module Main where

import Control.Exception
import Control.Monad
import Data.Fixed
import Data.Maybe
import Data.Time
import System.Console.GetOpt
import System.Directory
import System.Environment
import System.Exit
import System.IO
import System.IO.Error

version = "0.1.2"

tomatoState = "tomato.st"

data Options = Options
  { optHelp :: Bool,
    optStateFile :: Maybe FilePath,
    optTime :: Integer,
    optVersion :: Bool
  }

defOptions =
  Options
    { optHelp = False,
      optStateFile = Nothing,
      optTime = 45,
      optVersion = False
    }

options :: [OptDescr (Options -> Options)]
options =
  [ Option
      ['h']
      ["help"]
      (NoArg (\opts -> opts {optHelp = True}))
      "show help and exit",
    Option
      ['s']
      ["state"]
      (ReqArg (\f opts -> opts {optStateFile = Just f}) "FILE")
      "use FILE as state file",
    Option
      ['t']
      ["time"]
      (ReqArg (\t opts -> opts {optTime = read t :: Integer}) "MINUTES")
      ("use MINUTES as deadline (default: " ++ show (optTime defOptions) ++ ")"),
    Option
      ['v']
      ["version"]
      (NoArg (\opts -> opts {optVersion = True}))
      "output version and exit"
  ]

usage :: String -> [String] -> IO ()
usage progName errs
  | null errs = do
      putStrLn helpText
      exitSuccess
  | otherwise = do
      hPutStrLn stderr ("error: " ++ concat errs ++ "Try " ++ progName ++ " -h for more information.")
      exitFailure
  where
    header =
      "Yet another simple pomodoro tool\n"
        ++ "Usage: "
        ++ progName
        ++ " [OPTION...] [command]"
    helpText =
      usageInfo header options ++ "\nCommands are: start, show and stop.\n"

resolveEmoji :: NominalDiffTime -> String
resolveEmoji diff
  | diff > 0 = "🍅"
  | otherwise = "💢"

doShow :: String -> IO ()
doShow stateFile = do
  content <- try (readFile stateFile)
  case content of
    Left err ->
      if isDoesNotExistError err
        then putStrLn "⏸️  00:00:00"
        else ioError err
    Right str -> do
      currTime <- getCurrentTime
      let start = read str :: UTCTime
      let diff = diffUTCTime start currTime
      let emoji = resolveEmoji diff
      putStrLn (emoji ++ " " ++ formatTime defaultTimeLocale "%0H:%0M:%0S" diff)

doStop :: String -> IO ()
doStop stateFile = do
  result <- try (removeFile stateFile)
  case result of
    Left err ->
      if isDoesNotExistError err
        then putStrLn "OK"
        else ioError err
    Right _ -> putStrLn "Stopped"

doStart :: String -> Integer -> IO ()
doStart stateFile mins = do
  currTime <- getCurrentTime
  let deadline = addUTCTime secs currTime
  writeFile stateFile (show deadline)
  putStrLn ("Started, end on " ++ show deadline)
  where
    secs = secondsToNominalDiffTime (60 * fromInteger mins)

tomato :: String -> [String] -> String -> IO ()
tomato progName argv state =
  case getOpt Permute options argv of
    (o, n, []) ->
      do
        when (optHelp opts) $ usage progName []
        when (optVersion opts) $ putStrLn (progName ++ " " ++ version) >> exitSuccess
        case n of
          [] -> doShow stateFile
          ["show"] -> doShow stateFile
          ["start"] -> doStart stateFile (optTime opts)
          ["stop"] -> doStop stateFile
          _ -> usage progName ["invalid command\n"]
      where
        opts = foldl (flip id) defOptions o
        stateFile = fromMaybe state (optStateFile opts)
    (_, _, errs) -> usage progName errs

main :: IO ()
main = do
  args <- getArgs
  progName <- getProgName
  state <- getXdgDirectory XdgCache tomatoState
  tomato progName args state