{-# 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 (
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
--
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)
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
projects / dead / htsn.git / blobdiff