<?php

/**
 * Preload an important featured image for individual post page
 * For improving page loads
 * Ref: https://html.spec.whatwg.org/multipage/semantics.html#attr-link-imagesrcset
 */

// Disable lazy load for blocks
add_filter( 'render_block_core/post-featured-image', 'gtm_preload_render_block', 10, 3 );
add_filter( 'render_block_gtm/post-featured-image', 'gtm_preload_render_block', 10, 3 );
function gtm_preload_render_block( $block_content, $block, $wp_block ) {
	if ( ! empty( $wp_block->context['postId'] ) && ! empty( $block['attrs']['imageSize'] ) ) {
		$post_ID = $wp_block->context['postId'];

		if ( is_singular() && $post_ID === get_queried_object_id() && gtm_should_preload_the_image( $block['attrs']['imageSize'] ) ) {
			gtm_preload_important_featured_image( $block['attrs']['imageSize'] );
			$block_content = gtm_preload_remove_lazy_load( $block_content );
		}
	}

	return $block_content;
}

function gtm_should_preload_the_image( $image_size ) {
	static $img_count = 0;
	$img_count++;

	// Preload only the first featured image of the current post
	if ( $img_count == 1 ) {
		$ignore_sizes = ['thumbnail'];

		if ( is_singular() && has_post_thumbnail() && ! empty( $image_size ) && ! in_array( $image_size, $ignore_sizes ) ) {
			return true;
		}
	}
}

function gtm_preload_important_featured_image( $image_size ) {
	add_action( 'wp_head', function () use ( $image_size ) {
		$preload  = '<link rel="preload" as="image"';
		$img_html = get_the_post_thumbnail( get_queried_object_id(), $image_size );

		if ( preg_match( '|src="([^"]+)"|', $img_html, $src_matches ) ) {
			$preload .= sprintf( ' href="%s"', esc_url( $src_matches[1] ) );
		}

		if ( preg_match( '|srcset="([^"]+)"|', $img_html, $srcset_matches ) ) {
			$preload .= sprintf( ' imagesrcset="%s"', esc_attr( $srcset_matches[1] ) );
		}

		if ( preg_match( '|sizes="([^"]+)"|', $img_html, $sizes_matches ) ) {
			$preload .= sprintf( ' imagesizes="%s"', esc_attr( $sizes_matches[1] ) );
		}

		// To make sure there is rendered image
		if ( ! empty( $img_html ) ) {
			echo trim( $preload ?? '' ) . '>';
		}
	} );
}

// Remove lazy load since is was preloaded
function gtm_preload_remove_lazy_load( $content ) {
	$content = str_replace( 'loading="lazy"', '', $content );
	return $content;
}

/**
 * Additional allowance for using MIN() and MAX() in theme.json
 */
add_filter( 'safecss_filter_attr_allow_css', 'gtm_safecss_filter_attr_allow_css_functions', 10, 2 );
function gtm_safecss_filter_attr_allow_css_functions( $allow_css, $css_test_string ) {
	// The below code is checking the same way as wp-includes\kses.php@2471

	// Allow CSS min().
	$css_test_string = preg_replace( '/min\(((?:\([^()]*\)?|[^()])*)\)/', '', $css_test_string );
	// Allow CSS max().
	$css_test_string = preg_replace( '/max\(((?:\([^()]*\)?|[^()])*)\)/', '', $css_test_string );

	// Check for any CSS containing \ ( & } = or comments,
	// except for url(), calc(), or var() usage checked above.
	$allow_css = ! preg_match( '%[\\\(&=}]|/\*%', $css_test_string );

	return $allow_css;
}

/**
 * Disable all innerblocks inside comments query loop if comments is not open
 */
add_filter( 'render_block', 'gtm_disable_inner_blocks_in_comments_query_loop', 10, 2 );
function gtm_disable_inner_blocks_in_comments_query_loop( $block_content, $block ) {
	if ( $block['blockName'] === 'core/comments-query-loop' ) {
		if ( ! comments_open() ) {
			return '';
		}
	}

	return $block_content;
}