<?php
/**
 * Block support flags.
 *
 * @package WordPress
 *
 * @since 5.6.0
 */

/**
 * Class encapsulating and implementing Block Supports.
 *
 * @since 5.6.0
 *
 * @access private
 *
 * @phpstan-type ApplyCallback callable( WP_Block_Type, array<string, mixed> ): array<string, mixed>
 * @phpstan-type RegisterCallback callable( WP_Block_Type ): void
 */
#[AllowDynamicProperties]
class WP_Block_Supports {

	/**
	 * Config.
	 *
	 * @since 5.6.0
	 * @var array
	 * @phpstan-var array<string, array{
	 *     name: string,
	 *     apply?: ApplyCallback,
	 *     register_attribute?: RegisterCallback,
	 * }>
	 */
	private $block_supports = array();

	/**
	 * Tracks the current block to be rendered.
	 *
	 * @since 5.6.0
	 * @var array|null
	 * @phpstan-var array<string, mixed>|null
	 */
	public static $block_to_render = null;

	/**
	 * Container for the main instance of the class.
	 *
	 * @since 5.6.0
	 * @var WP_Block_Supports|null
	 */
	private static $instance = null;

	/**
	 * Utility method to retrieve the main instance of the class.
	 *
	 * The instance will be created if it does not exist yet.
	 *
	 * @since 5.6.0
	 *
	 * @return WP_Block_Supports The main instance.
	 */
	public static function get_instance() {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}

		return self::$instance;
	}

	/**
	 * Initializes the block supports. It registers the block supports block attributes.
	 *
	 * @since 5.6.0
	 *
	 * @return void
	 */
	public static function init() {
		$instance = self::get_instance();
		$instance->register_attributes();
	}

	/**
	 * Registers a block support.
	 *
	 * @since 5.6.0
	 *
	 * @link https://developer.wordpress.org/block-editor/reference-guides/block-api/block-supports/
	 *
	 * @param string $block_support_name   Block support name.
	 * @param array  $block_support_config Array containing the properties of the block support.
	 *
	 * @phpstan-param array{
	 *     apply?: ApplyCallback,
	 *     register_attribute?: RegisterCallback,
	 * } $block_support_config
	 *
	 * @return void
	 */
	public function register( $block_support_name, $block_support_config ) {
		$this->block_supports[ $block_support_name ] = array_merge(
			$block_support_config,
			array( 'name' => $block_support_name )
		);
	}

	/**
	 * Generates an array of HTML attributes, such as classes, by applying to
	 * the given block all of the features that the block supports.
	 *
	 * @since 5.6.0
	 *
	 * @return string[] Array of HTML attribute values keyed by their name.
	 */
	public function apply_block_supports() {
		if ( ! is_array( self::$block_to_render ) ) {
			return array();
		}

		$block_type = WP_Block_Type_Registry::get_instance()->get_registered(
			self::$block_to_render['blockName']
		);

		// If no render_callback, assume styles have been previously handled.
		if ( ! $block_type ) {
			return array();
		}

		$block_attributes = array_key_exists( 'attrs', self::$block_to_render ) && is_array( self::$block_to_render['attrs'] )
			? $block_type->prepare_attributes_for_render( self::$block_to_render['attrs'] )
			: array();

		$output = array();
		foreach ( $this->block_supports as $block_support_config ) {
			if ( ! isset( $block_support_config['apply'] ) ) {
				continue;
			}

			$new_attributes = call_user_func(
				$block_support_config['apply'],
				$block_type,
				$block_attributes
			);

			if ( ! empty( $new_attributes ) ) {
				foreach ( $new_attributes as $attribute_name => $attribute_value ) {
					if ( ! is_scalar( $attribute_value ) || is_bool( $attribute_value ) ) {
						continue;
					}
					$attribute_value = (string) $attribute_value;
					if ( ! array_key_exists( $attribute_name, $output ) || '' === $output[ $attribute_name ] ) {
						$output[ $attribute_name ] = $attribute_value;
					} else {
						$output[ $attribute_name ] .= " $attribute_value";
					}
				}
			}
		}

