fix(codewhisperer): fix auto-trigger regressions (#2947)

## Problem
1. The 15 character keystroke auto-trigger was accidentally removed in
fix(codewhisperer) update autotrigger filtering logic and fix enter key autotrigger blocked #2899.
2. Enter auto trigger by \r\n was removed in
fix(codewhisperer) update autotrigger filtering logic and fix enter key autotrigger blocked #2899.
3. Reverted the 2 second auto trigger limitation for Special characters | Enter |intelliSense auto triggers which was removed in
fix(codewhisperer) update autotrigger filtering logic and fix enter key autotrigger blocked #2899.

## Solution
Trigger auto trigger when there are more than 15 keystroke inputs.

Author: leigaol

.changes/next-release/Bug Fix-24b2f685-2010-4504-ace1-6bad1ca4b660.json

@@ -0,0 +1,4 @@
+{
+	"type": "Bug Fix",
+	"description": "CodeWhisperer auto trigger not working correctly in certain circumstances"
+}

src/codewhisperer/service/keyStrokeHandler.ts

@@ -57,11 +57,6 @@ export class KeyStrokeHandler {
             // Pause automated trigger when typed input matches recommendation prefix for inline suggestion
             if (InlineCompletion.instance.isTypeaheadInProgress) return
 
-            // Time duration between 2 invocations should be greater than the threshold
-            // This threshold does not applies to Enter | SpecialCharacters type auto trigger.
-            const duration = Math.floor((performance.now() - RecommendationHandler.instance.lastInvocationTime) / 1000)
-            if (duration < CodeWhispererConstants.invocationTimeIntervalThreshold) return
-
             // Skip Cloud9 IntelliSense acceptance event
             if (
                 isCloud9() &&
@@ -75,6 +70,9 @@ export class KeyStrokeHandler {
 
             let triggerType: CodewhispererAutomatedTriggerType | undefined
             const changedSource = new DefaultDocumentChangedType(event.contentChanges).checkChangeSource()
+            // Time duration between 2 invocations should be greater than the threshold
+            // This threshold does not applies to Enter | SpecialCharacters | IntelliSenseAcceptance type auto trigger.
+            const duration = Math.floor((performance.now() - RecommendationHandler.instance.lastInvocationTime) / 1000)
             switch (changedSource) {
                 case DocumentChangedSource.EnterKey: {
                     this.keyStrokeCount += 1
@@ -89,16 +87,25 @@ export class KeyStrokeHandler {
                 case DocumentChangedSource.IntelliSense: {
                     this.keyStrokeCount += 1
                     triggerType = 'IntelliSenseAcceptance'
+
                     break
                 }
                 case DocumentChangedSource.RegularKey: {
                     this.keyStrokeCount += 1
+                    if (
+                        this.keyStrokeCount >= 15 &&
+                        duration >= CodeWhispererConstants.invocationTimeIntervalThreshold
+                    ) {
+                        triggerType = 'KeyStrokeCount'
+                        this.keyStrokeCount = 0
+                    }
                     break
                 }
                 default: {
                     break
                 }
             }
+
             if (triggerType) {
                 this.invokeAutomatedTrigger(triggerType, editor, client, config)
             }
@@ -170,10 +177,13 @@ export abstract class DocumentChangedType {
 
     abstract checkChangeSource(): DocumentChangedSource
 
-    // Enter key should always start with ONE '\n' and potentially following spaces due to IDE reformat
+    // Enter key should always start with ONE '\n' or '\r\n' and potentially following spaces due to IDE reformat
     protected isEnterKey(str: string): boolean {
         if (str.length === 0) return false
-        return str[0] === '\n' && str.substring(1).trim().length === 0
+        return (
+            (str.startsWith('\r\n') && str.substring(2).trim() === '') ||
+            (str[0] === '\n' && str.substring(1).trim() === '')
+        )
     }
 
     // Tab should consist of space char only ' ' and the length % tabSize should be 0

src/test/codewhisperer/service/keyStrokeHandler.test.ts

@@ -113,6 +113,32 @@ describe('keyStrokeHandler', function () {
             assert.ok(!invokeSpy.called)
         })
 
+        it('Should call invokeAutomatedTrigger if previous text input is within 2 seconds but the new input is new line', async function () {
+            KeyStrokeHandler.instance.keyStrokeCount = 14
+            const mockEditor = createMockTextEditor()
+            const mockEvent: vscode.TextDocumentChangeEvent = createTextDocumentChangeEvent(
+                mockEditor.document,
+                new vscode.Range(new vscode.Position(0, 0), new vscode.Position(0, 1)),
+                '\n'
+            )
+            RecommendationHandler.instance.lastInvocationTime = performance.now() - 1500
+            await KeyStrokeHandler.instance.processKeyStroke(mockEvent, mockEditor, mockClient, config)
+            assert.ok(invokeSpy.called)
+        })
+
+        it('Should call invokeAutomatedTrigger if previous text input is within 2 seconds but the new input is a specialcharacter', async function () {
+            KeyStrokeHandler.instance.keyStrokeCount = 14
+            const mockEditor = createMockTextEditor()
+            const mockEvent: vscode.TextDocumentChangeEvent = createTextDocumentChangeEvent(
+                mockEditor.document,
+                new vscode.Range(new vscode.Position(0, 0), new vscode.Position(0, 1)),
+                '('
+            )
+            RecommendationHandler.instance.lastInvocationTime = performance.now() - 1500
+            await KeyStrokeHandler.instance.processKeyStroke(mockEvent, mockEditor, mockClient, config)
+            assert.ok(invokeSpy.called)
+        })
+
         it('Should call invokeAutomatedTrigger with Enter when inputing \n', async function () {
             const mockEditor = createMockTextEditor()
             const mockEvent: vscode.TextDocumentChangeEvent = createTextDocumentChangeEvent(
@@ -125,6 +151,18 @@ describe('keyStrokeHandler', function () {
             assert.ok(invokeSpy.called)
         })
 
+        it('Should call invokeAutomatedTrigger with Enter when inputing \r\n', async function () {
+            const mockEditor = createMockTextEditor()
+            const mockEvent: vscode.TextDocumentChangeEvent = createTextDocumentChangeEvent(
+                mockEditor.document,
+                new vscode.Range(new vscode.Position(0, 0), new vscode.Position(0, 2)),
+                '\r\n'
+            )
+            await KeyStrokeHandler.instance.processKeyStroke(mockEvent, mockEditor, mockClient, config)
+            invokeSpy('Enter', mockEditor, mockClient)
+            assert.ok(invokeSpy.called)
+        })
+
         it('Should call invokeAutomatedTrigger with SpecialCharacter when inputing {', async function () {
             const mockEditor = createMockTextEditor()
             const mockEvent: vscode.TextDocumentChangeEvent = createTextDocumentChangeEvent(