feat: velocity preview

Author: theBenForce

package.json

@@ -16,7 +16,8 @@
 		"Snippets"
 	],
 	"activationEvents": [
-		"onLanguage:velocity"
+		"onLanguage:velocity",
+		"onCommand:appsyncVtl.showPreview"
 	],
 	"contributes": {
 		"snippets": [
@@ -29,6 +30,21 @@
 			"triggerCharacters": [
 				"("
 			]
+		},
+		"commands": [
+			{
+				"command": "appsyncVtl.showPreview",
+				"title": "AppSync Resolver: Velocity Preview"
+			}
+		],
+		"menus": {
+			"editor/title": [
+				{
+					"command": "appsyncVtl.showPreview",
+					"when": "resourceLangId == velocity",
+					"group": "navigation"
+				}
+			]
 		}
 	},
 	"main": "./out/extension.js",

src/extension.ts

@@ -1,18 +1,18 @@
 // The module 'vscode' contains the VS Code extensibility API
 // Import the module and reference it with the alias vscode in your code below
-import * as vscode from 'vscode';
+import * as vscode from "vscode";
 
 import registerProviders from "./providers";
+import { VelocityPreviewProvider } from "./previewContentProvider";
 
 // this method is called when your extension is activated
 // your extension is activated the very first time the command is executed
 export function activate(context: vscode.ExtensionContext) {
+  console.info(`appsync resolver extension activated!`);
 
-	console.info(`appsync resolver extension activated!`);
-
-	registerProviders(context);
-
+  registerProviders(context);
+  VelocityPreviewProvider.register(context);
 }
 
 // this method is called when your extension is deactivated
-export function deactivate() { }
+export function deactivate() {}

src/previewContentProvider.ts

@@ -0,0 +1,69 @@
+import * as vscode from "vscode";
+import {render as renderVelocity} from "velocityjs";
+
+function isVelocityFile(document?: vscode.TextDocument): boolean {
+    return document?.languageId === "velocity";
+  }
+
+export class VelocityPreviewProvider
+  implements vscode.TextDocumentContentProvider {
+  onDidChangeEmitter = new vscode.EventEmitter<vscode.Uri>();
+  onDidChange = this.onDidChangeEmitter.event;
+
+  private contentProviderRegistration: vscode.Disposable;
+
+  static SCHEME = `appsyncvtl`;
+  static URI = vscode.Uri.parse(`${VelocityPreviewProvider.SCHEME}:preview.json`, true);
+
+  constructor() {
+    this.contentProviderRegistration = vscode.workspace.registerTextDocumentContentProvider(VelocityPreviewProvider.SCHEME, this);
+  }
+
+  provideTextDocumentContent(
+    uri: vscode.Uri,
+    token: vscode.CancellationToken
+  ): vscode.ProviderResult<string> {
+      const editor = vscode.window.activeTextEditor;
+
+    if(!isVelocityFile(editor?.document)) {
+        console.error(`Wrong document type`);
+        return `Unknown document type "${editor?.document?.languageId}"`;
+    }
+
+    const content = editor?.document?.getText() ?? ``;
+
+    return renderVelocity(content);
+  }
+
+  async updatePreview() {}
+
+  async onContentUpdated(
+    event?: vscode.TextDocumentChangeEvent | vscode.TextEditor
+  ) {
+    if (!event) {
+      return;
+    }
+
+    if (isVelocityFile(event.document)) {
+      this.onDidChangeEmitter.fire(VelocityPreviewProvider.URI);
+    }
+  }
+
+  static register(context: vscode.ExtensionContext): VelocityPreviewProvider {
+    const provider = new VelocityPreviewProvider();
+
+    context.subscriptions.push(
+      vscode.workspace.onDidChangeTextDocument(provider.onContentUpdated.bind(provider))
+    );
+    context.subscriptions.push(
+      vscode.window.onDidChangeActiveTextEditor(provider.onContentUpdated.bind(provider))
+    );
+
+    vscode.commands.registerCommand('appsyncVtl.showPreview', async () => {
+        let doc = await vscode.workspace.openTextDocument(this.URI);
+        await vscode.window.showTextDocument(doc, {preview: false, viewColumn: vscode.ViewColumn.Beside, preserveFocus: true});
+    });
+
+    return provider;
+  }
+}

test_templates/dynamo.vtl

@@ -0,0 +1,9 @@
+#set($range = [0..5])
+
+{
+    "test": true
+#foreach($i in $range)
+    ,"idx_$i": "The $i index"
+#end
+
+}