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
+  - buffers
+
+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": "*"
+  },
+  "devDependencies": {
+    "@codemod.com/jssg-types": "^1.0.9"
+  }
+}

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

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+import type { Edit, Kinds, Range, SgNode, SgRoot } from '@codemod.com/jssg-types/main';
+import type Js from '@codemod.com/jssg-types/langs/javascript';
+import { resolveBindingPath } from '@nodejs/codemod-utils/ast-grep/resolve-binding-path';
+import { getNodeRequireCalls } from '@nodejs/codemod-utils/ast-grep/require-call';
+import { getNodeImportStatements } from '@nodejs/codemod-utils/ast-grep/import-statement';
+import { removeLines } from '@nodejs/codemod-utils/ast-grep/remove-lines';
+import { removeBinding } from '@nodejs/codemod-utils/ast-grep/remove-binding';
+
+export default function transform(root: SgRoot<Js>): string | null {
+	const rootNode = root.root();
+	const bindingStatementFnTuples: [string, SgNode<Js>, (arg: string) => string][] = [];
+	const edits: Edit[] = [];
+	const linesToRemove: Range[] = [];
+
+	const updates = [
+		{
+			oldBind: "$.atob",
+			replaceFn: (arg: string) => `Buffer.from(${arg}, 'base64').toString('binary')`
+		},
+		{
+			oldBind: "$.btoa",
+			replaceFn: (arg: string) => `Buffer.from(${arg}, 'binary').toString('base64')`
+		}
+	];
+
+	const statements = [
+		...getNodeRequireCalls(root, 'buffer'),
+		...getNodeImportStatements(root, 'buffer')
+	];
+
+	for (const statement of statements) {
+		for (const update of updates) {
+			const binding = resolveBindingPath(statement, update.oldBind);
+			if (binding) bindingStatementFnTuples.push([binding, statement, update.replaceFn]);
+		}
+	}
+
+	for (const [binding, statement, fn] of bindingStatementFnTuples) {
+		const result = removeBinding(statement, binding);
+
+		if (result?.edit) edits.push(result.edit);
+		if (result?.lineToRemove) linesToRemove.push(result.lineToRemove);
+		// Check for calls to the specified binding
+		const calls = rootNode.findAll({
+			rule: {
+				pattern: `${binding}($ARG)`
+			}
+		});
+		// Check for any other calls, so as to not remove a statement that is still being used
+		const otherCalls = rootNode.findAll({
+			rule: {
+				all: [
+					{
+						pattern: 'buffer.$FN'
+					},
+					{
+						not: {
+							pattern: '$.btoa($ARG)'
+						}
+					},
+					{
+						not: {
+							pattern: '$.atob($ARG)'
+						}
+					}
+				]
+			}
+		});
+
+		for (const call of calls) {
+			const argMatch = call.getMatch("ARG");
+			if (argMatch) edits.push(call.replace(fn(argMatch.text())));
+		}
+
+		if (calls.length === otherCalls.length) {
+			linesToRemove.push(statement.range());
+		}
+	}
+
+	if (!edits.length) return null;
+
+	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/expected/file-02.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/expected/file-03.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/expected/file-04.js

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+import buffer from "node:buffer";
+buffer.constants.MAX_LENGTH;
+const data = 'Hello World!';
+Buffer.from(data, 'binary').toString('base64');

recipes/buffer-atob-btoa/tests/expected/file-05.js

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+import { isUtf8 } from "node:buffer";
+const data = 'Hello World!';
+isUtf8(data);
+Buffer.from(data, 'base64').toString('binary');

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/tests/input/file-02.js

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

recipes/buffer-atob-btoa/tests/input/file-03.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/tests/input/file-04.js

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+import buffer from "node:buffer";
+buffer.constants.MAX_LENGTH;
+const data = 'Hello World!';
+buffer.btoa(data);

recipes/buffer-atob-btoa/tests/input/file-05.js

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+import { atob, isUtf8 } from "node:buffer";
+const data = 'Hello World!';
+isUtf8(data);
+atob(data);

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