script.js

// Mobile Navigation Toggle
const navToggle = document.getElementById('navToggle');
const navMenu = document.getElementById('navMenu');
const navLinks = document.querySelectorAll('.nav-link');

navToggle.addEventListener('click', () => {
    navToggle.classList.toggle('active');
    navMenu.classList.toggle('active');
});

// Close mobile menu when clicking a link
navLinks.forEach(link => {
    link.addEventListener('click', () => {
        navToggle.classList.remove('active');
        navMenu.classList.remove('active');
    });
});

// Smooth scrolling for anchor links
document.querySelectorAll('a[href^="#"]').forEach(anchor => {
    anchor.addEventListener('click', function (e) {
        e.preventDefault();
        const target = document.querySelector(this.getAttribute('href'));
        if (target) {
            const offset = 80;
            const targetPosition = target.offsetTop - offset;
            window.scrollTo({
                top: targetPosition,
                behavior: 'smooth'
            });
        }
    });
});

// Active navigation link based on scroll position
const sections = document.querySelectorAll('section[id]');

function highlightNavigation() {
    const scrollPosition = window.scrollY + 100;

    sections.forEach(section => {
        const sectionTop = section.offsetTop;
        const sectionHeight = section.offsetHeight;
        const sectionId = section.getAttribute('id');
        
        if (scrollPosition >= sectionTop && scrollPosition < sectionTop + sectionHeight) {
            navLinks.forEach(link => {
                link.classList.remove('active');
                if (link.getAttribute('href') === `#${sectionId}`) {
                    link.classList.add('active');
                }
            });
        }
    });
}

window.addEventListener('scroll', highlightNavigation);
window.addEventListener('load', highlightNavigation);

// Intersection Observer for fade in animations
const observerOptions = {
    threshold: 0.1,
    rootMargin: '0px 0px -100px 0px'
};

const observer = new IntersectionObserver((entries) => {
    entries.forEach(entry => {
        if (entry.isIntersecting) {
            entry.target.style.opacity = '1';
            entry.target.style.transform = 'translateY(0)';
        }
    });
}, observerOptions);

// Observe elements for animations (grouped per section to keep stagger short)
document.querySelectorAll('.module-card, .flow-step, .problem-card, .publication-card, .code-card').forEach(element => {
    element.style.opacity = '0';
    element.style.transform = 'translateY(20px)';
    element.style.transition = 'opacity 0.5s ease, transform 0.5s ease';
    observer.observe(element);
});

// Animated section titles — split into letters on load, reveal on scroll
document.querySelectorAll('.section-title').forEach(title => {
    const text = title.textContent;
    title.innerHTML = '';
    let charIndex = 0;
    text.split(' ').forEach((word, wordIndex, arr) => {
        const wordSpan = document.createElement('span');
        wordSpan.style.display = 'inline-block';
        wordSpan.style.whiteSpace = 'nowrap';
        [...word].forEach(char => {
            const span = document.createElement('span');
            span.textContent = char;
            span.className = 'title-char';
            span.style.setProperty('--ci', charIndex++);
            wordSpan.appendChild(span);
        });
        title.appendChild(wordSpan);
        if (wordIndex < arr.length - 1) title.appendChild(document.createTextNode(' '));
    });
});

const titleObserver = new IntersectionObserver((entries) => {
    entries.forEach(entry => {
        if (entry.isIntersecting) {
            entry.target.classList.add('revealed');
            titleObserver.unobserve(entry.target);
        }
    });
}, { threshold: 0.3 });

document.querySelectorAll('.section-title').forEach(title => titleObserver.observe(title));

// Add scroll effect to navbar
let lastScroll = 0;
const navbar = document.querySelector('.navbar');

window.addEventListener('scroll', () => {
    const currentScroll = window.pageYOffset;
    
    if (currentScroll > 100) {
        navbar.style.boxShadow = '0 2px 20px rgba(0, 0, 0, 0.1)';
    } else {
        navbar.style.boxShadow = 'none';
    }
    
    lastScroll = currentScroll;
});

// Toggle hamburger menu animation
navToggle.addEventListener('click', () => {
    const spans = navToggle.querySelectorAll('span');
    if (navToggle.classList.contains('active')) {
        spans[0].style.transform = 'rotate(45deg) translate(5px, 5px)';
        spans[1].style.opacity = '0';
        spans[2].style.transform = 'rotate(-45deg) translate(7px, -6px)';
    } else {
        spans[0].style.transform = 'none';
        spans[1].style.opacity = '1';
        spans[2].style.transform = 'none';
    }
});