From 7b29416839537ed432bfaea95c4aff4a31974973 Mon Sep 17 00:00:00 2001
From: Allison Chou <allichou@microsoft.com>
Date: Tue, 26 Sep 2023 16:11:15 -0700
Subject: [PATCH] Fix completion bugs

---
 l10n/bundle.l10n.json                         |  1 +
 .../provisionalCompletionOrchestrator.ts      |  3 +-
 .../completion/razorCompletionItemProvider.ts | 45 ++++++++++++++++++-
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/l10n/bundle.l10n.json b/l10n/bundle.l10n.json
index e7ee67d46..a4601403c 100644
--- a/l10n/bundle.l10n.json
+++ b/l10n/bundle.l10n.json
@@ -110,6 +110,7 @@
   "Unexpected error when attaching to C# preview window.": "Unexpected error when attaching to C# preview window.",
   "Razor C# copied to clipboard": "Razor C# copied to clipboard",
   "Copy C#": "Copy C#",
+  "{0} Keyword": "{0} Keyword",
   "Unexpected completion trigger kind: {0}": "Unexpected completion trigger kind: {0}",
   "1 reference": "1 reference",
   "{0} references": "{0} references",
diff --git a/src/razor/src/completion/provisionalCompletionOrchestrator.ts b/src/razor/src/completion/provisionalCompletionOrchestrator.ts
index 62d446ac3..28d171482 100644
--- a/src/razor/src/completion/provisionalCompletionOrchestrator.ts
+++ b/src/razor/src/completion/provisionalCompletionOrchestrator.ts
@@ -134,7 +134,8 @@ export class ProvisionalCompletionOrchestrator {
             htmlPosition,
             provisionalPosition,
             completionContext,
-            projection.languageKind
+            projection.languageKind,
+            newDocument
         );
 
         // We track when we add provisional dots to avoid doing unnecessary work on commonly invoked events.
diff --git a/src/razor/src/completion/razorCompletionItemProvider.ts b/src/razor/src/completion/razorCompletionItemProvider.ts
index c0b11440d..39a65dbf1 100644
--- a/src/razor/src/completion/razorCompletionItemProvider.ts
+++ b/src/razor/src/completion/razorCompletionItemProvider.ts
@@ -30,7 +30,8 @@ export class RazorCompletionItemProvider extends RazorLanguageFeatureBase implem
         hostDocumentPosition: vscode.Position,
         projectedPosition: vscode.Position,
         context: vscode.CompletionContext,
-        language: LanguageKind
+        language: LanguageKind,
+        razorDocument: vscode.TextDocument
     ) {
         if (projectedUri) {
             // "@" is not a valid trigger character for C# / HTML and therefore we need to translate
@@ -86,6 +87,11 @@ export class RazorCompletionItemProvider extends RazorLanguageFeatureBase implem
             // In the code behind it's represented as __o = DateTime.
             const completionCharacterOffset = projectedPosition.character - hostDocumentPosition.character;
             for (const completionItem of completionItems) {
+                // vscode.CompletionItemKind is off by one compared to the LSP CompletionItemKind.
+                if (completionItem.kind !== undefined) {
+                    completionItem.kind = completionItem.kind - 1;
+                }
+
                 const doc = completionItem.documentation as vscode.MarkdownString;
                 if (doc && doc.value) {
                     // Without this, the documentation doesn't get rendered in the editor.
@@ -166,6 +172,8 @@ export class RazorCompletionItemProvider extends RazorLanguageFeatureBase implem
                 }
             }
 
+            this.addUsingKeyword(language, razorDocument, hostDocumentPosition, completionItems);
+
             const isIncomplete = completions instanceof Array ? false : completions ? completions.isIncomplete : false;
             return new vscode.CompletionList(completionItems, isIncomplete);
         }
@@ -221,7 +229,8 @@ export class RazorCompletionItemProvider extends RazorLanguageFeatureBase implem
             position,
             projection.position,
             context,
-            projection.languageKind
+            projection.languageKind,
+            document
         );
 
         return completionList;
@@ -278,6 +287,38 @@ export class RazorCompletionItemProvider extends RazorLanguageFeatureBase implem
 
         return item;
     }
+
+    private static addUsingKeyword(
+        language: LanguageKind,
+        razorDocument: vscode.TextDocument,
+        hostDocumentPosition: vscode.Position,
+        completionItems: vscode.CompletionItem[]
+    ) {
+        // This is an ugly hack, but it's needed to get the "using" keyword to show up in the completion list.
+        // The reason it doesn't show up is because the C# generated document puts the position of the cursor
+        // at '__o = [||]', which isn't a valid location for a using statement.
+        if (language == LanguageKind.CSharp) {
+            const line = razorDocument.lineAt(hostDocumentPosition.line);
+            const lineText = line.text.substring(0, hostDocumentPosition.character);
+            if (
+                lineText.endsWith('@') ||
+                lineText.endsWith(
+                    '@u' ||
+                        lineText.endsWith('@us') ||
+                        lineText.endsWith('@usi') ||
+                        lineText.endsWith('@usin') ||
+                        lineText.endsWith('@using')
+                )
+            ) {
+                const usingItem = new vscode.CompletionItem('using', vscode.CompletionItemKind.Keyword);
+
+                // Matching Roslyn's documentation behavior
+                (<CompletionItem>usingItem).documentation = vscode.l10n.t('{0} Keyword', 'using');
+
+                completionItems.push(usingItem);
+            }
+        }
+    }
 }
 
 function getTriggerKind(triggerKind: vscode.CompletionTriggerKind): CompletionTriggerKind {