/**
 * AI Creative Studio - Scroll Animations
 * Using Intersection Observer API (High Performance)
 */

(function() {
    'use strict';

    /**
     * Array of animation target classes
     */
    const animationClasses = [
        'is-style-aics-fade-in',
        'is-style-aics-fade-up',
        'is-style-aics-fade-down',
        'is-style-aics-slide-left',
        'is-style-aics-slide-right',
        'is-style-aics-zoom-in',
        'is-style-aics-rotate-in',
        'is-style-aics-bounce-in'
    ];

    /**
     * Detect and initialize animation target elements
     */
    function aicsInitAnimationElements() {
        const elements = [];
        
        animationClasses.forEach(function(className) {
            const found = document.querySelectorAll('.' + className);
            found.forEach(function(element, index) {
                if (!element.classList.contains('aics-animation-ready')) {
                    // Add hidden class as initial state
                    element.classList.add('aics-animation-pending');
                    element.classList.add('aics-animation-ready');
                    
                    // Set delay time for same page (100ms increments)
                    element.dataset.animationDelay = index * 100;
                    
                    elements.push(element);
                }
            });
        });
        
        return elements;
    }

    /**
     * Intersection Observer callback
     */
    function aicsHandleIntersection(entries, observer) {
        entries.forEach(function(entry) {
            if (entry.isIntersecting) {
                const element = entry.target;
                const delay = parseInt(element.dataset.animationDelay) || 0;
                
                // Start animation with delay
                setTimeout(function() {
                    element.classList.remove('aics-animation-pending');
                    element.classList.add('aics-animation-active');
                }, delay);
                
                // Stop observing after execution (performance optimization)
                observer.unobserve(element);
            }
        });
    }

    /**
     * Initialize scroll animations
     */
    function aicsInitScrollAnimations() {
        // Disable if user prefers reduced motion
        if (window.matchMedia && window.matchMedia('(prefers-reduced-motion: reduce)').matches) {
            // Show all elements immediately
            const elements = aicsInitAnimationElements();
            elements.forEach(function(element) {
                element.classList.remove('aics-animation-pending');
                element.classList.add('aics-animation-active');
            });
            return;
        }

        // Check Intersection Observer API support
        if (!('IntersectionObserver' in window)) {
            console.warn('Intersection Observer not supported. Showing all animations immediately.');
            const elements = aicsInitAnimationElements();
            elements.forEach(function(element) {
                element.classList.remove('aics-animation-pending');
                element.classList.add('aics-animation-active');
            });
            return;
        }

        // Observer configuration
        const observerOptions = {
            root: null, // viewport
            rootMargin: '0px 0px -50px 0px', // Trigger 50px before bottom
            threshold: 0.1 // Trigger when 10% visible
        };

        // Create Observer
        const observer = new IntersectionObserver(aicsHandleIntersection, observerOptions);

        // Get animation elements and start observing
        const elements = aicsInitAnimationElements();
        elements.forEach(function(element) {
            observer.observe(element);
        });

        console.log('AICS Scroll Animations initialized:', elements.length, 'elements');
    }

    /**
     * Initialize after DOM loaded
     */
    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', aicsInitScrollAnimations);
    } else {
        aicsInitScrollAnimations();
    }

})();