		return $output;
	}

	/**
	 * Registers the block attributes required by the different block supports.
	 *
	 * @since 5.6.0
	 *
	 * @return void
	 */
	private function register_attributes() {
		$block_registry         = WP_Block_Type_Registry::get_instance();
		$registered_block_types = $block_registry->get_all_registered();
		foreach ( $registered_block_types as $block_type ) {
			if ( ! ( $block_type instanceof WP_Block_Type ) ) {
				continue;
			}
			if ( ! $block_type->attributes ) {
				$block_type->attributes = array();
			}

			foreach ( $this->block_supports as $block_support_config ) {
				if ( ! isset( $block_support_config['register_attribute'] ) ) {
					continue;
				}

				call_user_func(
					$block_support_config['register_attribute'],
					$block_type
				);
			}
		}
	}
}

/**
 * Generates a string of attributes by applying to the current block being
 * rendered all of the features that the block supports.
 *
 * @since 5.6.0
 *
 * @param string[] $extra_attributes Optional. Array of extra attributes to render on the block wrapper.
 * @return string String of HTML attributes.
 */
function get_block_wrapper_attributes( $extra_attributes = array() ) {
	$new_attributes = WP_Block_Supports::get_instance()->apply_block_supports();

	if ( empty( $new_attributes ) && empty( $extra_attributes ) ) {
		return '';
	}

	// Attribute values are concatenated or overridden depending on the attribute type.
	// This is hardcoded on purpose, as we only support a fixed list of attributes.
	$attribute_merge_callbacks = array(
		'style'      => static function ( $new_attribute, $extra_attribute ) {
			$styles = array_filter(
				array(
					rtrim( trim( $new_attribute ), ';' ),
					rtrim( trim( $extra_attribute ), ';' ),
				)
			);
			return safecss_filter_attr( implode( ';', array_filter( $styles ) ) );
		},
		'class'      => static function ( $new_attribute, $extra_attribute ) {
			$classes = array_merge(
				(array) preg_split( '/\s+/', $extra_attribute, -1, PREG_SPLIT_NO_EMPTY ),
				(array) preg_split( '/\s+/', $new_attribute, -1, PREG_SPLIT_NO_EMPTY )
			);
			$classes = array_unique( $classes );
			return implode( ' ', $classes );
		},
		'id'         => static function ( $new_attribute, $extra_attribute ) {
			return '' !== $extra_attribute ? $extra_attribute : $new_attribute;
		},
		'aria-label' => static function ( $new_attribute, $extra_attribute ) {
			return '' !== $extra_attribute ? $extra_attribute : $new_attribute;
		},
	);

	// Accept strings and numbers (cast to string); reject other types (bool, null, array, object).
	$attributes = array();
	foreach ( $attribute_merge_callbacks as $attribute_name => $merge_callback ) {
		$new_attribute   = $new_attributes[ $attribute_name ] ?? '';
		$extra_attribute = $extra_attributes[ $attribute_name ] ?? '';
		$new_attribute   = is_scalar( $new_attribute ) && ! is_bool( $new_attribute ) ? (string) $new_attribute : '';
		$extra_attribute = is_scalar( $extra_attribute ) && ! is_bool( $extra_attribute ) ? (string) $extra_attribute : '';

		if ( '' === $new_attribute && '' === $extra_attribute ) {
			continue;
		}

		$attributes[ $attribute_name ] = $merge_callback( $new_attribute, $extra_attribute );
	}

	foreach ( $extra_attributes as $attribute_name => $value ) {
		if ( ! isset( $attribute_merge_callbacks[ $attribute_name ] ) && is_scalar( $value ) && ! is_bool( $value ) ) {
			$attributes[ $attribute_name ] = (string) $value;
		}
	}

	if ( empty( $attributes ) ) {
		return '';
	}

	$normalized_attributes = array();
	foreach ( $attributes as $key => $value ) {
		$normalized_attributes[] = $key . '="' . esc_attr( $value ) . '"';
	}

	return implode( ' ', $normalized_attributes );
}