`. * @return string */ private static function inner_blocks_of( \DOMNode $node ) { $blocks = []; foreach ( $node->childNodes as $child ) { $block = self::node_to_block( $child ); if ( '' !== $block ) { $blocks[] = $block; } } if ( empty( $blocks ) ) { $text = trim( self::inner_html( $node ) ); if ( '' === $text ) { return ''; } $blocks[] = self::block( 'core/paragraph', [], '

' . $text . '

' ); } return implode( "\n\n", $blocks ); } /** * The single `` a paragraph wraps, if that is all it holds. * * @since 4.9.0 * * @param \DOMNode $node The `

`. * @return \DOMNode|null */ private static function only_child_image( \DOMNode $node ) { $image = null; foreach ( $node->childNodes as $child ) { if ( XML_TEXT_NODE === $child->nodeType ) { if ( '' !== trim( $child->textContent ) ) { return null; } continue; } if ( XML_ELEMENT_NODE === $child->nodeType && 'img' === strtolower( $child->nodeName ) && null === $image ) { $image = $child; continue; } return null; } return $image; } /** * The text of a `

`, entity-escaped for a `` element.
	 *
	 * @since 4.9.0
	 *
	 * @param \DOMNode $node The `
`.
	 * @return string
	 */
	private static function code_text( \DOMNode $node ) {
		return esc_html( $node->textContent );
	}

	/**
	 * A node's children, serialised.
	 *
	 * @since 4.9.0
	 *
	 * @param \DOMNode $node Node.
	 * @return string
	 */
	private static function inner_html( \DOMNode $node ) {
		$html = '';

		foreach ( $node->childNodes as $child ) {
			$html .= self::outer_html( $child );
		}

		return $html;
	}

	/**
	 * A node, serialised.
	 *
	 * @since 4.9.0
	 *
	 * @param \DOMNode $node Node.
	 * @return string
	 */
	private static function outer_html( \DOMNode $node ) {
		$html = $node->ownerDocument->saveHTML( $node );

		return false === $html ? '' : $html;
	}

	// -------------------------------------------------------------------------
	// Block-tree helpers
	// -------------------------------------------------------------------------

	/**
	 * Whether any group in the list is missing its label.
	 *
	 * @since 4.9.0
	 *
	 * @param array $groups Decoded groups.
	 * @return bool
	 */
	private static function needs_repair( array $groups ) {
		foreach ( $groups as $group ) {
			if ( null === $group['label'] || '' === $group['label'] ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Call `$visitor` on every block, innermost included.
	 *
	 * @since 4.9.0
	 *
	 * @param array    $blocks  Parsed blocks.
	 * @param callable $visitor `fn( array $block ): void`.
	 * @return void
	 */
	private static function walk_blocks( array $blocks, callable $visitor ) {
		foreach ( $blocks as $block ) {
			call_user_func( $visitor, $block );

			if ( ! empty( $block['innerBlocks'] ) && is_array( $block['innerBlocks'] ) ) {
				self::walk_blocks( $block['innerBlocks'], $visitor );
			}
		}
	}

	/**
	 * Rewrite every block through `$mapper`, innermost first.
	 *
	 * @since 4.9.0
	 *
	 * @param array    $blocks Parsed blocks.
	 * @param callable $mapper `fn( array $block ): array`.
	 * @return array
	 */
	private static function map_blocks( array $blocks, callable $mapper ) {
		$mapped = [];

		foreach ( $blocks as $block ) {
			if ( ! empty( $block['innerBlocks'] ) && is_array( $block['innerBlocks'] ) ) {
				$block['innerBlocks'] = self::map_blocks( $block['innerBlocks'], $mapper );
			}

			$mapped[] = call_user_func( $mapper, $block );
		}

		return $mapped;
	}

	/**
	 * Drop every FAQ block from a parsed tree, at any depth.
	 *
	 * A removed inner block also has to lose its `null` placeholder in the
	 * parent's `innerContent`, or `serialize_block()` walks off the end of
	 * `innerBlocks`.
	 *
	 * @since 4.9.0
	 *
	 * @param array $blocks Parsed blocks.
	 * @return array
	 */
	private static function reject_faq_blocks( array $blocks ) {
		$kept = [];

		foreach ( $blocks as $block ) {
			$name = isset( $block['blockName'] ) ? $block['blockName'] : null;

			if ( self::FAQ_BLOCK === $name ) {
				continue;
			}

			if ( ! empty( $block['innerBlocks'] ) && is_array( $block['innerBlocks'] ) ) {
				$before               = count( $block['innerBlocks'] );
				$block['innerBlocks'] = self::reject_faq_blocks( $block['innerBlocks'] );

				if ( count( $block['innerBlocks'] ) !== $before ) {
					$block['innerContent'] = self::rebuild_inner_content( $block, $before - count( $block['innerBlocks'] ) );
				}
			}

			$kept[] = $block;
		}

		return $kept;
	}

	/**
	 * Drop `$removed` of the `null` placeholders from a block's `innerContent`.
	 *
	 * @since 4.9.0
	 *
	 * @param array $block   The parent block.
	 * @param int   $removed How many inner blocks went away.
	 * @return array
	 */
	private static function rebuild_inner_content( array $block, $removed ) {
		$content = isset( $block['innerContent'] ) && is_array( $block['innerContent'] ) ? $block['innerContent'] : [];
		$rebuilt = [];

		foreach ( $content as $chunk ) {
			if ( null === $chunk && $removed > 0 ) {
				--$removed;
				continue;
			}

			$rebuilt[] = $chunk;
		}

		return $rebuilt;
	}

	/**
	 * `wp_json_encode()` with the two flags block attributes are written with:
	 * unescaped slashes (a URL in an attribute stays readable) and unescaped
	 * unicode (so `\u65e5` does not appear where `日` belongs). Both match
	 * core's `serialize_block_attributes()`.
	 *
	 * @since 4.9.0
	 *
	 * @param mixed $value Value.
	 * @return string
	 */
	private static function json( $value ) {
		$json = wp_json_encode( $value, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );

		return false === $json ? '[]' : $json;
	}
}