import type { ModuleRunner, ModuleRunnerImportMeta, ModuleRunnerOptions } from 'vite/module-runner';

type ModuleRunnerModule = typeof import('vite/module-runner');

/** creates a module runner with Deno import and `import.meta` support */
export type CreateModuleRunner = (options: Pick<ModuleRunnerOptions, 'hmr' | 'transport'>) => ModuleRunner;

/**
 * loads the dev server's Vite module runner.
 *
 * @param url URL of `vite/module-runner`
 * @returns Deno module runner factory
 */
export const loadModuleRunner = async (url: string): Promise<CreateModuleRunner> => {
	const { createDefaultImportMeta, ESModulesEvaluator, ModuleRunner }: ModuleRunnerModule = await import(url);

	class DenoEvaluator extends ESModulesEvaluator {
		// import here because Deno doesn't resolve jsr: specifiers from inside npm packages such as Vite
		override runExternalModule(file: string): Promise<unknown> {
			return import(file);
		}
	}

	// Deno lacks the node:module hooks used by Vite's createNodeImportMeta
	const createImportMeta = (modulePath: string): ModuleRunnerImportMeta => {
		const meta = createDefaultImportMeta(modulePath);

		return {
			...meta,
			// evaluated modules are imports, not the process entrypoint
			main: false,
			resolve(specifier: string) {
				if (/^\.\.?\//.test(specifier)) {
					return new URL(specifier, meta.url).href;
				}

				// match externalized imports: resolve from the runner, not the evaluated module
				return import.meta.resolve(specifier);
			},
		};
	};

	return (options) => new ModuleRunner({ ...options, createImportMeta }, new DenoEvaluator());
};