run( $html ); } private function run( string $html ): string { $html = $this->normalize_html( $html ); $processor = WP_HTML_Processor::create_full_parser( $html ); if ( null === $processor ) { return $this->fallback( $html ); } try { $this->walk( $processor ); } catch ( \Exception $e ) { return $this->fallback( $html ); } $this->flush_inline(); $output = $this->output; $output = preg_replace( "/[ \t]+\n/", "\n", $output ); $output = preg_replace( "/\n{3,}/", "\n\n", $output ); return trim( $output ); } private function fallback( string $html ): string { $text = wp_strip_all_tags( $html ); $text = html_entity_decode( $text, ENT_QUOTES, 'UTF-8' ); return trim( preg_replace( "/\n{3,}/", "\n\n", $text ) ); } private function normalize_html( string $html ): string { $html = preg_replace( '/\r\n?/', "\n", $html ); $html = preg_replace( '#]*>.*?#is', '', $html ); $html = preg_replace( '#]*>.*?#is', '', $html ); $html = str_replace( "\xE2\x80\x8B", '', $html ); return $html; } private function walk( WP_HTML_Processor $p ): void { while ( $p->next_token() ) { $type = $p->get_token_type(); if ( '#text' === $type ) { $this->handle_text( $p->get_modifiable_text() ); continue; } if ( '#tag' !== $type ) { continue; } $tag = strtolower( (string) $p->get_tag() ); $is_closer = $p->is_tag_closer(); $is_void = in_array( $tag, self::VOID_TAGS, true ); if ( $is_closer ) { $this->handle_close( $tag ); continue; } $this->handle_open( $tag, $p ); if ( $is_void ) { $this->handle_close( $tag ); } } } private function handle_text( string $text ): void { if ( '' === $text ) { return; } if ( $this->in_pre ) { $this->pre_buffer .= $text; return; } if ( $this->in_table ) { $this->current_cell .= $this->escape_text( $text, false ); return; } $collapsed = preg_replace( '/[ \t\n]+/', ' ', $text ); $escaped = $this->escape_text( $collapsed, $this->in_code ); if ( $this->in_link ) { $this->link_buffer .= $escaped; return; } $this->inline_buffer .= $escaped; } private function handle_open( string $tag, WP_HTML_Processor $p ): void { switch ( $tag ) { case 'p': case 'div': case 'section': case 'article': case 'header': case 'footer': case 'main': case 'aside': case 'figure': $this->flush_inline(); return; case 'h1': case 'h2': case 'h3': case 'h4': case 'h5': case 'h6': $this->flush_inline(); $this->heading_level = (int) $tag[1]; $this->inline_buffer = str_repeat( '#', $this->heading_level ) . ' '; return; case 'br': if ( $this->in_table ) { $this->current_cell .= ' '; return; } if ( $this->heading_level > 0 ) { $this->inline_buffer .= ' '; return; } $this->inline_buffer .= "\n"; return; case 'hr': $this->flush_inline(); $this->output .= "\n\n---\n\n"; return; case 'strong': case 'b': $this->append_inline( '**' ); return; case 'em': case 'i': $this->append_inline( '*' ); return; case 'del': case 's': case 'strike': $this->append_inline( '~~' ); return; case 'code': if ( $this->in_pre ) { $lang = (string) $p->get_attribute( 'class' ); if ( preg_match( '/language-([A-Za-z0-9_+\-]+)/', $lang, $m ) ) { $this->pre_language = $m[1]; } return; } $this->in_code = true; $this->append_inline( '`CODE_OPEN`' ); return; case 'pre': $this->flush_inline(); $this->in_pre = true; $this->pre_buffer = ''; $this->pre_language = ''; return; case 'a': $href = (string) $p->get_attribute( 'href' ); $this->in_link = true; $this->link_href = $href; $this->link_buffer = ''; return; case 'img': $this->emit_image( $p ); return; case 'ul': case 'ol': if ( ! empty( $this->list_stack ) && '' !