todo.hs

module Todotxt where

import Data.List
import Control.Monad
import System.IO
import System.IO.Unsafe
import System.Environment
import System.Directory


main = do
  args <- getArgs
  let command = args !! 0
      additional_data = drop 1 args
  case args !! 0 of
    "add" -> addTask additional_data
    "delete"-> deleteTask
    _ -> putStrLn "Unrecognized command. Please, try again."


addTask :: [String] -> IO ()
addTask task =
  let text = intercalate " " task ++ "\n"
   in appendFile todoTxt text


deleteTask = do
  let tasks = getTasks
      numberedTasks = zipWith (\n task -> show n ++ " -- " ++ task) [1..] tasks
  (tempName, tempFile) <- openTempFile "." "temp"

  putStrLn ">>> These items are on your todo list:"
  putStrLn $ unlines numberedTasks

  putStr "What task you want to delete (0 to exit)? "
  numberStr <- getLine
  let number = read numberStr
      newTasks = delete (tasks !! (number - 1)) tasks

  hPutStr tempFile $ unlines newTasks
  hClose tempFile
  removeFile todoTxt
  renameFile tempName todoTxt

  putStrLn "Done."


getTasks = toList $ readFile todoTxt where
  toList = unsafePerformIO . liftM lines

-- the canonical location of the todo.txt file: ~/todo.txt
todoTxt = home ++ "/todo.txt" where
    home = unsafePerformIO getHomeDirectory