<?php
/**
 * WooCommerce Plugin Framework
 *
 * This source file is subject to the GNU General Public License v3.0
 * that is bundled with this package in the file license.txt.
 * It is also available through the world-wide-web at this URL:
 * http://www.gnu.org/licenses/gpl-3.0.html
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@skyverge.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade the plugin to newer
 * versions in the future. If you wish to customize the plugin for your
 * needs please refer to http://www.skyverge.com
 *
 * @package   SkyVerge/WooCommerce/Plugin/Classes
 * @author    SkyVerge
 * @copyright Copyright (c) 2013-2016, SkyVerge, Inc.
 * @license   http://www.gnu.org/licenses/gpl-3.0.html GNU General Public License v3.0
 */

defined( 'ABSPATH' ) or exit;

if ( ! class_exists( 'SV_WC_Plugin' ) ) :

/**
 * # WooCommerce Plugin Framework
 *
 * This framework class provides a base level of configurable and overrideable
 * functionality and features suitable for the implementation of a WooCommerce
 * plugin.  This class handles all the "non-feature" support tasks such
 * as verifying dependencies are met, loading the text domain, etc.
 *
 * @version 4.4.0
 */
abstract class SV_WC_Plugin {


	/** Plugin Framework Version */
	const VERSION = '4.4.0';

	/** @var object single instance of plugin */
	protected static $instance;

	/** @var string plugin id */
	private $id;

	/** @var string version number */
	private $version;

	/** @var string plugin path without trailing slash */
	private $plugin_path;

	/** @var string plugin uri */
	private $plugin_url;

	/** @var \WC_Logger instance */
	private $logger;

	/** @var  \SV_WP_Admin_Message_Handler instance */
	private $message_handler;

	/** @var array string names of required PHP extensions */
	private $dependencies = array();

	/** @var array string names of required PHP functions */
	private $function_dependencies = array();

	/** @var string the plugin text domain */
	private $text_domain;

	/** @var SV_WC_Admin_Notice_Handler the admin notice handler class */
	private $admin_notice_handler;


	/**
	 * Initialize the plugin
	 *
	 * Optional args:
	 *
	 * + `dependencies` - array string names of required PHP extensions
	 * + `function_dependencies` - array string names of required PHP functions
	 *
	 * Child plugin classes may add their own optional arguments
	 *
	 * @since 2.0.0
	 * @param string $id plugin id
	 * @param string $version plugin version number
	 * @param array $args optional plugin arguments
	 */
	public function __construct( $id, $version, $args = array() ) {

		// required params
		$this->id          = $id;
		$this->version     = $version;

		if ( isset( $args['dependencies'] ) )                $this->dependencies = $args['dependencies'];

		if ( isset( $args['function_dependencies'] ) )       $this->function_dependencies = $args['function_dependencies'];

		if ( isset( $args['text_domain'] ) ) {
			$this->text_domain = $args['text_domain'];
		}

		// include library files after woocommerce is loaded
		add_action( 'sv_wc_framework_plugins_loaded', array( $this, 'lib_includes' ) );

		// includes that are required to be available at all times
		$this->includes();

		$this->load_hook_deprecator();

		// Admin
		if ( is_admin() && ! is_ajax() ) {

			// admin message handler
			require_once( $this->get_framework_path() . '/class-sv-wp-admin-message-handler.php' );

			// render any admin notices, delayed notices, and
			add_action( 'admin_notices', array( $this, 'add_admin_notices'            ), 10 );
			add_action( 'admin_footer',  array( $this, 'add_delayed_admin_notices'    ), 10 );

			// add a 'Configure' link to the plugin action links
			add_filter( 'plugin_action_links_' . plugin_basename( $this->get_file() ), array( $this, 'plugin_action_links' ) );

			// defer until WP/WC has fully loaded
			add_action( 'wp_loaded', array( $this, 'do_install' ) );

			// register activation/deactivation hooks for convenience
			register_activation_hook(   $this->get_file(), array( $this, 'activate' ) );
			register_deactivation_hook( $this->get_file(), array( $this, 'deactivate' ) );
		}

		// automatically log HTTP requests from SV_WC_API_Base
		$this->add_api_request_logging();

		// Load translation files
		add_action( 'init', array( $this, 'load_translations' ) );
	}


	/**
	 * Cloning instances is forbidden due to singleton pattern.
	 *
	 * @since 3.1.0
	 */
	public function __clone() {
		/* translators: Placeholders: %s - plugin name */
		_doing_it_wrong( __FUNCTION__, sprintf( esc_html__( 'You cannot clone instances of %s.', 'woocommerce-plugin-framework' ), $this->get_plugin_name() ), '3.1.0' );
	}

