WordPress/wp-includes/blocks.php

<?php
/**
 * Functions related to registering and parsing blocks.
 *
 * @package WordPress
 * @subpackage Blocks
 * @since 5.0.0
 */

/**
 * Removes the block asset's path prefix if provided.
 *
 * @since 5.5.0
 *
 * @param string $asset_handle_or_path Asset handle or prefixed path.
 * @return string Path without the prefix or the original value.
 */
function remove_block_asset_path_prefix( $asset_handle_or_path ) {
	$path_prefix = 'file:';
	if ( ! str_starts_with( $asset_handle_or_path, $path_prefix ) ) {
		return $asset_handle_or_path;
	}
	$path = substr(
		$asset_handle_or_path,
		strlen( $path_prefix )
	);
	if ( str_starts_with( $path, './' ) ) {
		$path = substr( $path, 2 );
	}
	return $path;
}

/**
 * Generates the name for an asset based on the name of the block
 * and the field name provided.
 *
 * @since 5.5.0
 * @since 6.1.0 Added `$index` parameter.
 * @since 6.5.0 Added support for `viewScriptModule` field.
 *
 * @param string $block_name Name of the block.
 * @param string $field_name Name of the metadata field.
 * @param int    $index      Optional. Index of the asset when multiple items passed.
 *                           Default 0.
 * @return string Generated asset name for the block's field.
 */
function generate_block_asset_handle( $block_name, $field_name, $index = 0 ) {
	if ( str_starts_with( $block_name, 'core/' ) ) {
		$asset_handle = str_replace( 'core/', 'wp-block-', $block_name );
		if ( str_starts_with( $field_name, 'editor' ) ) {
			$asset_handle .= '-editor';
		}
		if ( str_starts_with( $field_name, 'view' ) ) {
			$asset_handle .= '-view';
		}
		if ( str_ends_with( strtolower( $field_name ), 'scriptmodule' ) ) {
			$asset_handle .= '-script-module';
		}
		if ( $index > 0 ) {
			$asset_handle .= '-' . ( $index + 1 );
		}
		return $asset_handle;
	}

	$field_mappings = array(
		'editorScript'     => 'editor-script',
		'editorStyle'      => 'editor-style',
		'script'           => 'script',
		'style'            => 'style',
		'viewScript'       => 'view-script',
		'viewScriptModule' => 'view-script-module',
		'viewStyle'        => 'view-style',
	);
	$asset_handle   = str_replace( '/', '-', $block_name ) .
		'-' . $field_mappings[ $field_name ];
	if ( $index > 0 ) {
		$asset_handle .= '-' . ( $index + 1 );
	}
	return $asset_handle;
}

/**
 * Gets the URL to a block asset.
 *
 * @since 6.4.0
 *
 * @param string $path A normalized path to a block asset.
 * @return string|false The URL to the block asset or false on failure.
 */
function get_block_asset_url( $path ) {
	if ( empty( $path ) ) {
		return false;
	}

	// Path needs to be normalized to work in Windows env.
	static $wpinc_path_norm = '';
	if ( ! $wpinc_path_norm ) {
		$wpinc_path_norm = wp_normalize_path( realpath( ABSPATH . WPINC ) );
	}

	if ( str_starts_with( $path, $wpinc_path_norm ) ) {
		return includes_url( str_replace( $wpinc_path_norm, '', $path ) );
	}

	static $template_paths_norm = array();

	$template = get_template();
	if ( ! isset( $template_paths_norm[ $template ] ) ) {
		$template_paths_norm[ $template ] = wp_normalize_path( realpath( get_template_directory() ) );
	}

	if ( str_starts_with( $path, trailingslashit( $template_paths_norm[ $template ] ) ) ) {
		return get_theme_file_uri( str_replace( $template_paths_norm[ $template ], '', $path ) );
	}

	if ( is_child_theme() ) {
		$stylesheet = get_stylesheet();
		if ( ! isset( $template_paths_norm[ $stylesheet ] ) ) {
			$template_paths_norm[ $stylesheet ] = wp_normalize_path( realpath( get_stylesheet_directory() ) );
		}

		if ( str_starts_with( $path, trailingslashit( $template_paths_norm[ $stylesheet ] ) ) ) {
			return get_theme_file_uri( str_replace( $template_paths_norm[ $stylesheet ], '', $path ) );
		}
	}

	return plugins_url( basename( $path ), $path );
}

/**
 * Finds a script module ID for the selected block metadata field. It detects
 * when a path to file was provided and optionally finds a corresponding asset
 * file with details necessary to register the script module under with an
 * automatically generated module ID. It returns unprocessed script module
 * ID otherwise.
 *
 * @since 6.5.0
 *
 * @param array  $metadata   Block metadata.
 * @param string $field_name Field name to pick from metadata.
 * @param int    $index      Optional. Index of the script module ID to register when multiple
 *                           items passed. Default 0.
 * @return string|false Script module ID or false on failure.
 */
function register_block_script_module_id( $metadata, $field_name, $index = 0 ) {
	if ( empty( $metadata[ $field_name ] ) ) {
		return false;
	}

	$module_id = $metadata[ $field_name ];
	if ( is_array( $module_id ) ) {
		if ( empty( $module_id[ $index ] ) ) {
			return false;
		}
		$module_id = $module_id[ $index ];
	}

	$module_path = remove_block_asset_path_prefix( $module_id );
	if ( $module_id === $module_path ) {
		return $module_id;
	}

	$path                  = dirname( $metadata['file'] );
	$module_asset_raw_path = $path . '/' . substr_replace( $module_path, '.asset.php', - strlen( '.js' ) );
	$module_id             = generate_block_asset_handle( $metadata['name'], $field_name, $index );
	$module_asset_path     = wp_normalize_path(
		realpath( $module_asset_raw_path )
	);

	$module_path_norm = wp_normalize_path( realpath( $path . '/' . $module_path ) );
	$module_uri       = get_block_asset_url( $module_path_norm );

	$module_asset        = ! empty( $module_asset_path ) ? require $module_asset_path : array();
	$module_dependencies = isset( $module_asset['dependencies'] ) ? $module_asset['dependencies'] : array();
	$block_version       = isset( $metadata['version'] ) ? $metadata['version'] : false;
	$module_version      = isset( $module_asset['version'] ) ? $module_asset['version'] : $block_version;

	wp_register_script_module(
		$module_id,
		$module_uri,
		$module_dependencies,
		$module_version
	);

	return $module_id;
}

/**
 * Finds a script handle for the selected block metadata field. It detects
 * when a path to file was provided and optionally finds a corresponding asset
 * file with details necessary to register the script under automatically
 * generated handle name. It returns unprocessed script handle otherwise.
 *
 * @since 5.5.0
 * @since 6.1.0 Added `$index` parameter.
 * @since 6.5.0 The asset file is optional. Added script handle support in the asset file.
 *
 * @param array  $metadata   Block metadata.
 * @param string $field_name Field name to pick from metadata.
 * @param int    $index      Optional. Index of the script to register when multiple items passed.
 *                           Default 0.
 * @return string|false Script handle provided directly or created through
 *                      script's registration, or false on failure.
 */
function register_block_script_handle( $metadata, $field_name, $index = 0 ) {
	if ( empty( $metadata[ $field_name ] ) ) {
		return false;
	}

	$script_handle_or_path = $metadata[ $field_name ];
	if ( is_array( $script_handle_or_path ) ) {
		if ( empty( $script_handle_or_path[ $index ] ) ) {
			return false;
		}
		$script_handle_or_path = $script_handle_or_path[ $index ];
	}

	$script_path = remove_block_asset_path_prefix( $script_handle_or_path );
	if ( $script_handle_or_path === $script_path ) {
		return $script_handle_or_path;
	}

	$path                  = dirname( $metadata['file'] );
	$script_asset_raw_path = $path . '/' . substr_replace( $script_path, '.asset.php', - strlen( '.js' ) );
	$script_asset_path     = wp_normalize_path(
		realpath( $script_asset_raw_path )
	);

	// Asset file for blocks is optional. See https://core.trac.wordpress.org/ticket/60460.
	$script_asset  = ! empty( $script_asset_path ) ? require $script_asset_path : array();
	$script_handle = isset( $script_asset['handle'] ) ?
		$script_asset['handle'] :
		generate_block_asset_handle( $metadata['name'], $field_name, $index );
	if ( wp_script_is( $script_handle, 'registered' ) ) {
		return $script_handle;
	}

	$script_path_norm    = wp_normalize_path( realpath( $path . '/' . $script_path ) );
	$script_uri          = get_block_asset_url( $script_path_norm );
	$script_dependencies = isset( $script_asset['dependencies'] ) ? $script_asset['dependencies'] : array();
	$block_version       = isset( $metadata['version'] ) ? $metadata['version'] : false;
	$script_version      = isset( $script_asset['version'] ) ? $script_asset['version'] : $block_version;
	$script_args         = array();
	if ( 'viewScript' === $field_name && $script_uri ) {
		$script_args['strategy'] = 'defer';
	}

	$result = wp_register_script(
		$script_handle,
		$script_uri,
		$script_dependencies,
		$script_version,
		$script_args
	);
	if ( ! $result ) {
		return false;
	}

	if ( ! empty( $metadata['textdomain'] ) && in_array( 'wp-i18n', $script_dependencies, true ) ) {
		wp_set_script_translations( $script_handle, $metadata['textdomain'] );
	}

	return $script_handle;
}

/**
 * Finds a style handle for the block metadata field. It detects when a path
 * to file was provided and registers the style under automatically
 * generated handle name. It returns unprocessed style handle otherwise.
 *
 * @since 5.5.0
 * @since 6.1.0 Added `$index` parameter.
 *
 * @param array  $metadata   Block metadata.
 * @param string $field_name Field name to pick from metadata.
 * @param int    $index      Optional. Index of the style to register when multiple items passed.
 *                           Default 0.
 * @return string|false Style handle provided directly or created through
 *                      style's registration, or false on failure.
 */
function register_block_style_handle( $metadata, $field_name, $index = 0 ) {
	if ( empty( $metadata[ $field_name ] ) ) {
		return false;
	}

	$style_handle = $metadata[ $field_name ];
	if ( is_array( $style_handle ) ) {
		if ( empty( $style_handle[ $index ] ) ) {
			return false;
		}
		$style_handle = $style_handle[ $index ];
	}

	$style_handle_name = generate_block_asset_handle( $metadata['name'], $field_name, $index );
	// If the style handle is already registered, skip re-registering.
	if ( wp_style_is( $style_handle_name, 'registered' ) ) {
		return $style_handle_name;
	}

	static $wpinc_path_norm = '';
	if ( ! $wpinc_path_norm ) {
		$wpinc_path_norm = wp_normalize_path( realpath( ABSPATH . WPINC ) );
	}

	$is_core_block = isset( $metadata['file'] ) && str_starts_with( $metadata['file'], $wpinc_path_norm );
	// Skip registering individual styles for each core block when a bundled version provided.
	if ( $is_core_block && ! wp_should_load_separate_core_block_assets() ) {
		return false;
	}

	$style_path      = remove_block_asset_path_prefix( $style_handle );
	$is_style_handle = $style_handle === $style_path;
	// Allow only passing style handles for core blocks.
	if ( $is_core_block && ! $is_style_handle ) {
		return false;
	}
	// Return the style handle unless it's the first item for every core block that requires special treatment.
	if ( $is_style_handle && ! ( $is_core_block && 0 === $index ) ) {
		return $style_handle;
	}

	// Check whether styles should have a ".min" suffix or not.
	$suffix = SCRIPT_DEBUG ? '' : '.min';
	if ( $is_core_block ) {
		$style_path = ( 'editorStyle' === $field_name ) ? "editor{$suffix}.css" : "style{$suffix}.css";
	}

	$style_path_norm = wp_normalize_path( realpath( dirname( $metadata['file'] ) . '/' . $style_path ) );
	$style_uri       = get_block_asset_url( $style_path_norm );

