module RandomExample2 where

import Control.Applicative (liftA3)
import Control.Monad (replicateM)
import Control.Monad.Trans.State
import System.Random
import RandomExample

rollDie :: State StdGen Die
rollDie = state $ do
    (n, s) <- randomR (1, 6)
    return (intToDie n, s)

rollDie' :: State StdGen Die
rollDie' = intToDie <$> state (randomR (1, 6))

rollDieThreeTimes' :: State StdGen (Die, Die, Die)
rollDieThreeTimes' = liftA3 (,,) rollDie rollDie rollDie

infiniteDie :: State StdGen [Die]
infiniteDie = repeat <$> rollDie

nDie :: Int -> State StdGen [Die]
nDie n = replicateM n rollDie

rollsToGetTwenty :: StdGen -> Int
rollsToGetTwenty g = go 0 0 g
    where
        go :: Int -> Int -> StdGen -> Int
        go sum count gen
          | sum >= 20 = count
          | otherwise =
              let (die, nextGen) = randomR (1, 6) gen
               in go (sum + die) (count + 1) nextGen

rollsToGetN :: Int -> StdGen -> Int
rollsToGetN limit g = go 0 0 g
    where
        go :: Int -> Int -> StdGen -> Int
        go sum count gen
          | sum >= limit = count
          | otherwise =
              let (die, nextGen) = randomR (1, 6) gen
               in go (sum + die) (count + 1) nextGen

rollsCountLogged :: Int -> StdGen -> (Int, [Die])
rollsCountLogged limit g = go 0 0 g []
    where
        go :: Int -> Int -> StdGen -> [Die] -> (Int, [Die])
        go sum count gen dies
          | sum >= limit = (count, dies)
          | otherwise =
              let (die, nextGen) = randomR (1, 6) gen
               in go (sum + die) (count + 1) nextGen ((intToDie die) : dies)