import Control.Monad.Random.Strict (MonadRandom, join, getRandom, getRandoms, getRandomR, uniform, fromList)

shrinkAbiCall (name, vals) = do

let numShrinkable = length $ filter canShrinkAbiValue vals

halfwayVal <- getRandomR (0, numShrinkable)

-- This list was made arbitrarily. Feel free to change

let numToShrinkOptions = [1, 2, halfwayVal, numShrinkable]

numToShrink <- min numShrinkable <$> uniform numToShrinkOptions

shrunkVals <- shrinkVals (fromIntegral numShrinkable) (fromIntegral numToShrink) vals

pure (name, shrunkVals)

where

shrinkVals 0 _ l = pure l

shrinkVals _ 0 l = pure l

shrinkVals _ _ [] = pure []

shrinkVals numShrinkable numToShrink (h:t)

| not (canShrinkAbiValue h) = (h:) <$> shrinkVals numShrinkable numToShrink t

| otherwise = do

-- We want to pick which ones to shrink uniformly from the vals list.

-- Odds of shrinking one element is numToShrink/numShrinkable.

shouldShrink <- fromList [(True, numToShrink), (False, numShrinkable-numToShrink)]

h' <- if shouldShrink then shrinkAbiValue h else pure h

let

numShrinkable' = numShrinkable-1

numToShrink' = if shouldShrink then numToShrink-1 else numToShrink

(h':) <$> shrinkVals numShrinkable' numToShrink' t