	$version = ! $is_core_block && isset( $metadata['version'] ) ? $metadata['version'] : false;
	$result  = wp_register_style(
		$style_handle_name,
		$style_uri,
		array(),
		$version
	);
	if ( ! $result ) {
		return false;
	}

	if ( $style_uri ) {
		wp_style_add_data( $style_handle_name, 'path', $style_path_norm );

		if ( $is_core_block ) {
			$rtl_file = str_replace( "{$suffix}.css", "-rtl{$suffix}.css", $style_path_norm );
		} else {
			$rtl_file = str_replace( '.css', '-rtl.css', $style_path_norm );
		}

		if ( is_rtl() && file_exists( $rtl_file ) ) {
			wp_style_add_data( $style_handle_name, 'rtl', 'replace' );
			wp_style_add_data( $style_handle_name, 'suffix', $suffix );
			wp_style_add_data( $style_handle_name, 'path', $rtl_file );
		}
	}

	return $style_handle_name;
}

/**
 * Gets i18n schema for block's metadata read from `block.json` file.
 *
 * @since 5.9.0
 *
 * @return object The schema for block's metadata.
 */
function get_block_metadata_i18n_schema() {
	static $i18n_block_schema;

	if ( ! isset( $i18n_block_schema ) ) {
		$i18n_block_schema = wp_json_file_decode( __DIR__ . '/block-i18n.json' );
	}

	return $i18n_block_schema;
}

/**
 * Registers a block metadata collection.
 *
 * This function allows core and third-party plugins to register their block metadata
 * collections in a centralized location. Registering collections can improve performance
 * by avoiding multiple reads from the filesystem and parsing JSON.
 *
 * @since 6.7.0
 *
 * @param string $path     The base path in which block files for the collection reside.
 * @param string $manifest The path to the manifest file for the collection.
 */
function wp_register_block_metadata_collection( $path, $manifest ) {
	WP_Block_Metadata_Registry::register_collection( $path, $manifest );
}

/**
 * Registers a block type from the metadata stored in the `block.json` file.
 *
 * @since 5.5.0
 * @since 5.7.0 Added support for `textdomain` field and i18n handling for all translatable fields.
 * @since 5.9.0 Added support for `variations` and `viewScript` fields.
 * @since 6.1.0 Added support for `render` field.
 * @since 6.3.0 Added `selectors` field.
 * @since 6.4.0 Added support for `blockHooks` field.
 * @since 6.5.0 Added support for `allowedBlocks`, `viewScriptModule`, and `viewStyle` fields.
 * @since 6.7.0 Allow PHP filename as `variations` argument.
 *
 * @param string $file_or_folder Path to the JSON file with metadata definition for
 *                               the block or path to the folder where the `block.json` file is located.
 *                               If providing the path to a JSON file, the filename must end with `block.json`.
 * @param array  $args           Optional. Array of block type arguments. Accepts any public property
 *                               of `WP_Block_Type`. See WP_Block_Type::__construct() for information
 *                               on accepted arguments. Default empty array.
 * @return WP_Block_Type|false The registered block type on success, or false on failure.
 */
function register_block_type_from_metadata( $file_or_folder, $args = array() ) {
	/*
	 * Get an array of metadata from a PHP file.
	 * This improves performance for core blocks as it's only necessary to read a single PHP file
	 * instead of reading a JSON file per-block, and then decoding from JSON to PHP.
	 * Using a static variable ensures that the metadata is only read once per request.
	 */

	$metadata_file = ( ! str_ends_with( $file_or_folder, 'block.json' ) ) ?
		trailingslashit( $file_or_folder ) . 'block.json' :
		$file_or_folder;

	$is_core_block        = str_starts_with( $file_or_folder, ABSPATH . WPINC );
	$metadata_file_exists = $is_core_block || file_exists( $metadata_file );
	$registry_metadata    = WP_Block_Metadata_Registry::get_metadata( $file_or_folder );

	if ( $registry_metadata ) {
		$metadata = $registry_metadata;
	} elseif ( $metadata_file_exists ) {
		$metadata = wp_json_file_decode( $metadata_file, array( 'associative' => true ) );
	} else {
		$metadata = array();
	}

	if ( ! is_array( $metadata ) || ( empty( $metadata['name'] ) && empty( $args['name'] ) ) ) {
		return false;
	}

	$metadata['file'] = $metadata_file_exists ? wp_normalize_path( realpath( $metadata_file ) ) : null;

	/**
	 * Filters the metadata provided for registering a block type.
	 *
	 * @since 5.7.0
	 *
	 * @param array $metadata Metadata for registering a block type.
	 */
	$metadata = apply_filters( 'block_type_metadata', $metadata );

	// Add `style` and `editor_style` for core blocks if missing.
	if ( ! empty( $metadata['name'] ) && str_starts_with( $metadata['name'], 'core/' ) ) {
		$block_name = str_replace( 'core/', '', $metadata['name'] );

		if ( ! isset( $metadata['style'] ) ) {
			$metadata['style'] = "wp-block-$block_name";
		}
		if ( current_theme_supports( 'wp-block-styles' ) && wp_should_load_separate_core_block_assets() ) {
			$metadata['style']   = (array) $metadata['style'];
			$metadata['style'][] = "wp-block-{$block_name}-theme";
		}
		if ( ! isset( $metadata['editorStyle'] ) ) {
			$metadata['editorStyle'] = "wp-block-{$block_name}-editor";
		}
	}

	$settings          = array();
	$property_mappings = array(
		'apiVersion'      => 'api_version',
		'name'            => 'name',
		'title'           => 'title',
		'category'        => 'category',
		'parent'          => 'parent',
		'ancestor'        => 'ancestor',
		'icon'            => 'icon',
		'description'     => 'description',
		'keywords'        => 'keywords',
		'attributes'      => 'attributes',
		'providesContext' => 'provides_context',
		'usesContext'     => 'uses_context',
		'selectors'       => 'selectors',
		'supports'        => 'supports',
		'styles'          => 'styles',
		'variations'      => 'variations',
		'example'         => 'example',
		'allowedBlocks'   => 'allowed_blocks',
	);
	$textdomain        = ! empty( $metadata['textdomain'] ) ? $metadata['textdomain'] : null;
	$i18n_schema       = get_block_metadata_i18n_schema();

	foreach ( $property_mappings as $key => $mapped_key ) {
		if ( isset( $metadata[ $key ] ) ) {
			$settings[ $mapped_key ] = $metadata[ $key ];
			if ( $metadata_file_exists && $textdomain && isset( $i18n_schema->$key ) ) {
				$settings[ $mapped_key ] = translate_settings_using_i18n_schema( $i18n_schema->$key, $settings[ $key ], $textdomain );
			}
		}
	}

	if ( ! empty( $metadata['render'] ) ) {
		$template_path = wp_normalize_path(
			realpath(
				dirname( $metadata['file'] ) . '/' .
				remove_block_asset_path_prefix( $metadata['render'] )
			)
		);
		if ( $template_path ) {
			/**
			 * Renders the block on the server.
			 *
			 * @since 6.1.0
			 *
			 * @param array    $attributes Block attributes.
			 * @param string   $content    Block default content.
			 * @param WP_Block $block      Block instance.
			 *
			 * @return string Returns the block content.
			 */
			$settings['render_callback'] = static function ( $attributes, $content, $block ) use ( $template_path ) {
				ob_start();
				require $template_path;
				return ob_get_clean();
			};
		}
	}

	// If `variations` is a string, it's the name of a PHP file that
	// generates the variations.
	if ( ! empty( $metadata['variations'] ) && is_string( $metadata['variations'] ) ) {
		$variations_path = wp_normalize_path(
			realpath(
				dirname( $metadata['file'] ) . '/' .
				remove_block_asset_path_prefix( $metadata['variations'] )
			)
		);
		if ( $variations_path ) {
			/**
			 * Generates the list of block variations.
			 *
			 * @since 6.7.0
			 *
			 * @return string Returns the list of block variations.
			 */
			$settings['variation_callback'] = static function () use ( $variations_path ) {
				$variations = require $variations_path;
				return $variations;
			};
			// The block instance's `variations` field is only allowed to be an array
			// (of known block variations). We unset it so that the block instance will
			// provide a getter that returns the result of the `variation_callback` instead.
			unset( $settings['variations'] );
		}
	}

	$settings = array_merge( $settings, $args );

	$script_fields = array(
		'editorScript' => 'editor_script_handles',
		'script'       => 'script_handles',
		'viewScript'   => 'view_script_handles',
	);
	foreach ( $script_fields as $metadata_field_name => $settings_field_name ) {
		if ( ! empty( $settings[ $metadata_field_name ] ) ) {
			$metadata[ $metadata_field_name ] = $settings[ $metadata_field_name ];
		}
		if ( ! empty( $metadata[ $metadata_field_name ] ) ) {
			$scripts           = $metadata[ $metadata_field_name ];
			$processed_scripts = array();
			if ( is_array( $scripts ) ) {
				for ( $index = 0; $index < count( $scripts ); $index++ ) {
					$result = register_block_script_handle(
						$metadata,
						$metadata_field_name,
						$index
					);
					if ( $result ) {
						$processed_scripts[] = $result;
					}
				}
			} else {
				$result = register_block_script_handle(
					$metadata,
					$metadata_field_name
				);
				if ( $result ) {
					$processed_scripts[] = $result;
				}
			}
			$settings[ $settings_field_name ] = $processed_scripts;
		}
	}

	$module_fields = array(
		'viewScriptModule' => 'view_script_module_ids',
	);
	foreach ( $module_fields as $metadata_field_name => $settings_field_name ) {
		if ( ! empty( $settings[ $metadata_field_name ] ) ) {
			$metadata[ $metadata_field_name ] = $settings[ $metadata_field_name ];
		}
		if ( ! empty( $metadata[ $metadata_field_name ] ) ) {
			$modules           = $metadata[ $metadata_field_name ];
			$processed_modules = array();
			if ( is_array( $modules ) ) {
				for ( $index = 0; $index < count( $modules ); $index++ ) {
					$result = register_block_script_module_id(
						$metadata,
						$metadata_field_name,
						$index
					);
					if ( $result ) {
						$processed_modules[] = $result;
					}
				}
			} else {
				$result = register_block_script_module_id(
					$metadata,
					$metadata_field_name
				);
				if ( $result ) {
					$processed_modules[] = $result;
				}
			}
			$settings[ $settings_field_name ] = $processed_modules;
		}
	}

	$style_fields = array(
		'editorStyle' => 'editor_style_handles',
		'style'       => 'style_handles',
		'viewStyle'   => 'view_style_handles',
	);
	foreach ( $style_fields as $metadata_field_name => $settings_field_name ) {
		if ( ! empty( $settings[ $metadata_field_name ] ) ) {
			$metadata[ $metadata_field_name ] = $settings[ $metadata_field_name ];
		}
		if ( ! empty( $metadata[ $metadata_field_name ] ) ) {
			$styles           = $metadata[ $metadata_field_name ];
			$processed_styles = array();
			if ( is_array( $styles ) ) {
				for ( $index = 0; $index < count( $styles ); $index++ ) {
					$result = register_block_style_handle(
						$metadata,
						$metadata_field_name,
						$index
					);
					if ( $result ) {
						$processed_styles[] = $result;
					}
				}
			} else {
				$result = register_block_style_handle(
					$metadata,
					$metadata_field_name
				);
				if ( $result ) {
					$processed_styles[] = $result;
				}
			}
			$settings[ $settings_field_name ] = $processed_styles;
		}
	}

	if ( ! empty( $metadata['blockHooks'] ) ) {
		/**
		 * Map camelCased position string (from block.json) to snake_cased block type position.
		 *
		 * @var array
		 */
		$position_mappings = array(
			'before'     => 'before',
			'after'      => 'after',
			'firstChild' => 'first_child',
			'lastChild'  => 'last_child',
		);

		$settings['block_hooks'] = array();
		foreach ( $metadata['blockHooks'] as $anchor_block_name => $position ) {
			// Avoid infinite recursion (hooking to itself).
			if ( $metadata['name'] === $anchor_block_name ) {
				_doing_it_wrong(
					__METHOD__,
					__( 'Cannot hook block to itself.' ),
					'6.4.0'
				);
				continue;
			}

			if ( ! isset( $position_mappings[ $position ] ) ) {
				continue;
			}

			$settings['block_hooks'][ $anchor_block_name ] = $position_mappings[ $position ];
		}
	}

	/**
	 * Filters the settings determined from the block type metadata.
	 *
	 * @since 5.7.0
	 *
	 * @param array $settings Array of determined settings for registering a block type.
	 * @param array $metadata Metadata provided for registering a block type.
	 */
	$settings = apply_filters( 'block_type_metadata_settings', $settings, $metadata );

	$metadata['name'] = ! empty( $settings['name'] ) ? $settings['name'] : $metadata['name'];

	return WP_Block_Type_Registry::get_instance()->register(
		$metadata['name'],
		$settings
	);
}

