Add scaffolding to allow logging via syslog or a file.

[dead/htsn.git] / src / OptionalConfiguration.hs

diff --git a/src/OptionalConfiguration.hs b/src/OptionalConfiguration.hs
index de2e97d892c31af6ab4e630118df94af7f1f099c..d133432bb3c23280b00690df4c2e774edf9f19ff 100644 (file)
--- a/src/OptionalConfiguration.hs
+++ b/src/OptionalConfiguration.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE DeriveDataTypeable #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE StandaloneDeriving #-}
 
 -- | An OptionalConfiguration is just like a 'Configuration', except
 --   all of its fields are optional. The user can set options in two
@@ -18,17 +19,27 @@ import qualified Data.Configurator as DC (
   Worth(Optional),
   load,
   lookup )
-import Data.Data (Data)
-import Data.Maybe (fromMaybe)
-import Data.Monoid (Monoid(..))
-import Data.Typeable (Typeable)
-import System.Directory (getHomeDirectory)
+import qualified Data.Configurator.Types as DCT (
+  Configured,
+  Value( String ),
+  convert )
+import Data.Data ( Data )
+import Data.Maybe ( fromMaybe )
+import Data.Monoid ( Monoid(..) )
+import Data.Typeable ( Typeable )
+import System.Directory ( getHomeDirectory )
 import System.FilePath ( (</>) )
-import System.IO.Error (catchIOError)
+import System.IO.Error ( catchIOError )
+import System.Log ( Priority(..) )
+import Logging ( log_error )
+import TSN.FeedHosts ( FeedHosts(..) )
 
-import Logging (log_error)
-import TSN.FeedHosts (FeedHosts(..))
 
+-- Derive standalone instances of Data and Typeable for Priority. This
+-- is necessary for OptionalConfiguration (which contains a Maybe
+-- Priority) to derive Data and Typeable.
+deriving instance Data Priority
+deriving instance Typeable Priority
 
 -- | The same as Configuration, except everything is optional. It's easy to
 --   merge two of these by simply dropping the Nothings in favor of
@@ -37,10 +48,13 @@ import TSN.FeedHosts (FeedHosts(..))
 --
 data OptionalConfiguration =
   OptionalConfiguration {
-    feed_hosts :: FeedHosts,
-    password  :: Maybe String,
+    feed_hosts       :: FeedHosts,
+    log_file         :: Maybe FilePath,
+    log_level        :: Maybe Priority,
+    password         :: Maybe String,
     output_directory :: Maybe FilePath,
-    username :: Maybe String }
+    syslog           :: Maybe Bool,
+    username         :: Maybe String }
     deriving (Show, Data, Typeable)
 
 
@@ -62,14 +76,20 @@ instance Monoid OptionalConfiguration where
              Nothing
              Nothing
              Nothing
+             Nothing
+             Nothing
+             Nothing
 
 
   -- | Combine @cfg1@ and @cfg2@, giving precedence to @cfg2@.
   cfg1 `mappend` cfg2 =
     OptionalConfiguration
       all_feed_hosts
+      (merge (log_file cfg1) (log_file cfg2))
+      (merge (log_level cfg1) (log_level cfg2))
       (merge (password cfg1) (password cfg2))
       (merge (output_directory cfg1) (output_directory cfg2))
+      (merge (syslog cfg1) (syslog cfg2))
       (merge (username cfg1) (username cfg2))
     where
       merge :: (Maybe a) -> (Maybe a) -> (Maybe a)
@@ -85,6 +105,17 @@ instance Monoid OptionalConfiguration where
                     else cfg2
 
 
+instance DCT.Configured Priority where
+  -- | This allows us to read a Priority level out of a Configurator
+  --   config file. By default Configurator wouldn't know what to do,
+  --   so we have to tell it that we expect one of the valid Priority
+  --   constructors.
+  convert (DCT.String "INFO") = Just INFO
+  convert (DCT.String "WARNING") = Just WARNING
+  convert (DCT.String "ERROR") = Just ERROR
+  convert _ = Nothing
+
+
 -- | Obtain an OptionalConfiguration from the file ".htsnrc" in the
 --   user's home directory.
 --
@@ -105,14 +136,20 @@ from_rc = do
                                            return "$(HOME)")
   let user_config_path = home </> ".htsnrc"
   cfg <- DC.load [ DC.Optional user_config_path ]
+  cfg_log_file <- DC.lookup cfg "log_file"
+  cfg_log_level <- DC.lookup cfg "log_level"
   cfg_password <- DC.lookup cfg "password"
   cfg_output_directory <- DC.lookup cfg "output_directory"
+  cfg_syslog <- DC.lookup cfg "syslog"
   cfg_username <- DC.lookup cfg "username"
   cfg_feed_hosts <- DC.lookup cfg "feed_hosts"
 
   return $ OptionalConfiguration
              (fromMaybe (FeedHosts []) cfg_feed_hosts)
+             cfg_log_file
+             cfg_log_level
              cfg_password
              cfg_output_directory
+             cfg_syslog
              cfg_username