < 0.5 then 4 * x - 1 else -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))
--type Oscillator = Semitone -> Seconds -> Signal.
osc :: Signal -> ADSR -> Oscillator
osc sig vector semi duration x = adsr vector duration (help sig (f semi)) x

help:: Signal -> Hz -> Signal
help sig freq z = sig ((freq * z) - fromIntegral (floor (freq * z)))

adsr :: ADSR -> Seconds -> Signal -> Signal
adsr (a,d,s,r) duration sig x
        | x < a = sig x * (x / a) --attac
        | x < d + a = let m = (s - 1.0) / d; t = 1.0 - m * a in sig x * (m * x + t) -- decay
        | x < (duration - r) = sig x * s -- sustain: m = 0, t = s
        | otherwise = let m = - s / r; t = s - (m * ( duration - r)) in sig x * (m * x + t)  --release

mix :: [SampledSignal] -> SampledSignal
mix xss = hilp [[ x / fromIntegral(length xss) | x <- xs]| xs <- xss]

hilp:: [SampledSignal] -> SampledSignal
hilp = foldr bincomrec []

bincomrec:: SampledSignal -> SampledSignal -> SampledSignal
bincomrec [] [] = []
bincomrec [] ys = ys
bincomrec xs [] = xs
bincomrec (x:xs) (y:ys) = [x+y]  ++ bincomrec xs ys

bincom:: SampledSignal -> SampledSignal -> SampledSignal
bincom xs ys = [(xs `safeget` i) + (ys `safeget` i )| i <- [0.. (max(length xs) (length ys)) - 1]]

safeget:: SampledSignal -> Int -> Sample
safeget xs i = if i < (length xs) then (xs !! i) else 0.0

--this would be nice, but we did not learn how to "unwrap" Maybes yet, so not useful
(!!!)::[a] -> Int -> Maybe a
(!!!) xs i = if i < length xs then Just (xs !! i) else Nothing

{-WETT-}

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

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

bass :: Oscillator
bass = osc sinPeriod (0.001, 0.8, 0.1, 0.01)

-- 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 [piano, bass, lead]
    audioTracks = zipWith playNotes instrs tracks
    audioNoEffects = mixTracks audioTracks [0.5, 0.9, 0.2]

    {-MCCOMMENT the source MIDI is called "frosty.mid". run like specified in the exercise
    I got my source MIDI from http://www.telewerkstatt.at/midis_xmas.htm#.X95UrS335QI 
    There is a surprise change in about the middle, at 41 sec. 
    -}

    --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 = applyEffectToInterval(41, 154) (addEffects [echo 0.25, clip 0.15] audioNoEffects) bitcrusher

    -- 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 (10, 20) audioNoEffects echo
{-TTEW-}