function init()
 {
     self::$active_plugins = (array) get_option('active_plugins', array());
     if (is_multisite()) {
         self::$active_plugins = array_merge(self::$active_plugins, get_site_option('active_sitewide_plugins', array()));
     }
 }
        /**
         * Add Product Data tab section.
         *
         * @return void
         */
        public function woo_tied_products_write_panel()
        {
            global $woocommerce, $post;
            $tied_products = maybe_unserialize(get_post_meta($post->ID, '_tied_products', true));
            $dependency_type = get_post_meta($post->ID, '_dependency_type', true);
            if (!$dependency_type) {
                $dependency_type = 3;
            }
            $product_id_options = array();
            if ($tied_products) {
                foreach ($tied_products as $item_id) {
                    $title = get_the_title($item_id);
                    $sku = get_post_meta($item_id, '_sku', true);
                    if (!$title) {
                        continue;
                    }
                    if ($sku) {
                        $title .= ' (SKU: ' . $sku . ')';
                    }
                    $product_id_options[$item_id] = $title;
                }
            }
            ?>
			<div id="tied_products_data" class="panel woocommerce_options_panel wc-metaboxes-wrapper">

				<p class="form-field">
					<label>
						<?php 
            _e('Product Dependencies', 'woocommerce-product-dependencies');
            ?>
					</label><?php 
            if (WC_Tied_Products_Dependencies::is_wc_version_gte_2_3()) {
                ?>
<input type="hidden" id="tied_products" name="tied_products" class="wc-product-search" style="width: 75%;" data-placeholder="<?php 
                _e('Search for products&hellip;', 'woocommerce-product-dependencies');
                ?>
" data-action="woocommerce_json_search_products" data-multiple="true" data-selected="<?php 
                echo esc_attr(json_encode($product_id_options));
                ?>
" value="<?php 
                echo implode(',', array_keys($product_id_options));
                ?>
" /><?php 
            } else {
                ?>
<select id="tied_products" multiple="multiple" name="tied_products[]" data-placeholder="<?php 
                _e('Search for products&hellip;', 'woocommerce-product-dependencies');
                ?>
" class="ajax_chosen_select_products"><?php 
                if (!empty($product_id_options)) {
                    foreach ($product_id_options as $product_id => $product_name) {
                        echo '<option value="' . $product_id . '" selected="selected">' . $product_name . '</option>';
                    }
                }
                ?>
</select><?php 
            }
            echo '<img class="help_tip" style="width:16px; height:16px;" data-tip="' . __('Restrict access to this product based on the ownership or purchase of the items added here.', 'woocommerce-product-dependencies') . '" src="' . WC()->plugin_url() . '/assets/images/help.png" />';
            ?>
</p>
		    	<p class="form-field">
					<label><?php 
            _e('Dependency Type', 'woocommerce-product-dependencies');
            ?>
					</label>
					<select name="dependency_type" id="dependency_type" style="min-width:150px;">
						<option value="1" <?php 
            echo $dependency_type == 1 ? 'selected="selected"' : '';
            ?>
><?php 
            _e('Ownership', 'woocommerce-product-dependencies');
            ?>
</option>
						<option value="2" <?php 
            echo $dependency_type == 2 ? 'selected="selected"' : '';
            ?>
><?php 
            _e('Purchase', 'woocommerce-product-dependencies');
            ?>
</option>
						<option value="3" <?php 
            echo $dependency_type == 3 ? 'selected="selected"' : '';
            ?>
><?php 
            _e('Either', 'woocommerce-product-dependencies');
            ?>
</option>
                   </select>
				</p>
		    </div>
		<?php 
        }