/**
 * Registers a block type. The recommended way is to register a block type using
 * the metadata stored in the `block.json` file.
 *
 * @since 5.0.0
 * @since 5.8.0 First parameter now accepts a path to the `block.json` file.
 *
 * @param string|WP_Block_Type $block_type Block type name including namespace, or alternatively
 *                                         a path to the JSON file with metadata definition for the block,
 *                                         or a path to the folder where the `block.json` file is located,
 *                                         or a complete WP_Block_Type instance.
 *                                         In case a WP_Block_Type is provided, the $args parameter will be ignored.
 * @param array                $args       Optional. Array of block type arguments. Accepts any public property
 *                                         of `WP_Block_Type`. See WP_Block_Type::__construct() for information
 *                                         on accepted arguments. Default empty array.
 *
 * @return WP_Block_Type|false The registered block type on success, or false on failure.
 */
function register_block_type( $block_type, $args = array() ) {
	if ( is_string( $block_type ) && file_exists( $block_type ) ) {
		return register_block_type_from_metadata( $block_type, $args );
	}

	return WP_Block_Type_Registry::get_instance()->register( $block_type, $args );
}

/**
 * Unregisters a block type.
 *
 * @since 5.0.0
 *
 * @param string|WP_Block_Type $name Block type name including namespace, or alternatively
 *                                   a complete WP_Block_Type instance.
 * @return WP_Block_Type|false The unregistered block type on success, or false on failure.
 */
function unregister_block_type( $name ) {
	return WP_Block_Type_Registry::get_instance()->unregister( $name );
}

/**
 * Determines whether a post or content string has blocks.
 *
 * This test optimizes for performance rather than strict accuracy, detecting
 * the pattern of a block but not validating its structure. For strict accuracy,
 * you should use the block parser on post content.
 *
 * @since 5.0.0
 *
 * @see parse_blocks()
 *
 * @param int|string|WP_Post|null $post Optional. Post content, post ID, or post object.
 *                                      Defaults to global $post.
 * @return bool Whether the post has blocks.
 */
function has_blocks( $post = null ) {
	if ( ! is_string( $post ) ) {
		$wp_post = get_post( $post );

		if ( ! $wp_post instanceof WP_Post ) {
			return false;
		}

		$post = $wp_post->post_content;
	}

	return str_contains( (string) $post, '<!-- wp:' );
}

/**
 * Determines whether a $post or a string contains a specific block type.
 *
 * This test optimizes for performance rather than strict accuracy, detecting
 * whether the block type exists but not validating its structure and not checking
 * synced patterns (formerly called reusable blocks). For strict accuracy,
 * you should use the block parser on post content.
 *
 * @since 5.0.0
 *
 * @see parse_blocks()
 *
 * @param string                  $block_name Full block type to look for.
 * @param int|string|WP_Post|null $post       Optional. Post content, post ID, or post object.
 *                                            Defaults to global $post.
 * @return bool Whether the post content contains the specified block.
 */
function has_block( $block_name, $post = null ) {
	if ( ! has_blocks( $post ) ) {
		return false;
	}

	if ( ! is_string( $post ) ) {
		$wp_post = get_post( $post );
		if ( $wp_post instanceof WP_Post ) {
			$post = $wp_post->post_content;
		}
	}

	/*
	 * Normalize block name to include namespace, if provided as non-namespaced.
	 * This matches behavior for WordPress 5.0.0 - 5.3.0 in matching blocks by
	 * their serialized names.
	 */
	if ( ! str_contains( $block_name, '/' ) ) {
		$block_name = 'core/' . $block_name;
	}

	// Test for existence of block by its fully qualified name.
	$has_block = str_contains( $post, '<!-- wp:' . $block_name . ' ' );

	if ( ! $has_block ) {
		/*
		 * If the given block name would serialize to a different name, test for
		 * existence by the serialized form.
		 */
		$serialized_block_name = strip_core_block_namespace( $block_name );
		if ( $serialized_block_name !== $block_name ) {
			$has_block = str_contains( $post, '<!-- wp:' . $serialized_block_name . ' ' );
		}
	}

	return $has_block;
}

/**
 * Returns an array of the names of all registered dynamic block types.
 *
 * @since 5.0.0
 *
 * @return string[] Array of dynamic block names.
 */
function get_dynamic_block_names() {
	$dynamic_block_names = array();

	$block_types = WP_Block_Type_Registry::get_instance()->get_all_registered();
	foreach ( $block_types as $block_type ) {
		if ( $block_type->is_dynamic() ) {
			$dynamic_block_names[] = $block_type->name;
		}
	}

	return $dynamic_block_names;
}

/**
 * Retrieves block types hooked into the given block, grouped by anchor block type and the relative position.
 *
 * @since 6.4.0
 *
 * @return array[] Array of block types grouped by anchor block type and the relative position.
 */
function get_hooked_blocks() {
	$block_types   = WP_Block_Type_Registry::get_instance()->get_all_registered();
	$hooked_blocks = array();
	foreach ( $block_types as $block_type ) {
		if ( ! ( $block_type instanceof WP_Block_Type ) || ! is_array( $block_type->block_hooks ) ) {
			continue;
		}
		foreach ( $block_type->block_hooks as $anchor_block_type => $relative_position ) {
			if ( ! isset( $hooked_blocks[ $anchor_block_type ] ) ) {
				$hooked_blocks[ $anchor_block_type ] = array();
			}
			if ( ! isset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] ) ) {
				$hooked_blocks[ $anchor_block_type ][ $relative_position ] = array();
			}
			$hooked_blocks[ $anchor_block_type ][ $relative_position ][] = $block_type->name;
		}
	}

	return $hooked_blocks;
}

/**
 * Returns the markup for blocks hooked to the given anchor block in a specific relative position.
 *
 * @since 6.5.0
 * @access private
 *
 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
 * @param string                          $relative_position   The relative position of the hooked blocks.
 *                                                             Can be one of 'before', 'after', 'first_child', or 'last_child'.
 * @param array                           $hooked_blocks       An array of hooked block types, grouped by anchor block and relative position.
 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, or pattern that the anchor block belongs to.
 * @return string
 */
function insert_hooked_blocks( &$parsed_anchor_block, $relative_position, $hooked_blocks, $context ) {
	$anchor_block_type  = $parsed_anchor_block['blockName'];
	$hooked_block_types = isset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] )
		? $hooked_blocks[ $anchor_block_type ][ $relative_position ]
		: array();

	/**
	 * Filters the list of hooked block types for a given anchor block type and relative position.
	 *
	 * @since 6.4.0
	 *
	 * @param string[]                        $hooked_block_types The list of hooked block types.
	 * @param string                          $relative_position  The relative position of the hooked blocks.
	 *                                                            Can be one of 'before', 'after', 'first_child', or 'last_child'.
	 * @param string                          $anchor_block_type  The anchor block type.
	 * @param WP_Block_Template|WP_Post|array $context            The block template, template part, post object,
	 *                                                            or pattern that the anchor block belongs to.
	 */
	$hooked_block_types = apply_filters( 'hooked_block_types', $hooked_block_types, $relative_position, $anchor_block_type, $context );

	$markup = '';
	foreach ( $hooked_block_types as $hooked_block_type ) {
		$parsed_hooked_block = array(
			'blockName'    => $hooked_block_type,
			'attrs'        => array(),
			'innerBlocks'  => array(),
			'innerContent' => array(),
		);

		/**
		 * Filters the parsed block array for a given hooked block.
		 *
		 * @since 6.5.0
		 *
		 * @param array|null                      $parsed_hooked_block The parsed block array for the given hooked block type, or null to suppress the block.
		 * @param string                          $hooked_block_type   The hooked block type name.
		 * @param string                          $relative_position   The relative position of the hooked block.
		 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
		 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, post object,
		 *                                                             or pattern that the anchor block belongs to.
		 */
		$parsed_hooked_block = apply_filters( 'hooked_block', $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		/**
		 * Filters the parsed block array for a given hooked block.
		 *
		 * The dynamic portion of the hook name, `$hooked_block_type`, refers to the block type name of the specific hooked block.
		 *
		 * @since 6.5.0
		 *
		 * @param array|null                      $parsed_hooked_block The parsed block array for the given hooked block type, or null to suppress the block.
		 * @param string                          $hooked_block_type   The hooked block type name.
		 * @param string                          $relative_position   The relative position of the hooked block.
		 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
		 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, post object,
		 *                                                             or pattern that the anchor block belongs to.
		 */
		$parsed_hooked_block = apply_filters( "hooked_block_{$hooked_block_type}", $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		if ( null === $parsed_hooked_block ) {
			continue;
		}

		// It's possible that the filter returned a block of a different type, so we explicitly
		// look for the original `$hooked_block_type` in the `ignoredHookedBlocks` metadata.
		if (
			! isset( $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'] ) ||
			! in_array( $hooked_block_type, $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'], true )
		) {
			$markup .= serialize_block( $parsed_hooked_block );
		}
	}

	return $markup;
}

/**
 * Adds a list of hooked block types to an anchor block's ignored hooked block types.
 *
 * This function is meant for internal use only.
 *
 * @since 6.5.0
 * @access private
 *
 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
 * @param string                          $relative_position   The relative position of the hooked blocks.
 *                                                             Can be one of 'before', 'after', 'first_child', or 'last_child'.
 * @param array                           $hooked_blocks       An array of hooked block types, grouped by anchor block and relative position.
 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, or pattern that the anchor block belongs to.
 * @return string Empty string.
 */
function set_ignored_hooked_blocks_metadata( &$parsed_anchor_block, $relative_position, $hooked_blocks, $context ) {
	$anchor_block_type  = $parsed_anchor_block['blockName'];
	$hooked_block_types = isset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] )
		? $hooked_blocks[ $anchor_block_type ][ $relative_position ]
		: array();

	/** This filter is documented in wp-includes/blocks.php */
	$hooked_block_types = apply_filters( 'hooked_block_types', $hooked_block_types, $relative_position, $anchor_block_type, $context );
	if ( empty( $hooked_block_types ) ) {
		return '';
	}

	foreach ( $hooked_block_types as $index => $hooked_block_type ) {
		$parsed_hooked_block = array(
			'blockName'    => $hooked_block_type,
			'attrs'        => array(),
			'innerBlocks'  => array(),
			'innerContent' => array(),
		);

		/** This filter is documented in wp-includes/blocks.php */
		$parsed_hooked_block = apply_filters( 'hooked_block', $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		/** This filter is documented in wp-includes/blocks.php */
		$parsed_hooked_block = apply_filters( "hooked_block_{$hooked_block_type}", $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		if ( null === $parsed_hooked_block ) {
			unset( $hooked_block_types[ $index ] );
		}
	}

	$previously_ignored_hooked_blocks = isset( $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'] )
		? $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks']
		: array();

	$parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'] = array_unique(
		array_merge(
			$previously_ignored_hooked_blocks,
			$hooked_block_types
		)
	);

	// Markup for the hooked blocks has already been created (in `insert_hooked_blocks`).
	return '';
}

/**
 * Runs the hooked blocks algorithm on the given content.
 *
 * @since 6.6.0
 * @since 6.7.0 Injects the `theme` attribute into Template Part blocks, even if no hooked blocks are registered.
 * @since 6.8.0 Have the `$context` parameter default to `null`, in which case `get_post()` will be called to use the current post as context.
 * @access private
 *
 * @param string                               $content  Serialized content.
 * @param WP_Block_Template|WP_Post|array|null $context  A block template, template part, post object, or pattern
 *                                                       that the blocks belong to. If set to `null`, `get_post()`
 *                                                       will be called to use the current post as context.
 *                                                       Default: `null`.
 * @param callable                             $callback A function that will be called for each block to generate
 *                                                       the markup for a given list of blocks that are hooked to it.
 *                                                       Default: 'insert_hooked_blocks'.
 * @return string The serialized markup.
 */
function apply_block_hooks_to_content( $content, $context = null, $callback = 'insert_hooked_blocks' ) {
	// Default to the current post if no context is provided.
	if ( null === $context ) {
		$context = get_post();
	}

	$hooked_blocks = get_hooked_blocks();

	$before_block_visitor = '_inject_theme_attribute_in_template_part_block';
	$after_block_visitor  = null;
	if ( ! empty( $hooked_blocks ) || has_filter( 'hooked_block_types' ) ) {
		$before_block_visitor = make_before_block_visitor( $hooked_blocks, $context, $callback );
		$after_block_visitor  = make_after_block_visitor( $hooked_blocks, $context, $callback );
	}

