From 5b057a448c7640a75957d4f1fe01fa16d42a1a38 Mon Sep 17 00:00:00 2001
From: Marcelo Lazaroni <lazaronijunior@gmail.com>
Date: Thu, 10 Sep 2020 21:57:32 +0100
Subject: [PATCH] Fix module suggestions

---
 src/Development/IDE/Plugin/Completions.hs     |  2 --
 .../IDE/Plugin/Completions/Logic.hs           | 25 ++++++++++++++++---
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/Development/IDE/Plugin/Completions.hs b/src/Development/IDE/Plugin/Completions.hs
index 6ff30e8a0..e3bad32f5 100644
--- a/src/Development/IDE/Plugin/Completions.hs
+++ b/src/Development/IDE/Plugin/Completions.hs
@@ -153,8 +153,6 @@ getCompletionsLSP lsp ide
             let !position' = fromCurrentPosition mapping position
             pfix <- maybe (return Nothing) (flip VFS.getCompletionPrefix cnts) position'
             case (pfix, completionContext) of
-              (Just (VFS.PosPrefixInfo _ "" _ _), Just CompletionContext { _triggerCharacter = Just "."})
-                -> return (Completions $ List [])
               (Just pfix', _) -> do
                   -- TODO pass the real capabilities here (or remove the logic for snippets)
                 let fakeClientCapabilities = ClientCapabilities Nothing Nothing Nothing Nothing
diff --git a/src/Development/IDE/Plugin/Completions/Logic.hs b/src/Development/IDE/Plugin/Completions/Logic.hs
index a7c406971..7b1ae2f8c 100644
--- a/src/Development/IDE/Plugin/Completions/Logic.hs
+++ b/src/Development/IDE/Plugin/Completions/Logic.hs
@@ -374,9 +374,28 @@ toggleSnippets ClientCapabilities { _textDocument } (WithSnippets with) x
 getCompletions :: IdeOptions -> CachedCompletions -> ParsedModule -> VFS.PosPrefixInfo -> ClientCapabilities -> WithSnippets -> IO [CompletionItem]
 getCompletions ideOpts CC { allModNamesAsNS, unqualCompls, qualCompls, importableModules }
                pm prefixInfo caps withSnippets = do
-  let VFS.PosPrefixInfo { VFS.fullLine, VFS.prefixModule, VFS.prefixText } = prefixInfo
-      enteredQual = if T.null prefixModule then "" else prefixModule <> "."
-      fullPrefix  = enteredQual <> prefixText
+  let VFS.PosPrefixInfo { VFS.fullLine, VFS.prefixModule, VFS.prefixText, VFS.cursorPos } = prefixInfo
+      maybeIndex ix = T.take 1 . T.drop ix
+
+      typedDot = "." == maybeIndex (_character cursorPos) fullLine
+
+      qualifiedBit
+        | T.null prefixModule = ""
+        | otherwise           = prefixModule <> "."
+
+      {- Items are only added to prefixModule after the first letter after a dot is typed.
+         "import Control"             -> CC { prefixModule = ""       , prefixText = "Control"    }
+         "import Control."            -> CC { prefixModule = ""       , prefixText = "Control"    }
+         "import Control.C"           -> CC { prefixModule = "Control", prefixText = "C"          }
+         "import Control.Concurrent"  -> CC { prefixModule = "Control", prefixText = "Concurrent" }
+         "import Control.Concurrent." -> CC { prefixModule = "Control", prefixText = "Concurrent" }
+      -}
+      enteredQual
+        | typedDot  = qualifiedBit <> prefixText <> "."
+        | otherwise = qualifiedBit
+
+      fullPrefix = qualifiedBit <> prefixText
+
 
       {- correct the position by moving 'foo :: Int -> String ->    '
                                                                     ^