/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    A state used to represent the player at level start when being 'beamed' into the level.

*/

import SpriteKit

import GameplayKit

class PlayerBotAppearState: GKState {

    // MARK: Properties

    unowned var entity: PlayerBot

    /// The amount of time the `PlayerBot` has been in the "appear" state.

    var elapsedTime: TimeInterval = 0.0

    /// The `AnimationComponent` associated with the `entity`.

    var animationComponent: AnimationComponent {

        guard let animationComponent = entity.component(ofType: AnimationComponent.self) else { fatalError("A PlayerBotAppearState's entity must have an AnimationComponent.") }

        return animationComponent

    }

    /// The `RenderComponent` associated with the `entity`.

    var renderComponent: RenderComponent {

        guard let renderComponent = entity.component(ofType: RenderComponent.self) else { fatalError("A PlayerBotAppearState's entity must have an RenderComponent.") }

        return renderComponent

    }

    /// The `OrientationComponent` associated with the `entity`.

    var orientationComponent: OrientationComponent {

        guard let orientationComponent = entity.component(ofType: OrientationComponent.self) else { fatalError("A PlayerBotAppearState's entity must have an OrientationComponent.") }

        return orientationComponent

    }

    /// The `InputComponent` associated with the `entity`.

    var inputComponent: InputComponent {

        guard let inputComponent = entity.component(ofType: InputComponent.self) else { fatalError("A PlayerBotAppearState's entity must have an InputComponent.") }

        return inputComponent

    }

    /// The `SKSpriteNode` used to show the player animating into the scene.

    var node = SKSpriteNode()

    // MARK: Initializers

    required init(entity: PlayerBot) {

        self.entity = entity

    }

    // MARK: GKState Life Cycle

    override func didEnter(from previousState: GKState?) {

        super.didEnter(from: previousState)

        // Reset the elapsed time.

        elapsedTime = 0.0

        /*

            The `PlayerBot` is about to appear in the level. We use an `SKShader` to

            provide a "teleport" effect to beam in the `PlayerBot`.

        */

        // Retrieve and use an initial texture for the `PlayerBot`, taken from the appropriate idle animation.

        guard let appearTextures = PlayerBot.appearTextures else {

            fatalError("Attempt to access PlayerBot.appearTextures before they have been loaded.")

        }

        let texture = appearTextures[orientationComponent.compassDirection]!

        node.texture = texture

        node.size = PlayerBot.textureSize

        // Add an `SKShader` to the node to render the "teleport" effect.

        node.shader = PlayerBot.teleportShader

        // Add the node to the `PlayerBot`'s render node.

        renderComponent.node.addChild(node)

        // Hide the animation component node until the `PlayerBot` exits this state.

        animationComponent.node.isHidden = true

        // Disable the input component while the `PlayerBot` appears.

        inputComponent.isEnabled = false

    }

    override func update(deltaTime seconds: TimeInterval) {

        super.update(deltaTime: seconds)

        // Update the amount of time that the `PlayerBot` has been teleporting in to the level.

        elapsedTime += seconds

        // Check if we have spent enough time

        if elapsedTime > GameplayConfiguration.PlayerBot.appearDuration {

            // Remove the node from the scene

            node.removeFromParent()

            // Switch the `PlayerBot` over to a "player controlled" state.

            stateMachine?.enter(PlayerBotPlayerControlledState.self)

        }

    }

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

        return stateClass is PlayerBotPlayerControlledState.Type

    }

    override func willExit(to nextState: GKState) {

        super.willExit(to: nextState)

        // Un-hide the animation component node.

        animationComponent.node.isHidden = false

        // Re-enable the input component

        inputComponent.isEnabled = true

    }

}