	$block_allows_multiple_instances = array();
	/*
	 * Remove hooked blocks from `$hooked_block_types` if they have `multiple` set to false and
	 * are already present in `$content`.
	 */
	foreach ( $hooked_blocks as $anchor_block_type => $relative_positions ) {
		foreach ( $relative_positions as $relative_position => $hooked_block_types ) {
			foreach ( $hooked_block_types as $index => $hooked_block_type ) {
				$hooked_block_type_definition =
					WP_Block_Type_Registry::get_instance()->get_registered( $hooked_block_type );

				$block_allows_multiple_instances[ $hooked_block_type ] =
					block_has_support( $hooked_block_type_definition, 'multiple', true );

				if (
					! $block_allows_multiple_instances[ $hooked_block_type ] &&
					has_block( $hooked_block_type, $content )
				) {
					unset( $hooked_blocks[ $anchor_block_type ][ $relative_position ][ $index ] );
				}
			}
			if ( empty( $hooked_blocks[ $anchor_block_type ][ $relative_position ] ) ) {
				unset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] );
			}
		}
		if ( empty( $hooked_blocks[ $anchor_block_type ] ) ) {
			unset( $hooked_blocks[ $anchor_block_type ] );
		}
	}

	/*
	 * We also need to cover the case where the hooked block is not present in
	 * `$content` at first and we're allowed to insert it once -- but not again.
	 */
	$suppress_single_instance_blocks = static function ( $hooked_block_types ) use ( &$block_allows_multiple_instances, $content ) {
		static $single_instance_blocks_present_in_content = array();
		foreach ( $hooked_block_types as $index => $hooked_block_type ) {
			if ( ! isset( $block_allows_multiple_instances[ $hooked_block_type ] ) ) {
				$hooked_block_type_definition =
					WP_Block_Type_Registry::get_instance()->get_registered( $hooked_block_type );

				$block_allows_multiple_instances[ $hooked_block_type ] =
					block_has_support( $hooked_block_type_definition, 'multiple', true );
			}

			if ( $block_allows_multiple_instances[ $hooked_block_type ] ) {
				continue;
			}

			// The block doesn't allow multiple instances, so we need to check if it's already present.
			if (
				in_array( $hooked_block_type, $single_instance_blocks_present_in_content, true ) ||
				has_block( $hooked_block_type, $content )
			) {
				unset( $hooked_block_types[ $index ] );
			} else {
				// We can insert the block once, but need to remember not to insert it again.
				$single_instance_blocks_present_in_content[] = $hooked_block_type;
			}
		}
		return $hooked_block_types;
	};
	add_filter( 'hooked_block_types', $suppress_single_instance_blocks, PHP_INT_MAX );
	$content = traverse_and_serialize_blocks(
		parse_blocks( $content ),
		$before_block_visitor,
		$after_block_visitor
	);
	remove_filter( 'hooked_block_types', $suppress_single_instance_blocks, PHP_INT_MAX );

	return $content;
}

/**
 * Accepts the serialized markup of a block and its inner blocks, and returns serialized markup of the inner blocks.
 *
 * @since 6.6.0
 * @access private
 *
 * @param string $serialized_block The serialized markup of a block and its inner blocks.
 * @return string The serialized markup of the inner blocks.
 */
function remove_serialized_parent_block( $serialized_block ) {
	$start = strpos( $serialized_block, '-->' ) + strlen( '-->' );
	$end   = strrpos( $serialized_block, '<!--' );
	return substr( $serialized_block, $start, $end - $start );
}

/**
 * Accepts the serialized markup of a block and its inner blocks, and returns serialized markup of the wrapper block.
 *
 * @since 6.7.0
 * @access private
 *
 * @see remove_serialized_parent_block()
 *
 * @param string $serialized_block The serialized markup of a block and its inner blocks.
 * @return string The serialized markup of the wrapper block.
 */
function extract_serialized_parent_block( $serialized_block ) {
	$start = strpos( $serialized_block, '-->' ) + strlen( '-->' );
	$end   = strrpos( $serialized_block, '<!--' );
	return substr( $serialized_block, 0, $start ) . substr( $serialized_block, $end );
}

/**
 * Updates the wp_postmeta with the list of ignored hooked blocks
 * where the inner blocks are stored as post content.
 *
 * @since 6.6.0
 * @since 6.8.0 Support non-`wp_navigation` post types.
 * @access private
 *
 * @param stdClass $post Post object.
 * @return stdClass The updated post object.
 */
function update_ignored_hooked_blocks_postmeta( $post ) {
	/*
	 * In this scenario the user has likely tried to create a new post object via the REST API.
	 * In which case we won't have a post ID to work with and store meta against.
	 */
	if ( empty( $post->ID ) ) {
		return $post;
	}

	/*
	 * Skip meta generation when consumers intentionally update specific fields
	 * and omit the content update.
	 */
	if ( ! isset( $post->post_content ) ) {
		return $post;
	}

	/*
	 * Skip meta generation if post type is not set.
	 */
	if ( ! isset( $post->post_type ) ) {
		return $post;
	}

	$attributes = array();

	$ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
	if ( ! empty( $ignored_hooked_blocks ) ) {
		$ignored_hooked_blocks  = json_decode( $ignored_hooked_blocks, true );
		$attributes['metadata'] = array(
			'ignoredHookedBlocks' => $ignored_hooked_blocks,
		);
	}

	if ( 'wp_navigation' === $post->post_type ) {
		$wrapper_block_type = 'core/navigation';
	} elseif ( 'wp_block' === $post->post_type ) {
		$wrapper_block_type = 'core/block';
	} else {
		$wrapper_block_type = 'core/post-content';
	}

	$markup = get_comment_delimited_block_content(
		$wrapper_block_type,
		$attributes,
		$post->post_content
	);

	$existing_post = get_post( $post->ID );
	// Merge the existing post object with the updated post object to pass to the block hooks algorithm for context.
	$context          = (object) array_merge( (array) $existing_post, (array) $post );
	$context          = new WP_Post( $context ); // Convert to WP_Post object.
	$serialized_block = apply_block_hooks_to_content( $markup, $context, 'set_ignored_hooked_blocks_metadata' );
	$root_block       = parse_blocks( $serialized_block )[0];

	$ignored_hooked_blocks = isset( $root_block['attrs']['metadata']['ignoredHookedBlocks'] )
		? $root_block['attrs']['metadata']['ignoredHookedBlocks']
		: array();

	if ( ! empty( $ignored_hooked_blocks ) ) {
		$existing_ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
		if ( ! empty( $existing_ignored_hooked_blocks ) ) {
			$existing_ignored_hooked_blocks = json_decode( $existing_ignored_hooked_blocks, true );
			$ignored_hooked_blocks          = array_unique( array_merge( $ignored_hooked_blocks, $existing_ignored_hooked_blocks ) );
		}

		if ( ! isset( $post->meta_input ) ) {
			$post->meta_input = array();
		}
		$post->meta_input['_wp_ignored_hooked_blocks'] = json_encode( $ignored_hooked_blocks );
	}

	$post->post_content = remove_serialized_parent_block( $serialized_block );
	return $post;
}

/**
 * Returns the markup for blocks hooked to the given anchor block in a specific relative position and then
 * adds a list of hooked block types to an anchor block's ignored hooked block types.
 *
 * This function is meant for internal use only.
 *
 * @since 6.6.0
 * @access private
 *
 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
 * @param string                          $relative_position   The relative position of the hooked blocks.
 *                                                             Can be one of 'before', 'after', 'first_child', or 'last_child'.
 * @param array                           $hooked_blocks       An array of hooked block types, grouped by anchor block and relative position.
 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, or pattern that the anchor block belongs to.
 * @return string
 */
function insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata( &$parsed_anchor_block, $relative_position, $hooked_blocks, $context ) {
	$markup  = insert_hooked_blocks( $parsed_anchor_block, $relative_position, $hooked_blocks, $context );
	$markup .= set_ignored_hooked_blocks_metadata( $parsed_anchor_block, $relative_position, $hooked_blocks, $context );

	return $markup;
}

/**
 * Hooks into the REST API response for the Posts endpoint and adds the first and last inner blocks.
 *
 * @since 6.6.0
 * @since 6.8.0 Support non-`wp_navigation` post types.
 *
 * @param WP_REST_Response $response The response object.
 * @param WP_Post          $post     Post object.
 * @return WP_REST_Response The response object.
 */
function insert_hooked_blocks_into_rest_response( $response, $post ) {
	if ( empty( $response->data['content']['raw'] ) ) {
		return $response;
	}

	$attributes            = array();
	$ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
	if ( ! empty( $ignored_hooked_blocks ) ) {
		$ignored_hooked_blocks  = json_decode( $ignored_hooked_blocks, true );
		$attributes['metadata'] = array(
			'ignoredHookedBlocks' => $ignored_hooked_blocks,
		);
	}

	if ( 'wp_navigation' === $post->post_type ) {
		$wrapper_block_type = 'core/navigation';
	} elseif ( 'wp_block' === $post->post_type ) {
		$wrapper_block_type = 'core/block';
	} else {
		$wrapper_block_type = 'core/post-content';
	}

	$content = get_comment_delimited_block_content(
		$wrapper_block_type,
		$attributes,
		$response->data['content']['raw']
	);

	$content = apply_block_hooks_to_content(
		$content,
		$post,
		'insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata'
	);

	// Remove mock block wrapper.
	$content = remove_serialized_parent_block( $content );

	$response->data['content']['raw'] = $content;

	// If the rendered content was previously empty, we leave it like that.
	if ( empty( $response->data['content']['rendered'] ) ) {
		return $response;
	}

	// `apply_block_hooks_to_content` is called above. Ensure it is not called again as a filter.
	$priority = has_filter( 'the_content', 'apply_block_hooks_to_content' );
	if ( false !== $priority ) {
		remove_filter( 'the_content', 'apply_block_hooks_to_content', $priority );
	}

	/** This filter is documented in wp-includes/post-template.php */
	$response->data['content']['rendered'] = apply_filters( 'the_content', $content );

	// Restore the filter if it was set initially.
	if ( false !== $priority ) {
		add_filter( 'the_content', 'apply_block_hooks_to_content', $priority );
	}

	return $response;
}

/**
 * Returns a function that injects the theme attribute into, and hooked blocks before, a given block.
 *
 * The returned function can be used as `$pre_callback` argument to `traverse_and_serialize_block(s)`,
 * where it will inject the `theme` attribute into all Template Part blocks, and prepend the markup for
 * any blocks hooked `before` the given block and as its parent's `first_child`, respectively.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @since 6.5.0 Added $callback argument.
 * @access private
 *
 * @param array                           $hooked_blocks An array of blocks hooked to another given block.
 * @param WP_Block_Template|WP_Post|array $context       A block template, template part, post object,
 *                                                       or pattern that the blocks belong to.
 * @param callable                        $callback      A function that will be called for each block to generate
 *                                                       the markup for a given list of blocks that are hooked to it.
 *                                                       Default: 'insert_hooked_blocks'.
 * @return callable A function that returns the serialized markup for the given block,
 *                  including the markup for any hooked blocks before it.
 */
function make_before_block_visitor( $hooked_blocks, $context, $callback = 'insert_hooked_blocks' ) {
	/**
	 * Injects hooked blocks before the given block, injects the `theme` attribute into Template Part blocks, and returns the serialized markup.
	 *
	 * If the current block is a Template Part block, inject the `theme` attribute.
	 * Furthermore, prepend the markup for any blocks hooked `before` the given block and as its parent's
	 * `first_child`, respectively, to the serialized markup for the given block.
	 *
	 * @param array $block        The block to inject the theme attribute into, and hooked blocks before. Passed by reference.
	 * @param array $parent_block The parent block of the given block. Passed by reference. Default null.
	 * @param array $prev         The previous sibling block of the given block. Default null.
	 * @return string The serialized markup for the given block, with the markup for any hooked blocks prepended to it.
	 */
	return function ( &$block, &$parent_block = null, $prev = null ) use ( $hooked_blocks, $context, $callback ) {
		_inject_theme_attribute_in_template_part_block( $block );

		$markup = '';

		if ( $parent_block && ! $prev ) {
			// Candidate for first-child insertion.
			$markup .= call_user_func_array(
				$callback,
				array( &$parent_block, 'first_child', $hooked_blocks, $context )
			);
		}

