/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A subclass of `Operation` that manages the loading of a `BaseScene`.

*/

import Foundation

class LoadSceneOperation: SceneOperation, ProgressReporting {

    // MARK: Properties

    /// The metadata for the scene to load.

    let sceneMetadata: SceneMetadata

    /// The scene this operation is responsible for loading. Set after completion.

    var scene: BaseScene?

    /// Progress used to report on the status of this operation.

    let progress: Progress

    // MARK: Initialization

    init(sceneMetadata: SceneMetadata) {

        self.sceneMetadata = sceneMetadata

        progress = Progress(totalUnitCount: 1)

        super.init()

    }

    // MARK: NSOperation

    override func start() {

        // If the operation is cancelled there's nothing to do.

        guard !isCancelled else { return }

        if progress.isCancelled {

            // Ensure the operation is marked as `cancelled`.

            cancel()

            return

        }

        // Mark the operation as executing.

        state = .executing

        // Load the scene into memory using `SKNode(fileNamed:)`.

        let scene = sceneMetadata.sceneType.init(fileNamed: sceneMetadata.fileName)!

        self.scene = scene

        // Set up the scene's camera and native size.

        scene.createCamera()

        // Update the progress object's completed unit count.

        progress.completedUnitCount = 1

        state = .finished

    }

}