From f7a8c1d76fa7ee17b7a81db535639ca2be1b77e5 Mon Sep 17 00:00:00 2001
From: Adrian Cochrane <adrian@openwork.nz>
Date: Fri, 17 Apr 2020 20:21:03 +1200
Subject: [PATCH] Improve data: URI handling, provide utility to convert other
 URIs to data: URIs.

---
 src/Network/URI/Fetch.hs | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/Network/URI/Fetch.hs b/src/Network/URI/Fetch.hs
index b0cf658..4ba8701 100644
--- a/src/Network/URI/Fetch.hs
+++ b/src/Network/URI/Fetch.hs
@@ -34,7 +34,7 @@ import Network.Connection
 #endif
 
 #ifdef WITH_DATA_URI
-import qualified Data.ByteString.Base64 as B64
+import qualified Data.ByteString.Base64.URL.Lazy as B64
 #endif
 
 import Network.URI.Locale
@@ -196,9 +196,9 @@ fetchURL' _ (defaultMIME:_) uri@URI {uriScheme = "data:"} =
     in case breakOn ',' $ unEscapeString request of
         ("", response) -> return (uri, defaultMIME, Left $ Txt.pack response)
         (mime', response) | '4':'6':'e':'s':'a':'b':';':mime <- reverse mime' ->
-            return $ case B64.decode $ C8.pack response of
-                Left str -> (uri, "text/plain", Left $ Txt.pack str)
-                Right bytes -> (uri, reverse mime, Right $ B.fromStrict bytes)
+            return $ case B64.decode $ B.fromStrict $ C8.pack response of
+                Left str -> (uri, "text/plain", Left $ Txt.pack $ unEscapeString str)
+                Right bytes -> (uri, reverse mime, Right bytes)
         (mime, response) -> return (uri, mime, Left $ Txt.pack response)
 #endif
 
@@ -222,6 +222,8 @@ dispatchByMIME Session {locale = l, apps = a} mime uri = do
 dispatchByMIME _ _ _ = return Nothing
 #endif
 
+-- Downloads utilities
+-- | write download to a file in the given directory.
 saveDownload :: URI -> FilePath -> (URI, String, Either Text ByteString) -> IO URI
 saveDownload baseURI dir (URI {uriPath = path}, mime, resp) = do
     dest <- unusedFilename (dir </> takeFileName path)
@@ -240,6 +242,17 @@ unusedFilename path = do
             exists <- doesFileExist path'
             if exists then go (n+1) else return path'
 
+-- | Convert a download into a data: URI
+downloadToURI :: (URI, String, Either Text ByteString) -> URI
+downloadToURI (_, mime, Left txt) = nullURI {
+        uriScheme = "data:",
+        uriPath = mime ++ "," ++ escapeURIString isReserved (Txt.unpack txt)
+    }
+downloadToURI (_, mime, Right bytes) = nullURI {
+        uriScheme = "data:",
+        uriPath = mime ++ ";base64," ++ C8.unpack (B.toStrict $ B64.encode bytes)
+    }
+
 -- Utils
 
 #ifdef WITH_DATA_URI
-- 
2.30.2