Table Of Contents

<?php

namespace WPDeveloper\BetterDocs\Shortcodes;

use WPDeveloper\BetterDocs\Utils\Node;
use WPDeveloper\BetterDocs\Core\Shortcode;

class ToC extends Shortcode {
	protected $html_attributes = [];

	public function get_name() {
		return 'betterdocs_toc';
	}

	public function get_style_depends() {
		return [ 'betterdocs-toc' ];
	}

	/**
	 * Summary of default_attributes
	 * @return array
	 */
	public function default_attributes() {
		return [
			'post_type'             => 'docs',
			'post_id'               => get_the_ID(),
			'htags'                 => '1,2,3,4,5,6',
			'hierarchy'             => '',
			'list_number'           => '',
			'collapsible_on_mobile' => $this->settings->get( 'collapsible_toc_mobile', false ),
			'toc_title'             => ''
		];
	}

	public function render( $atts, $content = null ) {
		$this->views( 'shortcodes/toc' );
	}

	public function view_params() {
		return [
			'post' => get_post( $this->attributes['post_id'] )
		];
	}

	/**
	 * This method is responsible for re-arranging the TOC data based on hierarchy or non-hierarchy
	 *
	 * @param string $post_content
	 * @param string $htag_support
	 * @return Node|null
	 */
	public function format_toc_data( $post_content, $htag_support, $toc_hierarchy ) {
		$matches = [];

		if ( $htag_support != '' ) {
			preg_match_all( '/(<h([' . $htag_support . ']{1})[^>]*>).*<\/h\2>/msuU', $post_content, $matches, PREG_SET_ORDER );
		}

		if ( ! empty( $matches ) ) {
			/*
			|--------------------------------------------------------------------------
			| Backtracking Algorithm Using Iteration | Main Login For Hierarchy TOC
			|--------------------------------------------------------------------------
			|
			| Initially an object with key null and empty item of arrays are inserted into the stack of arrays.
			| When inside the loop condition for the first time, the last stack value is assigned in a variable $last_data.
			| And a new node object $new_data which is instantiated and the tag number is inserted for comparison as key, and empty items
			| as a array are inserted into items property of the new node object. On the 'if' condition it checks, if the current tag number
			| is smaller or equal to the last stack number. If the condition is true, the it enters into the while loop condition, which also
			| checks if the current last stack tag number is greater or equal to the current tag number. It pops values from the stack until and unless the
			| condition becomes false. The while loop condition becomes false only when the last stack value tag number becomes null and the last stack number is not
			| greater or equal to the current node tag number.
			|
			| Backtracking occurs when the current tag_number $number[2] is less than or equal to the stacks last tag_number which is assigned as $last_data
			|
			| And then the last value is inserted as the new last_data, and the new_data node is inserted into the last_data node items.
			| Additionally the $new_data is inserted into the stack to keep track of the used node. Somehow if the if condition becomes false
			| then the stack last data is taken, and the new_data is inserted into the last_data->items and the new_data is inserted into the stack.
			|
			 */

			$dynamic_toc_title_switch = $this->settings->get( 'toc_dynamic_title' );
			$stack                    = [];
			$root                     = new Node();
			$root->key                = null;
			$root->items              = [];
			$tag_counter              = 0;

			array_push( $stack, $root );

			foreach ( $matches as $number ) {
				$last_data          = $stack[ count( $stack ) - 1 ];
				$current_tag_number = isset( $number[2] ) ? $number[2] : '';
				$current_title      = isset( $number[0] ) ? $number[0] : '';
				$current_tag        = isset( $number[1] ) ? $number[1] : '';

				$heading_name = preg_replace( '/<[^<]+?>/', '', $current_title );
				$heading_name = ! empty( $heading_name ) ? strtolower( str_replace( ' ', '-', preg_replace( '/[^\p{L}\p{N}\s]/u', '', $heading_name ) ) ) : '';
				preg_match( '/id="(.+?)"/', $current_title, $matches_id );
				$heading_id = isset( $matches_id[1] ) ? strtolower( $matches_id[1] ) : '';
				$tag_number = ! empty( $heading_id ) ? $heading_id : ( ! empty( $heading_name ) && $this->settings->get( 'toc_dynamic_title' ) ? $heading_name : $tag_counter . '-toc-title' );

				$new_data             = new Node();
				$new_data->key        = $current_tag_number;
				$new_data->tag        = $current_tag;
				$new_data->title      = $current_title;
				$new_data->tag_number = $tag_number;
				$new_data->items      = [];

				if ( $last_data->key != null && $current_tag_number <= $last_data->key ) {
					while ( $stack[ count( $stack ) - 1 ]->key != null && $stack[ count( $stack ) - 1 ]->key >= $current_tag_number ) {
						array_pop( $stack );
					}
					$last_data = $stack[ count( $stack ) - 1 ];
				}

				array_push( $last_data->items, $new_data );

				if ( $toc_hierarchy != 'off' && $toc_hierarchy != '' ) {
					array_push( $stack, $new_data );
				}

				++$tag_counter;
			}

			return $root;
		}

		return null;
	}
}