	/**
	 * Unserializing instances is forbidden due to singleton pattern.
	 *
	 * @since 3.1.0
	 */
	public function __wakeup() {
		/* translators: Placeholders: %s - plugin name */
		_doing_it_wrong( __FUNCTION__, sprintf( esc_html__( 'You cannot unserialize instances of %s.', 'woocommerce-plugin-framework' ), $this->get_plugin_name() ), '3.1.0' );
	}


	/**
	 * Load plugin & framework text domains
	 *
	 * @since 4.2.0
	 */
	public function load_translations() {

		// load the framework translation files
		$framework_domain = 'woocommerce-plugin-framework';
		$framework_locale = apply_filters( 'plugin_locale', get_locale(), $framework_domain );

		load_textdomain( $framework_domain, WP_LANG_DIR . '/' . $framework_domain . '/' . $framework_domain . '-' . $framework_locale . '.mo' );

		load_plugin_textdomain( $framework_domain, false, dirname( plugin_basename( $this->get_framework_file() ) ) . '/i18n/languages' );

		// if this plugin passes along its text domain, load its translation files
		if ( $this->text_domain ) {

			$domain = $this->text_domain;
			$locale = apply_filters( 'plugin_locale', get_locale(), $this->text_domain );

			load_textdomain( $domain, WP_LANG_DIR . '/' . $domain . '/' . $domain . '-' . $locale . '.mo' );

			load_plugin_textdomain( $domain, false, dirname( plugin_basename( $this->get_file() ) ) . '/i18n/languages' );

		// otherwise, let it do the work
		} else {

			// load plugin text domain
			$this->load_translation();
		}
	}


	/**
	 * Load plugin text domain
	 *
	 * @since 1.0.0
	 */
	abstract public function load_translation();


	/**
	 * Include required library files
	 *
	 * @since 2.0.0
	 */
	public function lib_includes() {

		if ( is_admin() ) {
			// instantiate the admin notice handler
			$this->get_admin_notice_handler();
		}
	}


	/**
	 * Include any critical files which must be available as early as possible
	 *
	 * @since 2.0.0
	 */
	private function includes() {

		$framework_path = $this->get_framework_path();

		// common exception class
		require_once(  $framework_path . '/class-sv-wc-plugin-exception.php' );

		// common utility methods
		require_once( $framework_path . '/class-sv-wc-helper.php' );

		// backwards compatibility for older WC versions
		require_once( $framework_path . '/class-sv-wc-plugin-compatibility.php' );

		if ( is_admin() ) {
			// load admin notice handler
			require_once( $framework_path . '/class-sv-wc-admin-notice-handler.php' );
		}

		// generic API base
		require_once( $framework_path . '/api/class-sv-wc-api-exception.php' );
		require_once( $framework_path . '/api/class-sv-wc-api-base.php' );
		require_once( $framework_path . '/api/interface-sv-wc-api-request.php' );
		require_once( $framework_path . '/api/interface-sv-wc-api-response.php' );

		// XML API base
		require_once( $framework_path . '/api/abstract-sv-wc-api-xml-request.php' );
		require_once( $framework_path . '/api/abstract-sv-wc-api-xml-response.php' );

		// JSON API base
		require_once( $framework_path . '/api/abstract-sv-wc-api-json-request.php' );
		require_once( $framework_path . '/api/abstract-sv-wc-api-json-response.php' );
	}


	/**
	 * Load and instantiate the hook deprecator class
	 *
	 * @since 4.3.0
	 */
	private function load_hook_deprecator() {

		require_once( $this->get_framework_path() . '/class-sv-wc-hook-deprecator.php' );

		$this->hook_deprecator = new SV_WC_Hook_Deprecator( $this->get_plugin_name(), $this->get_deprecated_hooks() );
	}


	/**
	 * Return deprecated/removed hooks. Implementing classes should override this
	 * and return an array of deprecated/removed hooks in the following format:
	 *
	 * $old_hook_name = array {
	 *   @type string $version version the hook was deprecated/removed in
	 *   @type bool $removed if present and true, the message will indicate the hook was removed instead of deprecated
	 *   @type string|bool $replacement if present and a string, the message will indicate the replacement hook to use,
	 *     otherwise (if bool and false) the message will indicate there is no replacement available.
	 * }
	 *
	 * @since 4.3.0
	 * @return array
	 */
	protected function get_deprecated_hooks() {

