/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A state for use in a dispenser's state machine. This state represents when the dispenser is empty. It flashes the dispenser's warning light.

*/

import SpriteKit

import GameplayKit

class EmptyState: DispenserState {

    // MARK: Properties

    /// Keeps track of time between indicator light toggles.

    var flashTimeCounter: TimeInterval = 0

    /// Defines the time interval between when the light is toggled.

    static let flashInterval = 0.6

    /// Changes the color of the indicator light to red or black when toggled.

    var lightOn = true {

        didSet {

            if lightOn {

                let redColor = SKColor.red

                changeIndicatorLightToColor(redColor)

            }

            else {

                let blackColor = SKColor.black

                changeIndicatorLightToColor(blackColor)

            }

        }

    }

    // MARK: Initialization

    required init(game: GameScene) {

        super.init(game: game, associatedNodeName: "EmptyState")

    }

    // MARK: GKState overrides

    override func didEnter(from previousState: GKState?) {

        super.didEnter(from: previousState)

        // Turn on the indicator light with a red color.

        let red = SKColor.red

        changeIndicatorLightToColor(red)

    }

    override func willExit(to nextState: GKState) {

        super.willExit(to: nextState)

        // Turn on the indicator light with a green color.

        let black = SKColor.black

        changeIndicatorLightToColor(black)

    }

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

        // This state can only transition to the refilling state. 

        return stateClass is RefillingState.Type

    }

    override func update(deltaTime: TimeInterval) {

        // Keep track of the time since the last update.

        flashTimeCounter += deltaTime

        /*

            If an interval of `flashInterval` has passed since the previous update,

            toggle the indicator light and reset the time counter.

        */

        if flashTimeCounter > EmptyState.flashInterval {

            lightOn = !lightOn

            flashTimeCounter = 0

        }

    }

}