<?php
/**
 * Core class to add new feature to WordPress Rewrite API (such as start points)
 *
 * todo: replace EP_* constants with SP_*
 *
 * @since 1.0.0
 */
class Amp_WP_Rewrite_Rules {

    /**
     * Store start pints rules like <amp>/category/slug
     *
     * @since 1.0.0
     *
     * @var array
     */
    public $startpints = array();

    /**
     *
     * Store list of permastructs keys
     *
     * @see register_extra_permastruct_hooks
     * @since   1.0.0
     *
     * @var array
     */
    protected $exclude_extra_permastructs = array(
        'category' => true,
        'post_tag' => true,
        'post_format' => true,
        
        # Woocommerce
        'product_variation' => true,
        'shop_order_refund' => true,
        
        # Visual Composer
        'vc_grid_item' => true,
    );

    /**
     * Amp_WP_Rewrite_Rules constructor.
     */
    public function __construct() {
        $this->add_rewrite_rules_hooks();
    }

    /**
     * Append hooks to when generating rewrite rules
     *
     * @since 1.0.0
     */
    public function add_rewrite_rules_hooks() {

        foreach (
        array(
            'post_rewrite_rules',
            'date_rewrite_rules',
            'root_rewrite_rules',
            'comments_rewrite_rules',
            'search_rewrite_rules',
            'author_rewrite_rules',
            'page_rewrite_rules',
            'category_rewrite_rules',
            'post_tag_rewrite_rules',
            'post_format_rewrite_rules',
        ) as $hook
        ) {
            add_filter($hook, array($this, 'generate_rewrite_rules'), 9999);
        }

        add_action('root_rewrite_rules', array($this, 'register_extra_permastruct_hooks'));
    }

    /**
     * Register "{$permastructname}_rewrite_rules" Filters
     *
     * @param      array  $rules      Root rewrite rules
     *
     * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
     * @since 1.0.0
     *
     * @return array
     */
    public function register_extra_permastruct_hooks($rules) {
        global $wp_rewrite;

        // Remove exluced items from extra_permastructs
        $extra_permastruct = array_diff_key($wp_rewrite->extra_permastructs, $this->get_exclude_extra_permastructs());

        foreach ($extra_permastruct as $permastructname => $struct) {
            if (empty($struct['walk_dirs'])) {
                continue;
            }
            if (!has_filter("{$permastructname}_rewrite_rules", array($this, 'generate_rewrite_rules'))) {
                add_filter("{$permastructname}_rewrite_rules", array($this, 'generate_rewrite_rules'), 9999);
            }
        }
        return $rules;
    }

    /**
     * Get list of extra_permastructs to skip append startpoint
     * @see   exclude_extra_permastructs
     *
     * @since 1.0.0
     * @return array
     */
    public function get_exclude_extra_permastructs() {
        return $this->exclude_extra_permastructs;
    }

    /**
     * Set list of extra_permastructs to skip append startpoint
     *
     * @since 1.0.0
     *
     * @param string|array $permastructname
     */
    public function set_exclude_extra_permastructs($permastructname) {
        foreach ((array) $permastructname as $name) {
            $this->exclude_extra_permastructs[$name] = true;
        }
    }

    /**
     * Flush exclude permastructs storage
     *
     * @since 1.0.0
     *
     * @return bool always true
     */
    public function flush_exclude_extra_permastructs() {
        $this->exclude_extra_permastructs = array();
        return true;
    }

    /**
     * Get Endpoint mask of rewrite groups
     *
     * todo: add support for EP_DAY,EP_MONTH,EP_YEAR
     * todo: detect EP_ATTACHMENT
     *
     * @global WP_Rewrite $wp_rewrite WordPress Rewrite Component.
     * @since 1.0.0
     *
     * @return int
     */
    protected function get_current_sp_mask() {
        global $wp_rewrite;

        $current_filter = current_filter();

        switch ($current_filter) {
            case 'post_rewrite_rules':
                $ep_mask = EP_PERMALINK;
                break;

            case 'date_rewrite_rules':
                $ep_mask = EP_DATE;
                break;

            case 'root_rewrite_rules':
                $ep_mask = EP_ROOT;
                break;

            case 'comments_rewrite_rules':
                $ep_mask = EP_COMMENTS;
                break;

            case 'search_rewrite_rules':
                $ep_mask = EP_SEARCH;
                break;

            case 'author_rewrite_rules':
                $ep_mask = EP_AUTHORS;
                break;

            case 'page_rewrite_rules':
                $ep_mask = EP_PAGES;
                break;

            case 'category_rewrite_rules':
                $ep_mask = EP_CATEGORIES;
                break;

            case 'post_tag_rewrite_rules':
                $ep_mask = EP_TAGS;
                break;

            default:

            $ep_mask = EP_NONE;

            if (preg_match('/(.+)_rewrite_rules$/', $current_filter, $matched)) {
                if (isset($wp_rewrite->extra_permastructs[$matched[1]]['ep_mask'])) {
                    $ep_mask = max( $wp_rewrite->extra_permastructs[$matched[1]]['ep_mask'], 1 );
                }
            }
        }

        return $ep_mask;
    }

    // get_current_ep_mask

    /**
     * Get list of start points to append
     *
     * @since 1.0.0
     */
    public function get_start_points() {
        static $query_append;
        if (is_null($query_append)) {
            $query_append = array();

            foreach ((array) $this->startpints as $endpoint) {
                if ($endpoint[3]) {
                    $spmatch = $endpoint[1] . '/';
                } else {
                    $spmatch = $endpoint[1] . '/([^/]+)?/?';
                }

