/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Handles logic, updates, and input for the scene. Primarily, it creates and manages the game's state machine.

*/

import SpriteKit

import GameplayKit

class GameScene: SKScene {

    // MARK: Properties

    /**

        Controls the states of the dispenser. This property is an implicitly 

        unwrapped optional because it will not be modified after it is 

        configured in `didMoveToView(_:)`.

    */

    var stateMachine: GKStateMachine!

    /// Keeps track of the time for use in the update method.

    var previousUpdateTime: TimeInterval = 0

    // MARK: SKScene overrides

    override func didMove(to _: SKView) {

        // Creates and adds states to the dispenser's state machine.

        stateMachine = GKStateMachine(states: [

            FullState(game: self),

            PartiallyFullState(game: self),

            EmptyState(game: self),

            RefillingState(game: self),

            ServeState(game: self)

        ])

        // Tells the state machine to enter the full state.

        stateMachine.enter(FullState.self)

    }

    override func didChangeSize(_ oldSize: CGSize) {

        let dispenser = childNode(withName: "dispenser")!

        dispenser.position.x = size.width / 2

    }

    override func update(_ currentTime: TimeInterval) {

        // Calculate the time change since the previous update.

        let timeSincePreviousUpdate = currentTime - previousUpdateTime

        // The Empty state uses this to keep the indicator light flashing.

        stateMachine.update(deltaTime: timeSincePreviousUpdate)

        /*

            Set previousUpdateTime to the current time, so the next update has

            accurate information.

        */

        previousUpdateTime = currentTime

    }

    // MARK: Game Logic

    /**

        Tells the state machine to enter the serve state. It will fail if the

        transition is not valid.

    */

    func attemptToDispense() {

        stateMachine.enter(ServeState.self)

    }

    /**

        Tells the state machine to enter the refilling state. It will fail if 

        the transition is not valid.

    */

    func attemptToRefill() {

        // Grab the refill button from the scene.

        let refillButton = childNode(withName: "//refillButton")!

        /*

            Create and run an animation on the refill button to show that the 

            button has been pressed.

        */

        let buttonPressedAction = SKAction(named: "buttonPressed", duration: 0.6)!

        refillButton.run(buttonPressedAction)

        // Attempt to enter the Refill state. 

        stateMachine.enter(RefillingState.self)

    }

    /**

        Decides whether to attempt to dispense or to refill the dispenser, 

        given a touch location or click location. If the refill button was 

        touched/clicked, attempt to refill. Otherwise, attempt to dispense.

    */

    func dispenseOrRefill(_ location: CGPoint) {

        // Grab the refill button from the scene.

        let refillButton = childNode(withName: "//refillButton")!

        /*

            If the refill button was touched/clicked, attempt to refill the 

            dispenser. Otherwise, attempt to dispense water.

        */

        if atPoint(location) === refillButton {

            attemptToRefill()

        }

        else {

            attemptToDispense()

        }

    }

    // MARK: Input Handling (OS X)

    #if os(OSX)

    override func keyDown(with _: NSEvent) {

        // Press any key to dispense.

        attemptToDispense()

    }

    override func mouseDown(with event: NSEvent) {

        // Click the refill button to refill, or anywhere else to dispense.

        let clickLocation = event.location(in: self)

        dispenseOrRefill(clickLocation)

    }

    // MARK: Input Handling (iOS)

    #elseif os(iOS)

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

        // Tap the refill button to refill, or anywhere else to dispense.

        let touchLocationInView = touches.first!.location(in: view)

        let touchLocationInScene = convertPoint(fromView: touchLocationInView)

        dispenseOrRefill(touchLocationInScene)

    }

    // MARK: Input Handling (tvOS)

    #elseif os(tvOS)

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

        // Tap the Siri Remote touch surface to dispense.

        attemptToDispense()

    }

    override func pressesEnded(_ presses: Set<UIPress>, with event: UIPressesEvent?) {

        // Click the Siri Remote touch surface to refill.

        attemptToRefill()

    }

    #endif

}