		$markup .= call_user_func_array(
			$callback,
			array( &$block, 'before', $hooked_blocks, $context )
		);

		return $markup;
	};
}

/**
 * Returns a function that injects the hooked blocks after a given block.
 *
 * The returned function can be used as `$post_callback` argument to `traverse_and_serialize_block(s)`,
 * where it will append the markup for any blocks hooked `after` the given block and as its parent's
 * `last_child`, respectively.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @since 6.5.0 Added $callback argument.
 * @access private
 *
 * @param array                           $hooked_blocks An array of blocks hooked to another block.
 * @param WP_Block_Template|WP_Post|array $context       A block template, template part, post object,
 *                                                       or pattern that the blocks belong to.
 * @param callable                        $callback      A function that will be called for each block to generate
 *                                                       the markup for a given list of blocks that are hooked to it.
 *                                                       Default: 'insert_hooked_blocks'.
 * @return callable A function that returns the serialized markup for the given block,
 *                  including the markup for any hooked blocks after it.
 */
function make_after_block_visitor( $hooked_blocks, $context, $callback = 'insert_hooked_blocks' ) {
	/**
	 * Injects hooked blocks after the given block, and returns the serialized markup.
	 *
	 * Append the markup for any blocks hooked `after` the given block and as its parent's
	 * `last_child`, respectively, to the serialized markup for the given block.
	 *
	 * @param array $block        The block to inject the hooked blocks after. Passed by reference.
	 * @param array $parent_block The parent block of the given block. Passed by reference. Default null.
	 * @param array $next         The next sibling block of the given block. Default null.
	 * @return string The serialized markup for the given block, with the markup for any hooked blocks appended to it.
	 */
	return function ( &$block, &$parent_block = null, $next = null ) use ( $hooked_blocks, $context, $callback ) {
		$markup = call_user_func_array(
			$callback,
			array( &$block, 'after', $hooked_blocks, $context )
		);

		if ( $parent_block && ! $next ) {
			// Candidate for last-child insertion.
			$markup .= call_user_func_array(
				$callback,
				array( &$parent_block, 'last_child', $hooked_blocks, $context )
			);
		}

		return $markup;
	};
}

/**
 * Given an array of attributes, returns a string in the serialized attributes
 * format prepared for post content.
 *
 * The serialized result is a JSON-encoded string, with unicode escape sequence
 * substitution for characters which might otherwise interfere with embedding
 * the result in an HTML comment.
 *
 * This function must produce output that remains in sync with the output of
 * the serializeAttributes JavaScript function in the block editor in order
 * to ensure consistent operation between PHP and JavaScript.
 *
 * @since 5.3.1
 *
 * @param array $block_attributes Attributes object.
 * @return string Serialized attributes.
 */
function serialize_block_attributes( $block_attributes ) {
	$encoded_attributes = wp_json_encode( $block_attributes, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );
	$encoded_attributes = preg_replace( '/--/', '\\u002d\\u002d', $encoded_attributes );
	$encoded_attributes = preg_replace( '/</', '\\u003c', $encoded_attributes );
	$encoded_attributes = preg_replace( '/>/', '\\u003e', $encoded_attributes );
	$encoded_attributes = preg_replace( '/&/', '\\u0026', $encoded_attributes );
	// Regex: /\\"/
	$encoded_attributes = preg_replace( '/\\\\"/', '\\u0022', $encoded_attributes );

	return $encoded_attributes;
}

/**
 * Returns the block name to use for serialization. This will remove the default
 * "core/" namespace from a block name.
 *
 * @since 5.3.1
 *
 * @param string|null $block_name Optional. Original block name. Null if the block name is unknown,
 *                                e.g. Classic blocks have their name set to null. Default null.
 * @return string Block name to use for serialization.
 */
function strip_core_block_namespace( $block_name = null ) {
	if ( is_string( $block_name ) && str_starts_with( $block_name, 'core/' ) ) {
		return substr( $block_name, 5 );
	}

	return $block_name;
}

/**
 * Returns the content of a block, including comment delimiters.
 *
 * @since 5.3.1
 *
 * @param string|null $block_name       Block name. Null if the block name is unknown,
 *                                      e.g. Classic blocks have their name set to null.
 * @param array       $block_attributes Block attributes.
 * @param string      $block_content    Block save content.
 * @return string Comment-delimited block content.
 */
function get_comment_delimited_block_content( $block_name, $block_attributes, $block_content ) {
	if ( is_null( $block_name ) ) {
		return $block_content;
	}

	$serialized_block_name = strip_core_block_namespace( $block_name );
	$serialized_attributes = empty( $block_attributes ) ? '' : serialize_block_attributes( $block_attributes ) . ' ';

	if ( empty( $block_content ) ) {
		return sprintf( '<!-- wp:%s %s/-->', $serialized_block_name, $serialized_attributes );
	}

	return sprintf(
		'<!-- wp:%s %s-->%s<!-- /wp:%s -->',
		$serialized_block_name,
		$serialized_attributes,
		$block_content,
		$serialized_block_name
	);
}

/**
 * Returns the content of a block, including comment delimiters, serializing all
 * attributes from the given parsed block.
 *
 * This should be used when preparing a block to be saved to post content.
 * Prefer `render_block` when preparing a block for display. Unlike
 * `render_block`, this does not evaluate a block's `render_callback`, and will
 * instead preserve the markup as parsed.
 *
 * @since 5.3.1
 *
 * @param array $block {
 *     An associative array of a single parsed block object. See WP_Block_Parser_Block.
 *
 *     @type string   $blockName    Name of block.
 *     @type array    $attrs        Attributes from block comment delimiters.
 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                  have the same structure as this one.
 *     @type string   $innerHTML    HTML from inside block comment delimiters.
 *     @type array    $innerContent List of string fragments and null markers where
 *                                  inner blocks were found.
 * }
 * @return string String of rendered HTML.
 */
function serialize_block( $block ) {
	$block_content = '';

	$index = 0;
	foreach ( $block['innerContent'] as $chunk ) {
		$block_content .= is_string( $chunk ) ? $chunk : serialize_block( $block['innerBlocks'][ $index++ ] );
	}

	if ( ! is_array( $block['attrs'] ) ) {
		$block['attrs'] = array();
	}

	return get_comment_delimited_block_content(
		$block['blockName'],
		$block['attrs'],
		$block_content
	);
}

/**
 * Returns a joined string of the aggregate serialization of the given
 * parsed blocks.
 *
 * @since 5.3.1
 *
 * @param array[] $blocks {
 *     Array of block structures.
 *
 *     @type array ...$0 {
 *         An associative array of a single parsed block object. See WP_Block_Parser_Block.
 *
 *         @type string   $blockName    Name of block.
 *         @type array    $attrs        Attributes from block comment delimiters.
 *         @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                      have the same structure as this one.
 *         @type string   $innerHTML    HTML from inside block comment delimiters.
 *         @type array    $innerContent List of string fragments and null markers where
 *                                      inner blocks were found.
 *     }
 * }
 * @return string String of rendered HTML.
 */
function serialize_blocks( $blocks ) {
	return implode( '', array_map( 'serialize_block', $blocks ) );
}

/**
 * Traverses a parsed block tree and applies callbacks before and after serializing it.
 *
 * Recursively traverses the block and its inner blocks and applies the two callbacks provided as
 * arguments, the first one before serializing the block, and the second one after serializing it.
 * If either callback returns a string value, it will be prepended and appended to the serialized
 * block markup, respectively.
 *
 * The callbacks will receive a reference to the current block as their first argument, so that they
 * can also modify it, and the current block's parent block as second argument. Finally, the
 * `$pre_callback` receives the previous block, whereas the `$post_callback` receives
 * the next block as third argument.
 *
 * Serialized blocks are returned including comment delimiters, and with all attributes serialized.
 *
 * This function should be used when there is a need to modify the saved block, or to inject markup
 * into the return value. Prefer `serialize_block` when preparing a block to be saved to post content.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @access private
 *
 * @see serialize_block()
 *
 * @param array    $block         An associative array of a single parsed block object. See WP_Block_Parser_Block.
 * @param callable $pre_callback  Callback to run on each block in the tree before it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $previous_block.
 *                                Its string return value will be prepended to the serialized block markup.
 * @param callable $post_callback Callback to run on each block in the tree after it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $next_block.
 *                                Its string return value will be appended to the serialized block markup.
 * @return string Serialized block markup.
 */
function traverse_and_serialize_block( $block, $pre_callback = null, $post_callback = null ) {
	$block_content = '';
	$block_index   = 0;

	foreach ( $block['innerContent'] as $chunk ) {
		if ( is_string( $chunk ) ) {
			$block_content .= $chunk;
		} else {
			$inner_block = $block['innerBlocks'][ $block_index ];

			if ( is_callable( $pre_callback ) ) {
				$prev = 0 === $block_index
					? null
					: $block['innerBlocks'][ $block_index - 1 ];

				$block_content .= call_user_func_array(
					$pre_callback,
					array( &$inner_block, &$block, $prev )
				);
			}

			if ( is_callable( $post_callback ) ) {
				$next = count( $block['innerBlocks'] ) - 1 === $block_index
					? null
					: $block['innerBlocks'][ $block_index + 1 ];

				$post_markup = call_user_func_array(
					$post_callback,
					array( &$inner_block, &$block, $next )
				);
			}

			$block_content .= traverse_and_serialize_block( $inner_block, $pre_callback, $post_callback );
			$block_content .= isset( $post_markup ) ? $post_markup : '';

			++$block_index;
		}
	}

	if ( ! is_array( $block['attrs'] ) ) {
		$block['attrs'] = array();
	}

	return get_comment_delimited_block_content(
		$block['blockName'],
		$block['attrs'],
		$block_content
	);
}

/**
 * Replaces patterns in a block tree with their content.
 *
 * @since 6.6.0
 *
 * @param array $blocks An array blocks.
 *
 * @return array An array of blocks with patterns replaced by their content.
 */
function resolve_pattern_blocks( $blocks ) {
	static $inner_content;
	// Keep track of seen references to avoid infinite loops.
	static $seen_refs = array();
	$i                = 0;
	while ( $i < count( $blocks ) ) {
		if ( 'core/pattern' === $blocks[ $i ]['blockName'] ) {
			$attrs = $blocks[ $i ]['attrs'];

			if ( empty( $attrs['slug'] ) ) {
				++$i;
				continue;
			}

			$slug = $attrs['slug'];

			if ( isset( $seen_refs[ $slug ] ) ) {
				// Skip recursive patterns.
				array_splice( $blocks, $i, 1 );
				continue;
			}

			$registry = WP_Block_Patterns_Registry::get_instance();
			$pattern  = $registry->get_registered( $slug );

			// Skip unknown patterns.
			if ( ! $pattern ) {
				++$i;
				continue;
			}

			$blocks_to_insert   = parse_blocks( $pattern['content'] );
			$seen_refs[ $slug ] = true;
			$prev_inner_content = $inner_content;
			$inner_content      = null;
			$blocks_to_insert   = resolve_pattern_blocks( $blocks_to_insert );
			$inner_content      = $prev_inner_content;
			unset( $seen_refs[ $slug ] );
			array_splice( $blocks, $i, 1, $blocks_to_insert );

			// If we have inner content, we need to insert nulls in the
			// inner content array, otherwise serialize_blocks will skip
			// blocks.
			if ( $inner_content ) {
				$null_indices  = array_keys( $inner_content, null, true );
				$content_index = $null_indices[ $i ];
				$nulls         = array_fill( 0, count( $blocks_to_insert ), null );
				array_splice( $inner_content, $content_index, 1, $nulls );
			}

			// Skip inserted blocks.
			$i += count( $blocks_to_insert );
		} else {
			if ( ! empty( $blocks[ $i ]['innerBlocks'] ) ) {
				$prev_inner_content           = $inner_content;
				$inner_content                = $blocks[ $i ]['innerContent'];
				$blocks[ $i ]['innerBlocks']  = resolve_pattern_blocks(
					$blocks[ $i ]['innerBlocks']
				);
				$blocks[ $i ]['innerContent'] = $inner_content;
				$inner_content                = $prev_inner_content;
			}
			++$i;
		}
	}
	return $blocks;
}

/**
 * Given an array of parsed block trees, applies callbacks before and after serializing them and
 * returns their concatenated output.
 *
 * Recursively traverses the blocks and their inner blocks and applies the two callbacks provided as
 * arguments, the first one before serializing a block, and the second one after serializing.
 * If either callback returns a string value, it will be prepended and appended to the serialized
 * block markup, respectively.
 *
 * The callbacks will receive a reference to the current block as their first argument, so that they
 * can also modify it, and the current block's parent block as second argument. Finally, the
 * `$pre_callback` receives the previous block, whereas the `$post_callback` receives
 * the next block as third argument.
 *
 * Serialized blocks are returned including comment delimiters, and with all attributes serialized.
 *
 * This function should be used when there is a need to modify the saved blocks, or to inject markup
 * into the return value. Prefer `serialize_blocks` when preparing blocks to be saved to post content.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @access private
 *
 * @see serialize_blocks()
 *
 * @param array[]  $blocks        An array of parsed blocks. See WP_Block_Parser_Block.
 * @param callable $pre_callback  Callback to run on each block in the tree before it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $previous_block.
 *                                Its string return value will be prepended to the serialized block markup.
 * @param callable $post_callback Callback to run on each block in the tree after it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $next_block.
 *                                Its string return value will be appended to the serialized block markup.
 * @return string Serialized block markup.
 */
function traverse_and_serialize_blocks( $blocks, $pre_callback = null, $post_callback = null ) {
	$result       = '';
	$parent_block = null; // At the top level, there is no parent block to pass to the callbacks; yet the callbacks expect a reference.

