chore: import upstream snapshot with attribution

packages/workers-utils/src/package-resolution.ts

@@ -0,0 +1,146 @@
+import { statSync } from "node:fs";
+import path from "node:path";
+import { parsePackageJSON, readFileSync } from "./parse";
+
+/**
+ * Resolves the filesystem path for an installed npm package.
+ *
+ * Tries two strategies:
+ * 1. `require.resolve("<pkg>/package.json")` -- works when the package exports its package.json
+ * 2. `require.resolve("<pkg>")` -- fallback for packages that don't export package.json
+ *
+ * @param packageName - The npm package name to resolve
+ * @param projectPath - The project directory to resolve from
+ * @returns The resolved directory path, or `undefined` if the package is not installed
+ */
+export function getPackagePath(
+	packageName: string,
+	projectPath: string
+): string | undefined {
+	try {
+		// Try to resolve the package.json directly — works when the package exports it
+		return path.dirname(
+			require.resolve(`${packageName}/package.json`, {
+				paths: [projectPath],
+			})
+		);
+	} catch {}
+
+	try {
+		// Fallback: resolve the package entry point and return its directory
+		return path.dirname(
+			require.resolve(packageName, {
+				paths: [projectPath],
+			})
+		);
+	} catch {}
+
+	return undefined;
+}
+
+/**
+ * Checks whether an npm package is installed in a target project.
+ *
+ * @param packageName - The name of the target package
+ * @param projectPath - The path of the project to check
+ * @returns `true` if the package is installed, `false` otherwise
+ */
+export function isPackageInstalled(
+	packageName: string,
+	projectPath: string
+): boolean {
+	return !!getPackagePath(packageName, projectPath);
+}
+
+/**
+ * Gets the exact version of an npm package installed in a project by resolving
+ * it from node_modules and reading its package.json.
+ *
+ * @param packageName - The name of the target package
+ * @param projectPath - The path of the project to check
+ * @param opts - Options
+ * @param opts.stopAtProjectPath - If `true`, stop walking up at the project's path
+ * @returns The installed version string, or `undefined` if the package is not installed
+ */
+export function getInstalledPackageVersion(
+	packageName: string,
+	projectPath: string,
+	opts: {
+		stopAtProjectPath?: boolean;
+	} = {}
+): string | undefined {
+	try {
+		const packagePath = getPackagePath(packageName, projectPath);
+		if (!packagePath) {
+			return undefined;
+		}
+
+		const lastDir = opts.stopAtProjectPath === true ? projectPath : undefined;
+		const packageJsonPath = findFileUp("package.json", packagePath, lastDir);
+
+		if (!packageJsonPath) {
+			return undefined;
+		}
+
+		const packageJson = parsePackageJSON(
+			readFileSync(packageJsonPath),
+			packageJsonPath
+		);
+		// The requested package may be installed under an alias (e.g. vite+
+		// installs `@voidzero-dev/vite-plus-core` under the `vite` alias). In that
+		// case the resolved package.json belongs to the aliased package, so its
+		// `version` is not the version of the requested package.
+		//
+		// `bundledVersions` is NOT a standard package.json field (it is not the
+		// standard `bundledDependencies`) — it is a vite+ convention that maps the
+		// names of the tools it bundles to the versions it provides. When the
+		// resolved package name doesn't match the requested one, prefer the version
+		// declared there for the requested package.
+		if (packageJson.name !== packageName) {
+			const bundledVersion = packageJson.bundledVersions?.[packageName];
+			if (bundledVersion !== undefined) {
+				return bundledVersion;
+			}
+		}
+		return packageJson.version;
+	} catch {}
+}
+
+/**
+ * Walks up from `startDir` looking for a file named `name`.
+ * Stops at `lastDir` (inclusive) if provided, otherwise walks to the filesystem root.
+ *
+ * @param name - The filename to search for
+ * @param startDir - The directory to start searching from
+ * @param lastDir - If provided, stop searching after reaching this directory
+ * @returns The full path to the found file, or `undefined`
+ */
+function findFileUp(
+	name: string,
+	startDir: string,
+	lastDir?: string
+): string | undefined {
+	let dir = startDir;
+	const root = path.parse(dir).root;
+
+	while (true) {
+		const candidate = path.join(dir, name);
+		try {
+			if (statSync(candidate).isFile()) {
+				return candidate;
+			}
+		} catch {}
+
+		if (lastDir !== undefined && dir === lastDir) {
+			break;
+		}
+
+		const parent = path.dirname(dir);
+		if (parent === dir || dir === root) {
+			break;
+		}
+		dir = parent;
+	}
+
+	return undefined;
+}