<?php
/**
 * Page speed changes, round 2, made only to the page's HTML on its way out (theme and plugin files are never edited):
 * - delay:  trackers and chat widgets (Google Analytics/Tag Manager, Meta Pixel, Hotjar, Clarity, chat bubbles…) load on
 *           the visitor's first scroll, tap or key press, or after 5 seconds, instead of holding up the page;
 * - unload: files of form, slider and Elementor add-on plugins are left out of pages that don't use those plugins;
 * - blocks: the block editor's CSS is left out of pages with no block-editor content;
 * - extras: WordPress's emoji and embed scripts are not loaded (browsers show emoji themselves).
 * Gralus tests each change in a real browser through a preview link before it is offered, and again after it goes live.
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

class Gralus_Speed_Scripts {
	/** Third-party scripts safe to load after the first interaction: analytics, ad pixels, heatmaps, chat widgets. */
	const DELAY_HOSTS = array(
		'googletagmanager.com',
		'google-analytics.com',
		'analytics.google.com',
		'googleadservices.com',
		'googleads.g.doubleclick.net',
		'connect.facebook.net',
		'static.hotjar.com',
		'script.hotjar.com',
		'clarity.ms',
		'embed.tawk.to',
		'client.crisp.chat',
		'widget.intercom.io',
		'js.intercomcdn.com',
		'cdn.livechatinc.com',
		'code.tidio.co',
		'js.hs-scripts.com',
		'js.hs-analytics.net',
		'js.hsadspixel.net',
		'snap.licdn.com',
		'analytics.tiktok.com',
		'static.ads-twitter.com',
		'bat.bing.com',
		'cdn.mouseflow.com',
		'static.zdassets.com',
	);

	/** Inline scripts that only start one of those services (their snippets). */
	const DELAY_INLINE = array( 'googletagmanager.com', 'google-analytics.com', 'gtag(', 'fbq(', '_hsq', 'clarity(', 'hotjar', '_linkedin_partner_id', 'ttq.load', 'twq(', 'uetq', 'Tawk_API', '$crisp', 'intercomSettings', 'tidioChatApi', 'mouseflow', 'zEmbed' );

	/** Plugins whose files can be left out of a page that has none of their markup: plugin folder => words in their markup. */
	const UNLOAD = array(
		'contact-form-7'                      => array( 'wpcf7' ),
		'wpforms-lite'                        => array( 'wpforms' ),
		'wpforms'                             => array( 'wpforms' ),
		'formidable'                          => array( 'frm_forms', 'frm-show-form', 'frm_form' ),
		'ninja-forms'                         => array( 'nf-form-cont', 'ninja-forms' ),
		'revslider'                           => array( 'rs-module', 'rev_slider', 'revslider', 'rs-slide' ),
		'smart-slider-3'                      => array( 'n2-section-smartslider', 'smartslider', 'n2-ss' ),
		'ml-slider'                           => array( 'metaslider', 'ml-slider' ),
		'jeg-elementor-kit'                   => array( 'jkit', 'jeg-elementor-kit', 'jeg_' ),
		'elementskit-lite'                    => array( 'ekit', 'elementskit' ),
		'royal-elementor-addons'              => array( 'wpr-', 'royal-elementor' ),
		'ultimate-elementor'                  => array( 'uael' ),
		'qi-addons-for-elementor'             => array( 'qodef', 'qi-addons' ),
		'rometheme-for-elementor'             => array( 'rkit', 'rtm-', 'rometheme' ),
		'gum-elementor-addon'                 => array( 'gum' ),
		'essential-addons-for-elementor-lite' => array( 'eael' ),
		'premium-addons-for-elementor'        => array( 'premium-' ),
		'happy-elementor-addons'              => array( 'ha-', 'happy' ),
	);

