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type V = "2.0";type Params = unknown[] | object;
interface ErrorObject {	code: number;	message: string;	data?: unknown;}
interface CallMessage {	method: string;	params: Params;	id?: string;	jsonrpc: V;}
interface ResultMessage {	result: unknown;	id: string;	jsonrpc: V;}
interface ErrorMessage {	error: ErrorObject;	id: string | null;	jsonrpc: V;}
interface Options {	log: boolean;}
type Message = CallMessage | ResultMessage | ErrorMessage;
export interface IO {	onData(str: string): void;	sendData(m: string): void;}
const V = "2.0";
function debug(msg: string, ...args: unknown[]) {	console.debug(`[jsonrpc] ${msg}`, ...args);}
function warn(msg: string, ...args: unknown[]) {	console.warn(`[jsonrpc] ${msg}`, ...args);}
function createErrorMessage(id: string | null, code: number, message: string, data?: unknown): ErrorMessage {	let error = {code, message } as ErrorObject;	if (data) { error.data = data; }	return {id, error, jsonrpc:V};}
function createResultMessage(id: string, result: unknown): ResultMessage {	return {id, result, jsonrpc:V};}
function createCallMessage(method: string, params: Params, id?: string): CallMessage {	let message = {method, params, jsonrpc:V} as CallMessage;	if (id) { message.id = id; }	return message;}
export default class JsonRpc {	_interface = new Map<string, Function>();	_pendingPromises = new Map<string, {resolve:Function, reject:Function}>();	_options: Options = {		log: false	}
	constructor(readonly _io: IO, options: Partial<Options> = {}) {		Object.assign(this._options, options);		_io.onData = (m:string) => this._onData(m);	}
	expose(name: string, method: Function) {		this._interface.set(name, method);	}
	async call(method: string, params: Params): Promise<any> {		let id = Math.random().toString();		let message = createCallMessage(method, params, id);		return new Promise((resolve, reject) => {			this._pendingPromises.set(id, {resolve, reject})			this._send(message);		});	}
	notify(method: string, params: Params) {		let message = createCallMessage(method, params);		this._send(message);	}
	_send(message: Message | Message[]) {		const str = JSON.stringify(message);		this._options.log && debug("sending", str);		this._io.sendData(str);	}
	_onData(str: string) {		this._options.log && debug("received", str);
		let message: Message | Message[];		try {			message = JSON.parse(str);		} catch (e) {			let reply = createErrorMessage(null, -32700, e.message);			this._send(reply);			return;		}
		let reply: Message | Message[] | null;		if (message instanceof Array) {			let mapped = message.map(m => this._processMessage(m)).filter(m => m) as Message[];			reply = (mapped.length ? mapped : null);		} else {			reply = this._processMessage(message);		}
		reply && this._send(reply);	}
	_processMessage(message: Message): Message | null {		if ("method" in message) { // call			const method = this._interface.get(message.method);			if (!method) {				return (message.id ? createErrorMessage(message.id, -32601, "method not found") : null);			}
			try {				const result = (message.params instanceof Array ? method(...message.params) : method(message.params));				return (message.id ? createResultMessage(message.id, result) : null);			} catch (e) {				this._options.log && warn("caught", e);				return (message.id ? createErrorMessage(message.id, -32000, e.message) : null);			}
		} else if (message.id) { // result/error
			let promise = this._pendingPromises.get(message.id);			if (!promise) { throw new Error(`Received a non-matching response id "${message.id}"`); }			this._pendingPromises.delete(message.id);			("error" in message ? promise.reject(message.error) : promise.resolve(message.result));
		} else {			throw new Error("Received a non-call non-id JSON-RPC message");		}
		return null;	}}