From bc861e3eebbb48793ccaa06280a671af68f001ad Mon Sep 17 00:00:00 2001
From: Tissevert <tissevert+devel@marvid.fr>
Date: Wed, 25 Mar 2020 19:46:35 +0100
Subject: [PATCH] Print a warning when --site-url is set but none of
 --open-graph-cards or --rss is set

---
 src/Blog/URL.hs | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/Blog/URL.hs b/src/Blog/URL.hs
index 1271734..359faae 100644
--- a/src/Blog/URL.hs
+++ b/src/Blog/URL.hs
@@ -11,6 +11,7 @@ import qualified Arguments as Arguments (Arguments(..))
 import Data.Aeson (ToJSON(..), (.=), pairs)
 import GHC.Generics (Generic)
 import System.Exit (die)
+import System.IO (hPutStrLn, stderr)
 import Text.Printf (printf)
 
 data URL = URL {
@@ -26,13 +27,19 @@ instance ToJSON URL where
 
 build :: Arguments -> IO URL
 build arguments = do
-  cards <- getSiteURL (Arguments.openGraphCards arguments) "Open Graph cards"
-  rss <- getSiteURL (Arguments.rss arguments) "RSS feeds"
+  cards <- getSiteURL argOGCards "Open Graph cards"
+  rss <- getSiteURL argRSS "RSS feeds"
+  checksUsed (argOGCards || argRSS) siteURL
   return $ URL {cards, comments, rss}
   where
     comments = Arguments.commentsURL arguments
     siteURL = Arguments.siteURL arguments
+    argOGCards = Arguments.openGraphCards arguments
+    argRSS = Arguments.rss arguments
     errorMsg :: String -> String
     errorMsg = printf "Enabling %s requires setting the site url with --site-url"
     getSiteURL False _ = return Nothing
     getSiteURL True name = maybe (die $ errorMsg name) (return . Just) siteURL
+    checksUsed False (Just _) =
+      hPutStrLn stderr "Site url is set but not used, did you forget --open-graph-cards or --rss ?"
+    checksUsed _ _ = return ()