CodeWhisperer: Fix inline suggestions not showing in the editor (#3717)

* CodeWhisperer: Fix inline suggestions not showing in the editor

There's a weird case that when an empty suggestion is provided
to the inline suggestion provider, the inline suggestion UI won't
show afterward even executing commands to hide/show it again.

Given that empty suggestions don't need to be shown to the users,
don't call onDidReceiveRecommendations until there's at least
one non-empty suggestion for the inline provider(so inline UI will
be able to pick this and show up correctly)

* Fix additional cases that inline suggestions won't show in the editor

* Add changelog entry

Author: andrewyuq

.changes/next-release/Bug Fix-1bdf6b9c-d49a-451d-acdc-1d4fb233e02b.json

@@ -0,0 +1,4 @@
+{
+	"type": "Bug Fix",
+	"description": "CodeWhisperer: Fix in some cases the inline suggestions are not showing in the editor"
+}

src/codewhisperer/service/inlineCompletionService.ts

@@ -51,31 +51,6 @@ export class CWInlineCompletionItemProvider implements vscode.InlineCompletionIt
         this.activeItemIndex = undefined
     }
 
-    private getGhostText(prefix: string, suggestion: string): string {
-        const prefixLines = prefix.split(/\r\n|\r|\n/)
-        const n = prefixLines.length
-        if (n <= 1) {
-            return suggestion
-        }
-        let count = 1
-        for (let i = 0; i < suggestion.length; i++) {
-            if (suggestion[i] === '\n') {
-                count++
-            }
-            if (count === n) {
-                return suggestion.slice(i + 1)
-            }
-        }
-        return ''
-    }
-
-    private getGhostTextStartPos(start: vscode.Position, current: vscode.Position): vscode.Position {
-        if (start.line === current.line) {
-            return start
-        }
-        return new vscode.Position(current.line, 0)
-    }
-
     // iterate suggestions and stop at index 0 or index len - 1
     private getIteratingIndexes() {
         const len = RecommendationHandler.instance.recommendations.length
@@ -132,8 +107,8 @@ export class CWInlineCompletionItemProvider implements vscode.InlineCompletionIt
             return undefined
         }
         return {
-            insertText: this.getGhostText(prefix, truncatedSuggestion),
-            range: new vscode.Range(this.getGhostTextStartPos(start, end), end),
+            insertText: truncatedSuggestion,
+            range: new vscode.Range(start, end),
             command: {
                 command: 'aws.codeWhisperer.accept',
                 title: 'On acceptance',
@@ -168,7 +143,14 @@ export class CWInlineCompletionItemProvider implements vscode.InlineCompletionIt
             this.activeItemIndex = undefined
             return
         }
-        const start = RecommendationHandler.instance.startPos
+
+        // There's a chance that the startPos is no longer valid in the current document (e.g.
+        // when CodeWhisperer got triggered by 'Enter', the original startPos is with indentation
+        // but then this indentation got removed by VSCode when another new line is inserted,
+        // before the code reaches here). In such case, we need to update the startPos to be a
+        // valid one. Otherwise, inline completion which utilizes this position will function
+        // improperly.
+        const start = document.validatePosition(RecommendationHandler.instance.startPos)
         const end = position
         const iteratingIndexes = this.getIteratingIndexes()
         const prefix = document.getText(new vscode.Range(start, end)).replace(/\r\n/g, '\n')

src/codewhisperer/service/recommendationHandler.ts

@@ -307,7 +307,7 @@ export class RecommendationHandler {
                 }
             })
             this.recommendations = pagination ? this.recommendations.concat(recommendation) : recommendation
-            if (isInlineCompletionEnabled()) {
+            if (isInlineCompletionEnabled() && this.hasAtLeastOneValidSuggestion(editor, typedPrefix)) {
                 this._onDidReceiveRecommendation.fire()
             }
         }
@@ -329,6 +329,10 @@ export class RecommendationHandler {
         }
     }
 
+    hasAtLeastOneValidSuggestion(editor: vscode.TextEditor, typedPrefix: string): boolean {
+        return this.recommendations.some(r => r.content.trim() !== '' && r.content.startsWith(typedPrefix))
+    }
+
     cancelPaginatedRequest() {
         this.nextToken = ''
         this.cancellationToken.cancel()