Add support multi-page in WordPress

src/Kunoichi/TocGenerator/Item.php

@@ -13,7 +13,7 @@ class Item {
 	/**
 	 * @var \DOMNode
 	 */
-	private $dom = null;
+	protected $dom = null;
 
 	/**
 	 * Item constructor.

src/Kunoichi/TocGenerator/Parser.php

@@ -27,17 +27,21 @@ class Parser {
 
 	protected $title = '';
 
+	protected $item_class = '';
+
 	/**
 	 * Constructor
 	 *
 	 * @param int    $max_depth
 	 * @param bool   $ignore_deeper
 	 * @param string $id
+	 * @param string $item_class
 	 */
-	public function __construct( $max_depth = 3, $ignore_deeper = false, $id = 'content-section-' ) {
+	public function __construct( $max_depth = 3, $ignore_deeper = false, $id = 'content-section-', $item_class = Item::class ) {
 		$this->id_prefix     = $id;
 		$this->max_depth     = $max_depth;
 		$this->ignore_deeper = $ignore_deeper;
+		$this->item_class    = $item_class;
 	}
 
 	/**
@@ -95,7 +99,7 @@ public function parse_html( $html ) {
 			if ( $this->ignore_deeper && ( (int) $level > $this->max_depth ) ) {
 				continue;
 			}
-			$items[] = new Item( $hn );
+			$items[] = new $this->item_class( $hn );
 		}
 		return $items;
 	}

src/Kunoichi/TocGenerator/WpItem.php

@@ -0,0 +1,76 @@
+<?php
+
+namespace Kunoichi\TocGenerator;
+
+/**
+ * Item for WordPress
+ *
+ * @package Kunoichi\TocGenerator
+ */
+class WpItem extends Item {
+
+	/**
+	 * Item constructor.
+	 *
+	 * @param \DOMNode $dom
+	 */
+	public function __construct( $dom ) {
+		parent::__construct( $dom );
+	}
+
+	/**
+	 * Get markup of contents.
+	 *
+	 * @return string
+	 */
+	public function get_markup() {
+		global $page;
+		$item_page = $this->page();
+
+		if ( $page !== $item_page ) {
+			// @see <a href="https://developer.wordpress.org/reference/functions/_wp_link_page/">_wp_link_page()</a>
+			global $wp_rewrite;
+			$post       = get_post();
+			$query_args = array();
+			$item_page  = $this->page();
+
+			if ( 1 === $item_page ) {
+				$url = get_permalink();
+			} else {
+				if ( ! get_option( 'permalink_structure' ) || in_array( get_post_status(), array(
+						'draft',
+						'pending'
+					), true ) ) {
+					$url = add_query_arg( 'page', $item_page, get_permalink() );
+				} elseif ( 'page' === get_option( 'show_on_front' ) && (int) get_option( 'page_on_front' ) === get_the_ID() ) {
+					$url = trailingslashit( get_permalink() ) . user_trailingslashit( "$wp_rewrite->pagination_base/" . $item_page, 'single_paged' );
+				} else {
+					$url = trailingslashit( get_permalink() ) . user_trailingslashit( $item_page, 'single_paged' );
+				}
+			}
+
+			if ( is_preview() ) {
+				if ( ( 'draft' !== $post->post_status ) && isset( $_GET['preview_id'], $_GET['preview_nonce'] ) ) {
+					$query_args['preview_id']    = wp_unslash( $_GET['preview_id'] );
+					$query_args['preview_nonce'] = wp_unslash( $_GET['preview_nonce'] );
+				}
+				$url = get_preview_post_link( $post, $query_args, $url );
+			}
+			$link = sprintf( '%s%s', $url, $this->href() );
+
+		} else {
+			$link = $this->href();
+		}
+
+		return sprintf( '<a href="%s" data-page="%s">%s</a>', esc_url( $link ), esc_attr( $item_page ), esc_html( $this->text() ) );
+	}
+
+	/**
+	 * Return page attributes
+	 *
+	 * @return int
+	 */
+	public function page() {
+		return (int) $this->dom->getAttribute( 'data-page' );
+	}
+}

src/Kunoichi/TocGenerator/WpParser.php

@@ -14,15 +14,18 @@ class WpParser extends Parser {
 
 	protected $done = false;
 
+	protected $page_counter = 0;
+
 	/**
 	 * Constructor
 	 *
 	 * @param int $max_depth
 	 * @param bool $ignore_deeper
 	 * @param string $id
+	 * @param string $item_class
 	 */
-	public function __construct( $max_depth = 3, $ignore_deeper = false, $id = 'content-section-' ) {
-		parent::__construct( $max_depth, $ignore_deeper, $id );
+	public function __construct( $max_depth = 3, $ignore_deeper = false, $id = 'content-section-', $item_class = WpItem::class ) {
+		parent::__construct( $max_depth, $ignore_deeper, $id, $item_class );
 		add_action( 'wp_head', [ $this, 'prepare' ] );
 		add_filter( 'the_content', [ $this, 'post_content' ] );
 		add_action( 'kunoichi_toc_generate', [ $this, 'generate' ], 10 );
@@ -56,9 +59,56 @@ public function post_content( $content ) {
 			$this->save_parsed_html( $content );
 			$this->done = true;
 		}
+
 		return $content;
 	}
 
+	/**
+	 * Add link id to html elements.
+	 *
+	 * @param string $html
+	 *
+	 * @return string
+	 */
+	public function add_link_html( $html ) {
+		$contents = preg_split( '/<!--nextpage-->/u', $html );
+		if ( is_array( $contents ) ) {
+			$replaced_html      = '';
+			$this->page_counter = 0;
+			foreach ( $contents as $content ) {
+				$this->counter = 0;
+				$this->page_counter ++;
+				$replaced_html .= preg_replace_callback( '/<(h[1-6])([^>]*?)>/u', [ $this, 'convert_link' ], $content );
+			}
+
+			return $replaced_html;
+		} else {
+			return preg_replace_callback( '/<(h[1-6])([^>]*?)>/u', [ $this, 'convert_link' ], $html );
+		}
+	}
+
+	/**
+	 * Add link to title elements.
+	 *
+	 * @param string[] $matches
+	 *
+	 * @return string
+	 */
+	protected function convert_link( $matches ) {
+		$this->counter ++;
+		$attributes = $matches[2];
+		if ( preg_match( '/id=\'|"([\'"]*)(\'|")/u', $matches[2], $id_matches ) ) {
+			$id = $id_matches[1];
+		} else {
+			$id         = sprintf( '%s%d', $this->id_prefix, $this->counter );
+			$attributes .= sprintf( ' id="%s"', $id ) . $matches[2];
+		}
+		// Add an attribute for the page number.
+		$attributes .= sprintf( ' data-page="%d"', $this->page_counter );
+
+		return sprintf( '<%s%s>', $matches[1], $attributes );
+	}
+
 	/**
 	 * If post id is
 	 *