bug fix: add input validation to showInputBoxWithButtons (#474)

fixes #468

Author: eleanorjboyd

src/common/window.apis.ts

@@ -255,8 +255,17 @@ export async function showInputBoxWithButtons(
                 inputBox.hide();
             }
         }),
-        inputBox.onDidAccept(() => {
+        inputBox.onDidAccept(async () => {
             if (!deferred.completed) {
+                let isValid = true;
+                if (options?.validateInput) {
+                    const validation = await options.validateInput(inputBox.value);
+                    isValid = validation === null || validation === undefined;
+                    if (!isValid) {
+                        inputBox.validationMessage = typeof validation === 'string' ? validation : 'Invalid input';
+                        return; // Do not resolve, keep the input box open
+                    }
+                }
                 deferred.resolve(inputBox.value);
                 inputBox.hide();
             }