-----------------------------------------------------------------------------
-- |
-- Module : Extract
-- Copyright : (C) Peter Robinson 2010-2012
-- License : GPL-2
--
-- Maintainer : Peter Robinson <thaldyron@gmail.com>
-- Stability : experimental
-- Portability : portable
--
-- Functions for retrieving data from the mathematics genealogy project.
--
-----------------------------------------------------------------------------
module Extract
where
import Network.HTTP
import Text.HTML.TagSoup
import Control.Monad
import Control.Exception
import Data.Char(isSpace)
import Data.Maybe
import Data.Text.Lazy(Text)
import Data.Text.Lazy.Encoding
import qualified Data.Text.Lazy as T
import qualified Data.ByteString.Lazy.Char8 as B
import Control.Applicative
import Entry
openURL x = return . T.pack =<< getResponseBody =<< simpleHTTP (getRequest x)
getTags :: Text -> IO [Tag Text]
getTags url = parseTags <$> openURL (T.unpack url)
parseEntry :: [Tag Text]
-> Entry
parseEntry tags =
Entry (scientist tags)
(graduationInfo tags)
(advisors tags)
scientist :: [Tag Text] -> Text
scientist tags =
let TagText sc = removeClutter $ head $ tail $ head $ sections (~== "<h2 style") tags in
decodeUtf8 $ B.pack $ T.unpack sc
graduationInfo :: [Tag Text] -> Maybe GraduationInfo
graduationInfo tags =
let offset = head $ sections (~== "<span style=\"margin-right: 0.5em\">") tags
getTag i = notEmptyMaybeTagText $ removeClutter $ offset !! i
degree = getTag 1
univ = getTag 3
year = getTag 5
diss = getTag 18
in matchLen offset degree univ year diss
where
matchLen offset degree univ year diss
| length offset >= 19 = Just $ GraduationInfo degree univ year diss
| length offset >= 6 = Just $ GraduationInfo degree univ year Nothing
| length offset >= 4 = Just $ GraduationInfo degree univ Nothing Nothing
| length offset >= 2 = Just $ GraduationInfo degree Nothing Nothing Nothing
| otherwise = Nothing
advisors :: [Tag Text] -> [(Text,Text)]
advisors tags =
let offset = sections (~== "<p style=\"text-align: center\">") tags
offset2 = sections (~== "<p style=\"text-align: center; line-height: 2.75ex\">")
tags
getTag :: Int -> [[Tag Text]] -> Maybe Text
getTag _ [] = Nothing
getTag i off =
let tag = removeClutter $ flip (!!) i $ head off in
case tag of
TagText t -> maybeAdv $ notEmptyMaybeTagText $
TagText (decodeUtf8 $ B.pack $ T.unpack t)
_ -> Nothing
getLink :: Int -> [[Tag Text]] -> Maybe Text
getLink _ [] = Nothing
getLink i off = maybeLink $ flip (!!) (i-1) $ head off
in
if null offset2
then catMaybes' [(getTag 1 offset,getLink 1 offset)]
else catMaybes' [ (getTag i offset2,getLink i offset2) | i <- [3,8] ]
where
-- TODO: rewrite
catMaybes' :: [(Maybe a,Maybe b)] -> [(a,b)]
catMaybes' [] = []
catMaybes' ((Just a,Just l):xs) = (a,l) : catMaybes' xs
catMaybes' ((Just a,Nothing):xs)= catMaybes' xs
catMaybes' ((Nothing,_):xs) = catMaybes' xs
maybeAdv adv@(Just t)
| T.unpack t == "Advisor: Unknown" = Nothing
| otherwise = adv
maybeAdv a = a
maybeLink t
| isTagOpenName (T.pack "a") t = Just $ fromAttrib (T.pack "href") t
| otherwise = Nothing
notEmptyMaybeTagText :: Tag Text -> Maybe Text
notEmptyMaybeTagText (TagText t)
| all isSpace (T.unpack t) = Nothing
| T.null t = Nothing
| otherwise = Just t
notEmptyMaybeTagText _ = Nothing
-- | Removes preceding, trailing and multiple inter-word spaces:
removeClutter :: Tag Text -> Tag Text
removeClutter (TagText s) =
TagText $ removeInterSpaces (T.strip s)
where
removeInterSpaces :: Text -> Text
removeInterSpaces t =
let (first,rest) = T.breakOn (T.pack " ") t in
if T.null first
then rest
else if T.null rest
then first
else removeInterSpaces $ first `T.append` T.tail rest
removeClutter t = t