/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    An extension on `LevelScene` which ensures that game play is paused when the app enters the background for a number of user initiated events.

*/

#if os(OSX)

import AppKit

#else

import UIKit

#endif

extension LevelScene {

    // MARK: Properties

    /**

        The scene's `paused` property is set automatically when the

        app enters the background. Override to check if an `overlay` node is

        being presented to determine if the game should be paused.

    */

    override var isPaused: Bool {

        didSet {

            if overlay != nil {

                worldNode.isPaused = true

            }

        }

    }

    /// Platform specific notifications about the app becoming inactive.

    private var pauseNotificationNames: [NSNotification.Name] {

        #if os(OSX)

        return [

           .NSApplicationWillResignActive,

           .NSWindowDidMiniaturize

        ]

        #else

        return [

            NSNotification.Name.UIApplicationWillResignActive

        ]

        #endif

    }

    // MARK: Convenience

    /**

        Register for notifications about the app becoming inactive in

        order to pause the game. 

    */

    func registerForPauseNotifications() {

        for notificationName in pauseNotificationNames {

            NotificationCenter.default.addObserver(self, selector: #selector(LevelScene.pauseGame), name: notificationName, object: nil)

        }

    }

    func pauseGame() {

        stateMachine.enter(LevelScenePauseState.self)

    }

    func unregisterForPauseNotifications() {

        for notificationName in pauseNotificationNames {

            NotificationCenter.default.removeObserver(self, name: notificationName, object: nil)

        }

    }

}