src/OptionalConfiguration.hs

   1 {-# LANGUAGE OverloadedStrings #-}
   2
   3 -- | The program will parse ~/.twatrc for any available configuration
   4 --   directives, resulting in an OptionalCfg. The command-line
   5 --   arguments will be used to create another OptionalCfg, and the two
   6 --   will be merged. Finally, a default_config will be updated from
   7 --   the merged OptionalCfgs.
   8 --
   9
  10 module OptionalConfiguration
  11 where
  12
  13 import Data.Monoid (Monoid(..))
  14 import qualified Data.Configurator as DC
  15
  16 -- The same as Cfg, except everything is optional. It's easy to merge
  17 -- two of these by simply dropping the Nothings in favor of the Justs.
  18 data OptionalCfg =
  19   OptionalCfg { consumer_key :: Maybe String,
  20                 consumer_secret :: Maybe String,
  21                 access_token :: Maybe String,
  22                 access_secret :: Maybe String,
  23                 heartbeat :: Maybe Int,
  24                 ignore_replies :: Maybe Bool,
  25                 ignore_retweets :: Maybe Bool,
  26                 sendmail_path :: Maybe String,
  27                 from_address :: Maybe String,
  28                 to_address :: Maybe String,
  29                 verbose :: Maybe Bool }
  30
  31 instance Monoid OptionalCfg where
  32   mempty = OptionalCfg
  33              Nothing
  34              Nothing
  35              Nothing
  36              Nothing
  37              Nothing
  38              Nothing
  39              Nothing
  40              Nothing
  41              Nothing
  42              Nothing
  43              Nothing
  44
  45   cfg1 `mappend` cfg2 =
  46     OptionalCfg
  47       (merge (consumer_key cfg1) (consumer_key cfg2))
  48       (merge (consumer_secret cfg1) (consumer_secret cfg2))
  49       (merge (access_token cfg1) (access_token cfg2))
  50       (merge (access_secret cfg1) (access_secret cfg2))
  51       (merge (heartbeat cfg1) (heartbeat cfg2))
  52       (merge (ignore_replies cfg1) (ignore_replies cfg2))
  53       (merge (ignore_retweets cfg1) (ignore_retweets cfg2))
  54       (merge (sendmail_path cfg1) (sendmail_path cfg2))
  55       (merge (from_address cfg1) (from_address cfg2))
  56       (merge (to_address cfg1) (to_address cfg2))
  57       (merge (verbose cfg1) (verbose cfg2))
  58     where
  59       merge :: (Maybe a) -> (Maybe a) -> (Maybe a)
  60       merge Nothing Nothing   = Nothing
  61       merge (Just x) Nothing  = Just x
  62       merge Nothing (Just x)  = Just x
  63       merge (Just _) (Just y) = Just y
  64
  65 from_rc :: IO OptionalCfg
  66 from_rc = do
  67   cfg <- DC.load [ DC.Optional "$(HOME)/.twatrc" ]
  68   cfg_consumer_key <- DC.lookup cfg "consumer-key"
  69   cfg_consumer_secret <- DC.lookup cfg "consumer-secret"
  70   cfg_access_token <- DC.lookup cfg "access-token"
  71   cfg_access_secret <- DC.lookup cfg "access-secret"
  72   cfg_heartbeat <- DC.lookup cfg "heartbeat"
  73   cfg_ignore_replies <- DC.lookup cfg "ignore-replies"
  74   cfg_ignore_retweets <- DC.lookup cfg "ignore-retweets"
  75   cfg_sendmail_path <- DC.lookup cfg "sendmail-path"
  76   cfg_from_address <- DC.lookup cfg "from"
  77   cfg_to_address <- DC.lookup cfg "to"
  78   cfg_verbose <- DC.lookup cfg "verbose"
  79   return $ OptionalCfg
  80              cfg_consumer_key
  81              cfg_consumer_secret
  82              cfg_access_token
  83              cfg_access_secret
  84              cfg_heartbeat
  85              cfg_ignore_replies
  86              cfg_ignore_retweets
  87              cfg_sendmail_path
  88              cfg_from_address
  89              cfg_to_address
  90              cfg_verbose
  91