+{-# LANGUAGE OverloadedStrings #-}
+
+-- | The program will parse ~/.twatrc for any available configuration
+-- directives, resulting in an OptionalCfg. The command-line
+-- arguments will be used to create another OptionalCfg, and the two
+-- will be merged. Finally, a default_config will be updated from
+-- the merged OptionalCfgs.
+--
+
+module OptionalConfiguration
+where
+
+import Data.Monoid (Monoid(..))
+import qualified Data.Configurator as DC
+
+-- The same as Cfg, except everything is optional. It's easy to merge
+-- two of these by simply dropping the Nothings in favor of the Justs.
+data OptionalCfg =
+ OptionalCfg { consumer_key :: Maybe String,
+ consumer_secret :: Maybe String,
+ access_token :: Maybe String,
+ access_secret :: Maybe String,
+ heartbeat :: Maybe Int,
+ ignore_replies :: Maybe Bool,
+ ignore_retweets :: Maybe Bool,
+ sendmail_path :: Maybe String,
+ from_address :: Maybe String,
+ to_address :: Maybe String,
+ verbose :: Maybe Bool }
+
+instance Monoid OptionalCfg where
+ mempty = OptionalCfg
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+ Nothing
+
+ cfg1 `mappend` cfg2 =
+ OptionalCfg
+ (merge (consumer_key cfg1) (consumer_key cfg2))
+ (merge (consumer_secret cfg1) (consumer_secret cfg2))
+ (merge (access_token cfg1) (access_token cfg2))
+ (merge (access_secret cfg1) (access_secret cfg2))
+ (merge (heartbeat cfg1) (heartbeat cfg2))
+ (merge (ignore_replies cfg1) (ignore_replies cfg2))
+ (merge (ignore_retweets cfg1) (ignore_retweets cfg2))
+ (merge (sendmail_path cfg1) (sendmail_path cfg2))
+ (merge (from_address cfg1) (from_address cfg2))
+ (merge (to_address cfg1) (to_address cfg2))
+ (merge (verbose cfg1) (verbose 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
+
+from_rc :: IO OptionalCfg
+from_rc = do
+ cfg <- DC.load [ DC.Optional "$(HOME)/.twatrc" ]
+ cfg_consumer_key <- DC.lookup cfg "consumer-key"
+ cfg_consumer_secret <- DC.lookup cfg "consumer-secret"
+ cfg_access_token <- DC.lookup cfg "access-token"
+ cfg_access_secret <- DC.lookup cfg "access-secret"
+ cfg_heartbeat <- DC.lookup cfg "heartbeat"
+ cfg_ignore_replies <- DC.lookup cfg "ignore-replies"
+ cfg_ignore_retweets <- DC.lookup cfg "ignore-retweets"
+ cfg_sendmail_path <- DC.lookup cfg "sendmail-path"
+ cfg_from_address <- DC.lookup cfg "from"
+ cfg_to_address <- DC.lookup cfg "to"
+ cfg_verbose <- DC.lookup cfg "verbose"
+ return $ OptionalCfg
+ cfg_consumer_key
+ cfg_consumer_secret
+ cfg_access_token
+ cfg_access_secret
+ cfg_heartbeat
+ cfg_ignore_replies
+ cfg_ignore_retweets
+ cfg_sendmail_path
+ cfg_from_address
+ cfg_to_address
+ cfg_verbose
+