From 10a12c7a173866e5b2a34be587554fc266b120bd Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Fri, 7 Feb 2025 13:01:08 +0100
Subject: [PATCH] cli/new: refactor template loading

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 packages/cli/src/lib/new/createNewPackage.ts  | 10 ++-
 .../src/lib/new/loader/NewTemplateLoader.ts   | 69 +++++++++++++++++++
 packages/cli/src/lib/new/templateSelector.ts  | 47 -------------
 packages/cli/src/lib/new/types.ts             |  3 +-
 4 files changed, 74 insertions(+), 55 deletions(-)
 delete mode 100644 packages/cli/src/lib/new/templateSelector.ts

diff --git a/packages/cli/src/lib/new/createNewPackage.ts b/packages/cli/src/lib/new/createNewPackage.ts
index b5cc85f1ec..19208f4c6b 100644
--- a/packages/cli/src/lib/new/createNewPackage.ts
+++ b/packages/cli/src/lib/new/createNewPackage.ts
@@ -23,7 +23,6 @@ import { paths } from '../paths';
 import { Task } from '../tasks';
 import { addCodeownersEntry, getCodeownersFilePath } from '../codeowners';
 
-import { verifyTemplate } from './templateSelector';
 import { promptOptions } from './prompts';
 import { populateOptions, createDirName, resolvePackageName } from './utils';
 import { runAdditionalActions } from './additionalActions';
@@ -47,12 +46,11 @@ export type CreateNewPackageOptions = {
 export async function createNewPackage(options: CreateNewPackageOptions) {
   const newConfig = await loadNewConfig();
 
-  const template = verifyTemplate(
-    await NewTemplateLoader.selectTemplateInteractively(
-      newConfig,
-      options.preselectedTemplateId,
-    ),
+  const selectedTemplate = await NewTemplateLoader.selectTemplateInteractively(
+    newConfig,
+    options.preselectedTemplateId,
   );
+  const template = await NewTemplateLoader.loadTemplate(selectedTemplate);
 
   const codeOwnersFilePath = await getCodeownersFilePath(paths.targetRoot);
 
diff --git a/packages/cli/src/lib/new/loader/NewTemplateLoader.ts b/packages/cli/src/lib/new/loader/NewTemplateLoader.ts
index 27a250ed84..c4bb873971 100644
--- a/packages/cli/src/lib/new/loader/NewTemplateLoader.ts
+++ b/packages/cli/src/lib/new/loader/NewTemplateLoader.ts
@@ -14,8 +14,41 @@
  * limitations under the License.
  */
 
+import { z } from 'zod';
+import fs from 'fs-extra';
 import inquirer from 'inquirer';
+import { dirname } from 'node:path';
+import { parse as parseYaml } from 'yaml';
+import { paths } from '../../paths';
 import { NewConfig, NewTemplatePointer } from '../config/types';
+import { Template } from '../types';
+import { ForwardedError } from '@backstage/errors';
+import { fromZodError } from 'zod-validation-error';
+
+const templateDefinitionSchema = z
+  .object({
+    description: z.string().optional(),
+    template: z.string(),
+    targetPath: z.string(),
+    plugin: z.boolean().optional(),
+    backendModulePrefix: z.boolean().optional(),
+    suffix: z.string().optional(),
+    prompts: z
+      .array(
+        z.union([
+          z.string(),
+          z.object({
+            id: z.string(),
+            prompt: z.string(),
+            validate: z.string().optional(),
+            default: z.union([z.string(), z.boolean(), z.number()]).optional(),
+          }),
+        ]),
+      )
+      .optional(),
+    additionalActions: z.array(z.string()).optional(),
+  })
+  .strict();
 
 export class NewTemplateLoader {
   static async selectTemplateInteractively(
@@ -49,4 +82,40 @@ export class NewTemplateLoader {
     }
     return template;
   }
+
+  static async loadTemplate({
+    id,
+    target,
+  }: NewTemplatePointer): Promise<Template> {
+    if (target.match(/https?:\/\//)) {
+      throw new Error('Remote templates are not supported yet');
+    }
+    if (!fs.existsSync(paths.resolveTargetRoot(target))) {
+      throw new Error(`Your CLI template does not exist: ${target}`);
+    }
+    const rawTemplate = parseYaml(
+      fs.readFileSync(paths.resolveTargetRoot(target), 'utf-8'),
+    );
+
+    const parsed = templateDefinitionSchema.safeParse(rawTemplate);
+    if (!parsed.success) {
+      throw new ForwardedError(
+        `Invalid template definition at '${target}'`,
+        fromZodError(parsed.error),
+      );
+    }
+
+    const template = parsed.data;
+
+    const templatePath = paths.resolveTargetRoot(
+      dirname(target),
+      template.template,
+    );
+    if (!fs.existsSync(templatePath)) {
+      throw new Error(
+        `Your CLI template skeleton does not exist: ${templatePath}`,
+      );
+    }
+    return { id, templatePath, ...template };
+  }
 }
diff --git a/packages/cli/src/lib/new/templateSelector.ts b/packages/cli/src/lib/new/templateSelector.ts
deleted file mode 100644
index d735ad2a66..0000000000
--- a/packages/cli/src/lib/new/templateSelector.ts
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright 2024 The Backstage Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import { dirname } from 'path';
-import { parse } from 'yaml';
-import fs from 'fs-extra';
-
-import { paths } from '../paths';
-import { Template, TemplateLocation } from './types';
-
-export function verifyTemplate({ id, target }: TemplateLocation): Template {
-  if (target.startsWith('http')) {
-    throw new Error('Remote templates are not supported yet');
-  }
-  if (!fs.existsSync(paths.resolveTargetRoot(target))) {
-    throw new Error(`Your CLI template does not exist: ${target}`);
-  }
-  const template = parse(
-    fs.readFileSync(paths.resolveTargetRoot(target), 'utf-8'),
-  );
-  const templatePath = paths.resolveTargetRoot(
-    dirname(target),
-    template.template,
-  );
-  if (!fs.existsSync(templatePath)) {
-    throw new Error(
-      `Your CLI template skeleton does not exist: ${templatePath}`,
-    );
-  }
-  if (!template.targetPath) {
-    throw new Error(`Your template, ${id}, is missing a targetPath`);
-  }
-  return { id, templatePath, ...template };
-}
diff --git a/packages/cli/src/lib/new/types.ts b/packages/cli/src/lib/new/types.ts
index 74c67897c2..a70a6c0f63 100644
--- a/packages/cli/src/lib/new/types.ts
+++ b/packages/cli/src/lib/new/types.ts
@@ -47,14 +47,13 @@ export type ConfigurablePrompt =
       id: string;
       prompt: string;
       validate?: string;
-      default?: string | boolean;
+      default?: string | boolean | number;
     }
   | string;
 
 export interface Template {
   id: string;
   description?: string;
-  template: string;
   templatePath: string;
   targetPath: string;
   plugin?: boolean;