import type { MessageFormat } from "../sendrecv.ts";

export function jsonFormat<TSend, TRecv = TSend>(): MessageFormat<TSend, TRecv> {
	return {
		parser: parseJson<TRecv>,
		formatter: formatJson<TSend>,
	};
}

function parseJson<T>(data: any): T {
	const throwUnexpectedFormat = () => {
		throw new Error("Expected message to be a JSON string");
	};

	if (typeof data !== "string") {
		return throwUnexpectedFormat();
	}

	try {
		return JSON.parse(data);
	} catch {
		return throwUnexpectedFormat();
	}
}

function formatJson<T>(message: T): string {
	return JSON.stringify(message);
}