*/
private array $raw_html_placeholders = [];
/**
* Prepare HTML for markdown conversion.
*
* @param string $html HTML fragment.
*
* @return string
*/
public function prepare( string $html ): string {
$this->raw_html_placeholders = [];
if ( '' === trim( $html ) || ! class_exists( '\DOMDocument' ) ) {
return $html;
}
$dom = $this->load_fragment_dom( $html );
if ( ! $dom instanceof \DOMDocument ) {
return $html;
}
$root = $dom->getElementById( 'wp-aisignal-markdown-converter-root' );
if ( ! $root instanceof \DOMElement ) {
return $html;
}
$this->normalize_picture_elements( $dom, $root );
$this->normalize_figure_elements( $dom, $root );
$this->replace_complex_tables( $dom, $root );
return $this->get_inner_html( $root );
}
/**
* Restore raw HTML placeholders after markdown conversion.
*
* @param string $markdown Markdown output.
*
* @return string
*/
public function restore( string $markdown ): string {
foreach ( $this->raw_html_placeholders as $placeholder => $html ) {
$markdown = str_replace( $placeholder, "\n\n{$html}\n\n", $markdown );
}
$markdown = preg_replace( "/\n{3,}/", "\n\n", $markdown );
return is_string( $markdown ) ? trim( $markdown ) : '';
}
/**
* Load an HTML fragment into a DOM document.
*
* @param string $html HTML fragment.
*
* @return \DOMDocument|null
*/
private function load_fragment_dom( string $html ) {
$dom = new \DOMDocument( '1.0', 'UTF-8' );
$libxml_previous = libxml_use_internal_errors( true );
$wrapped = '' . $html . '
';
$loaded = $dom->loadHTML( '' . $wrapped );
libxml_clear_errors();
libxml_use_internal_errors( $libxml_previous );
return $loaded ? $dom : null;
}
/**
* Replace picture elements with their fallback image.
*
* @param \DOMDocument $dom DOM document.
* @param \DOMElement $root Root element.
*
* @return void
*/
private function normalize_picture_elements( \DOMDocument $dom, \DOMElement $root ): void {
$pictures = [];
foreach ( $root->getElementsByTagName( 'picture' ) as $picture ) {
if ( $picture instanceof \DOMElement ) {
$pictures[] = $picture;
}
}
foreach ( $pictures as $picture ) {
$img = $this->find_first_descendant_by_tag( $picture, 'img' );
if ( ! $img instanceof \DOMElement ) {
continue;
}
$replacement = $dom->createElement( 'img' );
foreach ( [ 'src', 'alt', 'title' ] as $attribute ) {
$value = $img->getAttribute( $attribute );
if ( '' !== $value ) {
$replacement->setAttribute( $attribute, $value );
}
}
$this->replace_node( $picture, $replacement );
}
}
/**
* Normalize figure elements into markdown-friendly image/caption blocks.
*
* @param \DOMDocument $dom DOM document.
* @param \DOMElement $root Root element.
*
* @return void
*/
private function normalize_figure_elements( \DOMDocument $dom, \DOMElement $root ): void {
$figures = [];
foreach ( $root->getElementsByTagName( 'figure' ) as $figure ) {
if ( $figure instanceof \DOMElement ) {
$figures[] = $figure;
}
}
foreach ( $figures as $figure ) {
$replacement = $dom->createElement( 'div' );
$caption = '';
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
while ( $figure->firstChild ) {
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
$child = $figure->firstChild;
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
if ( $child instanceof \DOMElement && 'figcaption' === strtolower( $child->tagName ) ) {
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
$caption = trim( $child->textContent );
$figure->removeChild( $child );
continue;
}
$replacement->appendChild( $child );
}
if ( '' !== $caption ) {
$paragraph = $dom->createElement( 'p' );
$emphasis = $dom->createElement( 'em' );
$emphasis->appendChild( $dom->createTextNode( $caption ) );
$paragraph->appendChild( $emphasis );
$replacement->appendChild( $paragraph );
}
$this->replace_node( $figure, $replacement );
}
}
/**
* Replace complex tables with raw HTML placeholders.
*
* @param \DOMDocument $dom DOM document.
