import { Logger } from '@nestjs/common';
import type { Msg, NatsError } from 'nats';
import {
	createResponseFromRequest,
	type ServerRequest,
	type ServerResponse,
	type ServiceRegistry,
	ServiceRequestPayloadSchema,
	ServiceResponsePayloadSchema,
} from '../../service';
import { createMsgHdrFromResponse } from './createMsgHdrFromResponse';
import { createResponseFromMessageHeader } from './createResponseFromMessageHeader';
import type { KnownNatsServerMetadata } from './types';

export async function handleNatsServiceRequest({
	msg,
	registry: svc,
	logger: log = new Logger(`NatsServiceServerHandler`),
	err,
}: {
	msg: Msg;
	registry: ServiceRegistry;
	logger?: Logger;
	err?: NatsError | null;
}) {
	if (err) {
		log.error(String(err));
		return;
	}
	if (!msg.reply) {
		log.log(`No reply subject: ${msg.subject}`);
		return;
	}

	let res: ServerResponse | undefined;
	let cause: any | undefined;
	let req: ServerRequest;
	try {
		log.debug(`<- ${msg.subject}`);
		req = Object.assign({ metadata: {} }, ServiceRequestPayloadSchema.parse(JSON.parse(msg.string())));
		createResponseFromMessageHeader(req, msg.headers);
	} catch (error) {
		msg.respond(
			JSON.stringify(createResponseFromRequest({}, { code: 400, description: `Invalid request: ${String(error)}` })),
			{},
		);
		return;
	}

	const meta = req.metadata as KnownNatsServerMetadata;
	meta.NatsMsg = msg;

	try {
		res = await svc.handle(req);
	} catch (error) {
		cause = error;
	}

	if (!res) {
		if (cause) {
			log.error(`Handle ${req.service}#${req.method} error: ${cause}`);
			process.env.NODE_ENV === 'development' && console.error(cause);
			res = createResponseFromRequest(req, { status: 500, description: String(cause) });
		} else if (!res) {
			res = createResponseFromRequest(req, { status: 500, description: 'Invalid Response' });
		}
	}

	const { headers: _, ...write } = ServiceResponsePayloadSchema.parse(res);
	const hdr = createMsgHdrFromResponse(res);
	msg.respond(JSON.stringify(write), { headers: hdr });
}