nano-service/src/service.ts

import { z } from "zod";
import type Adaptor from "./adaptors/adaptor";
import { RequestError } from "./error";
import {
	type InternalRequest,
	InternalRequestSchema,
	type InternalResponse,
	InternalResponseSchema,
	type Request,
	type Response,
} from "./messages";
import type { RouteSubscribeTypeFn } from "./types";

export default class Service {
	private name: string;

	private adaptors: Record<string, Adaptor>;

	constructor(name: string) {
		this.name = name;
		this.adaptors = {};
	}

	public addAdaptor(name: string, adaptor: Adaptor) {
		this.adaptors[name] = adaptor;
	}

	public subscribe<T extends z.ZodType<O>, O, U>(
		adaptor: string,
		subject: string,
		fn: RouteSubscribeTypeFn<z.infer<T>, U>,
		schema: T | undefined = undefined,
	) {
		this.adaptors[adaptor].subscribe(
			`${this.name}.${subject}`,
			async (rawReq) => {
				const rawReqJson = JSON.parse(rawReq);
				const internalRequestJson = InternalRequestSchema.safeParse(rawReqJson);
				if (!internalRequestJson.success) {
					return JSON.stringify({
						statusCode: 400,
						data: "bad request structure",
					} satisfies InternalResponse);
				}

				const internalRequest = internalRequestJson.data;
				const req = {
					service: internalRequest.from,
					subject: subject,
				} as Request<z.infer<T>>;

				if (internalRequest.data && schema) {
					const validate = schema.safeParse(internalRequest.data);
					if (!validate.success) {
						return JSON.stringify({
							statusCode: 400,
							data: validate.error,
						} satisfies InternalResponse);
					}
					req.data = validate.data;
				}

				try {
					const res = await fn(req);
					const internalResponse = {
						statusCode: res.statusCode,
						data: res.data,
					} satisfies InternalResponse;

					return JSON.stringify(internalResponse);
				} catch (err) {
					if (err instanceof RequestError) {
						return JSON.stringify({
							statusCode: err.statusCode,
							data: err.message,
						} satisfies InternalResponse);
					}
					return JSON.stringify({
						statusCode: 500,
						data: "unknow error apend",
					} satisfies InternalResponse);
				}
			},
		);
	}

	public async request<T, O, U extends z.ZodType<O>>(
		adaptor: string,
		req: Request<T>,
		schema?: z.ZodType<O>,
	): Promise<Response<z.infer<U>>> {
		if (!this.adaptors[adaptor]) {
			throw new Error(`${adaptor} adaptor not exist`);
		}

		const internalRequest = {
			from: this.name,
			data: req.data,
		} satisfies InternalRequest;
		const internalRequestJson = JSON.stringify(internalRequest);

		try {
			const rawRes = await this.adaptors[adaptor].request(
				`${req.service}.${req.subject}`,
				internalRequestJson,
			);
			const rawResJson: unknown = JSON.parse(rawRes);
			const internalResponseJson = InternalResponseSchema.safeParse(rawResJson);
			if (!internalResponseJson.success) {
				throw new RequestError(internalResponseJson.error.toString(), 500);
			}

			const internalResponse = internalResponseJson.data;
			if (
				internalResponse.statusCode < 200 ||
				internalResponse.statusCode >= 299
			) {
				throw new RequestError(
					internalResponse.data,
					internalResponse.statusCode,
				);
			}
			const res: Response<z.infer<U>> = {
				statusCode: internalResponse.statusCode,
			};
			if (internalResponse.data && schema) {
				const validate = schema.safeParse(internalResponse.data);

				if (!validate.success) {
					throw new RequestError(validate.error.message, 400);
				}
				res.data = validate.data;
			}

			return res;
		} catch (err) {
			if (err instanceof RequestError) {
				throw err;
			}

			throw new RequestError("unexpected error", 500);
		}
	}

	public async listen() {
		for (const index in this.adaptors) {
			await this.adaptors[index].listen(this.name);
		}
	}

	public async stop() {
		for (const index in this.adaptors) {
			await this.adaptors[index].stop();
		}
	}
}