/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A state used by `SceneLoader` to indicate that all of the resources for the scene are loaded into memory and ready for use. This is the final state in the `SceneLoader`'s state machine.

*/

import GameplayKit

class SceneLoaderResourcesReadyState: GKState {

    // MARK: Properties

    unowned let sceneLoader: SceneLoader

    // MARK: Initialization

    init(sceneLoader: SceneLoader) {

        self.sceneLoader = sceneLoader

    }

    // MARK: GKState Life Cycle

    override func didEnter(from previousState: GKState?) {

        super.didEnter(from: previousState)

        // Clear the `sceneLoader`'s progress as loading is complete. 

        sceneLoader.progress = nil

        // Notify to any interested objects that the download has completed.

        NotificationCenter.default.post(name: NSNotification.Name.SceneLoaderDidCompleteNotification, object: sceneLoader)

    }

    override func isValidNextState(_ stateClass: AnyClass) -> Bool {

        switch stateClass {

            case is SceneLoaderResourcesAvailableState.Type, is SceneLoaderInitialState.Type:

                return true

            default:

                return false

        }

    }

    override func willExit(to nextState: GKState) {

        super.willExit(to: nextState)

        /*

            Presenting the scene is a one shot operation. Clear the scene when 

            exiting the ready state.

        */

        sceneLoader.scene = nil

    }

}