X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FOptionalConfiguration.hs;h=d133432bb3c23280b00690df4c2e774edf9f19ff;hb=52e788e676ea2a67ad20b23d2e5c5b351f27b834;hp=ea7a67830dd280cf2dbe7380e74b824b16d24d4d;hpb=3fbc7d861d1f95513151010cd0f2d620befc2870;p=dead%2Fhtsn.git

diff --git a/src/OptionalConfiguration.hs b/src/OptionalConfiguration.hs
index ea7a678..d133432 100644
--- a/src/OptionalConfiguration.hs
+++ b/src/OptionalConfiguration.hs
@@ -1,13 +1,13 @@
 {-# LANGUAGE DeriveDataTypeable #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE StandaloneDeriving #-}
 
--- | The program will parse ~/.htsnrc for any available configuration
---   directives, resulting in an OptionalConfiguration. The
---   command-line arguments will be used to create another
---   OptionalConfiguration, and the two will be merged. Finally, a
---   def :: Configuration will be updated from the merged
---   OptionalConfigurations.
+-- | An OptionalConfiguration is just like a 'Configuration', except
+--   all of its fields are optional. The user can set options in two
+--   places: the command-line, and a configuration file. Obviously if
+--   a parameter is set in one place, it doesn't need to be set in the
+--   other. Thus, the latter needs to be optional.
 --
 
 module OptionalConfiguration (
@@ -19,13 +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 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.Log ( Priority(..) )
+import Logging ( log_error )
+import TSN.FeedHosts ( FeedHosts(..) )
 
-import 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
@@ -34,25 +48,48 @@ import 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)
 
+
+-- | The Monoid instance for these lets us "combine" two
+--   OptionalConfigurations. The "combine" operation that we'd like to
+--   perform is, essentially, to mash them together. So if we have two
+--   OptionalConfigurations, each half full, we could combine them
+--   into one big one.
+--
+--   One of the two must take precedence during this mashing, and we
+--   choose the second one for no reason.
+--
+--   This is used to merge command-line and config-file settings.
+--
 instance Monoid OptionalConfiguration where
+  -- | An empty OptionalConfiguration.
   mempty = OptionalConfiguration
              (FeedHosts [])
              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)
@@ -67,18 +104,52 @@ instance Monoid OptionalConfiguration where
                     then cfg1
                     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.
+--
+--   We make an attempt at cross-platform compatibility; we will try
+--   to find the correct directory even on Windows. But if the call
+--   to getHomeDirectory fails for whatever reason, we fall back to
+--   using the environment variable $HOME.
+--
 from_rc :: IO OptionalConfiguration
 from_rc = do
-  cfg <- DC.load [ DC.Optional "/etc/htsnrc",
-                   DC.Optional "$(HOME)/.htsnrc" ]
+  -- After some thought, the "global" /etc/htsnrc configuration file
+  -- was left out. Since each config file needs a password, and this
+  -- should be run by a dedicated user anyway, the global file does
+  -- not serve much purpose. It could also be a security risk (visible
+  -- password) if the admin screws up.
+  home <- catchIOError getHomeDirectory (\e -> do
+                                           log_error (show e)
+                                           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