		// stub method
		return array();
	}


	/** Admin methods ******************************************************/


	/**
	 * Returns true if on the admin plugin settings page, if any
	 *
	 * @since 2.0.0
	 * @return boolean true if on the admin plugin settings page
	 */
	public function is_plugin_settings() {
		// optional method, not all plugins *have* a settings page
		return false;
	}


	/**
	 * Checks if required PHP extensions are loaded and adds an admin notice
	 * for any missing extensions.  Also plugin settings can be checked
	 * as well.
	 *
	 * @since 3.0.0
	 */
	public function add_admin_notices() {

		// notices for any missing dependencies
		$this->add_dependencies_admin_notices();
	}


	/**
	 * Convenience method to add delayed admin notices, which may depend upon
	 * some setting being saved prior to determining whether to render
	 *
	 * @since 3.0.0
	 */
	public function add_delayed_admin_notices() {
		// stub method
	}


	/**
	 * Checks if required PHP extensions are not loaded and adds a dismissible admin
	 * notice if so.  Notice will not be rendered to the admin user once dismissed
	 * unless on the plugin settings page, if any
	 *
	 * @since 3.0.0
	 */
	protected function add_dependencies_admin_notices() {

		// report any missing extensions
		$missing_extensions = $this->get_missing_dependencies();

		if ( count( $missing_extensions ) > 0 ) {

			$message = sprintf(
				/* translators: Placeholders: %1$s - plugin name, %2$s - a PHP extension/comma-separated list of PHP extensions */
				_n(
					'%1$s requires the %2$s PHP extension to function. Contact your host or server administrator to configure and install the missing extension.',
					'%1$s requires the following PHP extensions to function: %2$s. Contact your host or server administrator to configure and install the missing extensions.',
					count( $missing_extensions ),
					'woocommerce-plugin-framework'
				),
				$this->get_plugin_name(),
				'<strong>' . implode( ', ', $missing_extensions ) . '</strong>'
			);

			$this->get_admin_notice_handler()->add_admin_notice( $message, 'missing-extensions', array(
				'notice_class' => 'error',
			) );

		}

		// report any missing functions
		$missing_functions = $this->get_missing_function_dependencies();

		if ( count( $missing_functions ) > 0 ) {

			$message = sprintf(
				/* translators: Placeholders: %1$s - plugin name, %2$s - a PHP function/comma-separated list of PHP functions */
				_n(
					'%1$s requires the %2$s PHP function to exist.  Contact your host or server administrator to configure and install the missing function.',
					'%1$s requires the following PHP functions to exist: %2$s.  Contact your host or server administrator to configure and install the missing functions.',
					count( $missing_functions ),
					'woocommerce-plugin-framework'
				),
				$this->get_plugin_name(),
				'<strong>' . implode( ', ', $missing_functions ) . '</strong>'
			);

			$this->get_admin_notice_handler()->add_admin_notice( $message, 'missing-functions', array(
				'notice_class' => 'error',
			) );

		}
	}


	/**
	 * Return the plugin action links.  This will only be called if the plugin
	 * is active.
	 *
	 * @since 2.0.0
	 * @param array $actions associative array of action names to anchor tags
	 * @return array associative array of plugin action links
	 */
	public function plugin_action_links( $actions ) {

		$custom_actions = array();

		// settings url(s)
		if ( $this->get_settings_link( $this->get_id() ) ) {
			$custom_actions['configure'] = $this->get_settings_link( $this->get_id() );
		}

		// documentation url if any
		if ( $this->get_documentation_url() ) {
			/* translators: Docs as in Documentation */
			$custom_actions['docs'] = sprintf( '<a href="%s">%s</a>', $this->get_documentation_url(), esc_html__( 'Docs', 'woocommerce-plugin-framework' ) );
		}

		// support url if any
		if ( $this->get_support_url() ) {
			$custom_actions['support'] = sprintf( '<a href="%s">%s</a>', $this->get_support_url(), esc_html_x( 'Support', 'noun', 'woocommerce-plugin-framework' ) );
		}

		// add the links to the front of the actions list
		return array_merge( $custom_actions, $actions );
	}


	/** Helper methods ******************************************************/


	/**
	 * Automatically log API requests/responses when using SV_WC_API_Base
	 *
	 * @since 2.2.0
	 * @see SV_WC_API_Base::broadcast_request()
	 */
	public function add_api_request_logging() {

		if ( ! has_action( 'wc_' . $this->get_id() . '_api_request_performed' ) ) {
			add_action( 'wc_' . $this->get_id() . '_api_request_performed', array( $this, 'log_api_request' ), 10, 2 );
		}
	}


