Move MIME stuff into proper Codec.* namespace.

Add copyrights where missing.

1 files changed, 56 insertions, 0 deletions

diff --git a/Codec/MIME/Decode.hs b/Codec/MIME/Decode.hs
new file mode 100644
index 0000000..f23454a
--- /dev/null
+++ b/Codec/MIME/Decode.hs
@@ -0,0 +1,56 @@
+module MIME.Decode where
+
+import Data.Char
+import MIME.QuotedPrintable as QP
+import MIME.Base64 as Base64
+
+decodeBody :: String -> String -> String
+decodeBody enc body =
+ case map toLower enc of
+   "base64"           -> map (chr.fromIntegral) $ Base64.decode body
+   "quoted-printable" -> QP.decode body
+   _ -> body
+
+-- Decoding of RFC 2047's "encoded-words' production
+-- (as used in email-headers and some HTTP header cases
+-- (AtomPub's Slug: header))
+decodeWord :: String -> Maybe (String, String)
+decodeWord str =
+  case str of
+   '=':'?':xs ->
+     case dropLang $ break (\ch -> ch =='?' || ch == '*') xs of
+       (cs,_:x:'?':bs)
+         | isKnownCharset (map toLower cs) ->
+           case toLower x of
+             'q' -> decodeQ cs (break (=='?') bs)
+             'b' -> decodeB cs (break (=='?') bs)
+             _   -> Nothing
+       _ -> Nothing
+   _ -> Nothing
+ where
+  isKnownCharset cs = cs `elem` ["iso-8859-1", "us-ascii"]
+
+   -- ignore RFC 2231 extension of permitting a language tag to be supplied
+   -- after the charset.
+  dropLang (as,'*':bs) = (as,dropWhile (/='?') bs)
+  dropLang (as,bs) = (as,bs)
+
+  decodeQ cset (fs,'?':'=':rs) = Just (fromCharset cset (QP.decode fs),rs)
+  decodeQ _ _ = Nothing
+
+  decodeB cset (fs,'?':'=':rs) =
+    Just (fromCharset cset (Base64.decodeToString fs),rs)
+  decodeB _ _ = Nothing
+
+  fromCharset _cset cs = cs
+
+decodeWords :: String -> String
+decodeWords "" = ""
+decodeWords (x:xs)
+ | isSpace x = x : decodeWords xs
+ | otherwise =
+  case decodeWord (x:xs) of
+    Nothing -> x : decodeWords xs
+    Just (as,bs) -> as ++ decodeWords bs
+
+