enum Message {
	Farewell,
	Welcome,
	Attendee,
	Guest,
	Dropout,
	Pilgrim,
}

interface Player {
	socket: WebSocket,
	x: number,
	y: number,
	others: Array<Player>,
}

declare global {
	interface Array<T> {
		remove(item: T): void;
		swapRemove(item: T): void;
	}
}

Array.prototype.remove = function (item) {
	const index = this.indexOf(item);
	if (index > -1)
		this.splice(index, 1);
}

Array.prototype.swapRemove = function (item) {
	const last = this.pop();
	const index = this.indexOf(item);
	if (last !== undefined && index > -1)
		this.splice(index, 1, last);
}

const players = new Array<Player>();
let idCounter = 0;

Deno.serve({ port: 80 }, (request, info) => {
	if (request.headers.get("upgrade") != "websocket")
		return new Response(null, { status: 501 });
	const { socket, response } = Deno.upgradeWebSocket(request, { idleTimeout: 0 });
	const { hostname, port } = info.remoteAddr;
	const player = {
		socket,
		x: Math.floor(Math.random()*0x10000),
		y: Math.floor(Math.random()*0x10000),
		others: players.slice(),
	};
	const bytesRecv = new Uint8Array(new ArrayBuffer(4));
	let bytesRecvCount = 0;
	
	if (players.length > 64) {
		socket.addEventListener("open", () => {
			socket.close();
			console.log(`${hostname}:${port} denied, server over capacity`);
		});
		
		return response;
	}
	
	players.push(player);
	const id = idCounter++;
	
	socket.binaryType = "arraybuffer";
	
	socket.addEventListener("open", () => {
		console.log(`${hostname}:${port} connected as player ${id}`);
		const { x, y } = player;
		socket.send(new Uint8Array([Message.Welcome, x>>8, x&0xff, y>>8, y&0xff]));
		for (const other of player.others) {
			socket.send(new Uint8Array([Message.Attendee, other.x>>8, other.x&0xff, other.y>>8, other.y&0xff]));
			other.socket.send(new Uint8Array([Message.Guest, x>>8, x&0xff, y>>8, y&0xff]));
			other.others.push(player);
		}
	});
	
	socket.addEventListener("message", (event) => {
		if (typeof(event.data) == "string")
			return;
		const bytes = new Uint8Array(event.data);
		for (const byte of bytes) {
			bytesRecv[bytesRecvCount++] = byte;
			if (bytesRecvCount !== bytesRecv.byteLength)
				continue;
			bytesRecvCount = 0;
			const x = bytesRecv[0]<<8 | bytesRecv[1];
			const y = bytesRecv[2]<<8 | bytesRecv[3];
			player.x = x;
			player.y = y;
			for (const other of player.others)
				other.socket.send(new Uint8Array([Message.Pilgrim, other.others.indexOf(player), x>>8, x&0xff, y>>8, y&0xff]));
		}
	});
	
	socket.addEventListener("close", () => {
		for (const other of player.others) {
			other.socket.send(new Uint8Array([Message.Dropout, other.others.indexOf(player)]));
			other.others.swapRemove(player);
		}
		players.remove(player);
		console.log(`Player ${id} disconnected`);
	});
	
	return response;
});