<?php
namespace Elementor\Modules\LazyLoad;

use Elementor\Core\Base\Module as BaseModule;
use Elementor\Plugin;

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}

class Module extends BaseModule {

	public function get_name() {
		return 'lazyload';
	}

	public function __construct() {
		parent::__construct();

		add_action( 'init', [ $this, 'init' ] );
	}

	public function init() {
		if ( ! $this->is_lazy_load_background_images_enabled() ) {
			return;
		}

		if ( ! $this->should_lazy_load_background_images() ) {
			return;
		}

		add_action( 'wp_head', function() {
			?>
			<style>
				.e-con.e-parent:nth-of-type(n+4):not(.e-lazyloaded):not(.e-no-lazyload),
				.e-con.e-parent:nth-of-type(n+4):not(.e-lazyloaded):not(.e-no-lazyload) * {
					background-image: none !important;
				}
				@media screen and (max-height: 1024px) {
					.e-con.e-parent:nth-of-type(n+3):not(.e-lazyloaded):not(.e-no-lazyload),
					.e-con.e-parent:nth-of-type(n+3):not(.e-lazyloaded):not(.e-no-lazyload) * {
						background-image: none !important;
					}
				}
				@media screen and (max-height: 640px) {
					.e-con.e-parent:nth-of-type(n+2):not(.e-lazyloaded):not(.e-no-lazyload),
					.e-con.e-parent:nth-of-type(n+2):not(.e-lazyloaded):not(.e-no-lazyload) * {
						background-image: none !important;
					}
				}
			</style>
			<?php
		} );

		add_action( 'wp_footer', function() {
			?>
			<script>
				const lazyloadRunObserver = () => {
					const lazyloadBackgrounds = document.querySelectorAll( `.e-con.e-parent:not(.e-lazyloaded)` );
					const lazyloadBackgroundObserver = new IntersectionObserver( ( entries ) => {
						entries.forEach( ( entry ) => {
							if ( entry.isIntersecting ) {
								let lazyloadBackground = entry.target;
								if( lazyloadBackground ) {
									lazyloadBackground.classList.add( 'e-lazyloaded' );
								}
								lazyloadBackgroundObserver.unobserve( entry.target );
							}
						});
					}, { rootMargin: '200px 0px 200px 0px' } );
					lazyloadBackgrounds.forEach( ( lazyloadBackground ) => {
						lazyloadBackgroundObserver.observe( lazyloadBackground );
					} );
				};
				const events = [
					'DOMContentLoaded',
					'elementor/lazyload/observe',
				];
				events.forEach( ( event ) => {
					document.addEventListener( event, lazyloadRunObserver );
				} );
			</script>
			<?php
		} );
	}

	private function should_lazy_load_background_images(): bool {
		return ! is_admin() && ! Plugin::$instance->preview->is_preview_mode() && ! Plugin::$instance->editor->is_edit_mode();
	}

	private static function is_lazy_load_background_images_enabled(): bool {
		return '1' === get_option( 'elementor_lazy_load_background_images', '1' );
	}
}
