Fix documentation (or source) link when html file is less specific th…

…an module (#766)

* show doc/source link when html file name is less specific than module name

* try most qualified file names first, both dash and dot delimited

* small cleanup

* make hlint happy

* hlint again

src/Development/IDE/Spans/Documentation.hs

@@ -170,15 +170,20 @@ lookupSrcHtmlForModule =
 
 lookupHtmlForModule :: (FilePath -> FilePath -> FilePath) -> DynFlags -> Module -> IO (Maybe FilePath)
 lookupHtmlForModule mkDocPath df m = do
-  let mfs = go <$> (listToMaybe =<< lookupHtmls df ui)
+  -- try all directories
+  let mfs = fmap (concatMap go) (lookupHtmls df ui)
   htmls <- filterM doesFileExist (concat . maybeToList $ mfs)
   return $ listToMaybe htmls
   where
-    -- The file might use "." or "-" as separator
-    go pkgDocDir = [mkDocPath pkgDocDir mn | mn <- [mndot,mndash]]
+    go pkgDocDir = map (mkDocPath pkgDocDir) mns
     ui = moduleUnitId m
-    mndash = map (\x -> if x == '.' then '-' else x) mndot
-    mndot = moduleNameString $ moduleName m
+    -- try to locate html file from most to least specific name e.g.
+    --  first Language.Haskell.LSP.Types.Uri.html and Language-Haskell-LSP-Types-Uri.html
+    --  then Language.Haskell.LSP.Types.html and Language-Haskell-LSP-Types.html etc.
+    mns = do
+      chunks <- (reverse . drop1 . inits . splitOn ".") $ (moduleNameString . moduleName) m
+      -- The file might use "." or "-" as separator
+      map (`intercalate` chunks) [".", "-"]
 
 lookupHtmls :: DynFlags -> UnitId -> Maybe [FilePath]
 lookupHtmls df ui = haddockHTMLs <$> lookupPackage df ui