/**
 * ws-client.js — WebSocket 客户端单例
 * 全站共享一个 WS 连接，提供自动重连、消息分发、状态通知
 */
var WsClient = (function() {
    var ws = null;
    var url = '';
    var msgCallbacks = [];
    var statusCallbacks = [];
    var reconnectTimer = null;
    var reconnectDelay = 3000;
    var status = 'disconnected'; // 'connected' | 'disconnected' | 'connecting'

    function setStatus(s) {
        if (status !== s) {
            status = s;
            for (var i = 0; i < statusCallbacks.length; i++) {
                statusCallbacks[i](s);
            }
        }
    }

    function connect(wsUrl) {
        if (ws && (ws.readyState === WebSocket.OPEN || ws.readyState === WebSocket.CONNECTING)) {
            return;
        }

        url = wsUrl;
        setStatus('connecting');

        try {
            ws = new WebSocket(url);
        } catch (e) {
            setStatus('disconnected');
            scheduleReconnect();
            return;
        }

        ws.onopen = function() {
            setStatus('connected');
            if (reconnectTimer) {
                clearTimeout(reconnectTimer);
                reconnectTimer = null;
            }
        };

        ws.onclose = function() {
            setStatus('disconnected');
            ws = null;
            scheduleReconnect();
        };

        ws.onerror = function() {
            // onclose will fire after onerror
        };

        ws.onmessage = function(e) {
            var raw = e.data;

            // 写入监控日志
            if (typeof MonitorRing !== 'undefined') {
                MonitorRing.push('↓', raw);
            }

            // 尝试解析 JSON
            var data = null;
            try {
                data = JSON.parse(raw);
            } catch (ex) {
                // 非 JSON 消息也分发原始数据
            }

            // 分发给所有注册的回调
            for (var i = 0; i < msgCallbacks.length; i++) {
                try {
                    msgCallbacks[i](data || raw, raw);
                } catch (ex) {
                    console.error('WsClient msg callback error:', ex);
                }
            }
        };
    }

    function scheduleReconnect() {
        if (reconnectTimer) return;
        reconnectTimer = setTimeout(function() {
            reconnectTimer = null;
            if (status === 'disconnected') {
                connect(url);
            }
        }, reconnectDelay);
    }

    function send(data) {
        var raw = '';
        if (typeof data === 'object') {
            raw = JSON.stringify(data);
        } else {
            raw = String(data);
        }

        // 写入监控日志
        if (typeof MonitorRing !== 'undefined') {
            MonitorRing.push('↑', raw);
        }

        if (!ws || ws.readyState !== WebSocket.OPEN) {
            console.error('WsClient: not connected, cannot send');
            return false;
        }

        try {
            ws.send(raw);
            return true;
        } catch (e) {
            console.error('WsClient: send failed', e);
            return false;
        }
    }

    function onMessage(cb) {
        msgCallbacks.push(cb);
    }

    function onStatusChange(cb) {
        statusCallbacks.push(cb);
        // 立即通知当前状态
        cb(status);
    }

    function getStatus() {
        return status;
    }

    function disconnect() {
        if (reconnectTimer) {
            clearTimeout(reconnectTimer);
            reconnectTimer = null;
        }
        if (ws) {
            ws.onclose = null; // 阻止自动重连
            ws.close();
            ws = null;
        }
        setStatus('disconnected');
    }

    return {
        connect: connect,
        send: send,
        onMessage: onMessage,
        onStatusChange: onStatusChange,
        getStatus: getStatus,
        disconnect: disconnect
    };
})();