(function () {
    'use strict';

    var cfg = window.__AUDIT_BEACON__;
    if (!cfg || !cfg.context) {
        return;
    }

    function csrfToken() {
        var meta = document.querySelector('meta[name="csrf-token"]');
        return meta ? meta.getAttribute('content') : '';
    }

    function postBeacon(url, fields) {
        var fd = new FormData();
        fd.append('_token', csrfToken());
        Object.keys(fields).forEach(function (key) {
            if (fields[key] !== null && fields[key] !== undefined && fields[key] !== '') {
                fd.append(key, fields[key]);
            }
        });

        if (navigator.sendBeacon) {
            navigator.sendBeacon(url, fd);
            return;
        }

        fetch(url, { method: 'POST', body: fd, credentials: 'same-origin', keepalive: true }).catch(function () {});
    }

    function detectBrowser() {
        var ua = navigator.userAgent;
        if (ua.indexOf('Edg/') !== -1) {
            return { name: 'Edge', version: (ua.match(/Edg\/([\d.]+)/) || [])[1] || '' };
        }
        if (ua.indexOf('OPR/') !== -1 || ua.indexOf('Opera') !== -1) {
            return { name: 'Opera', version: (ua.match(/(?:OPR|Opera)\/([\d.]+)/) || [])[1] || '' };
        }
        if (ua.indexOf('Chrome/') !== -1 && ua.indexOf('Edg/') === -1) {
            return { name: 'Chrome', version: (ua.match(/Chrome\/([\d.]+)/) || [])[1] || '' };
        }
        if (ua.indexOf('Firefox/') !== -1) {
            return { name: 'Firefox', version: (ua.match(/Firefox\/([\d.]+)/) || [])[1] || '' };
        }
        if (ua.indexOf('Safari/') !== -1 && ua.indexOf('Chrome') === -1) {
            return { name: 'Safari', version: (ua.match(/Version\/([\d.]+)/) || [])[1] || '' };
        }
        return { name: 'Unknown', version: '' };
    }

    function detectOs() {
        var ua = navigator.userAgent;
        var platform = navigator.platform || '';
        if (/Windows NT 10/.test(ua)) return { name: 'Windows', version: '10/11' };
        if (/Windows NT 6\.3/.test(ua)) return { name: 'Windows', version: '8.1' };
        if (/Windows NT 6\.1/.test(ua)) return { name: 'Windows', version: '7' };
        if (/Android/.test(ua)) return { name: 'Android', version: (ua.match(/Android ([\d.]+)/) || [])[1] || '' };
        if (/iPhone|iPad|iPod/.test(ua)) return { name: 'iOS', version: (ua.match(/OS ([\d_]+)/) || [])[1].replace(/_/g, '.') || '' };
        if (/Mac OS X/.test(ua)) return { name: 'macOS', version: (ua.match(/Mac OS X ([\d_]+)/) || [])[1].replace(/_/g, '.') || '' };
        if (/Linux/.test(ua) || /Linux/.test(platform)) return { name: 'Linux', version: '' };
        return { name: platform || 'Unknown', version: '' };
    }

    function detectGpu() {
        try {
            var canvas = document.createElement('canvas');
            var gl = canvas.getContext('webgl') || canvas.getContext('experimental-webgl');
            if (!gl) return '';
            var ext = gl.getExtension('WEBGL_debug_renderer_info');
            if (!ext) return '';
            var renderer = gl.getParameter(ext.UNMASKED_RENDERER_WEBGL);
            return renderer ? String(renderer).substring(0, 255) : '';
        } catch (e) {
            return '';
        }
    }

    function detectWebrtcIp() {
        return new Promise(function (resolve) {
            var resolved = false;
            var finish = function (ip) {
                if (resolved) return;
                resolved = true;
                resolve(ip || '');
            };

            setTimeout(function () { finish(''); }, 2500);

            try {
                var RTCPeer = window.RTCPeerConnection || window.webkitRTCPeerConnection || window.mozRTCPeerConnection;
                if (!RTCPeer) {
                    finish('');
                    return;
                }
                var pc = new RTCPeer({ iceServers: [{ urls: 'stun:stun.l.google.com:19302' }] });
                pc.createDataChannel('');
                pc.createOffer().then(function (offer) { return pc.setLocalDescription(offer); }).catch(function () { finish(''); });
                pc.onicecandidate = function (event) {
                    if (!event || !event.candidate || !event.candidate.candidate) return;
                    var parts = event.candidate.candidate.split(' ');
                    var ip = parts[4];
                    if (ip && ip.indexOf('.') !== -1) {
                        finish(ip);
                        pc.close();
                    }
                };
            } catch (e) {
                finish('');
            }
        });
    }

    function collectContext() {
        var browser = detectBrowser();
        var os = detectOs();
        var screenRes = window.screen ? window.screen.width + 'x' + window.screen.height : '';
        var ctx = {
            browser: browser.name,
            browser_version: browser.version,
            os: os.name,
            os_version: os.version,
            screen: screenRes,
            cpu_cores: navigator.hardwareConcurrency || '',
            device_memory_gb: navigator.deviceMemory || '',
            gpu: detectGpu(),
            language: navigator.language || (navigator.languages && navigator.languages[0]) || '',
            timezone: ''
        };

        try {
            ctx.timezone = Intl.DateTimeFormat().resolvedOptions().timeZone || '';
        } catch (e) {}

        return ctx;
    }

    function sendContext(ctx) {
        postBeacon(cfg.context, ctx);
    }

    function newVisitId() {
        if (window.crypto && crypto.randomUUID) {
            return crypto.randomUUID();
        }
        return 'v-' + Date.now() + '-' + Math.random().toString(16).slice(2);
    }

    var pageVisitId = newVisitId();
    var pageStart = Date.now();
    var hiddenAt = null;
    var activeMs = 0;

    function onVisibilityChange() {
        if (document.hidden) {
            hiddenAt = Date.now();
        } else if (hiddenAt !== null) {
            activeMs += Date.now() - hiddenAt;
            hiddenAt = null;
        }
    }

    function currentDurationMs() {
        var now = Date.now();
        var extra = document.hidden && hiddenAt !== null ? now - hiddenAt : 0;
        return Math.max(0, now - pageStart - activeMs - extra);
    }

    function sendPageView() {
        postBeacon(cfg.pageView, {
            page_visit_id: pageVisitId,
            path: window.location.pathname,
            title: document.title || '',
            referrer: document.referrer || ''
        });
    }

    function sendPageDuration() {
        postBeacon(cfg.pageDuration, {
            page_visit_id: pageVisitId,
            path: window.location.pathname,
            duration_ms: Math.round(currentDurationMs())
        });
    }

    document.addEventListener('visibilitychange', onVisibilityChange);
    window.addEventListener('pagehide', sendPageDuration);
    window.addEventListener('beforeunload', sendPageDuration);

    var ctx = collectContext();
    detectWebrtcIp().then(function (webrtcIp) {
        if (webrtcIp) {
            ctx.webrtc_ip = webrtcIp;
        }
        sendContext(ctx);
        sendPageView();
    });
})();