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 import Paths_halcyon ( getSysconfDir )
  27 import System.Directory ( getHomeDirectory )
  28 import System.FilePath ( (</>) )
  29 import System.IO ( hPutStrLn, stderr )
  30 import System.IO.Error ( catchIOError )
  31
  32 import Usernames ( Usernames(..) )
  33
  34
  35 -- | The same as Cfg, except everything is optional. It's easy to
  36 --   merge two of these by simply dropping the Nothings in favor of
  37 --   the Justs. The 'usernames' are left un-maybed so that cmdargs
  38 --   can parse more than one of them.
  39 --
  40 data OptionalCfg =
  41   OptionalCfg { consumer_key :: Maybe String,
  42                 consumer_secret :: Maybe String,
  43                 access_token :: Maybe String,
  44                 access_secret :: Maybe String,
  45                 heartbeat :: Maybe Int,
  46                 ignore_replies :: Maybe Bool,
  47                 ignore_retweets :: Maybe Bool,
  48                 sendmail_path :: Maybe String,
  49                 from_address :: Maybe String,
  50                 to_address :: Maybe String,
  51                 verbose :: Maybe Bool,
  52                 usernames :: Usernames }
  53     deriving (Show, Data, Typeable)
  54
  55 instance Monoid OptionalCfg where
  56   mempty = OptionalCfg
  57              Nothing
  58              Nothing
  59              Nothing
  60              Nothing
  61              Nothing
  62              Nothing
  63              Nothing
  64              Nothing
  65              Nothing
  66              Nothing
  67              Nothing
  68              (Usernames [])
  69
  70   cfg1 `mappend` cfg2 =
  71     OptionalCfg
  72       (merge (consumer_key cfg1) (consumer_key cfg2))
  73       (merge (consumer_secret cfg1) (consumer_secret cfg2))
  74       (merge (access_token cfg1) (access_token cfg2))
  75       (merge (access_secret cfg1) (access_secret cfg2))
  76       (merge (heartbeat cfg1) (heartbeat cfg2))
  77       (merge (ignore_replies cfg1) (ignore_replies cfg2))
  78       (merge (ignore_retweets cfg1) (ignore_retweets cfg2))
  79       (merge (sendmail_path cfg1) (sendmail_path cfg2))
  80       (merge (from_address cfg1) (from_address cfg2))
  81       (merge (to_address cfg1) (to_address cfg2))
  82       (merge (verbose cfg1) (verbose cfg2))
  83       all_usernames
  84     where
  85       merge :: (Maybe a) -> (Maybe a) -> (Maybe a)
  86       merge Nothing Nothing   = Nothing
  87       merge (Just x) Nothing  = Just x
  88       merge Nothing (Just x)  = Just x
  89       merge (Just _) (Just y) = Just y
  90
  91       -- Use only the latter usernames if there are any.
  92       all_usernames =
  93         usernames $ if (null (get_usernames (usernames cfg2)))
  94                     then cfg1
  95                     else cfg2
  96
  97
  98 -- | Obtain an 'OptionalCfg' from halcyonrc in either the global
  99 --   configuration directory or the user's home directory. The one in
 100 --   $HOME is prefixed by a dot so that it is hidden.
 101 --
 102 --   We make an attempt at cross-platform compatibility; we will try
 103 --   to find the correct directory even on Windows. But if the calls
 104 --   to getHomeDirectory/getSysconfDir fail for whatever reason, we
 105 --   fall back to using the Unix-specific /etc and $HOME.
 106 --
 107 from_rc :: IO OptionalCfg
 108 from_rc = do
 109   etc  <- catchIOError getSysconfDir (\e -> do
 110                                         hPutStrLn stderr (show e)
 111                                         return "/etc")
 112   home <- catchIOError getHomeDirectory (\e -> do
 113                                            hPutStrLn stderr (show e)
 114                                            return "$(HOME)")
 115   let global_config_path = etc </> "halcyonrc"
 116   let user_config_path = home </> ".halcyonrc"
 117   cfg <- DC.load [ DC.Optional global_config_path,
 118                    DC.Optional user_config_path ]
 119
 120   cfg_consumer_key <- DC.lookup cfg "consumer-key"
 121   cfg_consumer_secret <- DC.lookup cfg "consumer-secret"
 122   cfg_access_token <- DC.lookup cfg "access-token"
 123   cfg_access_secret <- DC.lookup cfg "access-secret"
 124   cfg_heartbeat <- DC.lookup cfg "heartbeat"
 125   cfg_ignore_replies <- DC.lookup cfg "ignore-replies"
 126   cfg_ignore_retweets <- DC.lookup cfg "ignore-retweets"
 127   cfg_sendmail_path <- DC.lookup cfg "sendmail-path"
 128   cfg_from_address <- DC.lookup cfg "from"
 129   cfg_to_address <- DC.lookup cfg "to"
 130   cfg_verbose <- DC.lookup cfg "verbose"
 131   cfg_usernames <- DC.lookup cfg "usernames"
 132
 133   return $ OptionalCfg
 134              cfg_consumer_key
 135              cfg_consumer_secret
 136              cfg_access_token
 137              cfg_access_secret
 138              cfg_heartbeat
 139              cfg_ignore_replies
 140              cfg_ignore_retweets
 141              cfg_sendmail_path
 142              cfg_from_address
 143              cfg_to_address
 144              cfg_verbose
 145              (fromMaybe (Usernames []) cfg_usernames)