var net = require("net");

class RPCConn {
	constructor(ip, port) {
		this.ready = false;

		this._callbacks = {};
		this._onready = [];
		this._listeners = {};

		this._id = 1;
		this.sock = new net.Socket();
		this.sock.connect(port, ip, () => {
			console.log("Connected to RPC server "+ip+":"+port+".");
			this.ready = true;
			this._onready.forEach(x => x());
		});

		var onjson = json => {
			var obj;
			try {
				obj = JSON.parse(json);
			} catch (err) {
				console.log("Failed to parse JSON: '"+json+"'");
				return;
			}

			if (obj.id == null) {
				var listeners = this._listeners[obj.method];

				if (listeners)
					listeners.forEach(l => l(obj.params));
				if (!listeners || listeners.length === 0)
					console.log("Received method '"+obj.method+"', but no listeners.");

				return;
			}

			var cb = this._callbacks[obj.id];
			if (!cb)
				return console.log("Warning: received unknown ID "+obj.id);

			cb(obj.error, obj.result);
		}

		//Digest JSON lines as they come, but only if they're a whole line
		var currdata = "";
		this.sock.on("data", d => {
			currdata += d.toString();

			var start = 0;
			for (var i = 0; i < currdata.length; ++i) {
				if (currdata[i] === "\n") {
					var s = currdata.substring(start, i);
					start = i + 1;
					onjson(s);
				}
			}
			currdata = currdata.substring(start);
		});
	}

	wait() {
		return new Promise((resolve, reject) => {
			if (this.ready)
				return resolve();

			this._onready.push(resolve);
		});
	}


	call(name, ...params) {
		return new Promise((resolve, reject) => {
			var json = JSON.stringify({
				id: this._id,
				method: name,
				params: params
			});
			this._callbacks[this._id] = (err, res) => {
				if (err) reject(err);
				else resolve(res);
			}

			this.sock.write(json+"\n");
			this._id += 1;
		});
	}

	on(name, fn) {
		this._listeners[name] = this._listeners[name] || [];
		this._listeners[name].push(fn);
	}
}

module.exports = RPCConn;