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

/**
 * Registers 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. In case a WP_Block_Type
 *                                   is provided, the $args parameter will be ignored.
 * @param array                $args {
 *     Optional. Array of block type arguments. Any arguments may be defined, however the
 *     ones described below are supported by default. Default empty array.
 *
 *     @type callable $render_callback Callback used to render blocks of this block type.
 * }
 * @return WP_Block_Type|false The registered block type on success, or false on failure.
 */
function register_block_type( $name, $args = array() ) {
	return WP_Block_Type_Registry::get_instance()->register( $name, $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 );
}

/**
 * Determine 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 ) {
			$post = $wp_post->post_content;
		}
	}

	return false !== strpos( (string) $post, '<!-- wp:' );
}

/**
 * Determine whether a $post or a string contains a specific block type.
 *
 * This test optimizes for performance rather than strict accuracy, detecting
 * the block type exists 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 string                  $block_type 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_type, $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;
		}
	}

	return false !== strpos( $post, '<!-- wp:' . $block_type . ' ' );
}

/**
 * Returns an array of the names of all registered dynamic block types.
 *
 * @since 5.0.0
 *
 * @return array 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;
}

/**
 * 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 ) {
	$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_blocks = array_merge( $allowed_inner_blocks, array( 'core/columns' ) );

	/**
	 * 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 array $allowed_blocks The list 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 ( 'core/columns' === $block['blockName'] ) {
					$output .= _excerpt_render_inner_columns_blocks( $block, $allowed_inner_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;
}

/**
 * Render inner blocks from the `core/columns` block for generating an excerpt.
 *
 * @since 5.2.0
 * @access private
 *
 * @param array $columns        The parsed columns block.
 * @param array $allowed_blocks The list of allowed inner blocks.
 * @return string The rendered inner blocks.
 */
function _excerpt_render_inner_columns_blocks( $columns, $allowed_blocks ) {
	$output = '';

	foreach ( $columns['innerBlocks'] as $column ) {
		foreach ( $column['innerBlocks'] as $inner_block ) {
			if ( in_array( $inner_block['blockName'], $allowed_blocks, true ) && empty( $inner_block['innerBlocks'] ) ) {
				$output .= render_block( $inner_block );
			}
		}
	}

	return $output;
}

/**
 * Renders a single block into a HTML string.
 *
 * @since 5.0.0
 *
 * @global WP_Post $post The post to edit.
 *
 * @param array $block A single parsed block object.
 * @return string String of rendered HTML.
 */
function render_block( $block ) {
	global $post;

	/**
	 * Allows render_block() to be shortcircuited, by returning a non-null value.
	 *
	 * @since 5.1.0
	 *
	 * @param string $pre_render The pre-rendered content. Default null.
	 * @param array  $block      The block being rendered.
	 */
	$pre_render = apply_filters( 'pre_render_block', null, $block );
	if ( ! is_null( $pre_render ) ) {
		return $pre_render;
	}

	$source_block = $block;

	/**
	 * Filters the block being rendered in render_block(), before it's processed.
	 *
	 * @since 5.1.0
	 *
	 * @param array $block        The block being rendered.
	 * @param array $source_block An un-modified copy of $block, as it appeared in the source content.
	 */
	$block = apply_filters( 'render_block_data', $block, $source_block );

	$block_type    = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
	$is_dynamic    = $block['blockName'] && null !== $block_type && $block_type->is_dynamic();
	$block_content = '';
	$index         = 0;

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

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

	if ( $is_dynamic ) {
		$global_post   = $post;
		$block_content = $block_type->render( $block['attrs'], $block_content );
		$post          = $global_post;
	}

	/**
	 * Filters the content of a single block.
	 *
	 * @since 5.0.0
	 *
	 * @param string $block_content The block content about to be appended.
	 * @param array  $block         The full block, including name and attributes.
	 */
	return apply_filters( 'render_block', $block_content, $block );
}

/**
 * Parses blocks out of a content string.
 *
 * @since 5.0.0
 *
 * @param string $content Post content.
 * @return array Array of parsed block objects.
 */
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
 * @global WP_Post $post The post to edit.
 *
 * @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.
 *
 * @access private
 *
 * @since 5.0.0
 *
 * @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;
}
