module Automaton exposing (..)

import Random

-- MODEL

type alias Automaton s i = List ((s, i), s)

zip : List a -> List b -> List (a, b)
zip = List.map2 (,)

cart : List a -> List b -> List (a, b)
cart l1 l2 = List.concat <| List.map (\x -> List.map (\y -> (x, y)) l2) l1

genAut : Int -> Int -> Random.Generator (Automaton Int Int)
genAut n k = let
    allSI = cart [1..n] [1..k]
  in Random.map (zip allSI) (Random.list (n*k) <| Random.int 1 n)

step : Automaton s i -> Maybe s -> i -> Maybe s
step ls s0 i = case s0 of
  Nothing -> Nothing
  Just s -> List.filter (\((t, j), b) -> t == s && i == j) ls |> List.head |> Maybe.map snd