Parse durations

7 files changed, 121 insertions, 8 deletions

diff --git a/Data/ConfigManager.hs b/Data/ConfigManager.hs
index 37da8b6..a13457c 100644
--- a/Data/ConfigManager.hs
+++ b/Data/ConfigManager.hs
@@ -34,7 +34,6 @@ module Data.ConfigManager
   ) where
 
 import Prelude hiding (lookup)
-import Text.Read (readMaybe)
 
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -42,6 +41,7 @@ import qualified Data.HashMap.Strict as M
 
 import qualified Data.ConfigManager.Reader as R
 import Data.ConfigManager.Types
+import Data.ConfigManager.Instances ()
 
 -- | Load a 'Config' from a given 'FilePath'.
 
@@ -50,13 +50,13 @@ readConfig = R.readConfig Required
 
 -- | Lookup for the value associated to a name.
 
-lookup :: Read a => Name -> Config -> Either Text a
+lookup :: Configured a => Name -> Config -> Either Text a
 lookup name config =
   case M.lookup name (hashMap config) of
     Nothing ->
       Left . T.concat $ ["Value not found for Key ", name]
     Just value ->
-      case readMaybe . T.unpack $ value of
+      case convert value of
         Nothing -> Left . T.concat $ ["Reading error for key ", name]
         Just result -> Right result
 
diff --git a/Data/ConfigManager/Instances.hs b/Data/ConfigManager/Instances.hs
new file mode 100644
index 0000000..0855117
--- /dev/null
+++ b/Data/ConfigManager/Instances.hs
@@ -0,0 +1,24 @@
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE IncoherentInstances #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+module Data.ConfigManager.Instances
+  () where
+
+import qualified Data.Text as T
+import Data.Time.Clock (DiffTime, NominalDiffTime)
+
+import Text.Read (readMaybe)
+
+import Data.ConfigManager.Types.Internal
+import Data.ConfigManager.Parser.Duration (parseDuration)
+
+instance Configured DiffTime where
+  convert value = parseDuration value
+
+instance Configured NominalDiffTime where
+  convert value = realToFrac <$> parseDuration value
+
+instance Read a => Configured a where
+  convert = readMaybe . T.unpack
diff --git a/Data/ConfigManager/Parser/Duration.hs b/Data/ConfigManager/Parser/Duration.hs
new file mode 100644
index 0000000..f169c55
--- /dev/null
+++ b/Data/ConfigManager/Parser/Duration.hs
@@ -0,0 +1,36 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module Data.ConfigManager.Parser.Duration
+  ( parseDuration
+  ) where
+
+import Control.Applicative ((<|>))
+
+import Data.Text (Text)
+import qualified Data.Text as T
+import Data.Time.Clock (DiffTime)
+import qualified Data.Time.Clock as Time
+
+import Text.Read (readMaybe)
+
+parseDuration :: Text -> Maybe DiffTime
+parseDuration input =
+  case T.splitOn " " input of
+    [count, unit] -> do
+      n <- readMaybe . T.unpack $ count
+      let matchDuration singularUnit pluralUnit seconds =
+            if ((n == 0 || n == 1) && unit == singularUnit) || (n > 1 && unit == pluralUnit)
+              then Just . Time.secondsToDiffTime $ n * seconds
+              else Nothing
+      (matchDuration "second" "seconds" second)
+        <|> (matchDuration "minute" "minutes" minute)
+        <|> (matchDuration "hour" "hours" hour)
+        <|> (matchDuration "day" "days" day)
+        <|> (matchDuration "week" "weeks" week)
+    _ -> Nothing
+  where
+    second = 1
+    minute = 60 * second
+    hour = 60 * minute
+    day = 24 * hour
+    week = 7 * day
diff --git a/Data/ConfigManager/Types.hs b/Data/ConfigManager/Types.hs
index ea2691f..8939713 100644
--- a/Data/ConfigManager/Types.hs
+++ b/Data/ConfigManager/Types.hs
@@ -12,6 +12,8 @@ module Data.ConfigManager.Types
   , Name
   , Value
   , Requirement(..)
+  , Configured
+  , convert
   ) where
 
 import Data.ConfigManager.Types.Internal
diff --git a/Data/ConfigManager/Types/Internal.hs b/Data/ConfigManager/Types/Internal.hs
index c4d5d0e..4459b01 100644
--- a/Data/ConfigManager/Types/Internal.hs
+++ b/Data/ConfigManager/Types/Internal.hs
@@ -4,10 +4,11 @@ module Data.ConfigManager.Types.Internal
   , Name
   , Value
   , Requirement(..)
+  , Configured
+  , convert
   ) where
 
