import Control.Concurrent (forkIO, threadDelay)
import Control.Monad (forever, when)
+import Data.Maybe (fromJust)
import System.Exit (ExitCode(..), exitWith)
import System.IO (hPutStrLn, stderr)
import Twitter.User
--- |The length of all calls to sleep (or threadDelay), in seconds.
-heartbeat :: Int
-heartbeat = 600
-
-- |A wrapper around threadDelay which takes seconds instead of
-- microseconds as its argument.
thread_sleep :: Int -> IO ()
headers = ((headers message) ++ ["Date: " ++ date])}
--- |This is the main recursive loop. It takes 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 :: String -> Integer -> (Maybe Message) -> IO ()
-recurse username latest_status_id maybe_message = do
- thread_sleep heartbeat
+-- |This is the main recursive loop. It takes a length of time to
+-- delay (in seconds), 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 :: Int -> String -> Integer -> (Maybe Message) -> IO ()
+recurse delay username latest_status_id maybe_message = do
+ thread_sleep delay
xmldata <- get_user_new_statuses username latest_status_id
-- Parsing an empty result can blow up. Just pretend there are
case (length new_statuses) of
0 ->
- recurse username latest_status_id maybe_message
+ recurse delay username latest_status_id maybe_message
_ -> do
let new_latest_status_id = get_max_status_id new_statuses
_ <- mapM (putStrLn . pretty_print) new_statuses
case maybe_message of
Nothing -> do
- recurse username new_latest_status_id maybe_message
+ recurse delay username new_latest_status_id maybe_message
return ()
Just message -> do
date_header <- construct_date_header
let messages = map (message_from_status message (date_header)) new_statuses
sendmail_results <- mapM sendmail messages
_ <- mapM print_sendmail_result sendmail_results
- recurse username new_latest_status_id maybe_message
+ recurse delay username new_latest_status_id maybe_message
return ()
-- |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 :: String -> IO Integer
-get_latest_status_id username = do
+get_latest_status_id :: Int -> String -> IO Integer
+get_latest_status_id delay username = do
xmldata <- get_user_timeline username
let initial_statuses = case xmldata of
0 -> do
-- If the HTTP part barfs, try again after a while.
putStrLn ("Couldn't retrieve " ++ username ++ "'s timeline. Retrying...")
- thread_sleep heartbeat
- get_latest_status_id username
+ thread_sleep delay
+ get_latest_status_id delay username
_ -> return (get_max_status_id initial_statuses)
-- recursive loop that checks for updates forever. The message
-- argument is optional and is passed to recurse in case the updates
-- should be emailed.
-run_twat :: Maybe Message -> String -> IO ()
-run_twat message username = do
- latest_status_id <- get_latest_status_id username
- recurse username latest_status_id message
+run_twat :: Int -> Maybe Message -> String -> IO ()
+run_twat delay message username = do
+ latest_status_id <- get_latest_status_id delay username
+ recurse delay username latest_status_id message
return ()
to = toaddr,
from = fromaddr })
+ -- This should be safe since we checked for parse errors earlier.
+ delay <- fmap fromJust heartbeat
+
-- Execute run_twat on each username in a new thread.
- _ <- mapM (forkIO . (run_twat message)) usernames
+ _ <- mapM (forkIO . (run_twat delay message)) usernames
_ <- forever $ do
-- This thread (the one executing main) doesn't do anything,
-- but when it terminates, so do all the threads we forked.
-- As a result, we need to keep this thread on life support.
- thread_sleep heartbeat
+ thread_sleep delay
return ()