X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FOptionalConfiguration.hs;h=0913864e0bb064cfd61884e25940a1e326eda771;hb=160caf38b6e936b6541b31b3c9bbe952ba0a4b15;hp=ea7a67830dd280cf2dbe7380e74b824b16d24d4d;hpb=3fbc7d861d1f95513151010cd0f2d620befc2870;p=dead%2Fhtsn.git diff --git a/src/OptionalConfiguration.hs b/src/OptionalConfiguration.hs index ea7a678..0913864 100644 --- a/src/OptionalConfiguration.hs +++ b/src/OptionalConfiguration.hs @@ -1,32 +1,48 @@ {-# 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 ( OptionalConfiguration(..), - from_rc ) + from_rc, + merge_maybes ) where 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 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 -- the Justs. The 'feed_hosts' are left un-maybed so that cmdargs @@ -34,51 +50,109 @@ 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) + +-- | Combine two Maybes into one, essentially mashing them +-- together. We give precedence to the second argument when both are +-- Justs. +merge_maybes :: (Maybe a) -> (Maybe a) -> (Maybe a) +merge_maybes Nothing Nothing = Nothing +merge_maybes (Just x) Nothing = Just x +merge_maybes Nothing (Just x) = Just x +merge_maybes (Just _) (Just y) = Just y + + +-- | 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. +-- +-- 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 (password cfg1) (password cfg2)) - (merge (output_directory cfg1) (output_directory cfg2)) - (merge (username cfg1) (username cfg2)) + (merge_maybes (log_file cfg1) (log_file cfg2)) + (merge_maybes (log_level cfg1) (log_level cfg2)) + (merge_maybes (password cfg1) (password cfg2)) + (merge_maybes (output_directory cfg1) (output_directory cfg2)) + (merge_maybes (syslog cfg1) (syslog cfg2)) + (merge_maybes (username cfg1) (username cfg2)) where - merge :: (Maybe a) -> (Maybe a) -> (Maybe a) - merge Nothing Nothing = Nothing - merge (Just x) Nothing = Just x - merge Nothing (Just x) = Just x - merge (Just _) (Just y) = Just y - -- Use only the latter feed_hosts if there are any. all_feed_hosts = feed_hosts $ if (null (get_feed_hosts (feed_hosts cfg2))) 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