 import Data.Text (Text)
-
 import Data.HashMap.Strict
 
 -- | Configuration data.
@@ -37,3 +38,9 @@ data Requirement =
   Required
   | Optional
   deriving (Eq, Read, Show)
+
+-- | This class represents types that can be converted /from/ a value /to/ a
+-- destination type
+
+class Configured a where
+  convert :: Value -> Maybe a
diff --git a/config-manager.cabal b/config-manager.cabal
index 99d5b1b..2104e4f 100644
--- a/config-manager.cabal
+++ b/config-manager.cabal
@@ -1,5 +1,5 @@
 name:                  config-manager
-version:               0.1.0.0
+version:               0.2.0.0
 synopsis:              Configuration management
 description:
   A configuration management library which supports:
@@ -29,13 +29,16 @@ library
                        Data.ConfigManager.Types
   other-modules:       Data.ConfigManager.Reader
                        Data.ConfigManager.Parser
+                       Data.ConfigManager.Instances
                        Data.ConfigManager.Types.Internal
+                       Data.ConfigManager.Parser.Duration
   ghc-options:         -Wall -Werror
   build-depends:       base < 5,
                        text,
                        unordered-containers,
                        parsec,
-                       filepath
+                       filepath,
+                       time
   default-language:    Haskell2010
 
 source-repository      head
@@ -55,5 +58,6 @@ Test-Suite test-config-manager
                        test-framework-hunit,
                        temporary,
                        directory,
-                       unordered-containers
+                       unordered-containers,
+                       time
   default-language:    Haskell2010
diff --git a/tests/Test.hs b/tests/Test.hs
index 641e1e6..3956236 100644
--- a/tests/Test.hs
+++ b/tests/Test.hs
@@ -18,6 +18,8 @@ import Test.HUnit hiding (Test)
 import Data.ConfigManager
 import Data.ConfigManager.Types (Config(..))
 import qualified Data.Text as T
+import Data.Time.Clock (DiffTime)
+import qualified Data.Time.Clock as Time
 
 import Helper (forceGetConfig, getConfig, eitherToMaybe)
 
@@ -32,6 +34,7 @@ tests =
   , testCase "value" valueAssertion
   , testCase "skip" skipAssertion
   , testCase "import" importAssertion
+  , testCase "duration" durationAssertion
   ]
 
 bindingAssertion :: Assertion
@@ -41,7 +44,7 @@ bindingAssertion = do
 
   oneBinding <- forceGetConfig "x = \"foo\""
   assertEqual "one binding present" (Right "foo") (lookup "x" oneBinding)
-  assertBool "one binding missing" (isLeft $ (lookup "y" oneBinding :: Either Text Int))
+  assertBool "one binding missing" (isLeft (lookup "y" oneBinding :: Either Text Int))
   assertEqual "one binding count" 1 (M.size . hashMap $ oneBinding)
 
   multipleBindings <- forceGetConfig $ T.unlines
@@ -133,3 +136,40 @@ importAssertion = do
     , "x = 4"
     ]
   assertEqual "missing optional config" (Right 4) (lookup "x" missingOptionalConfig)
+
+durationAssertion :: Assertion
+durationAssertion = do
+  config <- forceGetConfig $ T.unlines
+    [ "a = 1 second"
+    , "b = 5 seconds"
+    , "c = 1 minute"
+    , "d = 10 minutes"
+    , "e = 1 hour"
+    , "f = 7 hours"
+    , "g = 1 day"
+    , "h = 2 days"
+    , "i = 1 week"
+    , "j = 9 weeks"
+    , ""
+    , "k = 1 minutes"
+    , "l = 20  weeks"
+    ]
+
+  let second = 1
+  let minute = 60 * second
+  let hour = 60 * minute
+  let day = 24 * hour
+  let week = 7 * day
+
+  assertEqual "a" (Right (Time.secondsToDiffTime $ 1 * second)) (lookup "a" config)
+  assertEqual "b" (Right (Time.secondsToDiffTime $ 5 * second)) (lookup "b" config)
+  assertEqual "c" (Right (Time.secondsToDiffTime $ 1 * minute)) (lookup "c" config)
+  assertEqual "d" (Right (Time.secondsToDiffTime $ 10 * minute)) (lookup "d" config)
+  assertEqual "e" (Right (Time.secondsToDiffTime $ 1 * hour)) (lookup "e" config)
+  assertEqual "f" (Right (Time.secondsToDiffTime $ 7 * hour)) (lookup "f" config)
+  assertEqual "g" (Right (Time.secondsToDiffTime $ 1 * day)) (lookup "g" config)
+  assertEqual "h" (Right (Time.secondsToDiffTime $ 2 * day)) (lookup "h" config)
+  assertEqual "i" (Right (Time.secondsToDiffTime $ 1 * week)) (lookup "i" config)
+  assertEqual "j" (Right (Time.secondsToDiffTime $ 9 * week)) (lookup "j" config)
+  assertBool "k" (isLeft (lookup "k" config :: Either Text DiffTime))
+  assertBool "l" (isLeft (lookup "l" config :: Either Text DiffTime))