fix(lambda): checking if folder exists (aws#6899)

## Problem
In the existing Serverless Land project, we need to check if a folder
with the same name already exists before downloading the code. This
could help avoid potential issues that might arise from overwriting
existing files or folders.

## Solution
The code checks if a folder with the same name already exists, and
prompts the user to choose whether to override it or not. This allows
the user to decide how to handle potential conflicts with existing files
or folders.

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

---------

Co-authored-by: Vandita Patidar <[email protected]>

Author: Vandita2020

packages/core/src/awsService/appBuilder/serverlessLand/main.ts

@@ -15,6 +15,7 @@ import { ExtContext } from '../../../shared/extensions'
 import { addFolderToWorkspace } from '../../../shared/utilities/workspaceUtils'
 import { ToolkitError } from '../../../shared/errors'
 import { fs } from '../../../shared/fs/fs'
+import { handleOverwriteConflict } from '../../../shared/utilities/messages'
 import { getPattern } from '../../../shared/utilities/downloadPatterns'
 import { MetadataManager } from './metadataManager'
 
@@ -89,6 +90,9 @@ export async function launchProjectCreationWizard(
 export async function downloadPatternCode(config: CreateServerlessLandWizardForm, assetName: string): Promise<void> {
     const fullAssetName = assetName + '.zip'
     const location = vscode.Uri.joinPath(config.location, config.name)
+
+    await handleOverwriteConflict(location)
+
     try {
         await getPattern(serverlessLandOwner, serverlessLandRepo, fullAssetName, location, true)
     } catch (error) {

packages/core/src/shared/utilities/messages.ts

@@ -5,6 +5,7 @@
 
 import * as vscode from 'vscode'
 import * as nls from 'vscode-nls'
+import * as path from 'path'
 import * as localizedText from '../localizedText'
 import { getLogger } from '../../shared/logger/logger'
 import { ProgressEntry } from '../../shared/vscode/window'
@@ -14,6 +15,8 @@ import { Timeout } from './timeoutUtils'
 import { addCodiconToString } from './textUtilities'
 import { getIcon, codicon } from '../icons'
 import globals from '../extensionGlobals'
+import { ToolkitError } from '../../shared/errors'
+import { fs } from '../../shared/fs/fs'
 import { openUrl } from './vsCodeUtils'
 import { AmazonQPromptSettings, ToolkitPromptSettings } from '../../shared/settings'
 import { telemetry, ToolkitShowNotification } from '../telemetry/telemetry'
@@ -140,6 +143,41 @@ export async function showViewLogsMessage(
     })
 }
 
+/**
+ * Checks if a path exists and prompts user for overwrite confirmation if it does.
+ * @param path The file or directory path to check
+ * @param itemName The name of the item for display in the message
+ * @returns Promise<boolean> - true if should proceed (path doesn't exist or user confirmed overwrite)
+ */
+export async function handleOverwriteConflict(location: vscode.Uri): Promise<boolean> {
+    if (!(await fs.exists(location))) {
+        return true
+    }
+
+    const choice = showConfirmationMessage({
+        prompt: localize(
+            'AWS.toolkit.confirmOverwrite',
+            '{0} already exists in the selected directory, overwrite?',
+            location.fsPath
+        ),
+        confirm: localize('AWS.generic.overwrite', 'Yes'),
+        cancel: localize('AWS.generic.cancel', 'No'),
+        type: 'warning',
+    })
+
+    if (!choice) {
+        throw new ToolkitError(`Folder already exists: ${path.basename(location.fsPath)}`)
+    }
+
+    try {
+        await fs.delete(location, { recursive: true, force: true })
+    } catch (error) {
+        throw ToolkitError.chain(error, `Failed to delete existing folder: ${path.basename(location.fsPath)}`)
+    }
+
+    return true
+}
+
 /**
  * Shows a modal confirmation (warning) message with buttons to confirm or cancel.
  *

packages/core/src/test/awsService/appBuilder/serverlessLand/main.test.ts

@@ -23,6 +23,7 @@ import { fs } from '../../../../shared/fs/fs'
 import * as downloadPatterns from '../../../../shared/utilities/downloadPatterns'
 import { ExtContext } from '../../../../shared/extensions'
 import { workspaceUtils } from '../../../../shared'
+import * as messages from '../../../../shared/utilities/messages'
 import * as downloadPattern from '../../../../shared/utilities/downloadPatterns'
 import * as wizardModule from '../../../../awsService/appBuilder/serverlessLand/wizard'
 
