import System.IO
import System.Random
import Control.Monad
import Data.List
import Data.Maybe

main :: IO ()
main = hSetEncoding stdout utf8 >> mapM_ (christmasTree >=> putStrLn) [1..7]

ornaments :: [Char]
ornaments = "*NiXJo%b"

christmasTree :: Int -> IO String
christmasTree h = do
  is <- mapM (flip replicateM (rollIkasamaDice dist)) ws
  let body   = ["☆"] ++ map (map (ornaments !!)) is ++ ["||"]
      indent = reverse $ map spacer $ [h - 1] ++ map (`div` 2) ws ++ [h - 1]
  return $ unlines $ zipWith (++) indent body
  where
    dist = 30 : replicate (length ornaments - 1) 1
    ws   = [2, 4 .. (h - 1) * 2]
    spacer = flip replicate ' '

rollIkasamaDice :: [Double] -> IO Int
rollIkasamaDice dist = do
  r <- getStdRandom (randomR (0, 1)) :: IO Double
  return $ snd $ fromJust $ find ((r <=) . fst) dice
  where
    thr  = scanl1 (+) $ map . flip (/) =<< sum $ dist
    dice = zip thr [0..] :: [(Double, Int)]