	/**
	 * Log API requests/responses
	 *
	 * @since 2.2.0
	 * @param array $request request data, see SV_WC_API_Base::broadcast_request() for format
	 * @param array $response response data
	 * @param string|null $log_id log to write data to
	 */
	public function log_api_request( $request, $response, $log_id = null ) {

		$this->log( "Request\n" . $this->get_api_log_message( $request ), $log_id );

		if ( ! empty( $response ) ) {
			$this->log( "Response\n" . $this->get_api_log_message( $response ), $log_id );
		}
	}


	/**
	 * Transform the API request/response data into a string suitable for logging
	 *
	 * @since 2.2.0
	 * @param array $data
	 * @return string
	 */
	public function get_api_log_message( $data ) {

		$messages = array();

		$messages[] = isset( $data['uri'] ) && $data['uri'] ? 'Request' : 'Response';

		foreach ( (array) $data as $key => $value ) {
			$messages[] = sprintf( '%s: %s', $key, is_array( $value ) || ( is_object( $value ) && 'stdClass' == get_class( $value ) ) ? print_r( (array) $value, true ) : $value );
		}

		return implode( "\n", $messages );
	}


	/**
	 * Gets the string name of any required PHP extensions that are not loaded
	 *
	 * @since 2.0.0
	 * @return array of missing dependencies
	 */
	public function get_missing_dependencies() {

		$missing_extensions = array();

		foreach ( $this->get_dependencies() as $ext ) {

			if ( ! extension_loaded( $ext ) ) {
				$missing_extensions[] = $ext;
			}
		}

		return $missing_extensions;
	}


	/**
	 * Gets the string name of any required PHP functions that are not loaded
	 *
	 * @since 2.1.0
	 * @return array of missing functions
	 */
	public function get_missing_function_dependencies() {

		$missing_functions = array();

		foreach ( $this->get_function_dependencies() as $fcn ) {

			if ( ! function_exists( $fcn ) ) {
				$missing_functions[] = $fcn;
			}
		}

		return $missing_functions;
	}


	/**
	 * Saves errors or messages to WooCommerce Log (woocommerce/logs/plugin-id-xxx.txt)
	 *
	 * @since 2.0.0
	 * @param string $message error or message to save to log
	 * @param string $log_id optional log id to segment the files by, defaults to plugin id
	 */
	public function log( $message, $log_id = null ) {

		if ( is_null( $log_id ) ) {
			$log_id = $this->get_id();
		}

		if ( ! is_object( $this->logger ) ) {
			$this->logger = new WC_Logger();
		}

		$this->logger->add( $log_id, $message );
	}


	/**
	 * Require and instantiate a class
	 *
	 * @since 4.2.0
	 * @param string $local_path path to class file in plugin, e.g. '/includes/class-wc-foo.php'
	 * @param string $class_name class to instantiate
	 * @return object instantiated class instance
	 */
	public function load_class( $local_path, $class_name ) {

		require_once( $this->get_plugin_path() . $local_path );

		return new $class_name;
	}


	/** Getter methods ******************************************************/


	/**
	 * The implementation for this abstract method should simply be:
	 *
	 * return __FILE__;
	 *
	 * @since 2.0.0
	 * @return string the full path and filename of the plugin file
	 */
	abstract protected function get_file();


	/**
	 * Returns the plugin id
	 *
	 * @since 2.0.0
	 * @return string plugin id
	 */
	public function get_id() {
		return $this->id;
	}


	/**
	 * Returns the plugin id with dashes in place of underscores, and
	 * appropriate for use in frontend element names, classes and ids
	 *
	 * @since 2.0.0
	 * @return string plugin id with dashes in place of underscores
	 */
	public function get_id_dasherized() {
		return str_replace( '_', '-', $this->get_id() );
	}


	/**
	 * Returns the plugin full name including "WooCommerce", ie
	 * "WooCommerce X".  This method is defined abstract for localization purposes
	 *
	 * @since 2.0.0
	 * @return string plugin name
	 */
	abstract public function get_plugin_name();


