#!/usr/bin/env stack
> --stack --install-ghc runghc

This is a command-line Pomodoro counter.

> module Pomodoro (session, countdown) where

> import Control.Concurrent (threadDelay)
> import System.Console.ANSI (clearLine,
>                             saveCursor,
>                             restoreCursor)
> import System.IO (hFlush,
>                   stdout)
> import Data.Time.Clock.POSIX (posixSecondsToUTCTime)
> import Data.Time.Format (formatTime, defaultTimeLocale)
>  
> data Pomodoro = First | Second | Third | Fourth
>     deriving (Eq, Ord, Show, Read, Bounded, Enum)

> {-| Given an integer number of seconds, secToTimestamp
>  returns the corresponding time in MM:SS.
> 
> >>> secToTimestamp 0
> "00:00"
> >>> secToTimestamp 1500
> "25:00"
> >>> secToTimestamp 3000
> "50:00"
> -}
> 
> secToTimestamp :: Int -> String
> secToTimestamp = formatTime defaultTimeLocale "%M:%S" . posixSecondsToUTCTime . fromIntegral

> -- | Manage Pomodoro sessions
> -- 
> -- Examples:
> --
> -- >>> putStrLn "Hello world!"
> -- Hello world!
> --
> -- >>> putStrLn "Test complete!"
> -- Test complete!

> countdown :: IO()
> countdown = do
>     wait_seconds $ 25 * 60 + 1

> -- | Replace a delay with no delay for testing purposes.
> no_del :: Int -> IO()
> no_del _ = do
>     return ()
 
> pom :: Show a => a -> IO ()
> pom m = do
>     putStr $ show m ++ " pomodoro" ++ " | "
>     saveCursor
>     wait_seconds $ 25 * 60 + 1
>     restoreCursor
>     putStrLn "Finished, take a 5 minute rest."

> to_work :: IO ()
> to_work = do
>     saveCursor
>     putStr "Get back to work"
>     delay 2
>     restoreCursor
>     clearLine

> pomodoro :: Pomodoro -> IO ()
> pomodoro Fourth = do
>     pom Fourth
>     putStrLn "Take a 30-minute rest now. You just completed 4 pomodoros."
>     putStrLn "Congratulations on 4 pomodoros finished in a row!"
> pomodoro m = do
>     pom m
>     delay $ 5 * 60
>     to_work
>     pomodoro $ succ m
>  
> wait_seconds :: Int -> IO()
> wait_seconds 0 = putStr ""
> wait_seconds n = do
>     saveCursor
>     putStr $ secToTimestamp $ n - 1
>     hFlush stdout
>     restoreCursor
>     delay 1
>     wait_seconds $ n - 1

> -- | delay: Pauses the thread for the given number of seconds.
> --
> -- Example:
> --
> -- >>> delay 0

> delay :: Int -> IO()
> delay n = threadDelay $ n * 1000 * 1000

> session :: IO()
> session = pomodoro First

> main :: IO()
> main = session