+import Control.Concurrent ( forkIO, threadDelay )
+import Control.Monad ( forever, when )
+import Data.Aeson ( decode )
+import Data.Maybe ( fromMaybe, isNothing )
+import Data.Monoid ( (<>) )
+import Data.Time.LocalTime ( TimeZone, getCurrentTimeZone )
+import System.Console.CmdArgs.Default ( Default(..) )
+import System.Exit ( ExitCode(..), exitWith )
+import System.IO ( hPutStrLn, stderr )
+
+import CommandLine ( get_args, show_help )
+import Configuration ( Cfg(..), merge_optional )
+import ExitCodes ( exit_no_usernames )
+import qualified OptionalConfiguration as OC ( from_rc )
+import Mail (
+ Message(..),
+ print_sendmail_result,
+ rfc822_now,
+ sendmail )
+import Twitter.Http ( get_user_new_statuses, get_user_timeline )
+import Twitter.Status (
+ Status(..),
+ Timeline,
+ get_max_status_id,
+ pretty_print,
+ utc_time_to_rfc822 )
+import Twitter.User ( User(..) )
+import Usernames ( Usernames(..) )
+
+-- | A wrapper around threadDelay which takes seconds instead of
+-- microseconds as its argument.
+--
+thread_sleep :: Int -> IO ()
+thread_sleep seconds = do
+ let microseconds = seconds * (10 ^ (6 :: Int))
+ threadDelay microseconds
+
+
+-- | Given a 'Message', 'Status', and date, update that message's body
+-- and subject with the information contained in the status. Adds a
+-- /Date: / header, and returns the updated message.
+--
+message_from_status :: Maybe TimeZone -> Message -> String -> Status -> Message
+message_from_status mtz message default_date status =
+ message { subject = "Halcyon: " ++ (screen_name (user status)),
+ body = (pretty_print mtz status),
+ headers = ((headers message) ++ ["Date: " ++ date])}
+ where
+ date = maybe
+ default_date -- default
+ (utc_time_to_rfc822 mtz) -- function to apply if not Nothing
+ (created_at status) -- the Maybe thing
+
+
+-- | If the given 'Message' is not 'Nothing', send a copy of it for
+-- every 'Status' in the @statuses@ list.
+--
+send_messages :: Cfg -> Maybe TimeZone -> Maybe Message -> [Status] -> IO ()
+send_messages cfg mtz maybe_message statuses =
+ case maybe_message of
+ Nothing -> return ()
+ Just message -> do
+ default_date <- rfc822_now
+ let mfs = message_from_status mtz message default_date
+ let messages = map mfs statuses
+ sendmail_results <- mapM sendmail' messages
+ mapM_ print_sendmail_result sendmail_results
+ where
+ sendmail' = sendmail (sendmail_path cfg)
+
+
+-- | Display the number of skipped replies if ignore_replies is true
+-- and verbose is enabled.
+--
+mention_replies :: Cfg -> [Status] -> IO ()
+mention_replies cfg ss = do
+ let replies = filter reply ss
+ when ((ignore_replies cfg) && (verbose cfg)) $ do
+ let countstr = show $ length replies
+ putStrLn $ "Ignoring " ++ countstr ++ " replies."
+
+
+-- | Display the number of skipped retweets if ignore_retweets is true
+-- and verbose is enabled.
+--
+mention_retweets :: Cfg -> [Status] -> IO ()
+mention_retweets cfg ss = do
+ let retweets = filter retweeted ss
+ when ((ignore_retweets cfg) && (verbose cfg)) $ do
+ let countstr = show $ length retweets
+ putStrLn $ "Ignoring " ++ countstr ++ " retweets."
+
+
+
+-- | Filter out replies/retweets based on the configuration.
+--
+filter_statuses :: Cfg -> [Status] -> [Status]
+filter_statuses cfg statuses =
+ (reply_filter . retweet_filter) statuses
+ where
+ reply_filter = if ignore_replies cfg
+ then filter (not . reply)
+ else id
+
+ retweet_filter = if ignore_retweets cfg
+ then filter (not . retweeted)
+ else id
+
+
+-- | This is the main recursive loop. It takes a the configuration, a
+-- username, a latest_status_id, and optionally a 'Message' as
+-- arguments. The @latest_status_id@ is the last status (that we know
+-- of) to be posted to username's Twitter account. If we find any
+-- newer statuses when we check, they are printed and optionally
+-- emailed (if a 'Message' was supplied). Then, the process repeats.
+--
+recurse :: Cfg -> String -> Integer -> (Maybe Message) -> IO ()
+recurse cfg username latest_status_id maybe_message = do
+ thread_sleep (heartbeat cfg)
+ timeline <- get_user_new_statuses cfg username latest_status_id
+
+ let decoded_timeline = decode timeline :: Maybe Timeline
+
+ when (isNothing decoded_timeline) $
+ hPutStrLn stderr $
+ "Couldn't retrieve "
+ ++ username
+ ++ "'s timeline. Skipping..."
+
+ let new_statuses = fromMaybe [] decoded_timeline
+
+ case new_statuses of
+ [] -> do_recurse latest_status_id
+ _ -> do
+ mention_replies cfg new_statuses
+ mention_retweets cfg new_statuses
+
+ let good_statuses = filter_statuses cfg new_statuses
+
+ tz <- getCurrentTimeZone
+ let mtz = Just tz
+ mapM_ (putStr . (pretty_print mtz)) good_statuses
+
+ send_messages cfg mtz maybe_message good_statuses
+
+ let new_latest_status_id = get_max_status_id new_statuses
+ do_recurse new_latest_status_id
+
+ where
+ -- This lets us write all of these parameters once rather
+ -- than... more than once.
+ do_recurse :: Integer -> IO ()
+ do_recurse lsi = recurse cfg username lsi maybe_message
+
+
+-- | Try continually to download username's timeline, and determine the
+-- latest status id to be posted once we have done so.
+--
+get_latest_status_id :: Cfg -> String -> IO Integer
+get_latest_status_id cfg username = do
+ let delay = heartbeat cfg
+ timeline <- get_user_timeline cfg username
+
+ let decoded_timeline = decode timeline :: Maybe Timeline
+
+ when (isNothing decoded_timeline) $
+ hPutStrLn stderr $
+ "Couldn't retrieve "
+ ++ username
+ ++ "'s timeline. Skipping..."
+
+ let initial_timeline = fromMaybe [] decoded_timeline
+
+ case initial_timeline of
+ [] -> do
+ -- If the HTTP part barfs, try again after a while.
+ thread_sleep delay
+ get_latest_status_id cfg username
+ _ ->
+ return (get_max_status_id initial_timeline)