module Task where

calc :: [Char] -> IO()
calc x =  putStr (machine "" x "" 0 0 1)

machine :: [Char] -> [Char] -> [Char] -> Int -> Int -> Int -> [Char]
machine answer (x:xs) subline state start current = case state of
    0 -> case x of
        '+' -> next answer "+" 6 current
        _   -> next answer "" 0 0
    1 -> case x of
        'a' -> next answer (subline ++ "a") 2 start
        'b' -> next answer (subline ++ "b") 3 start
        'c' -> next answer (subline ++ "c") 4 start
        '+' -> next answer "+" 1 current
        _   -> next answer "" 0 0
    2 -> case x of
        'a' -> next answer (subline ++ "a") 2 start
        '-' -> next answer (subline ++ "-") 1 start
        '+' -> next log "+" 5 current
        _   -> next answer "" 0 0
    3 -> case x of
        'b' -> next answer (subline ++ "b") 3 start
        '-' -> next answer (subline ++ "-") 1 start
        '+' -> next log "+" 5 current
        _   -> next answer "" 0 0
    4 -> case x of
        'c' -> next answer (subline ++ "c") 4 start
        '-' -> next answer (subline ++ "-") 1 start
        '+' -> next log "+" 5 current
        _   -> next answer "" 0 0
    5 -> case x of
        'a' -> next answer (subline ++ "a") 2 start
        'b' -> next answer (subline ++ "b") 3 start
        'c' -> next answer (subline ++ "c") 4 start
        '+' -> next log "+" 5 current
        _   -> next answer "" 0 0
    6 -> case x of
        'a' -> next answer (subline ++ "a") 2 start
        'b' -> next answer (subline ++ "b") 3 start
        'c' -> next answer (subline ++ "c") 4 start
        '+' -> next log "+" 5 current
        _   -> next answer "" 0 0
    _ -> "error"
    where   next a b c d = case xs of
                [] -> a
                _ -> machine a xs b c d (current + 1)
            log = answer ++ show start ++ "::" ++ show current ++ " " ++ subline ++ "+" ++ ['\n']