	/**
	 * Returns the admin notice handler instance
	 *
	 * @since 3.0.0
	 */
	public function get_admin_notice_handler() {

		if ( ! is_null( $this->admin_notice_handler ) ) {
			return $this->admin_notice_handler;
		}

		return $this->admin_notice_handler = new SV_WC_Admin_Notice_Handler( $this );
	}


	/**
	 * Returns the plugin version name.  Defaults to wc_{plugin id}_version
	 *
	 * @since 2.0.0
	 * @return string the plugin version name
	 */
	protected function get_plugin_version_name() {
		return 'wc_' . $this->get_id() . '_version';
	}


	/**
	 * Returns the current version of the plugin
	 *
	 * @since 2.0.0
	 * @return string plugin version
	 */
	public function get_version() {
		return $this->version;
	}


	/**
	 * Get the PHP dependencies for extension depending on the gateway being used
	 *
	 * @since 2.0.0
	 * @return array of required PHP extension names, based on the gateway in use
	 */
	protected function get_dependencies() {
		return $this->dependencies;
	}


	/**
	 * Get the PHP dependencies for functions depending on the gateway being used
	 *
	 * @since 2.1.0
	 * @return array of required PHP function names, based on the gateway in use
	 */
	protected function get_function_dependencies() {
		return $this->function_dependencies;
	}


	/**
	 * Returns the "Configure" plugin action link to go directly to the plugin
	 * settings page (if any)
	 *
	 * @since 2.0.0
	 * @see SV_WC_Plugin::get_settings_url()
	 * @param string $plugin_id optional plugin identifier.  Note that this can be a
	 *        sub-identifier for plugins with multiple parallel settings pages
	 *        (ie a gateway that supports both credit cards and echecks)
	 * @return string plugin configure link
	 */
	public function get_settings_link( $plugin_id = null ) {

		$settings_url = $this->get_settings_url( $plugin_id );

		if ( $settings_url ) {
			return sprintf( '<a href="%s">%s</a>', $settings_url, esc_html__( 'Configure', 'woocommerce-plugin-framework' ) );
		}

		// no settings
		return '';
	}


	/**
	 * Gets the plugin configuration URL
	 *
	 * @since 2.0.0
	 * @see SV_WC_Plugin::get_settings_link()
	 * @param string $plugin_id optional plugin identifier.  Note that this can be a
	 *        sub-identifier for plugins with multiple parallel settings pages
	 *        (ie a gateway that supports both credit cards and echecks)
	 * @return string plugin settings URL
	 */
	public function get_settings_url( $plugin_id = null ) {

		// stub method
		return '';
	}


	/**
	 * Returns true if the current page is the admin general configuration page
	 *
	 * @since 3.0.0
	 * @return boolean true if the current page is the admin general configuration page
	 */
	public function is_general_configuration_page() {

		return isset( $_GET['page'] ) && 'wc-settings' == $_GET['page'] && ( ! isset( $_GET['tab'] ) || 'general' == $_GET['tab'] );
	}


	/**
	 * Returns the admin configuration url for the admin general configuration page
	 *
	 * @since 3.0.0
	 * @return string admin configuration url for the admin general configuration page
	 */
	public function get_general_configuration_url() {

		return admin_url( 'admin.php?page=wc-settings&tab=general' );
	}


	/**
	 * Gets the plugin documentation url, used for the 'Docs' plugin action
	 *
	 * @since 2.0.0
	 * @return string documentation URL
	 */
	public function get_documentation_url() {

		return null;
	}


	/**
	 * Gets the support URL, used for the 'Support' plugin action link
	 *
	 * @since 4.0.0
	 * @return string support url
	 */
	public function get_support_url() {

		return null;
	}


	/**
	 * Returns the plugin's path without a trailing slash, i.e.
	 * /path/to/wp-content/plugins/plugin-directory
	 *
	 * @since 2.0.0
	 * @return string the plugin path
	 */
	public function get_plugin_path() {

		if ( $this->plugin_path ) {
			return $this->plugin_path;
		}

		return $this->plugin_path = untrailingslashit( plugin_dir_path( $this->get_file() ) );
	}


	/**
	 * Returns the plugin's url without a trailing slash, i.e.
	 * http://skyverge.com/wp-content/plugins/plugin-directory
	 *
	 * @since 2.0.0
	 * @return string the plugin URL
	 */
	public function get_plugin_url() {

		if ( $this->plugin_url ) {
			return $this->plugin_url;
		}

		return $this->plugin_url = untrailingslashit( plugins_url( '/', $this->get_file() ) );
	}


