<?php

/**

 * Server-side rendering of the `core/gallery` block.

 *

 * @package WordPress

 */

/**

 * Handles backwards compatibility for Gallery Blocks,

 * whose images feature a `data-id` attribute.

 *

 * Now that the Gallery Block contains inner Image Blocks,

 * we add a custom `data-id` attribute before rendering the gallery

 * so that the Image Block can pick it up in its render_callback.

 *

 * @since 5.9.0

 *

 * @param array $parsed_block The block being rendered.

 * @return array The migrated block object.

 */

function block_core_gallery_data_id_backcompatibility( $parsed_block ) {

	if ( 'core/gallery' === $parsed_block['blockName'] ) {

		foreach ( $parsed_block['innerBlocks'] as $key => $inner_block ) {

			if ( 'core/image' === $inner_block['blockName'] ) {

				if ( ! isset( $parsed_block['innerBlocks'][ $key ]['attrs']['data-id'] ) && isset( $inner_block['attrs']['id'] ) ) {

					$parsed_block['innerBlocks'][ $key ]['attrs']['data-id'] = esc_attr( $inner_block['attrs']['id'] );

				}

			}

		}

	}

	return $parsed_block;

}

add_filter( 'render_block_data', 'block_core_gallery_data_id_backcompatibility' );

/**

 * Renders the `core/gallery` block on the server.

 *

 * @since 6.0.0

 *

 * @param array  $attributes Attributes of the block being rendered.

 * @param string $content Content of the block being rendered.

 * @return string The content of the block being rendered.

 */

function block_core_gallery_render( $attributes, $content ) {

	// Adds a style tag for the --wp--style--unstable-gallery-gap var.

	// The Gallery block needs to recalculate Image block width based on

	// the current gap setting in order to maintain the number of flex columns

	// so a css var is added to allow this.

	$gap = $attributes['style']['spacing']['blockGap'] ?? null;

	// Skip if gap value contains unsupported characters.

	// Regex for CSS value borrowed from `safecss_filter_attr`, and used here

	// because we only want to match against the value, not the CSS attribute.

	if ( is_array( $gap ) ) {

		foreach ( $gap as $key => $value ) {

			// Make sure $value is a string to avoid PHP 8.1 deprecation error in preg_match() when the value is null.

			$value = is_string( $value ) ? $value : '';

			$value = $value && preg_match( '%[\\\(&=}]|/\*%', $value ) ? null : $value;

			// Get spacing CSS variable from preset value if provided.

			if ( is_string( $value ) && str_contains( $value, 'var:preset|spacing|' ) ) {

				$index_to_splice = strrpos( $value, '|' ) + 1;

				$slug            = _wp_to_kebab_case( substr( $value, $index_to_splice ) );

				$value           = "var(--wp--preset--spacing--$slug)";

			}

			$gap[ $key ] = $value;

		}

	} else {

		// Make sure $gap is a string to avoid PHP 8.1 deprecation error in preg_match() when the value is null.

		$gap = is_string( $gap ) ? $gap : '';

		$gap = $gap && preg_match( '%[\\\(&=}]|/\*%', $gap ) ? null : $gap;

		// Get spacing CSS variable from preset value if provided.

		if ( is_string( $gap ) && str_contains( $gap, 'var:preset|spacing|' ) ) {

			$index_to_splice = strrpos( $gap, '|' ) + 1;

			$slug            = _wp_to_kebab_case( substr( $gap, $index_to_splice ) );

			$gap             = "var(--wp--preset--spacing--$slug)";

		}

	}

	$unique_gallery_classname = wp_unique_id( 'wp-block-gallery-' );

	$processed_content        = new WP_HTML_Tag_Processor( $content );

	$processed_content->next_tag();

	$processed_content->add_class( $unique_gallery_classname );

	// --gallery-block--gutter-size is deprecated. --wp--style--gallery-gap-default should be used by themes that want to set a default

	// gap on the gallery.

	$fallback_gap = 'var( --wp--style--gallery-gap-default, var( --gallery-block--gutter-size, var( --wp--style--block-gap, 0.5em ) ) )';

	$gap_value    = $gap ? $gap : $fallback_gap;

	$gap_column   = $gap_value;

	if ( is_array( $gap_value ) ) {

		$gap_row    = isset( $gap_value['top'] ) ? $gap_value['top'] : $fallback_gap;

		$gap_column = isset( $gap_value['left'] ) ? $gap_value['left'] : $fallback_gap;

		$gap_value  = $gap_row === $gap_column ? $gap_row : $gap_row . ' ' . $gap_column;

	}

	// The unstable gallery gap calculation requires a real value (such as `0px`) and not `0`.

	if ( '0' === $gap_column ) {

		$gap_column = '0px';

	}

	// Set the CSS variable to the column value, and the `gap` property to the combined gap value.

	$gallery_styles = array(

		array(

			'selector'     => ".wp-block-gallery.{$unique_gallery_classname}",

			'declarations' => array(

				'--wp--style--unstable-gallery-gap' => $gap_column,

				'gap'                               => $gap_value,

			),

		),

	);

	wp_style_engine_get_stylesheet_from_css_rules(

		$gallery_styles,

		array(

			'context' => 'block-supports',

		)

	);

	// The WP_HTML_Tag_Processor class calls get_updated_html() internally

	// when the instance is treated as a string, but here we explicitly

	// convert it to a string.

	$updated_content = $processed_content->get_updated_html();

	/*

	 * Randomize the order of image blocks. Ideally we should shuffle

	 * the `$parsed_block['innerBlocks']` via the `render_block_data` hook.

	 * However, this hook doesn't apply inner block updates when blocks are

	 * nested.

	 * @todo In the future, if this hook supports updating innerBlocks in

	 * nested blocks, it should be refactored.

	 *

	 * @see: https://github.com/WordPress/gutenberg/pull/58733

	 */

	if ( empty( $attributes['randomOrder'] ) ) {

		return $updated_content;

	}

	// This pattern matches figure elements with the `wp-block-image` class to

	// avoid the gallery's wrapping `figure` element and extract images only.

	$pattern = '/<figure[^>]*\bwp-block-image\b[^>]*>.*?<\/figure>/';

	// Find all Image blocks.

	preg_match_all( $pattern, $updated_content, $matches );

	if ( ! $matches ) {

		return $updated_content;

	}

	$image_blocks = $matches[0];

	// Randomize the order of Image blocks.

	shuffle( $image_blocks );

	$i       = 0;

	$content = preg_replace_callback(

		$pattern,

		static function () use ( $image_blocks, &$i ) {

			$new_image_block = $image_blocks[ $i ];

			++$i;

			return $new_image_block;

		},

		$updated_content

	);

	return $content;

}

/**

 * Registers the `core/gallery` block on server.

 *

 * @since 5.9.0

 */

function register_block_core_gallery() {

	register_block_type_from_metadata(

		__DIR__ . '/gallery',

		array(

			'render_callback' => 'block_core_gallery_render',

		)

	);

}

add_action( 'init', 'register_block_core_gallery' );