@@ -80,63 +81,75 @@ describe('createNewServerlessLandProject', () => {
     })
 })
 
+function assertDownloadPatternCall(getPatternStub: sinon.SinonStub, mockConfig: any) {
+    const mockAssetName = 'test-project-sam-python.zip'
+    const serverlessLandOwner = 'aws-samples'
+    const serverlessLandRepo = 'serverless-patterns'
+    const mockLocation = vscode.Uri.joinPath(mockConfig.location, mockConfig.name)
+
+    assert(getPatternStub.calledOnce)
+    assert(getPatternStub.firstCall.args[0] === serverlessLandOwner)
+    assert(getPatternStub.firstCall.args[1] === serverlessLandRepo)
+    assert(getPatternStub.firstCall.args[2] === mockAssetName)
+    assert(getPatternStub.firstCall.args[3].toString() === mockLocation.toString())
+    assert(getPatternStub.firstCall.args[4] === true)
+}
+
 describe('downloadPatternCode', () => {
     let sandbox: sinon.SinonSandbox
     let getPatternStub: sinon.SinonStub
+    let mockConfig: any
 
     beforeEach(function () {
         sandbox = sinon.createSandbox()
         getPatternStub = sandbox.stub(downloadPatterns, 'getPattern')
+        mockConfig = {
+            name: 'test-project',
+            location: vscode.Uri.file('/test'),
+            pattern: 'test-project-sam-python',
+            runtime: 'python',
+            iac: 'sam',
+            assetName: 'test-project-sam-python',
+        }
     })
     afterEach(function () {
         sandbox.restore()
+        getPatternStub.restore()
     })
-    const mockConfig = {
-        name: 'test-project',
-        location: vscode.Uri.file('/test'),
-        pattern: 'test-project-sam-python',
-        runtime: 'python',
-        iac: 'sam',
-        assetName: 'test-project-sam-python',
-    }
     it('successfully downloads pattern code', async () => {
-        const mockAssetName = 'test-project-sam-python.zip'
-        const serverlessLandOwner = 'aws-samples'
-        const serverlessLandRepo = 'serverless-patterns'
-        const mockLocation = vscode.Uri.joinPath(mockConfig.location, mockConfig.name)
-
-        await downloadPatternCode(mockConfig, 'test-project-sam-python')
-        assert(getPatternStub.calledOnce)
-        assert(getPatternStub.firstCall.args[0] === serverlessLandOwner)
-        assert(getPatternStub.firstCall.args[1] === serverlessLandRepo)
-        assert(getPatternStub.firstCall.args[2] === mockAssetName)
-        assert(getPatternStub.firstCall.args[3].toString() === mockLocation.toString())
-        assert(getPatternStub.firstCall.args[4] === true)
-    })
-    it('handles download failure', async () => {
-        const mockAssetName = 'test-project-sam-python.zip'
-        const error = new Error('Download failed')
-        getPatternStub.rejects(error)
-        try {
-            await downloadPatternCode(mockConfig, mockAssetName)
-            assert.fail('Expected an error to be thrown')
-        } catch (err: any) {
-            assert.strictEqual(err.message, 'Failed to download pattern: Error: Download failed')
-        }
+        sandbox.stub(messages, 'handleOverwriteConflict').resolves(true)
+
+        await downloadPatternCode(mockConfig, mockConfig.assetName)
+        assertDownloadPatternCall(getPatternStub, mockConfig)
+    })
+    it('downloads pattern when directory exists and user confirms overwrite', async function () {
+        sandbox.stub(messages, 'handleOverwriteConflict').resolves(true)
+
+        await downloadPatternCode(mockConfig, mockConfig.assetName)
+        assertDownloadPatternCall(getPatternStub, mockConfig)
+    })
+    it('throws error when directory exists and user cancels overwrite', async function () {
+        const handleOverwriteStub = sandbox.stub(messages, 'handleOverwriteConflict')
+        handleOverwriteStub.rejects(new Error('Folder already exists: test-project'))
+
+        await assert.rejects(
+            () => downloadPatternCode(mockConfig, mockConfig.assetName),
+            /Folder already exists: test-project/
+        )
     })
 })
 
