SenSu/static/web_panel/pages/logs.js

window.LogsModule = {
    ws: null,
    reconnectTimer: null,
    reconnectDelay: 1000,
    maxLines: 500,
    lineCount: 0,
    batchBuffer: [],
    batchTimer: null,

    init: function() {
        var self = this;
        self.box = document.getElementById("log-box");
        if (!self.box) return;
        self.box.innerHTML = "";
        self.lineCount = 0;
        self._connect();
    },

    _connect: function() {
        var self = this;
        if (self.ws) {
            self.ws.onclose = null;
            self.ws.close();
            self.ws = null;
        }

        var base = window.location.pathname.split("/").slice(0, 2).join("/");
        var ws = new WebSocket("ws://" + location.host + base + "/api/logs/ws");
        self.ws = ws;

        ws.onopen = function() {
            self.reconnectDelay = 1000;
            self._appendHTML('<div style="color:var(--md-sys-color-primary)">🟢 Connected</div>');
        };

        ws.onmessage = function(e) {
            try {
                var d = JSON.parse(e.data);
                if (d.type === "log") {
                    self._bufferLog(d);
                }
            } catch(ex) {}
        };

        ws.onclose = function() {
            self.ws = null;
            self._appendHTML('<div style="color:var(--error)">🔴 Disconnected — reconnecting...</div>');
            self.reconnectTimer = setTimeout(function() {
                self.reconnectDelay = Math.min(self.reconnectDelay * 1.5, 15000);
                self._connect();
            }, self.reconnectDelay);
        };

        ws.onerror = function() {
            ws.close();
        };
    },

    /* Buffer log entries then flush at ~30fps to avoid DOM thrashing */
    _bufferLog: function(d) {
        var self = this;
        self.batchBuffer.push(d);
        if (!self.batchTimer) {
            self.batchTimer = setTimeout(function() {
                self._flush();
                self.batchTimer = null;
            }, 33); // ~30fps flush
        }
    },

    _flush: function() {
        var self = this;
        var batch = self.batchBuffer;
        self.batchBuffer = [];
        if (!batch.length || !self.box) return;

        var html = '';
        for (var i = 0; i < batch.length; i++) {
            var d = batch[i];
            var cls = d.level === "ERROR" ? "log-ERROR" : d.level === "WARNING" ? "log-WARNING" : "log-INFO";
            var t = d.timestamp ? new Date(d.timestamp * 1000).toLocaleTimeString() : "--";
            html += '<div class="log-entry">' +
                '<span style="color:#555;margin-right:5px">' + t + '</span>' +
                '<span class="' + cls + '">[' + d.level + ']</span> ' +
                self._escapeHtml(d.message || '') + '</div>';
        }

        self._appendHTML(html);
    },

    _appendHTML: function(html) {
        var self = this;
        if (!self.box) return;

        // Estimate line count from <div> tags
        var newLines = (html.match(/<div/g) || []).length;
        self.lineCount += newLines;

        // Trim old lines if over cap
        while (self.lineCount > self.maxLines && self.box.firstChild) {
            // Count lines in the first child
            var removed = 1;
            if (self.box.firstChild.nodeType === 1) {
                var inner = self.box.firstChild.innerHTML || '';
                removed = Math.max(1, (inner.match(/<div/g) || []).length);
            }
            self.box.removeChild(self.box.firstChild);
            self.lineCount = Math.max(0, self.lineCount - removed);
        }

        // Efficient append: insertAdjacentHTML instead of innerHTML +=
        self.box.insertAdjacentHTML("beforeend", html);
        self.box.scrollTop = self.box.scrollHeight;
    },

    _escapeHtml: function(text) {
        return String(text)
            .replace(/&/g, '&amp;')
            .replace(/</g, '&lt;')
            .replace(/>/g, '&gt;')
            .replace(/"/g, '&quot;')
            .replace(/'/g, '&#039;');
    },

    destroy: function() {
        if (this.reconnectTimer) { clearTimeout(this.reconnectTimer); this.reconnectTimer = null; }
        if (this.batchTimer) { clearTimeout(this.batchTimer); this.batchTimer = null; }
        if (this.ws) { this.ws.onclose = null; this.ws.close(); this.ws = null; }
        this.batchBuffer = [];
        this.box = null;
    }
};