* @param \DOMElement $root Root element.
*
* @return void
*/
private function replace_complex_tables( \DOMDocument $dom, \DOMElement $root ): void {
$tables = [];
foreach ( $root->getElementsByTagName( 'table' ) as $table ) {
if ( $table instanceof \DOMElement ) {
$tables[] = $table;
}
}
foreach ( $tables as $table ) {
if ( ! $this->is_complex_table( $table ) ) {
continue;
}
$placeholder = $this->store_raw_html_placeholder( $table );
$text_node = $dom->createTextNode( $placeholder );
$this->replace_node( $table, $text_node );
}
}
/**
* Determine whether a table cannot be represented safely as a pipe table.
*
* @param \DOMElement $table Table element.
*
* @return bool
*/
private function is_complex_table( \DOMElement $table ): bool {
foreach ( [ 'td', 'th' ] as $tag_name ) {
foreach ( $table->getElementsByTagName( $tag_name ) as $cell ) {
if ( ! $cell instanceof \DOMElement ) {
continue;
}
$colspan = (int) $cell->getAttribute( 'colspan' );
$rowspan = (int) $cell->getAttribute( 'rowspan' );
if ( $colspan > 1 || $rowspan > 1 ) {
return true;
}
if ( $this->table_cell_contains_complex_markup( $cell ) ) {
return true;
}
}
}
return $table->getElementsByTagName( 'table' )->length > 0;
}
/**
* Determine whether a table cell contains markup beyond simple inline content.
*
* @param \DOMElement $cell Table cell.
*
* @return bool
*/
private function table_cell_contains_complex_markup( \DOMElement $cell ): bool {
$allowed_inline_tags = [
'a',
'abbr',
'b',
'br',
'cite',
'code',
'em',
'i',
'img',
'q',
's',
'small',
'span',
'strong',
'sub',
'sup',
];
foreach ( $cell->getElementsByTagName( '*' ) as $descendant ) {
if ( ! $descendant instanceof \DOMElement ) {
continue;
}
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
$tag_name = strtolower( $descendant->tagName );
if ( ! in_array( $tag_name, $allowed_inline_tags, true ) ) {
return true;
}
}
return false;
}
/**
* Store raw HTML for later restoration.
*
* @param \DOMElement $node Node to preserve.
*
* @return string
*/
private function store_raw_html_placeholder( \DOMElement $node ): string {
$placeholder = 'MARKDOWNCONVERTERRAWHTMLTABLE' . ( count( $this->raw_html_placeholders ) + 1 ) . 'TOKEN';
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
$document = $node->ownerDocument;
$html = $document instanceof \DOMDocument ? trim( $document->saveHTML( $node ) ) : '';
$this->raw_html_placeholders[ $placeholder ] = $html;
return $placeholder;
}
/**
* Find the first descendant element with a given tag name.
*
* @param \DOMElement $element Root element.
* @param string $tag_name Tag name.
*
* @return \DOMElement|null
*/
private function find_first_descendant_by_tag( \DOMElement $element, string $tag_name ) {
foreach ( $element->getElementsByTagName( $tag_name ) as $node ) {
if ( $node instanceof \DOMElement ) {
return $node;
}
}
return null;
}
/**
* Replace a node in the DOM tree.
*
* @param \DOMNode $old_node Node to replace.
* @param \DOMNode|null $new_node Replacement node.
*
* @return void
*/
private function replace_node( \DOMNode $old_node, ?\DOMNode $new_node ): void {
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
$parent = $old_node->parentNode;
if ( ! $parent instanceof \DOMNode ) {
return;
}
if ( $new_node instanceof \DOMNode ) {
$parent->replaceChild( $new_node, $old_node );
return;
}
$parent->removeChild( $old_node );
}
/**
* Get the inner HTML for an element.
*
* @param \DOMElement $element Element.
*
* @return string
*/
private function get_inner_html( \DOMElement $element ): string {
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
$document = $element->ownerDocument;
if ( ! $document instanceof \DOMDocument ) {
return '';
}
$html = '';
// phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase -- DOM API property name.
foreach ( $element->childNodes as $child ) {
$html .= $document->saveHTML( $child );
}
return $html;
}
}