== trim( $this->inline_buffer ) ) { $this->emit_list_item(); } else { $this->flush_inline(); } $this->list_stack[] = [ 'type' => $tag, 'index' => 1, ]; return; case 'li': $this->flush_inline(); return; case 'blockquote': $this->flush_inline(); $this->blockquote_depth++; return; case 'table': $this->flush_inline(); $this->in_table = true; $this->table_headers = []; $this->table_rows = []; return; case 'thead': $this->in_table_head = true; return; case 'tr': if ( ! $this->in_table ) { return; } $this->current_row = []; $this->row_is_header = $this->in_table_head; return; case 'th': $this->row_is_header = true; $this->current_cell = ''; return; case 'td': $this->current_cell = ''; return; } } private function handle_close( string $tag ): void { switch ( $tag ) { case 'p': case 'div': case 'section': case 'article': case 'header': case 'footer': case 'main': case 'aside': case 'figure': $this->flush_inline(); return; case 'h1': case 'h2': case 'h3': case 'h4': case 'h5': case 'h6': $this->inline_buffer = preg_replace( '/[ \t]+/', ' ', $this->inline_buffer ); $this->flush_inline(); $this->heading_level = 0; return; case 'strong': case 'b': $this->append_inline( '**' ); return; case 'em': case 'i': $this->append_inline( '*' ); return; case 'del': case 's': case 'strike': $this->append_inline( '~~' ); return; case 'code': if ( $this->in_pre ) { return; } $this->append_inline( '`CODE_CLOSE`' ); $this->in_code = false; return; case 'pre': $this->emit_pre(); $this->in_pre = false; $this->pre_buffer = ''; $this->pre_language = ''; return; case 'a': $this->emit_link(); $this->in_link = false; $this->link_href = ''; $this->link_buffer = ''; return; case 'ul': case 'ol': $this->flush_inline(); array_pop( $this->list_stack ); if ( empty( $this->list_stack ) ) { $this->output .= "\n\n"; } return; case 'li': $this->emit_list_item(); return; case 'blockquote': $this->flush_inline(); $this->blockquote_depth = max( 0, $this->blockquote_depth - 1 ); if ( 0 === $this->blockquote_depth ) { $this->output .= "\n"; } return; case 'table': $this->emit_table(); $this->in_table = false; $this->table_headers = []; $this->table_rows = []; return; case 'thead': $this->in_table_head = false; return; case 'tr': if ( ! $this->in_table ) { return; } if ( $this->row_is_header && empty( $this->table_headers ) ) { $this->table_headers = $this->current_row; } else { $this->table_rows[] = $this->current_row; } $this->current_row = []; $this->row_is_header = false; return; case 'th': case 'td': $this->current_row[] = trim( preg_replace( '/\s+/', ' ', $this->current_cell ) ); $this->current_cell = ''; return; } } private function append_inline( string $marker ): void { if ( $this->in_link ) { $this->link_buffer .= $marker; return; } $this->inline_buffer .= $marker; } private function emit_link(): void { $text = $this->link_buffer; $href = $this->link_href; if ( '' === $href || '#' === $href ) { $this->inline_buffer .= $text; return; } if ( ! $this->is_safe_url( $href ) ) { $this->inline_buffer .= $text; return; } $href = $this->escape_url_for_markdown( $href ); $this->inline_buffer .= '[' . $text . '](' . $href . ')'; } private function emit_image( WP_HTML_Processor $p ): void { $src = (string) $p->get_attribute( 'src' ); $alt = (string) $p->get_attribute( 'alt' ); if ( '' === $src ) { return; } if ( ! $this->is_safe_url( $src ) ) { return; } $alt = $this->escape_text( $alt, false ); $src = $this->escape_url_for_markdown( $src ); $this->inline_buffer .= ''; } private function emit_pre(): void { $content = html_entity_decode( $this->pre_buffer, ENT_QUOTES, 'UTF-8' ); $content = rtrim( $content, "\n" ); $this->output .= "\n\n```" . $this->pre_language . "\n" . $content . "\n```\n\n"; } private function emit_list_item(): void { $content = trim( $this->inline_buffer ); $this->inline_buffer = ''; if ( '' === $content ) { return; } $top = end( $this->list_stack ); if ( false === $top ) { $this->output .