import { config } from "./config.js";
import type { AgentEvent, ConnectionStatus } from "./types.js";

type EventCallback = (event: AgentEvent) => void;

function createWebSocketClient(url: string) {
	let connectionStatus: ConnectionStatus = $state("disconnected");
	let ws: WebSocket | null = null;
	let reconnectDelay = 1000;
	let reconnectTimer: ReturnType<typeof setTimeout> | null = null;
	let manualDisconnect = false;
	const callbacks: EventCallback[] = [];

	function connect() {
		if (ws && (ws.readyState === WebSocket.OPEN || ws.readyState === WebSocket.CONNECTING)) {
			return;
		}
		manualDisconnect = false;
		connectionStatus = "connecting";
		ws = new WebSocket(url);

		ws.onopen = () => {
			connectionStatus = "connected";
			reconnectDelay = 1000;
		};

		ws.onmessage = (event: MessageEvent) => {
			try {
				const data = JSON.parse(event.data as string) as AgentEvent;
				for (const cb of callbacks) {
					cb(data);
				}
			} catch {
				// ignore malformed messages
			}
		};

		ws.onclose = () => {
			connectionStatus = "disconnected";
			ws = null;
			if (!manualDisconnect) {
				scheduleReconnect();
			}
		};

		ws.onerror = () => {
			ws?.close();
		};
	}

	function scheduleReconnect() {
		if (reconnectTimer) clearTimeout(reconnectTimer);
		reconnectTimer = setTimeout(() => {
			reconnectTimer = null;
			connect();
		}, reconnectDelay);
		reconnectDelay = Math.min(reconnectDelay * 2, 10000);
	}

	function disconnect() {
		manualDisconnect = true;
		if (reconnectTimer) {
			clearTimeout(reconnectTimer);
			reconnectTimer = null;
		}
		ws?.close();
		ws = null;
		connectionStatus = "disconnected";
	}

	function onEvent(callback: EventCallback) {
		callbacks.push(callback);
		return () => {
			const idx = callbacks.indexOf(callback);
			if (idx !== -1) callbacks.splice(idx, 1);
		};
	}

	return {
		get connectionStatus() {
			return connectionStatus;
		},
		connect,
		disconnect,
		onEvent,
	};
}

export const wsClient = createWebSocketClient(config.wsUrl);