 describe('openReadmeFile', () => {
-    let sandbox: sinon.SinonSandbox
+    let testsandbox: sinon.SinonSandbox
     let spyExecuteCommand: sinon.SinonSpy
 
     beforeEach(function () {
-        sandbox = sinon.createSandbox()
-        spyExecuteCommand = sandbox.spy(vscode.commands, 'executeCommand')
+        testsandbox = sinon.createSandbox()
+        spyExecuteCommand = testsandbox.spy(vscode.commands, 'executeCommand')
     })
 
     afterEach(function () {
-        sandbox.restore()
+        testsandbox.restore()
     })
     const mockConfig = {
         name: 'test-project',
@@ -148,43 +161,43 @@ describe('openReadmeFile', () => {
     }
     it('successfully opens README file', async () => {
         const mockReadmeUri = vscode.Uri.file('/test/README.md')
-        sandbox.stub(main, 'getProjectUri').resolves(mockReadmeUri)
+        testsandbox.stub(main, 'getProjectUri').resolves(mockReadmeUri)
 
-        sandbox.stub(fs, 'exists').resolves(true)
+        testsandbox.stub(fs, 'exists').resolves(true)
 
         // When
         await openReadmeFile(mockConfig)
         // Then
-        sandbox.assert.calledWith(spyExecuteCommand, 'workbench.action.focusFirstEditorGroup')
-        sandbox.assert.calledWith(spyExecuteCommand, 'markdown.showPreview')
+        testsandbox.assert.calledWith(spyExecuteCommand, 'workbench.action.focusFirstEditorGroup')
+        testsandbox.assert.calledWith(spyExecuteCommand, 'markdown.showPreview')
     })
 
     it('handles missing README file', async () => {
         const mockReadmeUri = vscode.Uri.file('/test/file.md')
-        sandbox.stub(main, 'getProjectUri').resolves(mockReadmeUri)
+        testsandbox.stub(main, 'getProjectUri').resolves(mockReadmeUri)
 
-        sandbox.stub(fs, 'exists').resolves(false)
+        testsandbox.stub(fs, 'exists').resolves(false)
 
         // When
         await openReadmeFile(mockConfig)
         // Then
-        sandbox.assert.neverCalledWith(spyExecuteCommand, 'markdown.showPreview')
+        testsandbox.assert.neverCalledWith(spyExecuteCommand, 'markdown.showPreview')
         assert.ok(true, 'Function should return without throwing error when README is not found')
     })
 
     it('handles error with opening README file', async () => {
         const mockReadmeUri = vscode.Uri.file('/test/README.md')
-        sandbox.stub(main, 'getProjectUri').resolves(mockReadmeUri)
+        testsandbox.stub(main, 'getProjectUri').resolves(mockReadmeUri)
 
-        sandbox.stub(fs, 'exists').rejects(new Error('File system error'))
+        testsandbox.stub(fs, 'exists').rejects(new Error('File system error'))
 
         // When
         await assert.rejects(() => openReadmeFile(mockConfig), {
             name: 'Error',
             message: 'Error processing README file',
         })
         // Then
-        sandbox.assert.neverCalledWith(spyExecuteCommand, 'markdown.showPreview')
+        testsandbox.assert.neverCalledWith(spyExecuteCommand, 'markdown.showPreview')
     })
 })