amend language pragma fix

Author: nini-faroux

plugins/hls-pragmas-plugin/src/Ide/Plugin/Pragmas.hs

@@ -182,25 +182,29 @@ completion _ide _ complParams = do
                       }
         _ -> return $ J.List []
 
--- ---------------------------------------------------------------------
+-----------------------------------------------------------------------
 
--- | Find first line after (last pragma / last shebang / beginning of file).
--- Useful for inserting pragmas.
+-- | Find first line after the last LANGUAGE pragma
+-- Defaults to line 0 if the file contains no shebang(s), OPTIONS_GHC pragma(s), or other LANGUAGE pragma(s)
+-- Otherwise it will be one after the count of line numbers, with order: Shebangs -> OPTIONS_GHC -> LANGUAGE
 endOfModuleHeader :: T.Text -> Range
 endOfModuleHeader contents = Range loc loc
   where
     loc = Position line 0
-    line = maybe 0 succ (lastShebang contents <|> lastOptsGhc contents <|> lastLangPrag contents)
-    lastShebang = lastLineWithPrefix $ T.isPrefixOf "#!"
-    lastLangPrag = lastLineWithPrefix $ checkPragma "LANGUAGE" 8
-    lastOptsGhc = lastLineWithPrefix $ checkPragma "OPTIONS_GHC" 11
+    line = afterLangPragma contents . afterOptsGhc contents $ afterShebang contents
+    afterLangPragma contents = afterPragma contents "LANGUAGE"
+    afterOptsGhc contents = afterPragma contents "OPTIONS_GHC"
+    afterShebang contents = maybe 0 succ $ lastLineWithPrefix (T.isPrefixOf "#!") contents
 
 lastLineWithPrefix :: (T.Text -> Bool) -> T.Text -> Maybe Int
 lastLineWithPrefix p contents = listToMaybe $ reverse $ findIndices p $ T.lines contents
 
-checkPragma :: T.Text -> Int -> T.Text -> Bool
-checkPragma name n = check
+afterPragma :: T.Text -> T.Text -> Int -> Int
+afterPragma contents name lineNum = maybe lineNum succ $ lastLineWithPrefix (checkPragma name) contents
+
+checkPragma :: T.Text -> T.Text -> Bool
+checkPragma name = check
   where
     check l = isPragma l && getName l == name
-    getName l = T.take n $ T.dropWhile isSpace $ T.drop 3 l
+    getName l = T.take (T.length name) $ T.dropWhile isSpace $ T.drop 3 l
     isPragma = T.isPrefixOf "{-#"