	$pre_callback_is_callable  = is_callable( $pre_callback );
	$post_callback_is_callable = is_callable( $post_callback );

	foreach ( $blocks as $index => $block ) {
		if ( $pre_callback_is_callable ) {
			$prev = 0 === $index
				? null
				: $blocks[ $index - 1 ];

			$result .= call_user_func_array(
				$pre_callback,
				array( &$block, &$parent_block, $prev )
			);
		}

		if ( $post_callback_is_callable ) {
			$next = count( $blocks ) - 1 === $index
				? null
				: $blocks[ $index + 1 ];

			$post_markup = call_user_func_array(
				$post_callback,
				array( &$block, &$parent_block, $next )
			);
		}

		$result .= traverse_and_serialize_block( $block, $pre_callback, $post_callback );
		$result .= isset( $post_markup ) ? $post_markup : '';
	}

	return $result;
}

/**
 * Filters and sanitizes block content to remove non-allowable HTML
 * from parsed block attribute values.
 *
 * @since 5.3.1
 *
 * @param string         $text              Text that may contain block content.
 * @param array[]|string $allowed_html      Optional. An array of allowed HTML elements and attributes,
 *                                          or a context name such as 'post'. See wp_kses_allowed_html()
 *                                          for the list of accepted context names. Default 'post'.
 * @param string[]       $allowed_protocols Optional. Array of allowed URL protocols.
 *                                          Defaults to the result of wp_allowed_protocols().
 * @return string The filtered and sanitized content result.
 */
function filter_block_content( $text, $allowed_html = 'post', $allowed_protocols = array() ) {
	$result = '';

	if ( str_contains( $text, '<!--' ) && str_contains( $text, '--->' ) ) {
		$text = preg_replace_callback( '%<!--(.*?)--->%', '_filter_block_content_callback', $text );
	}

	$blocks = parse_blocks( $text );
	foreach ( $blocks as $block ) {
		$block   = filter_block_kses( $block, $allowed_html, $allowed_protocols );
		$result .= serialize_block( $block );
	}

	return $result;
}

/**
 * Callback used for regular expression replacement in filter_block_content().
 *
 * @since 6.2.1
 * @access private
 *
 * @param array $matches Array of preg_replace_callback matches.
 * @return string Replacement string.
 */
function _filter_block_content_callback( $matches ) {
	return '<!--' . rtrim( $matches[1], '-' ) . '-->';
}

/**
 * Filters and sanitizes a parsed block to remove non-allowable HTML
 * from block attribute values.
 *
 * @since 5.3.1
 *
 * @param WP_Block_Parser_Block $block             The parsed block object.
 * @param array[]|string        $allowed_html      An array of allowed HTML elements and attributes,
 *                                                 or a context name such as 'post'. See wp_kses_allowed_html()
 *                                                 for the list of accepted context names.
 * @param string[]              $allowed_protocols Optional. Array of allowed URL protocols.
 *                                                 Defaults to the result of wp_allowed_protocols().
 * @return array The filtered and sanitized block object result.
 */
function filter_block_kses( $block, $allowed_html, $allowed_protocols = array() ) {
	$block['attrs'] = filter_block_kses_value( $block['attrs'], $allowed_html, $allowed_protocols, $block );

	if ( is_array( $block['innerBlocks'] ) ) {
		foreach ( $block['innerBlocks'] as $i => $inner_block ) {
			$block['innerBlocks'][ $i ] = filter_block_kses( $inner_block, $allowed_html, $allowed_protocols );
		}
	}

	return $block;
}

/**
 * Filters and sanitizes a parsed block attribute value to remove
 * non-allowable HTML.
 *
 * @since 5.3.1
 * @since 6.5.5 Added the `$block_context` parameter.
 *
 * @param string[]|string $value             The attribute value to filter.
 * @param array[]|string  $allowed_html      An array of allowed HTML elements and attributes,
 *                                           or a context name such as 'post'. See wp_kses_allowed_html()
 *                                           for the list of accepted context names.
 * @param string[]        $allowed_protocols Optional. Array of allowed URL protocols.
 *                                           Defaults to the result of wp_allowed_protocols().
 * @param array           $block_context     Optional. The block the attribute belongs to, in parsed block array format.
 * @return string[]|string The filtered and sanitized result.
 */
function filter_block_kses_value( $value, $allowed_html, $allowed_protocols = array(), $block_context = null ) {
	if ( is_array( $value ) ) {
		foreach ( $value as $key => $inner_value ) {
			$filtered_key   = filter_block_kses_value( $key, $allowed_html, $allowed_protocols, $block_context );
			$filtered_value = filter_block_kses_value( $inner_value, $allowed_html, $allowed_protocols, $block_context );

			if ( isset( $block_context['blockName'] ) && 'core/template-part' === $block_context['blockName'] ) {
				$filtered_value = filter_block_core_template_part_attributes( $filtered_value, $filtered_key, $allowed_html );
			}
			if ( $filtered_key !== $key ) {
				unset( $value[ $key ] );
			}

			$value[ $filtered_key ] = $filtered_value;
		}
	} elseif ( is_string( $value ) ) {
		return wp_kses( $value, $allowed_html, $allowed_protocols );
	}

	return $value;
}

/**
 * Sanitizes the value of the Template Part block's `tagName` attribute.
 *
 * @since 6.5.5
 *
 * @param string         $attribute_value The attribute value to filter.
 * @param string         $attribute_name  The attribute name.
 * @param array[]|string $allowed_html    An array of allowed HTML elements and attributes,
 *                                        or a context name such as 'post'. See wp_kses_allowed_html()
 *                                        for the list of accepted context names.
 * @return string The sanitized attribute value.
 */
function filter_block_core_template_part_attributes( $attribute_value, $attribute_name, $allowed_html ) {
	if ( empty( $attribute_value ) || 'tagName' !== $attribute_name ) {
		return $attribute_value;
	}
	if ( ! is_array( $allowed_html ) ) {
		$allowed_html = wp_kses_allowed_html( $allowed_html );
	}
	return isset( $allowed_html[ $attribute_value ] ) ? $attribute_value : '';
}

/**
 * Parses blocks out of a content string, and renders those appropriate for the excerpt.
 *
 * As the excerpt should be a small string of text relevant to the full post content,
 * this function renders the blocks that are most likely to contain such text.
 *
 * @since 5.0.0
 *
 * @param string $content The content to parse.
 * @return string The parsed and filtered content.
 */
function excerpt_remove_blocks( $content ) {
	if ( ! has_blocks( $content ) ) {
		return $content;
	}

	$allowed_inner_blocks = array(
		// Classic blocks have their blockName set to null.
		null,
		'core/freeform',
		'core/heading',
		'core/html',
		'core/list',
		'core/media-text',
		'core/paragraph',
		'core/preformatted',
		'core/pullquote',
		'core/quote',
		'core/table',
		'core/verse',
	);

	$allowed_wrapper_blocks = array(
		'core/columns',
		'core/column',
		'core/group',
	);

	/**
	 * Filters the list of blocks that can be used as wrapper blocks, allowing
	 * excerpts to be generated from the `innerBlocks` of these wrappers.
	 *
	 * @since 5.8.0
	 *
	 * @param string[] $allowed_wrapper_blocks The list of names of allowed wrapper blocks.
	 */
	$allowed_wrapper_blocks = apply_filters( 'excerpt_allowed_wrapper_blocks', $allowed_wrapper_blocks );

	$allowed_blocks = array_merge( $allowed_inner_blocks, $allowed_wrapper_blocks );

	/**
	 * Filters the list of blocks that can contribute to the excerpt.
	 *
	 * If a dynamic block is added to this list, it must not generate another
	 * excerpt, as this will cause an infinite loop to occur.
	 *
	 * @since 5.0.0
	 *
	 * @param string[] $allowed_blocks The list of names of allowed blocks.
	 */
	$allowed_blocks = apply_filters( 'excerpt_allowed_blocks', $allowed_blocks );
	$blocks         = parse_blocks( $content );
	$output         = '';

	foreach ( $blocks as $block ) {
		if ( in_array( $block['blockName'], $allowed_blocks, true ) ) {
			if ( ! empty( $block['innerBlocks'] ) ) {
				if ( in_array( $block['blockName'], $allowed_wrapper_blocks, true ) ) {
					$output .= _excerpt_render_inner_blocks( $block, $allowed_blocks );
					continue;
				}

				// Skip the block if it has disallowed or nested inner blocks.
				foreach ( $block['innerBlocks'] as $inner_block ) {
					if (
						! in_array( $inner_block['blockName'], $allowed_inner_blocks, true ) ||
						! empty( $inner_block['innerBlocks'] )
					) {
						continue 2;
					}
				}
			}

			$output .= render_block( $block );
		}
	}

	return $output;
}

/**
 * Parses footnotes markup out of a content string,
 * and renders those appropriate for the excerpt.
 *
 * @since 6.3.0
 *
 * @param string $content The content to parse.
 * @return string The parsed and filtered content.
 */
function excerpt_remove_footnotes( $content ) {
	if ( ! str_contains( $content, 'data-fn=' ) ) {
		return $content;
	}

	return preg_replace(
		'_<sup data-fn="[^"]+" class="[^"]+">\s*<a href="[^"]+" id="[^"]+">\d+</a>\s*</sup>_',
		'',
		$content
	);
}

/**
 * Renders inner blocks from the allowed wrapper blocks
 * for generating an excerpt.
 *
 * @since 5.8.0
 * @access private
 *
 * @param array $parsed_block   The parsed block.
 * @param array $allowed_blocks The list of allowed inner blocks.
 * @return string The rendered inner blocks.
 */
function _excerpt_render_inner_blocks( $parsed_block, $allowed_blocks ) {
	$output = '';

	foreach ( $parsed_block['innerBlocks'] as $inner_block ) {
		if ( ! in_array( $inner_block['blockName'], $allowed_blocks, true ) ) {
			continue;
		}

		if ( empty( $inner_block['innerBlocks'] ) ) {
			$output .= render_block( $inner_block );
		} else {
			$output .= _excerpt_render_inner_blocks( $inner_block, $allowed_blocks );
		}
	}

	return $output;
}

/**
 * Renders a single block into a HTML string.
 *
 * @since 5.0.0
 *
 * @global WP_Post $post The post to edit.
 *
 * @param array $parsed_block {
 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
 *
 *     @type string   $blockName    Name of block.
 *     @type array    $attrs        Attributes from block comment delimiters.
 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                  have the same structure as this one.
 *     @type string   $innerHTML    HTML from inside block comment delimiters.
 *     @type array    $innerContent List of string fragments and null markers where
 *                                  inner blocks were found.
 * }
 * @return string String of rendered HTML.
 */
function render_block( $parsed_block ) {
	global $post;
	$parent_block = null;

