/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Contains an `SKScene` subclass that provides the ability to display 

                a preview for a `Dream`, including effects. Note that the `DreamScene`

                uses a `DreamEffectLayout` to layout its nodes.

*/

import SpriteKit

/**

    Displays a `Dream` inside of a `SKScene`. Performs layout of the scene using

    the `DreamEffectLayout`. This is used in the `DreamPreviewHeaderReusableView`.

*/

class DreamScene: SKScene {

    // MARK: Properties

    var dream: Dream {

        didSet {

            dataDidChange()

        }

    }

    private var decoration: SKSpriteNode?

    private var content: SKLabelNode?

    private var effectNodes: [(Dream.Effect, SKNode)] = []

    // MARK: Initialization

    init(dream: Dream, size: CGSize) {

        self.dream = dream

        super.init(size: size)

        backgroundColor = .clear

    }

    required init?(coder aDecoder: NSCoder) {

        fatalError("\(#function) has not been implemented")

    }

    // MARK: Scene Callbacks

    override func sceneDidLoad() {

        dataDidChange()

    }

    func dataDidChange() {

        // Add all of the nodes to the scene if they haven't been added.

        decoration = decoration ?? {

            let decoration = SKSpriteNode()

            addChild(decoration)

            return decoration

        }()

        decoration!.texture = SKTexture(image: dream.creature.image)

        content = content ?? {

            let content = SKLabelNode()

            content.fontColor = .black

            addChild(content)

            return content

        }()

        content!.text = dream.description

        /*

            Always remove the effect nodes——we'll start from scratch with the new

            effects.

        */

        removeChildren(in: effectNodes.map { $1 })

        effectNodes = dream.effects.map { ($0, $0.makeNode()) }

        // Add all the new effect nodes to the scene.

        for (idx, (_, effectNode)) in effectNodes.enumerated() {

            effectNode.zPosition = CGFloat(idx)

            addChild(effectNode)

        }

        // Now we can layout all the nodes.

        layout()

    }

    override func didMove(to view: SKView) {

        layout()

    }

    override func didChangeSize(_ oldSize: CGSize) {

        layout()

    }

    /**

        Lays out all of the nodes in the scene based on the current `Dream`.

        This is the intersection between the SpriteKit node code and this sample's

        value based layout system.

    */

    func layout() {

        guard let decoration = decoration, let content = content else { return }

        /*

            Inset each of the effect nodes an amount that will position the effect

            in the correct place.

        */

        let insettedEffectNodes = effectNodes.map { effect, effectNode in

            return effectNode.withInsets(effect.insetsForDisplaying)

        }

        var dreamEffectLayout = DreamEffectLayout(content: content, decoration: decoration, effects: insettedEffectNodes)

        dreamEffectLayout.layout(in: frame)

        /*

            Make the z index for each node in the scene based on the index its in

            the effect layout's contents.

        */

        for (idx, leaf) in dreamEffectLayout.contents.enumerated() {

            leaf.zPosition = CGFloat(idx)

        }

    }

}

extension Dream.Effect {

    fileprivate var insetsForDisplaying: UIEdgeInsets {

        switch self {

            case .fireBreathing:

                return UIEdgeInsets(top: 0, left: 100, bottom: -80, right: 0)

            case .laserFocus:

                return UIEdgeInsets(top: 0, left: 30, bottom: 20, right: 0)

            case .magic, .fireflies, .rain, .snow:

                return .zero

        }

    }

}