module REPL

where

-- import Calc

import System.Console.Readline
import System

-- import Useful


{-
untag ('<':xs) = intag xs
untag (x:xs)   = x : untag xs
untag []       = []
intag ('>':xs) = untag xs
intag (x:xs)   = intag xs
intag []       = []
-}

main = do
   path <- checkPath "units.txt"
   cnts <- readFile path
   hs <- newHashes
   errors <- mapM (\s -> run hs s) (lines cnts)
   mapM_ myPutStrLn errors
   putStrLn startMessage
   loop (myF hs) -- (untag . calc)


prompt = ">>> "

isQuit (':':'q':_) = True
isQuit _           = False

-- isHelp (':':'h':_) = True
-- isHelp _           = False

version = "0.2.1"
startMessage   = "calc "++version++"\n"++
                 ":q or ^D to quit"
leavingMessage = "Leaving calc"

loop f = do
   s <- readline prompt
   case s of
      Nothing -> putStrLn $ "\n" ++ leavingMessage
      Just str -> do
         if isQuit str
           then putStrLn leavingMessage
           else do
             addHistory str
             result <- f str
             putStrLn result -- $ f str
             loop f
myF hs x = do
   c <- calc hs x
   return $ untag c

myPutStrLn x = if x == "" then return () else putStrLn $ untag x