feat(migrate-legacy-buffer-atob-btoa): introduce

recipes/buffer-atob-btoa/README.md

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+# Migrate legacy `buffer.atob()` and `buffer.btoa()` APIs
+
+Migrates usage of the legacy APIs `buffer.atob()` and `buffer.btoa()` to the current recommended approaches.
+
+## Example
+
+### Migrating buffer.atob(data)
+
+**Before:**
+```js
+const buffer = require('node:buffer');
+const data = 'SGVsbG8gV29ybGQh'; // "Hello World!" in base64
+const decodedData = buffer.atob(data);
+console.log(decodedData); // Outputs: Hello World!
+```
+
+**After:**
+```js
+const data = 'SGVsbG8gV29ybGQh'; // "Hello World!" in base64
+const decodedData = Buffer.from(data, 'base64').toString('binary');
+console.log(decodedData); // Outputs: Hello World!
+```
+
+### Migrating buffer.btoa(data)
+
+**Before:**
+```js
+const buffer = require('node:buffer');
+const data = 'Hello World!';
+const encodedData = buffer.btoa(data);
+console.log(encodedData); // Outputs: SGVsbG8gV29ybGQh
+```
+
+**After:**
+```js
+const data = 'Hello World!';
+const encodedData = Buffer.from(data, 'binary').toString('base64');
+console.log(encodedData); // Outputs: SGVsbG8gV29ybGQh
+```
+
+## REFS
+* [Node.js Documentation: Buffer](https://nodejs.org/api/buffer.html)

recipes/buffer-atob-btoa/codemod.yaml

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+schema_version: "1.0"
+name: "@nodejs/buffer-atob-btoa"
+version: "1.0.0"
+description: Migrates usage of the legacy APIs `buffer.atob()` and `buffer.btoa()` to the current recommended approaches
+author: nekojanai (Jana)
+license: MIT
+workflow: workflow.yaml
+category: migration
+
+targets:
+  languages:
+    - javascript
+    - typescript
+
+keywords:
+  - transformation
+  - migration
+
+registry:
+  access: public
+  visibility: public

recipes/buffer-atob-btoa/package.json

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+{
+  "name": "@nodejs/buffer-atob-btoa",
+  "version": "1.0.0",
+  "description": "Migrates usage of the legacy APIs `buffer.atob()` and `buffer.btoa()` to the current recommended approaches",
+  "type": "module",
+  "scripts": {
+    "test": "npx codemod jssg test -l typescript ./src/workflow.ts ./"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/nodejs/userland-migrations.git",
+    "directory": "recipes/buffer-atob-btoa",
+    "bugs": "https://github.com/nodejs/userland-migrations/issues"
+  },
+  "author": "nekojanai (Jana)",
+  "license": "MIT",
+  "homepage": "https://github.com/nodejs/userland-migrations/blob/main/recipes/buffer-atob-btoa/README.md",
+  "dependencies": {
+    "@nodejs/codemod-utils": "*"
+  }
+}

recipes/buffer-atob-btoa/src/workflow.ts

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+import type { Edit, Range, SgRoot } from '@codemod.com/jssg-types/main';
+import type Js from '@codemod.com/jssg-types/langs/javascript';
+import { getNodeRequireCalls } from '@nodejs/codemod-utils/ast-grep/require-call';
+import { removeLines } from '@nodejs/codemod-utils/ast-grep/remove-lines';
+
+export default function transform(root: SgRoot<Js>): string | null {
+  const rootNode = root.root()
+  const edits: Edit[] = [];
+  const linesToRemove: Range[] = [];
+
+  // @ts-expect-error - ast-grep types are not fully compatible with JSSG types
+  const requireStatements = getNodeRequireCalls(root, 'buffer');
+  const atobFunctionCalls = rootNode.findAll({
+    rule: {
+      pattern: 'buffer.atob($ARG)'
+    }
+  });
+
+  // Remove all buffer require statements
+  for (const statement of requireStatements) {
+    linesToRemove.push(statement.range());
+  }
+
+  // Rewrite atob function calls
+  for (const call of atobFunctionCalls) {
+    const argMatch = call.getMatch("ARG");
+    if (argMatch) {
+      const arg = argMatch.text();
+      const replacement = `Buffer.from(${arg}, 'base64').toString('binary')`;
+      edits.push(call.replace(replacement));
+    }
+  }
+
+  const btoaFunctionCalls = rootNode.findAll({
+    rule: {
+      pattern: 'buffer.btoa($ARG)'
+    }
+  });
+
+  // Rewrite btoa function calls
+  for (const call of btoaFunctionCalls) {
+    const argMatch = call.getMatch("ARG");
+    if (argMatch) {
+      const arg = argMatch.text();
+      const replacement = `Buffer.from(${arg}, 'binary').toString('base64')`;
+      edits.push(call.replace(replacement));
+    }
+  }
+
+  return removeLines(rootNode.commitEdits(edits), linesToRemove);
+}

recipes/buffer-atob-btoa/tests/expected/file-00.js

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+const data = 'SGVsbG8gV29ybGQh'; // "Hello World!" in base64
+const decodedData = Buffer.from(data, 'base64').toString('binary');
+console.log(decodedData); // Outputs: Hello World!

recipes/buffer-atob-btoa/tests/expected/file-01.js

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+const data = 'Hello World!';
+const encodedData = Buffer.from(data, 'binary').toString('base64');
+console.log(encodedData); // Outputs: SGVsbG8gV29ybGQh

recipes/buffer-atob-btoa/tests/input/file-00.js

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+const buffer = require('node:buffer');
+const data = 'SGVsbG8gV29ybGQh'; // "Hello World!" in base64
+const decodedData = buffer.atob(data);
+console.log(decodedData); // Outputs: Hello World!

recipes/buffer-atob-btoa/tests/input/file-01.js

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+const buffer = require('node:buffer');
+const data = 'Hello World!';
+const encodedData = buffer.btoa(data);
+console.log(encodedData); // Outputs: SGVsbG8gV29ybGQh

recipes/buffer-atob-btoa/workflow.yaml

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+# yaml-language-server: $schema=https://raw.githubusercontent.com/codemod-com/codemod/refs/heads/main/schemas/workflow.json
+
+version: "1"
+
+nodes:
+  - id: apply-transforms
+    name: Apply AST Transformations
+    type: automatic
+    runtime:
+      type: direct
+    steps:
+      - name: Migrates usage of the legacy APIs `buffer.atob()` and `buffer.btoa()` to the current recommended approaches
+        js-ast-grep:
+          js_file: src/workflow.ts
+          base_path: .
+          include:
+            - "**/*.cjs"
+            - "**/*.js"
+            - "**/*.jsx"
+            - "**/*.mjs"
+            - "**/*.cts"
+            - "**/*.mts"
+            - "**/*.ts"
+            - "**/*.tsx"
+          exclude:
+            - "**/node_modules/**"
+          language: typescript