import type { Plugin } from 'vite';

const SERVER_ONLY = /^@webavatar\/webavatar-core\/(server|vite)(\/|$)/;

/**
 * Build-time backstop for the server-only boundary: SvelteKit's own
 * `$lib/server` guard is path-based and doesn't reach into `node_modules`, so
 * once core's server code is a package this is what makes a client-side
 * import of `@webavatar/webavatar-core/server` (or `/vite`) fail the build
 * rather than only failing at runtime via the package's `browser` stub. See
 * docs/ARCHITECTURE.md's "Server-only safety" section.
 */
export function serverOnlyGuard(): Plugin {
	return {
		name: 'webavatar-server-only-guard',
		enforce: 'pre',
		resolveId(id, importer, options) {
			const isClient = this.environment ? this.environment.name === 'client' : !options?.ssr;
			if (isClient && SERVER_ONLY.test(id)) {
				throw new Error(
					`${id} is server-only; import it through $lib/server instead (importer: ${importer}).`
				);
			}
			return null;
		}
	};
}