Added Http parsing

1 files changed, 75 insertions, 0 deletions

diff --git a/Utils.hs b/Utils.hs
new file mode 100644
index 0000000..94ad0fb
--- /dev/null
+++ b/Utils.hs
@@ -0,0 +1,75 @@
+module Utils (parseQs, parseHttp) where
+
+import Network.HTTP.Types.URI as URI
+import qualified Data.ByteString as S
+import Data.ByteString (ByteString)
+
+import qualified Data.Text as T
+import Data.Text.Encoding (encodeUtf8, decodeUtf8)
+import Data.Text (Text)
+
+-- Query string parser
+
+decodeUrl :: Text -> Text
+decodeUrl = decodeUtf8 . URI.urlDecode True . encodeUtf8
+
+parseQs :: Text -> (Text, [(Text, Text)])
+parseQs url =
+  let
+    decoded = decodeUrl url
+    path = T.takeWhile (\c -> c /= '?') decoded
+    rest = T.dropWhile (\c -> c /= '?') decoded
+
+    parsePair :: Text -> Maybe (Text, Text)
+    parsePair s
+      | T.any ((==) '=') s = Just (a, b)
+      | otherwise = Nothing
+      where a : b : _ = T.splitOn (T.pack "=") s
+    
+    get (Just p : rest) = p : get rest
+    get (Nothing : rest) = get rest
+    get [] = []
+
+    pairs = 
+      if T.null rest
+      then []
+      else get $ map parsePair $ T.splitOn (T.pack "&") $ T.tail rest
+
+  in (path, pairs)
+
+-- HTTP Parser
+
+rev :: [a] -> [a]
+rev = foldl (flip (:)) []
+
+parseFirstLine :: Text -> (Text, Text)
+parseFirstLine l = (method, url)
+  where [method, url, _] = T.words l
+
+parseHeader :: Text -> (Text, Text)
+parseHeader line = 
+  (T.takeWhile p line, T.strip $ T.tail
+   $ T.dropWhile p line)
+    where p = (\c -> c /= ':')
+
+parseHeaders :: [Text] -> [(Text, Text)]
+parseHeaders = map parseHeader
+
+parseHttp :: Text -> ((Text, Text, [(Text, Text)]), [(Text, Text)], [Text])
+parseHttp text = 
+  let
+    lines = T.splitOn (T.pack "\r\n") text
+
+    getFirstLine (l : rest) = (l, rest)
+
+    getHeaders (l : rest) acc
+      | T.null l  = (rev acc, rest)
+      | otherwise = getHeaders rest (l : acc)
+    
+    (fl, rest1) = getFirstLine lines
+    (headers, rest2) = getHeaders rest1 []
+
+    (method, url) = parseFirstLine fl
+    (path, query) = parseQs url
+  in 
+    ((method, path, query), parseHeaders headers, rest2)