src/Twitter/Http.hs

   1 module Twitter.Http
   2 where
   3
   4 import Network.Curl
   5 import System.IO (hPutStrLn, stderr)
   6
   7 -- |The API URL of username's timeline.
   8 --
   9 -- See,
  10 --
  11 --   <http://dev.twitter.com/doc/get/statuses/user_timeline>
  12 --
  13 user_timeline_url :: String -> String
  14 user_timeline_url username =
  15     concat [ "http://api.twitter.com/1/statuses/user_timeline.xml",
  16              "?screen_name=" ++ username,
  17              "&include_rts=true",
  18              "&count=10" ]
  19
  20 -- |Given username's last status id, constructs the API URL for
  21 -- username's new statuses. Essentially, 'user_timeline_url' with a
  22 -- "since_id" parameter tacked on.
  23 user_new_statuses_url :: String -> Integer -> String
  24 user_new_statuses_url username last_status_id =
  25     concat [ user_timeline_url username,
  26              "&since_id=" ++ (show last_status_id) ]
  27
  28
  29 -- |Return's username's timeline, or 'Nothing' if there was an error.
  30 get_user_timeline :: String -> IO (Maybe String)
  31 get_user_timeline username = do
  32   let uri = (user_timeline_url username)
  33   timeline <- (http_get uri)
  34   return timeline
  35
  36
  37 -- Returns the XML representing all of username's statuses that are
  38 -- newer than last_status_id.
  39 get_user_new_statuses :: String -> Integer -> IO (Maybe String)
  40 get_user_new_statuses username last_status_id = do
  41   let uri = (user_new_statuses_url username last_status_id)
  42   new_statuses <- (http_get uri)
  43   return new_statuses
  44
  45
  46 -- |Uses the CURL API to retrieve uri. Returns 'Nothing' if there was
  47 -- an error.
  48 http_get :: String -> IO (Maybe String)
  49 http_get uri = withCurlDo $ do
  50   resp <- curlGetString uri [CurlTimeout 45]
  51
  52   case resp of
  53     (CurlOK, body) -> return (Just body)
  54     (code, _) -> do
  55         hPutStrLn stderr ("HTTP Error: " ++ (show code))
  56         return Nothing