Add FromConfig instances for time

packages/conferer/conferer.cabal

@@ -4,7 +4,7 @@ cabal-version: 1.18
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: e95018cf9b8ebe424a2926412853affcae168760a3b9ea0530fbf3a4c1d83b14
+-- hash: 786dba20a9ab2782cc8ca0d70b30fe8b384aff3f45f378ac4ce2fe78537e82bd
 
 name:           conferer
 version:        1.0.0.1
@@ -57,6 +57,7 @@ library
     , directory >=1.2 && <2.0
     , filepath >=1.0 && <2.0
     , text >=1.1 && <1.3
+    , time
   if impl(ghc >= 8.4.1)
     ghc-options: -Wpartial-fields
   default-language: Haskell2010
@@ -73,6 +74,7 @@ test-suite specs
       Conferer.FromConfig.MaybeSpec
       Conferer.FromConfig.NumbersSpec
       Conferer.FromConfig.StringLikeSpec
+      Conferer.FromConfig.TimeSpec
       Conferer.FromConfigSpec
       Conferer.GenericsSpec
       Conferer.KeySpec
@@ -100,6 +102,7 @@ test-suite specs
     , filepath >=1.0 && <2.0
     , hspec
     , text >=1.1 && <1.3
+    , time
   if impl(ghc >= 8.4.1)
     ghc-options: -Wpartial-fields
   default-language: Haskell2010

packages/conferer/package.yaml

@@ -16,6 +16,7 @@ dependencies:
   - text >= 1.1 && < 1.3
   - directory >= 1.2 && < 2.0
   - filepath >= 1.0 && < 2.0
+  - time
 
 tests:
   specs:

packages/conferer/src/Conferer/FromConfig/Internal.hs

@@ -26,7 +26,10 @@ import Data.Typeable
 import Text.Read (readMaybe)
 import Data.Dynamic
 import GHC.Generics
-import Data.Function ((&))
+import Data.Function (on, (&))
+import qualified Data.Time as Time
+import qualified Data.Time.Format.ISO8601 as Time
+import qualified Data.Time.Clock as Time
 
 import Conferer.Key
 import Conferer.Config.Internal.Types
@@ -215,6 +218,58 @@ instance FromConfig File where
       applyIfPresent f maybeComponent =
         (\fp -> maybe fp (f fp) maybeComponent)
 
+instance FromConfig Time.DayOfWeek where
+  fromConfig =
+    fetchFromConfigWith $
+    (\case
+      "sunday" -> Just Time.Sunday
+      "sun" -> Just Time.Sunday
+
+      "monday" -> Just Time.Monday
+      "mon" -> Just Time.Monday
+
+      "tuesday" -> Just Time.Tuesday
+      "tue" -> Just Time.Tuesday
+
+      "wednesday" -> Just Time.Wednesday
+      "wed" -> Just Time.Wednesday
+
+      "thursday" -> Just Time.Thursday
+      "thu" -> Just Time.Thursday
+
+      "friday" -> Just Time.Friday
+      "fri" -> Just Time.Friday
+
+      "saturday" -> Just Time.Saturday
+      "sat" -> Just Time.Saturday
+
+      _ -> Nothing
+      ) . Text.toLower
+
+instance FromConfig Time.Day where
+  fromConfig = fetchFromConfigByIso8601
+
+instance FromConfig Time.TimeOfDay where
+  fromConfig = fetchFromConfigByIso8601
+
+instance FromConfig Time.UTCTime where
+  fromConfig = fetchFromConfigByIso8601
+
+instance FromConfig Time.LocalTime where
+  fromConfig = fetchFromConfigByIso8601
+
+instance FromConfig Time.TimeZone where
+  fromConfig = fetchFromConfigByIso8601
+
+instance FromConfig Time.ZonedTime where
+  fromConfig = fetchFromConfigByIso8601
+
+instance FromConfig Time.CalendarDiffDays where
+  fromConfig = fetchFromConfigByIso8601
+
+instance FromConfig Time.CalendarDiffTime where
+  fromConfig = fetchFromConfigByIso8601
+
 -- | Helper function to parse a 'Bool' from 'Text'
 parseBool :: Text -> Maybe Bool
 parseBool text =
@@ -235,6 +290,10 @@ data OverrideFromConfig a =
 fetchFromConfigByRead :: (Typeable a, Read a) => Key -> Config -> IO a
 fetchFromConfigByRead = fetchFromConfigWith (readMaybe . Text.unpack)
 
