src/OptionalConfiguration.hs

   1 {-# LANGUAGE DeriveDataTypeable #-}
   2 {-# LANGUAGE FlexibleInstances #-}
   3 {-# LANGUAGE OverloadedStrings #-}
   4
   5 -- | The program will parse ~/.halcyonrc for any available configuration
   6 --   directives, resulting in an OptionalCfg. The command-line
   7 --   arguments will be used to create another OptionalCfg, and the two
   8 --   will be merged. Finally, a default_config will be updated from
   9 --   the merged OptionalCfgs.
  10 --
  11
  12 module OptionalConfiguration (
  13   OptionalCfg(..),
  14   from_rc )
  15 where
  16
  17 import qualified Data.Configurator as DC (
  18   Worth (Optional),
  19   load,
  20   lookup )
  21
  22 import Data.Data ( Data )
  23 import Data.Maybe ( fromMaybe )
  24 import Data.Monoid ( Monoid(..) )
  25 import Data.Typeable ( Typeable )
  26
  27 import Usernames ( Usernames(..) )
  28
  29
  30 -- | The same as Cfg, except everything is optional. It's easy to
  31 --   merge two of these by simply dropping the Nothings in favor of
  32 --   the Justs. The 'usernames' are left un-maybed so that cmdargs
  33 --   can parse more than one of them.
  34 --
  35 data OptionalCfg =
  36   OptionalCfg { consumer_key :: Maybe String,
  37                 consumer_secret :: Maybe String,
  38                 access_token :: Maybe String,
  39                 access_secret :: Maybe String,
  40                 heartbeat :: Maybe Int,
  41                 ignore_replies :: Maybe Bool,
  42                 ignore_retweets :: Maybe Bool,
  43                 sendmail_path :: Maybe String,
  44                 from_address :: Maybe String,
  45                 to_address :: Maybe String,
  46                 verbose :: Maybe Bool,
  47                 usernames :: Usernames }
  48     deriving (Show, Data, Typeable)
  49
  50 instance Monoid OptionalCfg where
  51   mempty = OptionalCfg
  52              Nothing
  53              Nothing
  54              Nothing
  55              Nothing
  56              Nothing
  57              Nothing
  58              Nothing
  59              Nothing
  60              Nothing
  61              Nothing
  62              Nothing
  63              (Usernames [])
  64
  65   cfg1 `mappend` cfg2 =
  66     OptionalCfg
  67       (merge (consumer_key cfg1) (consumer_key cfg2))
  68       (merge (consumer_secret cfg1) (consumer_secret cfg2))
  69       (merge (access_token cfg1) (access_token cfg2))
  70       (merge (access_secret cfg1) (access_secret cfg2))
  71       (merge (heartbeat cfg1) (heartbeat cfg2))
  72       (merge (ignore_replies cfg1) (ignore_replies cfg2))
  73       (merge (ignore_retweets cfg1) (ignore_retweets cfg2))
  74       (merge (sendmail_path cfg1) (sendmail_path cfg2))
  75       (merge (from_address cfg1) (from_address cfg2))
  76       (merge (to_address cfg1) (to_address cfg2))
  77       (merge (verbose cfg1) (verbose cfg2))
  78       all_usernames
  79     where
  80       merge :: (Maybe a) -> (Maybe a) -> (Maybe a)
  81       merge Nothing Nothing   = Nothing
  82       merge (Just x) Nothing  = Just x
  83       merge Nothing (Just x)  = Just x
  84       merge (Just _) (Just y) = Just y
  85
  86       -- Use only the latter usernames if there are any.
  87       all_usernames =
  88         usernames $ if (null (get_usernames (usernames cfg2)))
  89                     then cfg1
  90                     else cfg2
  91
  92 from_rc :: IO OptionalCfg
  93 from_rc = do
  94   cfg <- DC.load [ DC.Optional "$(HOME)/.halcyonrc" ]
  95   cfg_consumer_key <- DC.lookup cfg "consumer-key"
  96   cfg_consumer_secret <- DC.lookup cfg "consumer-secret"
  97   cfg_access_token <- DC.lookup cfg "access-token"
  98   cfg_access_secret <- DC.lookup cfg "access-secret"
  99   cfg_heartbeat <- DC.lookup cfg "heartbeat"
 100   cfg_ignore_replies <- DC.lookup cfg "ignore-replies"
 101   cfg_ignore_retweets <- DC.lookup cfg "ignore-retweets"
 102   cfg_sendmail_path <- DC.lookup cfg "sendmail-path"
 103   cfg_from_address <- DC.lookup cfg "from"
 104   cfg_to_address <- DC.lookup cfg "to"
 105   cfg_verbose <- DC.lookup cfg "verbose"
 106   cfg_usernames <- DC.lookup cfg "usernames"
 107
 108   return $ OptionalCfg
 109              cfg_consumer_key
 110              cfg_consumer_secret
 111              cfg_access_token
 112              cfg_access_secret
 113              cfg_heartbeat
 114              cfg_ignore_replies
 115              cfg_ignore_retweets
 116              cfg_sendmail_path
 117              cfg_from_address
 118              cfg_to_address
 119              cfg_verbose
 120              (fromMaybe (Usernames []) cfg_usernames)