Take the heartbeat (in seconds) from the command line. Default to ten minutes.

[dead/halcyon.git] / src / CommandLine.hs

diff --git a/src/CommandLine.hs b/src/CommandLine.hs
index da6a04b06b35e2f2cdf3472bb68d53311611e05c..8d8ceab521037a38dca6e7f19b9c505b0884d61e 100644 (file)
--- a/src/CommandLine.hs
+++ b/src/CommandLine.hs
@@ -2,7 +2,8 @@
 -- It should more or less be a black box, providing Main with only the
 -- information it requires.
 module CommandLine
-( help_set,
+( heartbeat,
+  help_set,
   help_text,
   from_email_address,
   to_email_address,
@@ -17,7 +18,8 @@ import System.Environment (getArgs)
 
 
 -- |A record containing values for all available options.
-data Options = Options { opt_help  :: Bool,
+data Options = Options { opt_heartbeat :: Maybe Int,
+                         opt_help  :: Bool,
                          opt_from :: Maybe String,
                          opt_to :: Maybe String }
 
@@ -25,7 +27,8 @@ data Options = Options { opt_help  :: Bool,
 -- |Constructs an instance of Options, with each of its members set to
 -- default values.
 default_options :: Options
-default_options = Options { opt_help = False,
+default_options = Options { opt_heartbeat = Just 600,
+                            opt_help = False,
                             opt_from = Nothing,
                             opt_to = Nothing }
 
@@ -41,11 +44,25 @@ default_options = Options { opt_help = False,
 options :: [OptDescr (Options -> IO Options)]
 options =
   [ Option ['h'][] (NoArg set_help) "Prints this help message.",
+    Option ['n'][] (ReqArg set_heartbeat "heartbeat") "How many seconds to wait between polling.",
     Option ['t'][] (ReqArg set_to "email_address") "Send tweets TO email_address.",
     Option ['f'][] (ReqArg set_from "email_address") "Send tweets FROM email_address."
   ]
 
 
+-- | Attempt to parse an 'Int' from a 'String'. This is just a 'Maybe'
+--   wrapper around 'reads'.
+parse_int :: String -> Maybe Int
+parse_int s =
+  case (reads s) of
+    [(n,_)]   -> Just n
+    _         -> Nothing
+
+set_heartbeat :: String -> Options -> IO Options
+set_heartbeat arg opts = do
+  let new_heartbeat = parse_int arg
+  return opts { opt_heartbeat = new_heartbeat }
+
 set_help :: Options -> IO Options
 set_help opts = do
   return opts { opt_help = True }
@@ -61,7 +78,7 @@ set_from arg opts = do
 
 -- The usage header.
 usage :: String
-usage = "Usage: twat [-t to_address] [-f from_address] <username1> [username2, [username3]...]"
+usage = "Usage: twat [-n heartbeat] [-t to_address] [-f from_address] <username1> [username2, [username3]...]"
 
 
 -- The usage header, and all available flags (as generated by GetOpt)
@@ -84,6 +101,14 @@ parse_options = do
   return opts
 
 
+-- | A list of parse errors relating to the heartbeat.
+heartbeat_errors :: IO [String]
+heartbeat_errors = do
+  hb <- heartbeat
+  if (isNothing hb)
+    then return ["\"heartbeat\" does not appear to be an integer."]
+    else return []
+
 -- |Parse errors relating to the list of usernames.
 username_errors :: IO [String]
 username_errors = do
@@ -91,7 +116,7 @@ username_errors = do
   let (_, usernames, _) = getOpt Permute options argv
 
   if (null usernames)
-    then return ["No usernames provided."]
+    then return ["no usernames provided."]
     else return []
 
 
@@ -101,7 +126,7 @@ to_errors = do
   toaddr <- to_email_address
   fromaddr <- from_email_address
   if (isNothing toaddr) && (isJust fromaddr)
-    then return ["\"From\" address specified without \"To\" address."]
+    then return ["\"from\" address specified without \"to\" address."]
     else return []
 
 
@@ -111,7 +136,7 @@ from_errors = do
   toaddr <- to_email_address
   fromaddr <- from_email_address
   if (isJust toaddr) && (isNothing fromaddr)
-    then return ["\"To\" address specified without \"From\" address."]
+    then return ["\"to\" address specified without \"from\" address."]
     else return []
 
 
@@ -125,10 +150,15 @@ parse_errors :: IO [String]
 parse_errors = do
   argv <- getArgs
   let (_, _, errors) = getOpt Permute options argv
+  errs_heartbeat <- heartbeat_errors
   errs_username <- username_errors
   errs_to <- to_errors
   errs_from <- from_errors
-  return $ map format_error (errors ++ errs_username ++ errs_to ++ errs_from)
+  return $ map format_error (errors ++
+                             errs_heartbeat ++
+                             errs_username ++
+                             errs_to ++
+                             errs_from)
 
 -- |Was the "help" option passed on the command line?
 help_set :: IO Bool
@@ -136,6 +166,11 @@ help_set = do
     opts <- parse_options
     return (opt_help opts)
 
+-- |What's the heartbeat?
+heartbeat :: IO (Maybe Int)
+heartbeat = do
+  opts <- parse_options
+  return (opt_heartbeat opts)
 
 -- |What "To" address was given on the command line?
 to_email_address :: IO (Maybe String)