module ANSI where


csi = ("\27[" ++)

up   n = csi (show n ++ "A")
down n = csi (show n ++ "B")

clear = csi "J"

ansi = putStr . concat

line = "\n-----------------------------\n"

header n = ansi [up (n+5), clear, line, down (n+3)]

display f strs = do ansi [up (length strs+2), clear]
                    mapM_ putStrLn strs
                    ansi [down 1]
                    r <- getLine
                    if take 1 r == "q" 
                       then return () 
                       else display f (f r strs)


test f strs = header (length strs) >> display f strs


main = test (const (rotate 1)) ["Hello.", "", "  This is a test.", "  Only a test.", ""]


rotate n xs = drop n xs ++ take n xs

-----------------------------------------

test' f s x = header (length (s x)) >> disp f s x

disp  f s x = do let strs = s x
                 ansi [up (length strs+2), clear]
                 mapM_ putStrLn strs
                 ansi [down 1]
                 r <- getLine
                 if take 1 r == "q" 
                    then return () 
                    else disp f s (f r x)