src/Configuration.hs

   1 -- | This module defines the 'Cfg' type, which is just a wrapper
   2 --   around all of the configuration options we accept on the command
   3 --   line. We thread this throughout the rest of the program.
   4 --
   5
   6 module Configuration (
   7   Cfg(..),
   8   merge_optional )
   9 where
  10
  11 import System.Console.CmdArgs.Default ( Default(..) )
  12
  13 import qualified OptionalConfiguration as OC ( OptionalCfg(..) )
  14 import Usernames ( Usernames(..) )
  15
  16
  17 -- | The main configuration data type. It contains all options that
  18 --   can be set in a config file or on the command line.
  19 --
  20 data Cfg =
  21   Cfg { consumer_key :: String,
  22         consumer_secret :: String,
  23         access_token :: String,
  24         access_secret :: String,
  25         heartbeat :: Int,
  26         ignore_replies :: Bool,
  27         ignore_retweets :: Bool,
  28         sendmail_path :: FilePath,
  29         from_address :: Maybe String,
  30         to_address :: Maybe String,
  31         verbose :: Bool,
  32         usernames :: Usernames }
  33     deriving (Show)
  34
  35
  36 instance Default Cfg where
  37   -- | A 'Cfg' with all of its fields set to their default values.
  38   --
  39   def = Cfg { consumer_key = def,
  40               consumer_secret = def,
  41               access_token = def,
  42               access_secret = def,
  43               heartbeat = 600,
  44               ignore_replies = def,
  45               ignore_retweets = def,
  46               sendmail_path = "/usr/sbin/sendmail",
  47               from_address = def,
  48               to_address = def,
  49               verbose = def,
  50               usernames = def }
  51
  52
  53 -- | Merge a 'Cfg' with an 'OptionalCfg'. This is more or less the
  54 --   Monoid instance for 'OptionalCfg', but since the two types are
  55 --   different, we have to repeat ourselves.
  56 --
  57 merge_optional :: Cfg -> OC.OptionalCfg -> Cfg
  58 merge_optional cfg opt_cfg =
  59   Cfg
  60     (merge (consumer_key cfg) (OC.consumer_key opt_cfg))
  61     (merge (consumer_secret cfg) (OC.consumer_secret opt_cfg))
  62     (merge (access_token cfg) (OC.access_token opt_cfg))
  63     (merge (access_secret cfg) (OC.access_secret opt_cfg))
  64     (merge (heartbeat cfg) (OC.heartbeat opt_cfg))
  65     (merge (ignore_replies cfg) (OC.ignore_replies opt_cfg))
  66     (merge (ignore_retweets cfg) (OC.ignore_retweets opt_cfg))
  67     (merge (sendmail_path cfg) (OC.sendmail_path opt_cfg))
  68     (merge' (from_address cfg) (OC.from_address opt_cfg))
  69     (merge' (to_address cfg) (OC.to_address opt_cfg))
  70     (merge (verbose cfg) (OC.verbose opt_cfg))
  71     all_usernames
  72   where
  73     merge :: a -> Maybe a -> a
  74     merge x Nothing  = x
  75     merge _ (Just y) = y
  76
  77     -- Used for the to/from address
  78     merge' :: Maybe a -> Maybe a -> Maybe a
  79     merge' Nothing Nothing = Nothing
  80     merge' (Just x) Nothing  = Just x
  81     merge' Nothing (Just x)  = Just x
  82     merge' (Just _) (Just y) = Just y
  83
  84     -- If there are any optional usernames, use only those.
  85     all_usernames = if (null (get_usernames (OC.usernames opt_cfg)))
  86                     then (usernames cfg)
  87                     else (OC.usernames opt_cfg)