	/** Settings of other plugins that already do one of these parts: [plugin file, option, key path or '', part]. */
	public static function handled() {
		$out    = array();
		$active = (array) get_option( 'active_plugins', array() );
		$on     = function ( $file ) use ( $active ) {
			return in_array( $file, $active, true );
		};
		if ( $on( 'wp-rocket/wp-rocket.php' ) ) {
			$r = get_option( 'wp_rocket_settings', array() );
			if ( ! empty( $r['delay_js'] ) ) {
				$out['delay'] = 'WP Rocket';
			}
		}
		if ( $on( 'perfmatters/perfmatters.php' ) ) {
			$p = get_option( 'perfmatters_options', array() );
			if ( ! empty( $p['assets']['delay_js'] ) ) {
				$out['delay'] = 'Perfmatters';
			}
			if ( ! empty( $p['disable_emojis'] ) ) {
				$out['extras'] = 'Perfmatters';
			}
			$out['unload'] = 'Perfmatters';
		}
		if ( $on( 'flying-scripts/flying-scripts.php' ) ) {
			$out['delay'] = 'Flying Scripts';
		}
		if ( $on( 'flying-press/flying-press.php' ) ) {
			$out['delay'] = 'FlyingPress';
		}
		if ( $on( 'litespeed-cache/litespeed-cache.php' ) ) {
			if ( 2 === (int) get_option( 'litespeed.conf.optm-js_defer' ) ) {
				$out['delay'] = 'LiteSpeed Cache';
			}
			if ( get_option( 'litespeed.conf.optm-emoji_rm' ) ) {
				$out['extras'] = 'LiteSpeed Cache';
			}
		}
		if ( $on( 'wp-asset-clean-up/wpacu.php' ) || $on( 'wp-asset-clean-up-pro/wpacu.php' ) ) {
			$out['unload'] = 'Asset CleanUp';
		}
		return $out;
	}

	/** WordPress extras: emoji detection script and styles, and the oEmbed script. Hooked on init when the part is on. */
	public static function remove_extras() {
		remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
		remove_action( 'wp_print_styles', 'print_emoji_styles' );
		remove_action( 'wp_enqueue_scripts', 'wp_enqueue_emoji_styles' );
		remove_filter( 'the_content_feed', 'wp_staticize_emoji' );
		add_filter( 'emoji_svg_url', '__return_false' );
		add_action(
			'wp_footer',
			function () {
				wp_dequeue_script( 'wp-embed' );
			},
			1
		);
	}

	/** The page's markup without scripts, styles and links: what is actually on the page. */
	private static function markup( $html ) {
		$pos  = stripos( $html, '</head>' );
		$body = false === $pos ? $html : substr( $html, $pos );
		$body = preg_replace( '#<script\b[^>]*>.*?</script>#is', '', $body );
		$body = preg_replace( '#<style\b[^>]*>.*?</style>#is', '', (string) $body );
		$body = preg_replace( '#<link\b[^>]*>#i', '', (string) $body );
		return strtolower( (string) $body );
	}

	private static function host_of( $src ) {
		$src = html_entity_decode( $src, ENT_QUOTES );
		if ( 0 === strpos( $src, '//' ) ) {
			$src = 'https:' . $src;
		}
		$host = wp_parse_url( $src, PHP_URL_HOST );
		return is_string( $host ) ? strtolower( $host ) : '';
	}

	private static function host_listed( $host ) {
		foreach ( self::DELAY_HOSTS as $h ) {
			if ( $host === $h || substr( $host, -strlen( '.' . $h ) ) === '.' . $h ) {
				return true;
			}
		}
		return false;
	}

