import { EngineConfig, ExecutionsConfig } from '@n8n/config';
import type { ModuleInterface } from '@n8n/decorators';
import { BackendModule, OnShutdown } from '@n8n/decorators';
import { Container } from '@n8n/di';
import { UserError } from 'n8n-workflow';
import { randomBytes } from 'node:crypto';

/**
 * Runs the engine 2.0 data plane in-process.
 *
 * Not a default module: enable it with `N8N_ENABLED_MODULES=engine-v2`. When it
 * is off, nothing here loads and no data plane connection is opened.
 *
 * Main-only, and regular mode only. The in-process engine uses
 * `InMemoryWorkQueue`, so its work does not survive the process and cannot be
 * shared with other mains or workers.
 */
@BackendModule({ name: 'engine-v2', instanceTypes: ['main'] })
export class EngineV2Module implements ModuleInterface {
	async init() {
		if (Container.get(ExecutionsConfig).mode === 'queue') {
			throw new UserError('The engine-v2 module does not support queue mode.');
		}

		const engineConfig = Container.get(EngineConfig);
		// Both planes live in this process, so a generated secret is enough and the
		// integrated engine is never unauthenticated. A separate CP must set it.
		if (!engineConfig.authSecret) {
			engineConfig.authSecret = randomBytes(32).toString('hex');
		}

		// Before the engine, so nothing is reported with no server to receive it.
		const { EngineControlPlaneServer } = await import('./engine-control-plane-server.js');
		await Container.get(EngineControlPlaneServer).start();

		const { EngineV2Runtime } = await import('./engine-v2.runtime.js');
		await Container.get(EngineV2Runtime).init();

		const { EngineDataPlaneClient } = await import('./engine-data-plane-client.js');
		const { EngineDataPlaneProxyService } = await import(
			'@/services/engine-data-plane-proxy.service.js'
		);
		Container.get(EngineDataPlaneProxyService).registerProvider(
			Container.get(EngineDataPlaneClient),
		);
	}

	@OnShutdown()
	async shutdown() {
		const { EngineV2Runtime } = await import('./engine-v2.runtime.js');
		await Container.get(EngineV2Runtime).shutdown();

		// After the engine, so its final flush still has somewhere to land.
		const { EngineControlPlaneServer } = await import('./engine-control-plane-server.js');
		await Container.get(EngineControlPlaneServer).stop();
	}
}