	/**
	 * Allows render_block() to be short-circuited, by returning a non-null value.
	 *
	 * @since 5.1.0
	 * @since 5.9.0 The `$parent_block` parameter was added.
	 *
	 * @param string|null   $pre_render   The pre-rendered content. Default null.
	 * @param array         $parsed_block {
	 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param WP_Block|null $parent_block If this is a nested block, a reference to the parent block.
	 */
	$pre_render = apply_filters( 'pre_render_block', null, $parsed_block, $parent_block );
	if ( ! is_null( $pre_render ) ) {
		return $pre_render;
	}

	$source_block = $parsed_block;

	/**
	 * Filters the block being rendered in render_block(), before it's processed.
	 *
	 * @since 5.1.0
	 * @since 5.9.0 The `$parent_block` parameter was added.
	 *
	 * @param array         $parsed_block {
	 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param array         $source_block {
	 *     An un-modified copy of `$parsed_block`, as it appeared in the source content.
	 *     See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param WP_Block|null $parent_block If this is a nested block, a reference to the parent block.
	 */
	$parsed_block = apply_filters( 'render_block_data', $parsed_block, $source_block, $parent_block );

	$context = array();

	if ( $post instanceof WP_Post ) {
		$context['postId'] = $post->ID;

		/*
		 * The `postType` context is largely unnecessary server-side, since the ID
		 * is usually sufficient on its own. That being said, since a block's
		 * manifest is expected to be shared between the server and the client,
		 * it should be included to consistently fulfill the expectation.
		 */
		$context['postType'] = $post->post_type;
	}

	/**
	 * Filters the default context provided to a rendered block.
	 *
	 * @since 5.5.0
	 * @since 5.9.0 The `$parent_block` parameter was added.
	 *
	 * @param array         $context      Default context.
	 * @param array         $parsed_block {
	 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param WP_Block|null $parent_block If this is a nested block, a reference to the parent block.
	 */
	$context = apply_filters( 'render_block_context', $context, $parsed_block, $parent_block );

	$block = new WP_Block( $parsed_block, $context );

	return $block->render();
}

/**
 * Parses blocks out of a content string.
 *
 * @since 5.0.0
 *
 * @param string $content Post content.
 * @return array[] {
 *     Array of block structures.
 *
 *     @type array ...$0 {
 *         An associative array of a single parsed block object. See WP_Block_Parser_Block.
 *
 *         @type string   $blockName    Name of block.
 *         @type array    $attrs        Attributes from block comment delimiters.
 *         @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                      have the same structure as this one.
 *         @type string   $innerHTML    HTML from inside block comment delimiters.
 *         @type array    $innerContent List of string fragments and null markers where
 *                                      inner blocks were found.
 *     }
 * }
 */
function parse_blocks( $content ) {
	/**
	 * Filter to allow plugins to replace the server-side block parser.
	 *
	 * @since 5.0.0
	 *
	 * @param string $parser_class Name of block parser class.
	 */
	$parser_class = apply_filters( 'block_parser_class', 'WP_Block_Parser' );

	$parser = new $parser_class();
	return $parser->parse( $content );
}

/**
 * Parses dynamic blocks out of `post_content` and re-renders them.
 *
 * @since 5.0.0
 *
 * @param string $content Post content.
 * @return string Updated post content.
 */
function do_blocks( $content ) {
	$blocks = parse_blocks( $content );
	$output = '';

	foreach ( $blocks as $block ) {
		$output .= render_block( $block );
	}

	// If there are blocks in this content, we shouldn't run wpautop() on it later.
	$priority = has_filter( 'the_content', 'wpautop' );
	if ( false !== $priority && doing_filter( 'the_content' ) && has_blocks( $content ) ) {
		remove_filter( 'the_content', 'wpautop', $priority );
		add_filter( 'the_content', '_restore_wpautop_hook', $priority + 1 );
	}

	return $output;
}

/**
 * If do_blocks() needs to remove wpautop() from the `the_content` filter, this re-adds it afterwards,
 * for subsequent `the_content` usage.
 *
 * @since 5.0.0
 * @access private
 *
 * @param string $content The post content running through this filter.
 * @return string The unmodified content.
 */
function _restore_wpautop_hook( $content ) {
	$current_priority = has_filter( 'the_content', '_restore_wpautop_hook' );

	add_filter( 'the_content', 'wpautop', $current_priority - 1 );
	remove_filter( 'the_content', '_restore_wpautop_hook', $current_priority );

	return $content;
}

/**
 * Returns the current version of the block format that the content string is using.
 *
 * If the string doesn't contain blocks, it returns 0.
 *
 * @since 5.0.0
 *
 * @param string $content Content to test.
 * @return int The block format version is 1 if the content contains one or more blocks, 0 otherwise.
 */
function block_version( $content ) {
	return has_blocks( $content ) ? 1 : 0;
}

/**
 * Registers a new block style.
 *
 * @since 5.3.0
 * @since 6.6.0 Added support for registering styles for multiple block types.
 *
 * @link https://developer.wordpress.org/block-editor/reference-guides/block-api/block-styles/
 *
 * @param string|string[] $block_name       Block type name including namespace or array of namespaced block type names.
 * @param array           $style_properties Array containing the properties of the style name, label,
 *                                          style_handle (name of the stylesheet to be enqueued),
 *                                          inline_style (string containing the CSS to be added),
 *                                          style_data (theme.json-like array to generate CSS from).
 *                                          See WP_Block_Styles_Registry::register().
 * @return bool True if the block style was registered with success and false otherwise.
 */
function register_block_style( $block_name, $style_properties ) {
	return WP_Block_Styles_Registry::get_instance()->register( $block_name, $style_properties );
}

/**
 * Unregisters a block style.
 *
 * @since 5.3.0
 *
 * @param string $block_name       Block type name including namespace.
 * @param string $block_style_name Block style name.
 * @return bool True if the block style was unregistered with success and false otherwise.
 */
function unregister_block_style( $block_name, $block_style_name ) {
	return WP_Block_Styles_Registry::get_instance()->unregister( $block_name, $block_style_name );
}

/**
 * Checks whether the current block type supports the feature requested.
 *
 * @since 5.8.0
 * @since 6.4.0 The `$feature` parameter now supports a string.
 *
 * @param WP_Block_Type $block_type    Block type to check for support.
 * @param string|array  $feature       Feature slug, or path to a specific feature to check support for.
 * @param mixed         $default_value Optional. Fallback value for feature support. Default false.
 * @return bool Whether the feature is supported.
 */
function block_has_support( $block_type, $feature, $default_value = false ) {
	$block_support = $default_value;
	if ( $block_type instanceof WP_Block_Type ) {
		if ( is_array( $feature ) && count( $feature ) === 1 ) {
			$feature = $feature[0];
		}

		if ( is_array( $feature ) ) {
			$block_support = _wp_array_get( $block_type->supports, $feature, $default_value );
		} elseif ( isset( $block_type->supports[ $feature ] ) ) {
			$block_support = $block_type->supports[ $feature ];
		}
	}

	return true === $block_support || is_array( $block_support );
}

/**
 * Converts typography keys declared under `supports.*` to `supports.typography.*`.
 *
 * Displays a `_doing_it_wrong()` notice when a block using the older format is detected.
 *
 * @since 5.8.0
 *
 * @param array $metadata Metadata for registering a block type.
 * @return array Filtered metadata for registering a block type.
 */
function wp_migrate_old_typography_shape( $metadata ) {
	if ( ! isset( $metadata['supports'] ) ) {
		return $metadata;
	}

	$typography_keys = array(
		'__experimentalFontFamily',
		'__experimentalFontStyle',
		'__experimentalFontWeight',
		'__experimentalLetterSpacing',
		'__experimentalTextDecoration',
		'__experimentalTextTransform',
		'fontSize',
		'lineHeight',
	);

	foreach ( $typography_keys as $typography_key ) {
		$support_for_key = isset( $metadata['supports'][ $typography_key ] ) ? $metadata['supports'][ $typography_key ] : null;

		if ( null !== $support_for_key ) {
			_doing_it_wrong(
				'register_block_type_from_metadata()',
				sprintf(
					/* translators: 1: Block type, 2: Typography supports key, e.g: fontSize, lineHeight, etc. 3: block.json, 4: Old metadata key, 5: New metadata key. */
					__( 'Block "%1$s" is declaring %2$s support in %3$s file under %4$s. %2$s support is now declared under %5$s.' ),
					$metadata['name'],
					"<code>$typography_key</code>",
					'<code>block.json</code>',
					"<code>supports.$typography_key</code>",
					"<code>supports.typography.$typography_key</code>"
				),
				'5.8.0'
			);

			_wp_array_set( $metadata['supports'], array( 'typography', $typography_key ), $support_for_key );
			unset( $metadata['supports'][ $typography_key ] );
		}
	}

	return $metadata;
}

/**
 * Helper function that constructs a WP_Query args array from
 * a `Query` block properties.
 *
 * It's used in Query Loop, Query Pagination Numbers and Query Pagination Next blocks.
 *
 * @since 5.8.0
 * @since 6.1.0 Added `query_loop_block_query_vars` filter and `parents` support in query.
 * @since 6.7.0 Added support for the `format` property in query.
 *
 * @param WP_Block $block Block instance.
 * @param int      $page  Current query's page.
 *
 * @return array Returns the constructed WP_Query arguments.
 */
function build_query_vars_from_query_block( $block, $page ) {
	$query = array(
		'post_type'    => 'post',
		'order'        => 'DESC',
		'orderby'      => 'date',
		'post__not_in' => array(),
		'tax_query'    => array(),
	);

	if ( isset( $block->context['query'] ) ) {
		if ( ! empty( $block->context['query']['postType'] ) ) {
			$post_type_param = $block->context['query']['postType'];
			if ( is_post_type_viewable( $post_type_param ) ) {
				$query['post_type'] = $post_type_param;
			}
		}
		if ( isset( $block->context['query']['sticky'] ) && ! empty( $block->context['query']['sticky'] ) ) {
			$sticky = get_option( 'sticky_posts' );
			if ( 'only' === $block->context['query']['sticky'] ) {
				/*
				 * Passing an empty array to post__in will return have_posts() as true (and all posts will be returned).
				 * Logic should be used before hand to determine if WP_Query should be used in the event that the array
				 * being passed to post__in is empty.
				 *
				 * @see https://core.trac.wordpress.org/ticket/28099
				 */
				$query['post__in']            = ! empty( $sticky ) ? $sticky : array( 0 );
				$query['ignore_sticky_posts'] = 1;
			} else {
				$query['post__not_in'] = array_merge( $query['post__not_in'], $sticky );
			}
		}
		if ( ! empty( $block->context['query']['exclude'] ) ) {
			$excluded_post_ids     = array_map( 'intval', $block->context['query']['exclude'] );
			$excluded_post_ids     = array_filter( $excluded_post_ids );
			$query['post__not_in'] = array_merge( $query['post__not_in'], $excluded_post_ids );
		}
		if (
			isset( $block->context['query']['perPage'] ) &&
			is_numeric( $block->context['query']['perPage'] )
		) {
			$per_page = absint( $block->context['query']['perPage'] );
			$offset   = 0;

			if (
				isset( $block->context['query']['offset'] ) &&
				is_numeric( $block->context['query']['offset'] )
			) {
				$offset = absint( $block->context['query']['offset'] );
			}

			$query['offset']         = ( $per_page * ( $page - 1 ) ) + $offset;
			$query['posts_per_page'] = $per_page;
		}
		// Migrate `categoryIds` and `tagIds` to `tax_query` for backwards compatibility.
		if ( ! empty( $block->context['query']['categoryIds'] ) || ! empty( $block->context['query']['tagIds'] ) ) {
			$tax_query_back_compat = array();
			if ( ! empty( $block->context['query']['categoryIds'] ) ) {
				$tax_query_back_compat[] = array(
					'taxonomy'         => 'category',
					'terms'            => array_filter( array_map( 'intval', $block->context['query']['categoryIds'] ) ),
					'include_children' => false,
				);
			}
			if ( ! empty( $block->context['query']['tagIds'] ) ) {
				$tax_query_back_compat[] = array(
					'taxonomy'         => 'post_tag',
					'terms'            => array_filter( array_map( 'intval', $block->context['query']['tagIds'] ) ),
					'include_children' => false,
				);
			}
			$query['tax_query'] = array_merge( $query['tax_query'], $tax_query_back_compat );
		}
		if ( ! empty( $block->context['query']['taxQuery'] ) ) {
			$tax_query = array();
			foreach ( $block->context['query']['taxQuery'] as $taxonomy => $terms ) {
				if ( is_taxonomy_viewable( $taxonomy ) && ! empty( $terms ) ) {
					$tax_query[] = array(
						'taxonomy'         => $taxonomy,
						'terms'            => array_filter( array_map( 'intval', $terms ) ),
						'include_children' => false,
					);
				}
			}
			$query['tax_query'] = array_merge( $query['tax_query'], $tax_query );
		}
		if ( ! empty( $block->context['query']['format'] ) && is_array( $block->context['query']['format'] ) ) {
			$formats = $block->context['query']['format'];
			/*
			 * Validate that the format is either `standard` or a supported post format.
			 * - First, add `standard` to the array of valid formats.
			 * - Then, remove any invalid formats.
			 */
			$valid_formats = array_merge( array( 'standard' ), get_post_format_slugs() );
			$formats       = array_intersect( $formats, $valid_formats );

