Adding Favorites API Class to Navigation Feature (https://github.com/woocommerce/woocommerce-admin/pull/6270)

plugins/woocommerce-admin/src/Features/Navigation/Favorites.php

@@ -0,0 +1,109 @@
+<?php
+/**
+ * WooCommerce Navigation Favorite
+ *
+ * @package Woocommerce Navigation
+ */
+
+namespace Automattic\WooCommerce\Admin\Features\Navigation;
+
+use Automattic\WooCommerce\Admin\Loader;
+
+/**
+ * Contains logic for the WooCommerce Navigation menu.
+ */
+class Favorites {
+
+	/**
+	 * Array index of menu capability.
+	 *
+	 * @var int
+	 */
+	const META_NAME = 'navigation_favorites';
+
+	/**
+	 * Get class instance.
+	 */
+	final public static function instance() {
+		if ( ! static::$instance ) {
+			static::$instance = new static();
+		}
+		return static::$instance;
+	}
+
+	/**
+	 * Set given favorites string to the user meta data.
+	 *
+	 * @param string|number $user_id User id.
+	 * @param array         $favorites Array of favorite values to set.
+	 */
+	private static function set_meta_value( $user_id, $favorites ) {
+		Loader::update_user_data_field( $user_id, self::META_NAME, wp_json_encode( (array) $favorites ) );
+	}
+
+	/**
+	 * Add item to favorites
+	 *
+	 * @param string        $item_id Identifier of item to add.
+	 * @param string|number $user_id Identifier of user to add to.
+	 */
+	public static function add_item( $item_id, $user_id = null ) {
+		$user = $user_id ? $user_id : get_current_user_id();
+
+		if ( ! $user || ! $item_id ) {
+			return;
+		}
+
+		$all_favorites = self::get_all( $user );
+
+		if ( in_array( $item_id, $all_favorites, true ) ) {
+			return;
+		}
+
+		$all_favorites[] = $item_id;
+
+		self::set_meta_value( $user, $all_favorites );
+	}
+
+	/**
+	 * Remove item from favorites
+	 *
+	 * @param string        $item_id Identifier of item to remove.
+	 * @param string|number $user_id Identifier of user to remove from.
+	 */
+	public static function remove_item( $item_id, $user_id = null ) {
+		$user = $user_id ? $user_id : get_current_user_id();
+
+		if ( ! $user || ! $item_id ) {
+			return;
+		}
+
+		$all_favorites = self::get_all( $user );
+
+		if ( ! in_array( $item_id, $all_favorites, true ) ) {
+			return;
+		}
+
+		$remaining = array_diff( $all_favorites, [ $item_id ] );
+
+		self::set_meta_value( $user, array_values( $remaining ) );
+	}
+
+	/**
+	 * Get all registered favorites.
+	 *
+	 * @param string|number $user_id Identifier of user to query.
+	 */
+	public static function get_all( $user_id = null ) {
+		$user = $user_id ? $user_id : get_current_user_id();
+
+		if ( ! $user ) {
+			return;
+		}
+
+		$response = Loader::get_user_data_field( $user, self::META_NAME );
+
+		return $response ? json_decode( $response, true ) : array();
+	}
+
+}