module REPL where

import Eval
import Lexer
import Parser
import Research

import Data.List                 (intercalate)
import qualified Data.Map as Map
import System.Console.Haskeline
import System.IO                 (hFlush, stdout)

repl :: Map.Map String T -> IO ()
repl env = runInputT defaultSettings (loop env)
  where
    loop :: Map.Map String T -> InputT IO ()
    loop env = do
      minput <- getInputLine "sapling < "
      case minput of
        Nothing -> outputStrLn "Goodbye!"
        Just ":_exit" -> outputStrLn "Goodbye!"
        Just "" -> do
          outputStrLn ""
          loop env
        Just input -> do
          let clearEnv = Map.delete "__result" env
              newEnv   = evalSingle clearEnv (parseSingle input)
          case Map.lookup "__result" newEnv of
            Just r -> do
              outputStrLn $ "sapling > " ++ show r
              outputStrLn $ "DECODE -: " ++ decodeResult r
            Nothing -> return ()
          loop newEnv

decodeResult :: T -> String
decodeResult tc = case toNumber tc of
  Right num -> show num
  Left _ -> case toString tc of
    Right str -> "\"" ++ str ++ "\""
    Left _ -> case toList tc of
      Right list -> "[" ++ intercalate ", " (map decodeResult list) ++ "]"
      Left _ -> ""