106 lines
2.4 KiB
Haskell
106 lines
2.4 KiB
Haskell
{- Time for humans.
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-
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- Copyright 2012-2013 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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module Utility.HumanTime (
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Duration(..),
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durationSince,
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durationToPOSIXTime,
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durationToDays,
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daysToDuration,
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parseDuration,
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fromDuration,
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prop_duration_roundtrips
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) where
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import Utility.PartialPrelude
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import Utility.QuickCheck
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import qualified Data.Map as M
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import Data.Time.Clock
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import Data.Time.Clock.POSIX (POSIXTime)
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import Data.Char
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import Control.Applicative
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import Prelude
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newtype Duration = Duration { durationSeconds :: Integer }
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deriving (Eq, Ord, Read, Show)
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durationSince :: UTCTime -> IO Duration
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durationSince pasttime = do
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now <- getCurrentTime
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return $ Duration $ round $ diffUTCTime now pasttime
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durationToPOSIXTime :: Duration -> POSIXTime
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durationToPOSIXTime = fromIntegral . durationSeconds
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durationToDays :: Duration -> Integer
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durationToDays d = durationSeconds d `div` dsecs
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daysToDuration :: Integer -> Duration
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daysToDuration i = Duration $ i * dsecs
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{- Parses a human-input time duration, of the form "5h", "1m", "5h1m", etc -}
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parseDuration :: String -> Either String Duration
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parseDuration d
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| null d = parsefail
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| otherwise = maybe parsefail (Right . Duration) $ go 0 d
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where
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go n [] = return n
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go n s = do
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num <- readish s :: Maybe Integer
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case dropWhile isDigit s of
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(c:rest) -> do
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u <- M.lookup c unitmap
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go (n + num * u) rest
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_ -> return $ n + num
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parsefail = Left $ "failed to parse duration \"" ++ d ++ "\" (expected eg \"5m\" or \"1h5m\")"
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fromDuration :: Duration -> String
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fromDuration Duration { durationSeconds = d }
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| d == 0 = "0s"
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| otherwise = concatMap showunit $ take 2 $ go [] units d
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where
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showunit (u, n) = show n ++ [u]
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go c [] _ = reverse c
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go c ((u, n):us) v =
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let (q,r) = v `quotRem` n
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in if q > 0
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then go ((u, q):c) us r
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else if null c
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then go c us r
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else reverse c
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units :: [(Char, Integer)]
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units =
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[ ('y', ysecs)
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, ('d', dsecs)
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, ('h', hsecs)
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, ('m', msecs)
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, ('s', 1)
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]
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unitmap :: M.Map Char Integer
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unitmap = M.fromList units
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ysecs :: Integer
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ysecs = dsecs * 365
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dsecs :: Integer
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dsecs = hsecs * 24
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hsecs :: Integer
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hsecs = msecs * 60
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msecs :: Integer
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msecs = 60
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-- Durations cannot be negative.
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instance Arbitrary Duration where
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arbitrary = Duration <$> nonNegative arbitrary
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prop_duration_roundtrips :: Duration -> Bool
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prop_duration_roundtrips d = parseDuration (fromDuration d) == Right d
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