Move FeedHosts under the TSN namespace.

[dead/htsn.git] / src / OptionalConfiguration.hs

diff --git a/src/OptionalConfiguration.hs b/src/OptionalConfiguration.hs
index ea7a67830dd280cf2dbe7380e74b824b16d24d4d..f636a17e2d623104dc2b06ea4983a9ff09c81d74 100644 (file)
--- a/src/OptionalConfiguration.hs
+++ b/src/OptionalConfiguration.hs
@@ -2,12 +2,11 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE OverloadedStrings #-}
 
--- | The program will parse ~/.htsnrc for any available configuration
---   directives, resulting in an OptionalConfiguration. The
---   command-line arguments will be used to create another
---   OptionalConfiguration, and the two will be merged. Finally, a
---   def :: Configuration will be updated from the merged
---   OptionalConfigurations.
+-- | An OptionalConfiguration is just like a 'Configuration', except
+--   all of its fields are optional. The user can set options in two
+--   places: the command-line, and a configuration file. Obviously if
+--   a parameter is set in one place, it doesn't need to be set in the
+--   other. Thus, the latter needs to be optional.
 --
 
 module OptionalConfiguration (
@@ -23,8 +22,12 @@ import Data.Data (Data)
 import Data.Maybe (fromMaybe)
 import Data.Monoid (Monoid(..))
 import Data.Typeable (Typeable)
+import System.Directory (getHomeDirectory)
+import System.FilePath ( (</>) )
+import System.IO.Error (catchIOError)
 
-import FeedHosts (FeedHosts(..))
+import Terminal (report_error)
+import TSN.FeedHosts (FeedHosts(..))
 
 
 -- | The same as Configuration, except everything is optional. It's easy to
@@ -40,7 +43,20 @@ data OptionalConfiguration =
     username :: Maybe String }
     deriving (Show, Data, Typeable)
 
+
+-- | The Monoid instance for these lets us "combine" two
+--   OptionalConfigurations. The "combine" operation that we'd like to
+--   perform is, essentially, to mash them together. So if we have two
+--   OptionalConfigurations, each half full, we could combine them
+--   into one big one.
+--
+--   One of the two must take precedence during this mashing, and we
+--   choose the second one for no reason.
+--
+--   This is used to merge command-line and config-file settings.
+--
 instance Monoid OptionalConfiguration where
+  -- | An empty OptionalConfiguration.
   mempty = OptionalConfiguration
              (FeedHosts [])
              Nothing
@@ -48,6 +64,7 @@ instance Monoid OptionalConfiguration where
              Nothing
 
 
+  -- | Combine @cfg1@ and @cfg2@, giving precedence to @cfg2@.
   cfg1 `mappend` cfg2 =
     OptionalConfiguration
       all_feed_hosts
@@ -67,10 +84,27 @@ instance Monoid OptionalConfiguration where
                     then cfg1
                     else cfg2
 
+
+-- | Obtain an OptionalConfiguration from the file ".htsnrc" in the
+--   user's home directory.
+--
+--   We make an attempt at cross-platform compatibility; we will try
+--   to find the correct directory even on Windows. But if the call
+--   to getHomeDirectory fails for whatever reason, we fall back to
+--   using the environment variable $HOME.
+--
 from_rc :: IO OptionalConfiguration
 from_rc = do
-  cfg <- DC.load [ DC.Optional "/etc/htsnrc",
-                   DC.Optional "$(HOME)/.htsnrc" ]
+  -- After some thought, the "global" /etc/htsnrc configuration file
+  -- was left out. Since each config file needs a password, and this
+  -- should be run by a dedicated user anyway, the global file does
+  -- not serve much purpose. It could also be a security risk (visible
+  -- password) if the admin screws up.
+  home <- catchIOError getHomeDirectory (\e -> do
+                                           report_error (show e)
+                                           return "$(HOME)")
+  let user_config_path = home </> ".htsnrc"
+  cfg <- DC.load [ DC.Optional user_config_path ]
   cfg_password <- DC.lookup cfg "password"
   cfg_output_directory <- DC.lookup cfg "output_directory"
   cfg_username <- DC.lookup cfg "username"