	/**
	 * Returns the woocommerce uploads path, without trailing slash.  Oddly WooCommerce
	 * core does not provide a way to get this
	 *
	 * @since 2.0.0
	 * @return string upload path for woocommerce
	 */
	public static function get_woocommerce_uploads_path() {
		$upload_dir = wp_upload_dir();
		return $upload_dir['basedir'] . '/woocommerce_uploads';
	}


	/**
	 * Returns the loaded framework __FILE__
	 *
	 * @since 4.0.0
	 * @return string
	 */
	public function get_framework_file() {

		return __FILE__;
	}


	/**
	 * Returns the loaded framework path, without trailing slash. Ths is the highest
	 * version framework that was loaded by the bootstrap.
	 *
	 * @since 4.0.0
	 * @return string
	 */
	public function get_framework_path() {

		return untrailingslashit( plugin_dir_path( $this->get_framework_file() ) );
	}


	/**
	 * Returns the absolute path to the loaded framework image directory, without a
	 * trailing slash
	 *
	 * @since 4.0.0
	 * @return string
	 */
	public function get_framework_assets_path() {

		return $this->get_framework_path() . '/assets';
	}


	/**
	 * Returns the loaded framework assets URL without a trailing slash
	 *
	 * @since 4.0.0
	 * @return string
	 */
	public function get_framework_assets_url() {

		return untrailingslashit( plugins_url( '/assets', $this->get_framework_file() ) );
	}


	/**
	 * Returns the WP Admin Message Handler instance for use with
	 * setting/displaying admin messages & errors
	 *
	 * @since 2.0.0
	 * @return SV_WP_Admin_Message_Handler
	 */
	public function get_message_handler() {

		if ( is_object( $this->message_handler ) ) {

			return $this->message_handler;
		}

		return $this->message_handler = new SV_WP_Admin_Message_Handler( $this->get_id() );
	}


	/**
	 * Helper function to determine whether a plugin is active
	 *
	 * @since 2.0.0
	 * @param string $plugin_name plugin name, as the plugin-filename.php
	 * @return boolean true if the named plugin is installed and active
	 */
	public function is_plugin_active( $plugin_name ) {

		$active_plugins = (array) get_option( 'active_plugins', array() );

		if ( is_multisite() ) {
			$active_plugins = array_merge( $active_plugins, array_keys( get_site_option( 'active_sitewide_plugins', array() ) ) );
		}

		$plugin_filenames = array();

		foreach ( $active_plugins as $plugin ) {

			if ( SV_WC_Helper::str_exists( $plugin, '/' ) ) {

				// normal plugin name (plugin-dir/plugin-filename.php)
				list( , $filename ) = explode( '/', $plugin );

			} else {

				// no directory, just plugin file
				$filename = $plugin;
			}

			$plugin_filenames[] = $filename;
		}

		return in_array( $plugin_name, $plugin_filenames );
	}


	/** Lifecycle methods ******************************************************/


	/**
	 * Handles version checking
	 *
	 * @since 2.0.0
	 */
	public function do_install() {

		$installed_version = get_option( $this->get_plugin_version_name() );

		// installed version lower than plugin version?
		if ( version_compare( $installed_version, $this->get_version(), '<' ) ) {

			if ( ! $installed_version ) {
				$this->install();
			} else {
				$this->upgrade( $installed_version );
			}

			// new version number
			update_option( $this->get_plugin_version_name(), $this->get_version() );
		}
	}


	/**
	 * Helper method to install default settings for a plugin
	 *
	 * @since 4.2.0
	 * @param array $settings array of settings in format required by WC_Admin_Settings
	 */
	public function install_default_settings( array $settings ) {

		foreach ( $settings as $setting ) {

			if ( isset( $setting['id'] ) && isset( $setting['default'] ) ) {

				update_option( $setting['id'], $setting['default'] );
			}
		}
	}


	/**
	 * Plugin install method.  Perform any installation tasks here
	 *
	 * @since 2.0.0
	 */
	protected function install() {
		// stub
	}


	/**
	 * Plugin upgrade method.  Perform any required upgrades here
	 *
	 * @since 2.0.0
	 * @param string $installed_version the currently installed version
	 */
	protected function upgrade( $installed_version ) {
		// stub
	}


	/**
	 * Plugin activated method. Perform any activation tasks here.
	 * Note that this _does not_ run during upgrades.
	 *
	 * @since 4.2.0
	 */
	public function activate() {
		// stub
	}


	/**
	 * Plugin deactivation method. Perform any deactivation tasks here.
	 *
	 * @since 4.2.0
	 */
	public function deactivate() {
		// stub
	}


}

endif; // Class exists check