script.js

'use strict';

const modal = document.querySelector('.modal');
const overlay = document.querySelector('.overlay');
const btnCloseModal = document.querySelector('.btn--close-modal');
const btnsOpenModal = document.querySelectorAll('.btn--show-modal');
const btnScrollTo = document.querySelector('.btn--scroll-to');
const section1 = document.querySelector('#section--1');
const nav = document.querySelector('.nav');
const tabs = document.querySelectorAll('.operations__tab');
const tabsContainer = document.querySelector('.operations__tab-container');
const tabsContent = document.querySelectorAll('.operations__content');

// Modal window
const openModal = function (e) {
  e.preventDefault();
  modal.classList.remove('hidden');
  overlay.classList.remove('hidden');
};

const closeModal = function () {
  modal.classList.add('hidden');
  overlay.classList.add('hidden');
};

btnsOpenModal.forEach(btn => btn.addEventListener('click', openModal));

btnCloseModal.addEventListener('click', closeModal);
overlay.addEventListener('click', closeModal);

document.addEventListener('keydown', function (e) {
  if (e.key === 'Escape' && !modal.classList.contains('hidden')) {
    closeModal();
  }
});

// Button scrolling
btnScrollTo.addEventListener('click', function (e) {
  const s1coords = section1.getBoundingClientRect();

  section1.scrollIntoView({
    behavior: 'smooth',
  });
});

// Page navigation
document.querySelector('.nav__links').addEventListener('click', function (e) {
  e.preventDefault();

  if (e.target.classList.contains('nav__link')) {
    e.preventDefault();
    const id = e.target.getAttribute('href');
    document.querySelector(id).scrollIntoView({ behavior: 'smooth' });
  }
});

// Tabbed component
tabsContainer.addEventListener('click', function (e) {
  const clicked = e.target.closest('.operations__tab');

  if (!clicked) return; // Guard clause

  // Remove active classes
  tabs.forEach(t => t.classList.remove('operations__tab--active'));
  tabsContent.forEach(c => c.classList.remove('operations__content--active'));

  // Activate tab
  clicked.classList.add('operations__tab--active');

  // Activate content area
  document
    .querySelector(`.operations__content--${clicked.dataset.tab}`)
    .classList.add('operations__content--active');
});

// Menu fade animation
const handlerHover = function (e) {
  if (e.target.classList.contains('nav__link')) {
    const link = e.target;
    const siblings = link.closest('.nav').querySelectorAll('.nav__link');
    const logo = link.closest('.nav').querySelector('img');

    siblings.forEach(el => {
      if (el !== link) el.style.opacity = this;
    });
    logo.style.opacity = this;
  }
};

nav.addEventListener('mouseover', handlerHover.bind(0.5));
nav.addEventListener('mouseout', handlerHover.bind(1));

const header = document.querySelector('.header');
const navHeight = nav.getBoundingClientRect().height;

const stickyNav = function (entries) {
  const [entry] = entries;

  if (!entry.isIntersecting) {
    nav.classList.add('sticky');
  } else {
    nav.classList.remove('sticky');
  }
};

const headerObserver = new IntersectionObserver(stickyNav, {
  root: null,
  threshold: 0,
  rootMargin: `-${navHeight}px`, // хедер появится не на самом пересечении, а на navHeight пикселей раньше
});
headerObserver.observe(header);

// Reveal sections
const allSections = document.querySelectorAll('.section');

const revealSection = function (entries, observer) {
  const [entry] = entries;

  if (!entry.isIntersecting) {
    return;
  }
  entry.target.classList.remove('section--hidden');
  observer.unobserve(entry.target);
};

const sectionObserver = new IntersectionObserver(revealSection, {
  root: null,
  threshold: 0.15,
});

allSections.forEach(function (section) {
  sectionObserver.observe(section);
});

// lazy loading images
const imgTargets = document.querySelectorAll('img[data-src]');

const loadImg = function (entries, observer) {
  const [entry] = entries;

  if (!entry.isIntersecting) return;

  // Replace src with data-src
  entry.target.src = entry.target.dataset.src;

  entry.target.addEventListener('load', function () {
    entry.target.classList.remove('lazy-img');
  });

  observer.unobserve(entry.target);
};

const imgObserver = new IntersectionObserver(loadImg, {
  root: null,
  threshold: 0,
  rootMargin: '-200px',
});

imgTargets.forEach(img => imgObserver.observe(img));

// Slider
const slider = function () {
  const slides = document.querySelectorAll('.slide');
  const btnLeft = document.querySelector('.slider__btn--left');
  const btnRight = document.querySelector('.slider__btn--right');
  const dotContainer = document.querySelector('.dots');

  let curSlide = 0;
  const maxSlide = slides.length;

  // Functions
  const createDots = function () {
    slides.forEach(function (_, i) {
      dotContainer.insertAdjacentHTML(
        'beforeend',
        `<button class="dots__dot dots__dot--active" data-slide="${i}"></button>`
      );
    });
  };

  const activateDot = function (slide) {
    document
      .querySelectorAll('.dots__dot')
      .forEach(dot => dot.classList.remove('dots__dot--active'));

    document
      .querySelector(`.dots__dot[data-slide="${slide}"]`)
      .classList.add('dots__dot--active');
  };

  const goToSlide = function (slide) {
    slides.forEach(
      (s, i) => (s.style.transform = `translateX(${100 * (i - slide)}%)`)
    );
  };

  const nextSlide = function () {
    if (curSlide === maxSlide - 1) {
      curSlide = 0;
    } else {
      curSlide++;
    }

    goToSlide(curSlide);
    activateDot(curSlide);
  };

  const prevSlide = function () {
    if (curSlide === 0) {
      curSlide = maxSlide - 1;
    } else {
      curSlide--;
    }

    goToSlide(curSlide);
    activateDot(curSlide);
  };

  const init = function () {
    goToSlide(0);
    createDots();
    activateDot(0);
  };
  init();

  // Event handlers
  btnRight.addEventListener('click', nextSlide);
  btnLeft.addEventListener('click', prevSlide);

  document.addEventListener('keydown', function (e) {
    if (e.key === 'ArrowLeft') prevSlide();
    if (e.key === 'ArrowRight') nextSlide();
  });

  dotContainer.addEventListener('click', function (e) {
    if (e.target.classList.contains('dots__dot')) {
      const [slide] = e.target.dataset.slide;
      goToSlide(slide);
      activateDot(slide);
    }
  });
};
slider();