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 $ drop nSamplesBefore signal -- effected
      samplesAfter  = drop (nSamplesBefore + nSamplesDuring) signal -- unaffected

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

{-
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 ++ take nSamplesDuring samplesDuring ++ samplesOverlap ++ drop overlap samplesAfter where
      samplesBefore = take nSamplesBefore signal -- unaffected
      samplesDuring = effect $ take nSamplesDuring $ drop nSamplesBefore signal -- effected
      samplesAfter  = drop (nSamplesBefore + nSamplesDuring) signal -- unaffected
      samplesOverlap = map sum $ transpose [drop nSamplesDuring samplesDuring, take overlap samplesAfter]

      nSamplesBefore = samplesPerSecond from
      nSamplesDuring = samplesPerSecond (to - from)
      overlap = length samplesDuring - nSamplesDuring
-}

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

-- works meh when applied to an interval
echo :: DSPEffect 
echo prev = map sum $ transpose [prev, map (/ 1.5) $ delay 0.15 prev]

delay :: Double -> DSPEffect 
delay n prev = replicate (samplesPerSecond n) 0 ++ prev

-- 10 - 100 sounds decent-ish
reduceSmplRate :: Int -> DSPEffect
reduceSmplRate n prev = concatMap (replicate n) (shortener prev)
  where shortener [] = []
        shortener xs = head xs : shortener (drop n xs)

-- cuts every sample after the log(n)-th decimal place
reduceResolution :: Double -> DSPEffect 
reduceResolution n = map (\x -> fromInteger (truncate (x * n)) / n)