module Effects where
    
import Data.List
import Types

addEffects :: [DSPEffect] -> SampledSignal -> SampledSignal
addEffects = foldr (.) id

applyEffectToInterval :: (Seconds, Seconds) -> SampledSignal -> DSPEffect -> SampledSignal
applyEffectToInterval (from, to) signal effect
  -- assert that from >= 0, to - from >= 0, to <= length signal and simply return original signal if constraints aren't met
  | from < 0 || from > to || samplesPerSecond to > length signal = signal
  | otherwise =
    samplesBefore ++ samplesDuring ++ samplesAfter where
      samplesBefore = take nSamplesBefore signal -- unaffected
      samplesDuring = effect $ take nSamplesDuring signal -- effected
      samplesAfter  = drop (nSamplesBefore + nSamplesDuring) signal -- unaffected

      nSamplesBefore = samplesPerSecond from
      nSamplesDuring = samplesPerSecond (to - from)

gain :: Double
gain = 2.0

clippingThreshold :: Double
clippingThreshold = 0.8

clip :: Double -> DSPEffect
clip threshold = map (\sample -> if sample > 0 then min threshold sample else max (negate threshold) sample) -- clip positive and negative samples

addGain :: Double -> DSPEffect
addGain value = map (* value)

distortion :: DSPEffect
distortion = clip clippingThreshold . addGain gain

-- add more effects here

addActualGain :: Double -> DSPEffect
addActualGain vol [] = []
addActualGain vol (s:ss) = (s*vol/fromIntegral(length ss)) : addActualGain vol ss

tremolo :: (Double, Double) -> DSPEffect
tremolo (min,max) [] = []
tremolo (min,max) (s:ss) = (s*min) : tremolo (max,min) ss

slowTremolo :: (Double, Double) -> Int -> Int -> DSPEffect
slowTremolo (min,max) rep i [] = []
slowTremolo (min,max) rep 0 (s:ss) = (s*min) : slowTremolo (max,min) rep rep ss
slowTremolo (min,max) rep i (s:ss) = (s*min) : slowTremolo (min,max) rep (i-1) ss

bitCrunchSpeed :: DSPEffect
bitCrunchSpeed [] = []
bitCrunchSpeed (x:y:xs) = x:bitCrunchSpeed xs
bitCrunchSpeed (x:xs) = x:bitCrunchSpeed xs

bitCrunch :: DSPEffect
bitCrunch [] = []
bitCrunch (x:_:xs) = x:x:bitCrunch xs
bitCrunch (x:xs) = x:bitCrunch xs

wreck :: Double -> Double -> Double -> DSPEffect
wreck i add factor [] = []
wreck i add factor (x:xs) = (x * (1 + factor * sin i)) : wreck (i+add) add factor xs