Add the extension-names codemod.

Signed-off-by: Eric Peterson <ericpeterson@spotify.com>

.changeset/whats-in-a-name.md

@@ -0,0 +1,11 @@
+---
+'@backstage/codemods': patch
+---
+
+Added an `extension-names` codemod, which adds a `name` key to all extensions
+provided by plugins. Extension names are used to provide richer context to
+events captured by the new Analytics API, and may also appear in debug output
+and other situations.
+
+To apply this codemod, run `npx @backstage/codemods apply extension-names` in
+the root of your Backstage monorepo.

packages/codemods/src/codemods.ts

@@ -25,4 +25,9 @@ export const codemods: Codemod[] = [
     description:
       'Updates @backstage/core imports to use @backstage/core-* imports instead.',
   },
+  {
+    name: 'extension-names',
+    description:
+      'Adds a "name" property to all core extensions provided by plugins.',
+  },
 ];

packages/codemods/transforms/extension-names.js

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2021 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.
+ */
+
+module.exports = (file, /** @type {import('jscodeshift').API} */ api) => {
+  const j = api.jscodeshift;
+  const root = j(file.source);
+
+  // Find all variables set to *.provide() with an invocation of an extension
+  // creator as its first argument.
+  // For example: somePlugin.provide(createReactExtension({}))
+  const extensionCreators = [
+    'createReactExtension',
+    'createComponentExtension',
+    'createRoutableExtension',
+  ];
+  const extensions = root
+    .findVariableDeclarators()
+    .filter(
+      n =>
+        n.node.init?.type === 'CallExpression' &&
+        n.node.init?.callee.type === 'MemberExpression' &&
+        n.node.init?.callee?.property.name === 'provide' &&
+        n.node.init?.arguments.length === 1 &&
+        extensionCreators.includes(n.node.init?.arguments[0].callee?.name),
+    );
+
+  // Abort if no such variable declarations exist in this file.
+  if (extensions.size === 0) {
+    return undefined;
+  }
+
+  // For each variable, parse out its name and apply the name as the value of
+  // the "name" key on the argument passed to the extension creator's argument.
+  // For example: createReactExtension({ name: 'Some Extension' })
+  let numberAffected = 0;
+  extensions.nodes().flatMap(node => {
+    const creatorArgObject = node.init?.arguments[0].arguments[0];
+    const hasNameKeyAlready =
+      creatorArgObject.properties.filter(p => p.key.name === 'name').length ===
+      1;
+    const nameProp = j.objectProperty(
+      j.identifier('name'),
+      j.literal(node.id.name),
+    );
+
+    // Apply this change only once.
+    if (!hasNameKeyAlready) {
+      numberAffected++;
+      creatorArgObject.properties.unshift(nameProp);
+    }
+  });
+
+  // Abort if no changes were made.
+  if (numberAffected === 0) {
+    return undefined;
+  }
+
+  // Check for code styles to be applied to this file.
+  const useSingleQuote =
+    root.find(j.ImportDeclaration).nodes()[0]?.source.extra.raw[0] === "'";
+  const useTrailingComma = root
+    .find(j.ObjectExpression)
+    .nodes()[0]
+    ?.extra?.hasOwnProperty('trailingComma');
+
+  return root.toSource({
+    quote: useSingleQuote ? 'single' : 'double',
+    trailingComma: useTrailingComma,
+  });
+};