/**
 * Spark Platform - Client-Side Analytics Tracker
 * 
 * Lightweight tracking script that:
 * - Tracks pageviews with UTM params
 * - Tracks custom events
 * - Generates session/visitor IDs
 * - Integrates with Google Tag Manager, GA4, Clarity, FB Pixel
 * 
 * Usage:
 * <script src="/js/tracker.js" data-site-id="your-site-id"></script>
 */

(function () {
    'use strict';

    // Get site ID from script tag
    const scriptTag = document.currentScript || document.querySelector('script[data-site-id]');
    const SITE_ID = scriptTag?.getAttribute('data-site-id');
    const API_BASE = scriptTag?.getAttribute('data-api-base') || '';

    if (!SITE_ID) {
        console.warn('[Spark Tracker] Missing data-site-id attribute');
        return;
    }

    // Generate or get visitor ID (persisted in localStorage)
    function getVisitorId() {
        let id = localStorage.getItem('spark_visitor_id');
        if (!id) {
            id = 'v_' + Math.random().toString(36).substring(2, 15);
            localStorage.setItem('spark_visitor_id', id);
        }
        return id;
    }

    // Generate session ID (persisted in sessionStorage)
    function getSessionId() {
        let id = sessionStorage.getItem('spark_session_id');
        if (!id) {
            id = 's_' + Math.random().toString(36).substring(2, 15);
            sessionStorage.setItem('spark_session_id', id);
        }
        return id;
    }

    const VISITOR_ID = getVisitorId();
    const SESSION_ID = getSessionId();

    // Track pageview
    function trackPageview() {
        const data = {
            site_id: SITE_ID,
            page_path: window.location.pathname + window.location.search,
            page_title: document.title,
            referrer: document.referrer,
            session_id: SESSION_ID,
            visitor_id: VISITOR_ID
        };

        fetch(API_BASE + '/api/track/pageview', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(data),
            keepalive: true
        }).catch(() => { });
    }

    // Track custom event
    window.sparkTrack = function (eventName, eventData = {}) {
        const data = {
            site_id: SITE_ID,
            event_name: eventName,
            event_category: eventData.category,
            event_label: eventData.label,
            event_value: eventData.value,
            page_path: window.location.pathname,
            session_id: SESSION_ID,
            visitor_id: VISITOR_ID,
            metadata: eventData.metadata || eventData
        };

        fetch(API_BASE + '/api/track/event', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(data),
            keepalive: true
        }).catch(() => { });

        // Also send to Google Analytics if available
        if (typeof gtag !== 'undefined') {
            gtag('event', eventName, eventData);
        }

        // Send to Facebook Pixel if available
        if (typeof fbq !== 'undefined') {
            fbq('trackCustom', eventName, eventData);
        }
    };

    // Track conversion (lead form, etc.)
    window.sparkConversion = function (conversionType, value, options = {}) {
        const data = {
            site_id: SITE_ID,
            conversion_type: conversionType,
            value: value,
            source: options.source,
            campaign: options.campaign,
            gclid: new URLSearchParams(window.location.search).get('gclid'),
            fbclid: new URLSearchParams(window.location.search).get('fbclid'),
            send_to_google: options.sendToGoogle !== false,
            send_to_facebook: options.sendToFacebook !== false
        };

        fetch(API_BASE + '/api/track/conversion', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(data)
        }).catch(() => { });
    };

    // Auto-track form submissions
    document.addEventListener('submit', function (e) {
        const form = e.target;
        if (form.tagName === 'FORM') {
            window.sparkTrack('form_submit', {
                category: 'engagement',
                label: form.id || form.name || 'unknown_form'
            });
        }
    });

    // Auto-track outbound link clicks AND click-to-call
    document.addEventListener('click', function (e) {
        const link = e.target.closest('a');
        if (!link) return;

        // Track click-to-call (tel: links)
        if (link.href && link.href.startsWith('tel:')) {
            const phoneNumber = link.href.replace('tel:', '');
            const urlParams = new URLSearchParams(window.location.search);

            // Fire call conversion to our API
            fetch(API_BASE + '/api/track/call-click', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({
                    site_id: SITE_ID,
                    phone_number: phoneNumber,
                    page_url: window.location.href,
                    page_title: document.title,
                    utm_source: urlParams.get('utm_source'),
                    utm_medium: urlParams.get('utm_medium'),
                    utm_campaign: urlParams.get('utm_campaign'),
                    gclid: urlParams.get('gclid'),
                    fbclid: urlParams.get('fbclid'),
                    visitor_id: VISITOR_ID,
                    session_id: SESSION_ID
                }),
                keepalive: true
            }).catch(() => { });

            // Also track as event
            window.sparkTrack('call_click', {
                category: 'conversion',
                label: phoneNumber
            });

            // Fire to Google Ads if gtag exists
            if (typeof gtag !== 'undefined') {
                gtag('event', 'conversion', {
                    'send_to': 'AW-CONVERSION_ID/CONVERSION_LABEL',
                    'value': 75,
                    'currency': 'USD'
                });
            }

            // Fire to Facebook if fbq exists
            if (typeof fbq !== 'undefined') {
                fbq('track', 'Contact', { value: 75, currency: 'USD' });
            }
            return;
        }

        // Track outbound links
        if (link.hostname !== window.location.hostname) {
            window.sparkTrack('outbound_click', {
                category: 'engagement',
                label: link.href
            });
        }
    });

    // Track initial pageview
    if (document.readyState === 'complete') {
        trackPageview();
    } else {
        window.addEventListener('load', trackPageview);
    }

    // Track SPA navigation (for frameworks that use history API)
    let lastPath = window.location.pathname;
    const observer = new MutationObserver(function () {
        if (window.location.pathname !== lastPath) {
            lastPath = window.location.pathname;
            trackPageview();
        }
    });
    observer.observe(document.body, { childList: true, subtree: true });

})();