+-- | Helper function to implement fetchFromConfig using the 'Time.ISO8601' instance
+fetchFromConfigByIso8601 :: (Typeable a, Time.ISO8601 a) => Key -> Config -> IO a
+fetchFromConfigByIso8601 = fetchFromConfigWith (Time.iso8601ParseM . Text.unpack)
+
 -- | Helper function to implement fetchFromConfig using the 'IsString' instance
 fetchFromConfigByIsString :: (Typeable a, IsString a) => Key -> Config -> IO a
 fetchFromConfigByIsString = fetchFromConfigWith (Just . fromString . Text.unpack)

packages/conferer/test/Conferer/FromConfig/TimeSpec.hs

@@ -0,0 +1,46 @@
+{-# LANGUAGE TypeApplications #-}
+
+module Conferer.FromConfig.TimeSpec (spec) where
+
+import Test.Hspec
+import Conferer.FromConfig.Extended
+import Data.Time
+import Data.Time.Calendar.OrdinalDate (fromOrdinalDate)
+import Data.Time.Calendar.WeekDate
+import Data.Maybe
+
+spec :: Spec
+spec = do
+  fcontext "Basic fetching" $ do
+    describe "fetching a Day from config" $ do
+      let
+        februay3th2021 = fromOrdinalDate 2021 3
+      ensureEmptyConfigThrows @Day
+      ensureUsingDefaultReturnsSameValue @Day februay3th2021
+      ensureSingleConfigParsesTheRightThing @Day "2021-01-03" februay3th2021
+      ensureSingleConfigParsesTheRightThing @Day "0000-01-03" $ fromOrdinalDate 0 3
+      describe "with missing leading zeros" $ do
+        ensureSingleConfigThrowsParserError @Day "2021-1-3"
+        ensureSingleConfigThrowsParserError @Day "2021-1-03"
+        ensureSingleConfigThrowsParserError @Day "2021-01-3"
+
+    describe "fetching a DayOfWeek" $ do
+      ensureEmptyConfigThrows @DayOfWeek
+      ensureUsingDefaultReturnsSameValue @DayOfWeek Monday
+      ensureSingleConfigParsesTheRightThing @DayOfWeek "Monday" Monday
+      context "with a lower case day" $ do
+        ensureSingleConfigParsesTheRightThing @DayOfWeek "monday" Monday
+      context "with a three letter abreviation" $ do
+        ensureSingleConfigParsesTheRightThing @DayOfWeek "mon" Monday
+
+    describe "fetching a TimeOfDay from config" $ do
+      ensureEmptyConfigThrows @TimeOfDay
+      ensureUsingDefaultReturnsSameValue @TimeOfDay midnight
+      ensureSingleConfigParsesTheRightThing @TimeOfDay "00:30:00" $ fromJust $ makeTimeOfDayValid 0 30 0
+      ensureSingleConfigParsesTheRightThing @TimeOfDay "00:30:00.5" $ fromJust $ makeTimeOfDayValid 0 30 0.5
+      ensureSingleConfigParsesTheRightThing @TimeOfDay "00:00:00" $ midnight
+
+      describe "with values that overflow" $ do
+        ensureSingleConfigThrowsParserError @TimeOfDay "70:00:00"
+        ensureSingleConfigThrowsParserError @TimeOfDay "00:70:00"
+        ensureSingleConfigThrowsParserError @TimeOfDay "00:00:70"