import Control.Monad
import Data.Char
import Data.Maybe
import qualified Data.Map.Strict as Map

data Ref = Reg Char | Num Int
  deriving Show

data Ins = Set Char Ref | Add Char Ref | Mul Char Ref | Mod Char Ref | Snd Ref | Rcv Char | Jgz Ref Ref
  deriving Show

parseRef :: String -> Ref
parseRef str = if all (\c -> isDigit c || c == '-') str then Num (read str) else Reg (head str)

parse :: String -> Ins
parse str = case words str of
    ["set", [d], s] -> Set d (parseRef s)
    ["add", [d], s] -> Add d (parseRef s)
    ["mul", [d], s] -> Mul d (parseRef s)
    ["mod", [d], s] -> Mod d (parseRef s)
    ["snd", r] -> Snd (parseRef r)
    ["rcv", [d]] -> Rcv d
    ["jgz", c, t] -> Jgz (parseRef c) (parseRef t)
    _ -> undefined

get :: Ref -> Map.Map Char Int -> Int
get (Num i) _ = i
get (Reg c) vmap = fromMaybe 0 (Map.lookup c vmap)

exec1 :: [Ins] -> Int
exec1 inss' = go inss' 0 Map.empty 0
  where
    go :: [Ins] -> Int -> Map.Map Char Int -> Int -> Int
    go inss idx vmap snd
        | idx < 0 = undefined
        | idx >= length inss = undefined
        | otherwise = case inss !! idx of
            Set d ref -> go inss (idx+1) (Map.insert d (get ref vmap) vmap) snd
            Add d ref -> go inss (idx+1) (Map.insert d (get (Reg d) vmap + get ref vmap) vmap) snd
            Mul d ref -> go inss (idx+1) (Map.insert d (get (Reg d) vmap * get ref vmap) vmap) snd
            Mod d ref -> go inss (idx+1) (Map.insert d (get (Reg d) vmap `mod` get ref vmap) vmap) snd
            Snd ref -> go inss (idx+1) vmap (get ref vmap)
            Rcv d -> if get (Reg d) vmap == 0 then go inss (idx+1) vmap snd else snd
            Jgz cd tg -> go inss (idx + if get cd vmap > 0 then get tg vmap else 1) vmap snd

data State = State [Ins] Int (Map.Map Char Int) [Int]
  deriving Show

makeState :: [Ins] -> Int -> State
makeState inss pid = State inss 0 (Map.fromList [('p', pid)]) []

supplyInput :: State -> [Int] -> State
supplyInput (State inss idx vmap inp) input = State inss idx vmap (inp ++ input)

exec2 :: State -> (State, [Int])
exec2 state@(State inss idx vmap inp)
    | idx < 0 = (state, [])
    | idx >= length inss = (state, [])
    | otherwise = case inss !! idx of
        Set d ref -> exec2 $ State inss (idx+1) (Map.insert d (get ref vmap) vmap) inp
        Add d ref -> exec2 $ State inss (idx+1) (Map.insert d (get (Reg d) vmap + get ref vmap) vmap) inp
        Mul d ref -> exec2 $ State inss (idx+1) (Map.insert d (get (Reg d) vmap * get ref vmap) vmap) inp
        Mod d ref -> exec2 $ State inss (idx+1) (Map.insert d (get (Reg d) vmap `mod` get ref vmap) vmap) inp
        Snd ref -> fmap (get ref vmap :) $ exec2 $ State inss (idx+1) vmap inp
        Rcv d -> case inp of
            [] -> (state, [])
            x:xs -> exec2 $ State inss (idx+1) (Map.insert d x vmap) xs
        Jgz cd tg -> exec2 $ State inss (idx + if get cd vmap > 0 then get tg vmap else 1) vmap inp

parallel :: State -> State -> Int
parallel state0 state1 =
    let (state0', out0) = exec2 state0
        (state1', out1) = exec2 (supplyInput state1 out0)
        state0'' = supplyInput state0' out1
    in if null out0 && null out1
        then 0
        else length out1 + parallel state0'' state1'

main :: IO ()
main = do
    input <- liftM (map parse . lines) (readFile "18.in")
    print (exec1 input)

    print $ parallel (makeState input 0) (makeState input 1)