src/Configuration.hs

   1 -- | This module defines the 'Configuration' type, which is just a
   2 --   wrapper around all of the configuration options we accept on the
   3 --   command line.
   4 --
   5 module Configuration (
   6   Configuration(..),
   7   merge_optional )
   8 where
   9
  10 import System.Console.CmdArgs.Default ( Default(..) )
  11 import System.Log ( Priority( INFO ) )
  12
  13 import qualified OptionalConfiguration as OC (
  14   OptionalConfiguration(..),
  15   merge_maybes )
  16 import TSN.FeedHosts (FeedHosts(..))
  17
  18 -- | The main configuration data type. This will be passed to most of
  19 --   the important functions once it has been created.
  20 data Configuration =
  21   Configuration {
  22     daemonize        :: Bool,
  23     feed_hosts       :: FeedHosts,
  24     log_file         :: Maybe FilePath,
  25     log_level        :: Priority,
  26     output_directory :: FilePath,
  27     password         :: String,
  28     pidfile          :: FilePath,
  29     run_as_group     :: Maybe String,
  30     run_as_user      :: Maybe String,
  31     syslog           :: Bool,
  32     username         :: String }
  33     deriving (Show)
  34
  35 -- | A Configuration with all of its fields set to their default
  36 --   values.
  37 instance Default Configuration where
  38   def = Configuration {
  39           daemonize        = def,
  40           feed_hosts       = def,
  41           log_file         = def,
  42           log_level        = INFO,
  43           output_directory = ".",
  44           password         = def,
  45           pidfile          = "/run/htsn.pid",
  46           run_as_group     = def,
  47           run_as_user      = def,
  48           syslog           = def,
  49           username         = def }
  50
  51
  52 -- | Merge a Configuration with an OptionalConfiguration. This is more
  53 --   or less the Monoid instance for OptionalConfiguration, but since
  54 --   the two types are different, we have to repeat ourselves.
  55 merge_optional :: Configuration
  56                -> OC.OptionalConfiguration
  57                -> Configuration
  58 merge_optional cfg opt_cfg =
  59   Configuration
  60     (merge (daemonize cfg) (OC.daemonize opt_cfg))
  61     all_feed_hosts
  62     (OC.merge_maybes (log_file cfg) (OC.log_file opt_cfg))
  63     (merge (log_level cfg) (OC.log_level opt_cfg))
  64     (merge (output_directory cfg) (OC.output_directory opt_cfg))
  65     (merge (password cfg) (OC.password opt_cfg))
  66     (merge (pidfile cfg) (OC.pidfile opt_cfg))
  67     (OC.merge_maybes (run_as_group cfg) (OC.run_as_group opt_cfg))
  68     (OC.merge_maybes (run_as_user cfg) (OC.run_as_user opt_cfg))
  69     (merge (syslog cfg) (OC.syslog opt_cfg))
  70     (merge (username cfg) (OC.username opt_cfg))
  71   where
  72     -- | If the thing on the right is Just something, return that
  73     --   something, otherwise return the thing on the left.
  74     merge :: a -> Maybe a -> a
  75     merge x Nothing  = x
  76     merge _ (Just y) = y
  77
  78     -- If there are any optional usernames, use only those.
  79     all_feed_hosts = if (null (get_feed_hosts (OC.feed_hosts opt_cfg)))
  80                      then (feed_hosts cfg)
  81                      else (OC.feed_hosts opt_cfg)
  82