= $content . "\n"; return; } $depth = count( $this->list_stack ) - 1; $indent = str_repeat( ' ', $depth ); if ( 'ol' === $top['type'] ) { $marker = $top['index'] . '. '; $this->list_stack[ array_key_last( $this->list_stack ) ]['index']++; } else { $marker = '- '; } $lines = explode( "\n", $content ); $first = array_shift( $lines ); $rendered = $indent . $marker . $first; foreach ( $lines as $line ) { $rendered .= "\n" . $indent . ' ' . $line; } $this->output .= $this->prefix_blockquote( $rendered ) . "\n"; } private function emit_table(): void { if ( empty( $this->table_headers ) && empty( $this->table_rows ) ) { return; } if ( empty( $this->table_headers ) && ! empty( $this->table_rows ) ) { $this->table_headers = array_fill( 0, count( $this->table_rows[0] ), '' ); } $column_count = count( $this->table_headers ); $lines = []; $lines[] = '| ' . implode( ' | ', array_map( [ $this, 'escape_table_cell' ], $this->table_headers ) ) . ' |'; $lines[] = '|' . str_repeat( ' --- |', $column_count ); foreach ( $this->table_rows as $row ) { $row = array_pad( $row, $column_count, '' ); $row = array_slice( $row, 0, $column_count ); $lines[] = '| ' . implode( ' | ', array_map( [ $this, 'escape_table_cell' ], $row ) ) . ' |'; } $this->output .= "\n\n" . implode( "\n", $lines ) . "\n\n"; } private function escape_table_cell( string $value ): string { return str_replace( [ '|', "\n" ], [ '\\|', ' ' ], $value ); } private function flush_inline(): void { if ( '' === $this->inline_buffer ) { return; } $content = $this->finalize_inline( $this->inline_buffer ); $this->inline_buffer = ''; $content = trim( $content ); if ( '' === $content ) { return; } if ( ! empty( $this->list_stack ) ) { $this->inline_buffer = $content; return; } $content = $this->prefix_blockquote( $content ); $this->output .= "\n\n" . $content . "\n\n"; } private function finalize_inline( string $buffer ): string { return preg_replace_callback( '/`CODE_OPEN`(.*?)`CODE_CLOSE`/s', function ( $matches ) { return $this->render_inline_code( $matches[1] ); }, $buffer ); } private function render_inline_code( string $content ): string { $content = preg_replace( '/\s+/', ' ', $content ); preg_match_all( '/`+/', $content, $runs ); $max = 0; foreach ( $runs[0] as $run ) { $max = max( $max, strlen( $run ) ); } $fence = str_repeat( '`', $max + 1 ); $pad = ( '' !== $content && ( '`' === $content[0] || '`' === substr( $content, -1 ) ) ) ? ' ' : ''; return $fence . $pad . $content . $pad . $fence; } private function prefix_blockquote( string $content ): string { if ( 0 === $this->blockquote_depth ) { return $content; } $prefix = str_repeat( '> ', $this->blockquote_depth ); $lines = explode( "\n", $content ); return implode( "\n", array_map( function ( $line ) use ( $prefix ) { return $prefix . $line; }, $lines ) ); } private function escape_text( string $text, bool $in_code ): string { $text = html_entity_decode( $text, ENT_QUOTES, 'UTF-8' ); if ( $in_code ) { return $text; } $replacements = []; foreach ( self::ESCAPABLE_MARKDOWN_CHARS as $char ) { $replacements[ $char ] = '\\' . $char; } return strtr( $text, $replacements ); } private function escape_url_for_markdown( string $url ): string { return strtr( $url, [ ' ' => '%20', '(' => '%28', ')' => '%29', '<' => '%3C', '>' => '%3E', ] ); } private function is_safe_url( string $url ): bool { $url = trim( $url ); if ( '' === $url ) { return false; } if ( '#' === $url[0] || '/' === $url[0] || '?' === $url[0] ) { return true; } $lower = strtolower( $url ); foreach ( self::SAFE_DATA_PREFIXES as $prefix ) { if ( 0 === strpos( $lower, $prefix ) ) { return true; } } if ( ! preg_match( '#^([a-z][a-z0-9+.\-]*):#i', $url, $m ) ) { return true; } return in_array( strtolower( $m[1] ), self::SAFE_URL_SCHEMES, true ); } }