display destination file before youtube-dl download

Rather than after it, which can leave one wondering what file it's
downloading.

youtubeDl should not ever return Right Nothing in normal operation,
becaause it's already asked youtube-dl if it supports the url. So it
would have to succeed at that, then not download any file, but also
exit successfully, in order for the new error message to display.

Also display the name of yt-dlp when using it.

Annex/YoutubeDl.hs

@@ -12,6 +12,7 @@ module Annex.YoutubeDl (
 	youtubeDlCheck,
 	youtubeDlFileName,
 	youtubeDlFileNameHtmlOnly,
+	youtubeDlCommand,
 ) where
 
 import Annex.Common
@@ -74,18 +75,18 @@ youtubeDl' url workdir p uo
 			( runcmd cmd >>= \case
 				Right True -> downloadedfiles cmd >>= \case
 					(f:[]) -> return (Right (Just f))
-					[] -> return nofiles
+					[] -> return (nofiles cmd)
-					fs -> return (toomanyfiles fs)
+					fs -> return (toomanyfiles cmd fs)
 				Right False -> workdirfiles >>= \case
 					[] -> return (Right Nothing)
-					_ -> return (Left "yt-dlp download is incomplete. Run the command again to resume.")
+					_ -> return (Left $ cmd ++ " download is incomplete. Run the command again to resume.")
 				Left msg -> return (Left msg)
 			, return (Right Nothing)
 			)
 	| otherwise = return (Right Nothing)
   where
-	nofiles = Left "yt-dlp did not put any media in its work directory, perhaps it's been configured to store files somewhere else?"
+	nofiles cmd = Left $ cmd ++ " did not put any media in its work directory, perhaps it's been configured to store files somewhere else?"
-	toomanyfiles fs = Left $ "yt-dlp downloaded multiple media files; git-annex is only able to deal with one per url: " ++ show fs
+	toomanyfiles cmd fs = Left $ cmd ++ " downloaded multiple media files; git-annex is only able to deal with one per url: " ++ show fs
 	downloadedfiles cmd
 		| isytdlp cmd = liftIO $ 
 			(lines <$> readFile filelistfile)
@@ -95,7 +96,7 @@ youtubeDl' url workdir p uo
 		<$> (filterM (doesFileExist) =<< dirContents workdir)
 	filelistfile = workdir </> filelistfilebase
 	filelistfilebase = "git-annex-file-list-file"
-	isytdlp cmd = "yt-dlp" `isInfixOf` cmd
+	isytdlp cmd = cmd == "yt-dlp"
 	runcmd cmd = youtubeDlMaxSize workdir >>= \case
 		Left msg -> return (Left msg)
 		Right maxsize -> do
@@ -271,7 +272,10 @@ youtubeDlOpts addopts = do
 youtubeDlCommand :: Annex String
 youtubeDlCommand = annexYoutubeDlCommand <$> Annex.getGitConfig >>= \case
 	Just c -> pure c
-	Nothing -> fromMaybe "youtube-dl" <$> liftIO (searchPath "yt-dlp")
+	Nothing -> ifM (liftIO $ inSearchPath "yt-dlp")
+		( return "yt-dlp"
+		, return "youtube-dl"
+		)
 
 supportedScheme :: UrlOptions -> URLString -> Bool
 supportedScheme uo url = case parseURIRelaxed url of

Command/AddUrl.hs

@@ -353,21 +353,25 @@ downloadWeb addunlockedmatcher o url urlinfo file =
 	  where
 		dl dest = withTmpWorkDir mediakey $ \workdir -> do
 			let cleanuptmp = pruneTmpWorkDirBefore tmp (liftIO . removeWhenExistsWith R.removeLink)
-			showNote "using youtube-dl"
+			dlcmd <- youtubeDlCommand
+			showNote ("using " <> UnquotedString dlcmd)
 			Transfer.notifyTransfer Transfer.Download url $
-				Transfer.download' webUUID mediakey (AssociatedFile Nothing) Nothing Transfer.noRetry $ \p ->
+				Transfer.download' webUUID mediakey (AssociatedFile Nothing) Nothing Transfer.noRetry $ \p -> do
+					showDestinationFile dest
 					youtubeDl url (fromRawFilePath workdir) p >>= \case
 						Right (Just mediafile) -> do
 							cleanuptmp
 							checkCanAdd o dest $ \canadd -> do
-								showDestinationFile dest
 								addWorkTree canadd addunlockedmatcher webUUID mediaurl dest mediakey (Just (toRawFilePath mediafile))
 								return $ Just mediakey
-						Right Nothing -> checkRaw Nothing o (pure Nothing) (normalfinish tmp backend)
 						Left msg -> do
 							cleanuptmp
 							warning (UnquotedString msg)
 							return Nothing
+						Right Nothing -> do
+							cleanuptmp
+							warning (UnquotedString dlcmd <> " did not download anything")
+							return Nothing
 		mediaurl = setDownloader url YoutubeDownloader
 		mediakey = Backend.URL.fromUrl mediaurl Nothing
 		-- Does the already annexed file have the mediaurl