src/Twitter/Status.hs

   1 -- |Functions and data for working with Twitter statuses.
   2 module Twitter.Status
   3 where
   4
   5 import Data.Maybe
   6 import Text.XML.HaXml
   7
   8 import Twitter.User
   9 import Twitter.Xml
  10
  11 -- |Represents one Twitter status. We don't care about any of their
  12 -- other properties.
  13 data Status = Status { status_id  :: Integer,
  14                        created_at :: String,
  15                        text       :: String,
  16                        user       :: User }
  17             deriving (Show, Eq)
  18
  19
  20 -- |Given some XML content, create a 'Status' from it.
  21 status_from_content :: Content -> (Maybe Status)
  22 status_from_content content =
  23
  24     if (length status_ids) == 0
  25         || (length created_ats) == 0
  26         || (length texts) == 0
  27         || (length users) == 0
  28     then
  29         Nothing
  30     else
  31         case first_status_id of
  32           Nothing -> Nothing
  33           (Just status_id_data) ->
  34               case first_created_at of
  35                   Nothing -> Nothing
  36                   (Just created_at_data) ->
  37                           case first_user of
  38                               Nothing -> Nothing
  39                               (Just user_object) ->
  40                                   case (reads status_id_data :: [(Integer, String)]) of
  41                                     []   -> Nothing
  42                                     parseresult:_ -> Just (Status (fst parseresult) created_at_data all_text user_object)
  43
  44     where
  45       status_ids = (unique_id content)
  46       first_status_id = get_char_data (status_ids !! 0)
  47
  48       created_ats = (status_created_at content)
  49       first_created_at = get_char_data (created_ats !! 0)
  50
  51       texts = (status_text content)
  52       all_text = concat $ catMaybes (map get_char_data texts)
  53
  54       users = (status_user content)
  55       first_user = user_from_content (users !! 0)
  56
  57
  58 -- |Takes an XML String as an argument, and returns the
  59 -- status that was parsed from it. Should only be used
  60 -- on XML string where a <status> is a top-level element.
  61 parse_status :: String -> [Status]
  62 parse_status xml_data =
  63     catMaybes maybe_status
  64     where
  65       (Document _ _ root _) = xmlParse xml_file_name xml_data
  66       root_elem = CElem root
  67       status_element = (single_status root_elem)
  68       maybe_status = map status_from_content status_element
  69
  70
  71 -- |Takes an XML String as an argument, and returns the list of
  72 -- statuses that can be parsed from it.
  73 parse_statuses :: String -> [Status]
  74 parse_statuses xml_data =
  75     catMaybes maybe_statuses
  76     where
  77       (Document _ _ root _) = xmlParse xml_file_name xml_data
  78       root_elem = CElem root
  79       status_elements = (all_statuses root_elem)
  80       maybe_statuses = map status_from_content status_elements
  81
  82
  83 -- |This is a required parameter to the xmlParse function used in
  84 -- error reporting. We're not parsing a function, though, so we leave
  85 -- it blank.
  86 xml_file_name :: String
  87 xml_file_name = ""
  88
  89 -- |Returns a nicely-formatted String representing the given 'Status'
  90 -- object.
  91 pretty_print :: Status -> String
  92 pretty_print status =
  93     concat [ name,
  94              " - ",
  95              (created_at status),
  96              "\n",
  97              replicate ((length name) + 3 + (length (created_at status))) '-',
  98              "\n",
  99              replace_entities (text status),
 100              "\n" ]
 101              where
 102                name = screen_name (user status)
 103
 104
 105
 106 -- |Given a list of statuses, returns the greatest status_id belonging
 107 -- to one of the statuses in the list.
 108 get_max_status_id :: [Status] -> Integer
 109 get_max_status_id statuses =
 110   maximum status_ids
 111   where
 112     status_ids = map status_id statuses