	/** Trackers and chat widgets switched to load after the first interaction, in their original order. */
	public static function delay( $html ) {
		$count = 0;
		$out   = preg_replace_callback(
			'#<script\b([^>]*)>(.*?)</script>#is',
			function ( $m ) use ( &$count ) {
				$attrs = $m[1];
				$code  = $m[2];
				if ( preg_match( '#\btype\s*=\s*["\']?([^"\'\s>]+)#i', $attrs, $t ) ) {
					$type = strtolower( $t[1] );
					if ( ! in_array( $type, array( 'text/javascript', 'application/javascript', 'module' ), true ) ) {
						return $m[0];
					}
				}
				if ( preg_match( '#data-(no-delay|gralus-keep)#i', $attrs ) ) {
					return $m[0];
				}
				$src = preg_match( '#\bsrc\s*=\s*["\']([^"\']+)["\']#i', $attrs, $s ) ? $s[1] : '';
				if ( '' !== $src ) {
					if ( ! self::host_listed( self::host_of( $src ) ) ) {
						return $m[0];
					}
				} else {
					$hit = false;
					foreach ( self::DELAY_INLINE as $word ) {
						if ( false !== stripos( $code, $word ) ) {
							$hit = true;
							break;
						}
					}
					if ( ! $hit || strlen( $code ) > 6000 ) {
						return $m[0];
					}
				}
				++$count;
				$kept = '';
				if ( isset( $type ) && 'module' === $type ) {
					$kept = ' data-gralus-type="module"';
				}
				$attrs = preg_replace( '#\btype\s*=\s*["\']?[^"\'\s>]+["\']?#i', '', $attrs );
				$attrs = preg_replace( '#\bsrc\s*=#i', 'data-gralus-src=', (string) $attrs );
				return '<script type="gralus/delay"' . $kept . rtrim( (string) $attrs ) . '>' . $code . '</script>';
			},
			$html
		);
		if ( ! is_string( $out ) || ! $count ) {
			return $html;
		}
		// Code that is not delayed may still push to dataLayer before Tag Manager arrives: keep the array there from the start.
		$out = preg_replace( '#<head\b[^>]*>#i', '$0<script data-gralus-keep>window.dataLayer=window.dataLayer||[];</script>', $out, 1 );
		$loader = '<script data-gralus-keep>(function(){var d=!1,e=["mousemove","touchstart","keydown","scroll","pointerdown","wheel"];function r(){if(d)return;d=!0;e.forEach(function(n){removeEventListener(n,r,{passive:!0})});var l=[].slice.call(document.querySelectorAll(\'script[type="gralus/delay"]\'));(function x(i){if(i>=l.length)return;var o=l[i],s=document.createElement("script");for(var a=0;a<o.attributes.length;a++){var t=o.attributes[a].name;if(t!=="type"&&t!=="data-gralus-src"&&t!=="data-gralus-type")s.setAttribute(t,o.attributes[a].value)}if(o.getAttribute("data-gralus-type"))s.type="module";var u=o.getAttribute("data-gralus-src");if(u){s.src=u;s.async=!1;s.onload=s.onerror=function(){x(i+1)};o.parentNode.replaceChild(s,o)}else{s.text=o.text;o.parentNode.replaceChild(s,o);x(i+1)}})(0)}e.forEach(function(n){addEventListener(n,r,{passive:!0})});setTimeout(r,5000)})();</script>';
		$pos    = strripos( $out, '</body>' );
		return false === $pos ? $out . $loader : substr( $out, 0, $pos ) . $loader . substr( $out, $pos );
	}

	/** Files of plugins with nothing on this page (see UNLOAD), with their inline before/after scripts. */
	public static function unload( $html ) {
		$markup  = self::markup( $html );
		$out     = $html;
		$handles = array();
		foreach ( self::UNLOAD as $slug => $words ) {
			if ( false === stripos( $html, '/wp-content/plugins/' . $slug . '/' ) ) {
				continue;
			}
			$used = false;
			foreach ( $words as $w ) {
				if ( false !== strpos( $markup, $w ) ) {
					$used = true;
					break;
				}
			}
			if ( $used ) {
				continue;
			}
			$path = preg_quote( '/wp-content/plugins/' . $slug . '/', '#' );
			$out  = preg_replace_callback(
				'#<script\b[^>]*\bsrc\s*=\s*["\'][^"\']*' . $path . '[^"\']*["\'][^>]*>\s*</script>\s*#i',
				function ( $m ) use ( &$handles ) {
					if ( preg_match( '#\bid\s*=\s*["\']([^"\']+)-js["\']#i', $m[0], $id ) ) {
						$handles[] = $id[1];
					}
					return '';
				},
				(string) $out
			);
			$out = preg_replace( '#<link\b[^>]*\bhref\s*=\s*["\'][^"\']*' . $path . '[^"\']*["\'][^>]*>\s*#i', '', (string) $out );
		}
		foreach ( array_unique( $handles ) as $h ) {
			$out = preg_replace( '#<script\b[^>]*\bid\s*=\s*["\']' . preg_quote( $h, '#' ) . '-js-(before|after)["\'][^>]*>.*?</script>\s*#is', '', (string) $out );
		}
		return is_string( $out ) && '' !== $out ? $out : $html;
	}

	/** The block editor's CSS when the page has no block-editor content (pages built with Elementor or the classic editor). */
	public static function blocks( $html ) {
		if ( false !== strpos( self::markup( $html ), 'wp-block-' ) ) {
			return $html;
		}
		$out = preg_replace( '#<link\b[^>]*\bid\s*=\s*["\'](wp-block-library|wp-block-library-theme|classic-theme-styles)-css["\'][^>]*>\s*#i', '', $html );
		$out = preg_replace( '#<style\b[^>]*\bid\s*=\s*["\'](wp-block-library|wp-block-library-theme|classic-theme-styles)-inline-css["\'][^>]*>.*?</style>\s*#is', '', (string) $out );
		return is_string( $out ) && '' !== $out ? $out : $html;
	}
}