src/TSN/Picklers.hs

   1 -- | (Un)picklers for data types present in The Sports Network XML
   2 --   feed.
   3 --
   4 module TSN.Picklers (
   5   xp_date,
   6   xp_team_id )
   7 where
   8
   9 import Data.Time.Clock ( UTCTime )
  10 import Data.Time.Format ( formatTime, parseTime )
  11 import System.Locale ( defaultTimeLocale )
  12 import Text.Printf ( printf )
  13 import Text.Read ( readMaybe )
  14 import Text.XML.HXT.Arrow.Pickle (
  15   XmlPickler(..),
  16   xpText,
  17   xpWrapMaybe )
  18 import Text.XML.HXT.Arrow.Pickle.Xml ( PU )
  19
  20 instance XmlPickler Bool where
  21   xpickle =
  22     (to_bool, from_bool) `xpWrapMaybe` xpText
  23     where
  24       to_bool :: String -> Maybe Bool
  25       to_bool = readMaybe
  26
  27       from_bool :: Bool -> String
  28       from_bool = show
  29
  30
  31 -- | (Un)pickle a UTCTime without the time portion.
  32 --
  33 xp_date :: PU UTCTime
  34 xp_date =
  35   (to_date, from_date) `xpWrapMaybe` xpText
  36   where
  37     format = "%-m/%-d/%Y"
  38
  39     to_date :: String -> Maybe UTCTime
  40     to_date = parseTime defaultTimeLocale format
  41
  42     from_date :: UTCTime -> String
  43     from_date = formatTime defaultTimeLocale format
  44
  45
  46 -- | Parse a team_id. This *should* just be an 'Int', but TSN is doing
  47 --   something weird. First of all, player IDs do look like normal
  48 --   'Int's. But the team IDs are all stuck in the triple digits, and
  49 --   double-digit team IDs appear to be padded to three characters
  50 --   with a leading '0'. So maybe they're treating these as text?
  51 --
  52 --   In any case, we do the simplest thing that is correct for all the
  53 --   XML we've got: pad it to (only) three digits on pickling.
  54 --
  55 xp_team_id :: PU Int
  56 xp_team_id =
  57   (to_team_id, from_team_id) `xpWrapMaybe` xpText
  58   where
  59     to_team_id :: String -> Maybe Int
  60     to_team_id = readMaybe
  61
  62     from_team_id :: Int -> String
  63     from_team_id = printf "%03d"