-- | Tirages.
module Htirage.Draw where

import Htirage.Bits

-- * Sélection de choix

-- | @draw1 bs cs@ retourne un choix de la liste de choix 'cs'
-- déterminé par le premier nombre binaire formé par l’entropie 'bs'
-- qui a le potentiel d’atteindre tous les choix,
-- et qui en atteint effectivement un.
draw1 :: [Bool] -> [a] -> a
draw1 bs cs
 | given < enough = error (show (enough - given) ++ " missing bits")
 | i > iMax       = draw1 (tail bits ++ bs') cs
 | otherwise      = cs !! i
	where (bits, bs') = splitAt enough bs
	      i           = intOfBits bits
	      iMax        = length cs - 1
	      enough      = nbBits iMax
	      given       = length bs

{-
-- | @drawComb k cs ns@ retourne les 'k' choix parmi 'cs', déterminés par les bits 'bs'.
drawComb :: Int -> [a] -> [Bool] -> [a]
drawComb k cs bs = draw1 bs (k`combs'Dyn`cs)
drawComb k cs bs =
 | given < enough = error (show (enough - given) ++ " missing bits")
 | i > iMax       = drawComb k (tail bits ++ bs') cs
 | otherwise      = combOfRank k n i `applyPerm` cs
	where (bits, bs') = splitAt enough bs
	      n           = length cs
	      i           = intOfBits bits
	      iMax        = pred n
	      enough      = nbBits iMax
	      given       = length bs
-}
{-
pr l = putStrLn (foldMap (\x -> show x ++ " ") l)

res = forM_ (zipWith (,) [0..] $ allCombsB 5 9) (\(i,l) -> putStr (show i ++ ":  ") >> pr l)
allCombsB k n = combAt'Buckles k n <$> [0..k`combsIn`n - 1]
-}