                $epquery = '&' . $endpoint[2] . '=';
                $query_append[$spmatch] = array($endpoint[0], $epquery, $endpoint[3]);
            }
        }
        return $query_append;
    }

    /**
     * Callback for preg_replace_callback to
     * Increase rewrite query vars preg_index index number
     *
     * @see   increase_pattern_preg_index
     * @see   \WP_Rewrite::preg_index
     *
     * @private
     *
     * @param string      $matched
     *
     * @global WP_Rewrite $wp_rewrite WordPress Rewrite Component.
     *
     * @since 1.0.0
     *
     * @return string
     */
    protected function _increase_preg_index_replace_callback($matched) {
        global $wp_rewrite;
        $index = intval($matched[1]);
        return $wp_rewrite->preg_index($index + 1);
    }

    /**
     * Generate startpoint rewrite rules
     *
     * @param array       $rewrite_rules
     *
     * @global WP_Rewrite $wp_rewrite WordPress Rewrite Component.
     *
     * @since 1.0.0
     *
     * @return array
     */
    public function generate_rewrite_rules($rewrite_rules) {
        global $wp_rewrite;
        $current_SP = $this->get_current_sp_mask();
        $startpints = $this->get_start_points();
        if (!$startpints) {
            return $rewrite_rules;
        }

        $results = array();
		$permalink_structure = get_option( 'permalink_structure' );
		$url_prefix = substr( $permalink_structure, 0, strpos( $permalink_structure, '%' ) );
		$url_prefix = preg_quote( ltrim( $url_prefix, '/' ), '#' );
		
        foreach ($rewrite_rules as $regex => $query) {
            $vars = array();
            wp_parse_str($query, $vars);
            if (!isset($vars['feed'])) { //skip feeds regex
                foreach ($startpints as $spregex => $sp) {
					if ($sp[0] & $current_SP) {
						if ($sp[2]) {
							$startpint_query = $query . $sp[1] . '1';
						} else {
							$startpint_query = $this->increase_pattern_preg_index($query) . $sp[1] . $wp_rewrite->preg_index(1);
						}
						
						if( $url_prefix && preg_match( "#^($url_prefix)(.+)$#", $regex, $match ) ) {
							$results[$match[1] . $spregex . ltrim($match[2], '/')] = $startpint_query;
						} else {
							$results[$spregex . ltrim($regex, '/')] = $startpint_query;
						}
					}
                }
            }
            $results[$regex] = $query;
        }
        return $results;
    }

// generate_rewrite_rules

    /**
     * Increase rewrite query vars preg_index index number
     *
     * @param string      $query
     *
     * @global WP_Rewrite $wp_rewrite WordPress Rewrite Component.
     *
     * @since 1.0.0
     *
     * @return string
     */
    protected function increase_pattern_preg_index($query) {

        global $wp_rewrite;

        $pattern = preg_quote($wp_rewrite->preg_index('PLACEHOLDER'));
        $pattern = '/' . str_replace('PLACEHOLDER', '(\\d+)', $pattern) . '/';

        $query = preg_replace_callback($pattern, array($this, '_increase_preg_index_replace_callback'), $query);

        return $query;
    }

    /**
     * Add a start point
     *
     *
     * @param string      $name
     * @param int         $places
     * @param string|bool $query_var
     * @param bool        $single_match {@see amp_wp_add_rewrite_start point for documentation}
     *
     * @see   add_rewrite_endpoint for parameters documentation
     *
     * @global WP         $wp           Current WordPress environment instance.
     *
     * @since 1.0.0
     */
    public function add_startpint($name, $places, $query_var = true, $single_match = true) {

        global $wp;

        // For backward compatibility, if null has explicitly been passed as `$query_var`, assume `true`.
        if (true === $query_var || null === func_get_arg(2)) {
            $query_var = $name;
        }
        $this->startpints[] = array($places, $name, $query_var, $single_match);

        if ($query_var) {
            $wp->add_query_var($query_var);
        }
    }
    // add_startpint
}

// Amp_WP_Rewrite_Rules
$GLOBALS['amp_wp_rewrite_rules'] = new Amp_WP_Rewrite_Rules();

/**
 * Add a startpoint to rewrite rules
 *
 *
 * @since 1.0.0
 *
 * @param string                    $name
 * @param int                       $places
 * @param string|bool               $query_var
 * @param bool                      $single_match             if false: user can pass any thing after start pint
 *                                                            for Ex: my-start-point/<something> if true:  just $name
 *                                                            at start of the url will accept  for Ex: my-start/ WP
 *                                                            Category URL
 *
 * @global Amp_WP_Rewrite_Rules $amp_wp_rewrite_rules AMP WP Rewrite API
 *
 * @see add_rewrite_endpoint for parameters documentation
 *
 * @version 1.0.0
 * @since   1.0.0
 */
function amp_wp_add_rewrite_startpoint($name, $places, $query_var = true, $single_match = true) {
    global $amp_wp_rewrite_rules;
    $amp_wp_rewrite_rules->add_startpint( $name, $places, $query_var, $single_match );
}