			/*
			 * The relation needs to be set to `OR` since the request can contain
			 * two separate conditions. The user may be querying for items that have
			 * either the `standard` format or a specific format.
			 */
			$formats_query = array( 'relation' => 'OR' );

			/*
			 * The default post format, `standard`, is not stored in the database.
			 * If `standard` is part of the request, the query needs to exclude all post items that
			 * have a format assigned.
			 */
			if ( in_array( 'standard', $formats, true ) ) {
				$formats_query[] = array(
					'taxonomy' => 'post_format',
					'field'    => 'slug',
					'operator' => 'NOT EXISTS',
				);
				// Remove the `standard` format, since it cannot be queried.
				unset( $formats[ array_search( 'standard', $formats, true ) ] );
			}
			// Add any remaining formats to the formats query.
			if ( ! empty( $formats ) ) {
				// Add the `post-format-` prefix.
				$terms           = array_map(
					static function ( $format ) {
						return "post-format-$format";
					},
					$formats
				);
				$formats_query[] = array(
					'taxonomy' => 'post_format',
					'field'    => 'slug',
					'terms'    => $terms,
					'operator' => 'IN',
				);
			}

			/*
			 * Add `$formats_query` to `$query`, as long as it contains more than one key:
			 * If `$formats_query` only contains the initial `relation` key, there are no valid formats to query,
			 * and the query should not be modified.
			 */
			if ( count( $formats_query ) > 1 ) {
				// Enable filtering by both post formats and other taxonomies by combining them with `AND`.
				if ( empty( $query['tax_query'] ) ) {
					$query['tax_query'] = $formats_query;
				} else {
					$query['tax_query'] = array(
						'relation' => 'AND',
						$query['tax_query'],
						$formats_query,
					);
				}
			}
		}

		if (
			isset( $block->context['query']['order'] ) &&
				in_array( strtoupper( $block->context['query']['order'] ), array( 'ASC', 'DESC' ), true )
		) {
			$query['order'] = strtoupper( $block->context['query']['order'] );
		}
		if ( isset( $block->context['query']['orderBy'] ) ) {
			$query['orderby'] = $block->context['query']['orderBy'];
		}
		if (
			isset( $block->context['query']['author'] )
		) {
			if ( is_array( $block->context['query']['author'] ) ) {
				$query['author__in'] = array_filter( array_map( 'intval', $block->context['query']['author'] ) );
			} elseif ( is_string( $block->context['query']['author'] ) ) {
				$query['author__in'] = array_filter( array_map( 'intval', explode( ',', $block->context['query']['author'] ) ) );
			} elseif ( is_int( $block->context['query']['author'] ) && $block->context['query']['author'] > 0 ) {
				$query['author'] = $block->context['query']['author'];
			}
		}
		if ( ! empty( $block->context['query']['search'] ) ) {
			$query['s'] = $block->context['query']['search'];
		}
		if ( ! empty( $block->context['query']['parents'] ) && is_post_type_hierarchical( $query['post_type'] ) ) {
			$query['post_parent__in'] = array_filter( array_map( 'intval', $block->context['query']['parents'] ) );
		}
	}

	/**
	 * Filters the arguments which will be passed to `WP_Query` for the Query Loop Block.
	 *
	 * Anything to this filter should be compatible with the `WP_Query` API to form
	 * the query context which will be passed down to the Query Loop Block's children.
	 * This can help, for example, to include additional settings or meta queries not
	 * directly supported by the core Query Loop Block, and extend its capabilities.
	 *
	 * Please note that this will only influence the query that will be rendered on the
	 * front-end. The editor preview is not affected by this filter. Also, worth noting
	 * that the editor preview uses the REST API, so, ideally, one should aim to provide
	 * attributes which are also compatible with the REST API, in order to be able to
	 * implement identical queries on both sides.
	 *
	 * @since 6.1.0
	 *
	 * @param array    $query Array containing parameters for `WP_Query` as parsed by the block context.
	 * @param WP_Block $block Block instance.
	 * @param int      $page  Current query's page.
	 */
	return apply_filters( 'query_loop_block_query_vars', $query, $block, $page );
}

/**
 * Helper function that returns the proper pagination arrow HTML for
 * `QueryPaginationNext` and `QueryPaginationPrevious` blocks based
 * on the provided `paginationArrow` from `QueryPagination` context.
 *
 * It's used in QueryPaginationNext and QueryPaginationPrevious blocks.
 *
 * @since 5.9.0
 *
 * @param WP_Block $block   Block instance.
 * @param bool     $is_next Flag for handling `next/previous` blocks.
 * @return string|null The pagination arrow HTML or null if there is none.
 */
function get_query_pagination_arrow( $block, $is_next ) {
	$arrow_map = array(
		'none'    => '',
		'arrow'   => array(
			'next'     => '→',
			'previous' => '←',
		),
		'chevron' => array(
			'next'     => '»',
			'previous' => '«',
		),
	);
	if ( ! empty( $block->context['paginationArrow'] ) && array_key_exists( $block->context['paginationArrow'], $arrow_map ) && ! empty( $arrow_map[ $block->context['paginationArrow'] ] ) ) {
		$pagination_type = $is_next ? 'next' : 'previous';
		$arrow_attribute = $block->context['paginationArrow'];
		$arrow           = $arrow_map[ $block->context['paginationArrow'] ][ $pagination_type ];
		$arrow_classes   = "wp-block-query-pagination-$pagination_type-arrow is-arrow-$arrow_attribute";
		return "<span class='$arrow_classes' aria-hidden='true'>$arrow</span>";
	}
	return null;
}

/**
 * Helper function that constructs a comment query vars array from the passed
 * block properties.
 *
 * It's used with the Comment Query Loop inner blocks.
 *
 * @since 6.0.0
 *
 * @param WP_Block $block Block instance.
 * @return array Returns the comment query parameters to use with the
 *               WP_Comment_Query constructor.
 */
function build_comment_query_vars_from_block( $block ) {

	$comment_args = array(
		'orderby'       => 'comment_date_gmt',
		'order'         => 'ASC',
		'status'        => 'approve',
		'no_found_rows' => false,
	);

	if ( is_user_logged_in() ) {
		$comment_args['include_unapproved'] = array( get_current_user_id() );
	} else {
		$unapproved_email = wp_get_unapproved_comment_author_email();

		if ( $unapproved_email ) {
			$comment_args['include_unapproved'] = array( $unapproved_email );
		}
	}

	if ( ! empty( $block->context['postId'] ) ) {
		$comment_args['post_id'] = (int) $block->context['postId'];
	}

	if ( get_option( 'thread_comments' ) ) {
		$comment_args['hierarchical'] = 'threaded';
	} else {
		$comment_args['hierarchical'] = false;
	}

	if ( get_option( 'page_comments' ) === '1' || get_option( 'page_comments' ) === true ) {
		$per_page     = get_option( 'comments_per_page' );
		$default_page = get_option( 'default_comments_page' );
		if ( $per_page > 0 ) {
			$comment_args['number'] = $per_page;

			$page = (int) get_query_var( 'cpage' );
			if ( $page ) {
				$comment_args['paged'] = $page;
			} elseif ( 'oldest' === $default_page ) {
				$comment_args['paged'] = 1;
			} elseif ( 'newest' === $default_page ) {
				$max_num_pages = (int) ( new WP_Comment_Query( $comment_args ) )->max_num_pages;
				if ( 0 !== $max_num_pages ) {
					$comment_args['paged'] = $max_num_pages;
				}
			}
		}
	}

	return $comment_args;
}

/**
 * Helper function that returns the proper pagination arrow HTML for
 * `CommentsPaginationNext` and `CommentsPaginationPrevious` blocks based on the
 * provided `paginationArrow` from `CommentsPagination` context.
 *
 * It's used in CommentsPaginationNext and CommentsPaginationPrevious blocks.
 *
 * @since 6.0.0
 *
 * @param WP_Block $block           Block instance.
 * @param string   $pagination_type Optional. Type of the arrow we will be rendering.
 *                                  Accepts 'next' or 'previous'. Default 'next'.
 * @return string|null The pagination arrow HTML or null if there is none.
 */
function get_comments_pagination_arrow( $block, $pagination_type = 'next' ) {
	$arrow_map = array(
		'none'    => '',
		'arrow'   => array(
			'next'     => '→',
			'previous' => '←',
		),
		'chevron' => array(
			'next'     => '»',
			'previous' => '«',
		),
	);
	if ( ! empty( $block->context['comments/paginationArrow'] ) && ! empty( $arrow_map[ $block->context['comments/paginationArrow'] ][ $pagination_type ] ) ) {
		$arrow_attribute = $block->context['comments/paginationArrow'];
		$arrow           = $arrow_map[ $block->context['comments/paginationArrow'] ][ $pagination_type ];
		$arrow_classes   = "wp-block-comments-pagination-$pagination_type-arrow is-arrow-$arrow_attribute";
		return "<span class='$arrow_classes' aria-hidden='true'>$arrow</span>";
	}
	return null;
}

/**
 * Strips all HTML from the content of footnotes, and sanitizes the ID.
 *
 * This function expects slashed data on the footnotes content.
 *
 * @access private
 * @since 6.3.2
 *
 * @param string $footnotes JSON-encoded string of an array containing the content and ID of each footnote.
 * @return string Filtered content without any HTML on the footnote content and with the sanitized ID.
 */
function _wp_filter_post_meta_footnotes( $footnotes ) {
	$footnotes_decoded = json_decode( $footnotes, true );
	if ( ! is_array( $footnotes_decoded ) ) {
		return '';
	}
	$footnotes_sanitized = array();
	foreach ( $footnotes_decoded as $footnote ) {
		if ( ! empty( $footnote['content'] ) && ! empty( $footnote['id'] ) ) {
			$footnotes_sanitized[] = array(
				'id'      => sanitize_key( $footnote['id'] ),
				'content' => wp_unslash( wp_filter_post_kses( wp_slash( $footnote['content'] ) ) ),
			);
		}
	}
	return wp_json_encode( $footnotes_sanitized );
}

/**
 * Adds the filters for footnotes meta field.
 *
 * @access private
 * @since 6.3.2
 */
function _wp_footnotes_kses_init_filters() {
	add_filter( 'sanitize_post_meta_footnotes', '_wp_filter_post_meta_footnotes' );
}

/**
 * Removes the filters for footnotes meta field.
 *
 * @access private
 * @since 6.3.2
 */
function _wp_footnotes_remove_filters() {
	remove_filter( 'sanitize_post_meta_footnotes', '_wp_filter_post_meta_footnotes' );
}

/**
 * Registers the filter of footnotes meta field if the user does not have `unfiltered_html` capability.
 *
 * @access private
 * @since 6.3.2
 */
function _wp_footnotes_kses_init() {
	_wp_footnotes_remove_filters();
	if ( ! current_user_can( 'unfiltered_html' ) ) {
		_wp_footnotes_kses_init_filters();
	}
}

/**
 * Initializes the filters for footnotes meta field when imported data should be filtered.
 *
 * This filter is the last one being executed on {@see 'force_filtered_html_on_import'}.
 * If the input of the filter is true, it means we are in an import situation and should
 * enable kses, independently of the user capabilities. So in that case we call
 * _wp_footnotes_kses_init_filters().
 *
 * @access private
 * @since 6.3.2
 *
 * @param string $arg Input argument of the filter.
 * @return string Input argument of the filter.
 */
function _wp_footnotes_force_filtered_html_on_import_filter( $arg ) {
	// If `force_filtered_html_on_import` is true, we need to init the global styles kses filters.
	if ( $arg ) {
		_wp_footnotes_kses_init_filters();
	}
	return $arg;
}