/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Defines a collection view cell that displays a `Dream.Effect` inside

                the cell.

*/

import UIKit

import SpriteKit

/// A collection view cell that displays a `Dream.Effect` in an `SKView`.

class EffectCollectionViewCell: UICollectionViewCell {

    // MARK: Types

    private enum NodeName: String {

        case effect = "effect"

        case border = "border"

    }

    // MARK: Properties

    static let reuseIdentifier = "\(EffectCollectionViewCell.self)"

    private var scene: SKScene?

    var effect: Dream.Effect! {

        didSet {

            guard let scene = scene else { return }

            let emitterNode = scene.childNode(withName: NodeName.effect.rawValue) as! SKEmitterNode

            emitterNode.removeFromParent()

            addNode(for: effect, in: scene)

        }

    }

    func addNode(for effect: Dream.Effect, in scene: SKScene) {

        let effectNode = effect.makeNode()

        effectNode.position = effect.position(in: bounds)

        effectNode.name = NodeName.effect.rawValue

        scene.addChild(effectNode)

    }

    // MARK: Selection

    override var isSelected: Bool {

        set {

            super.isSelected = isSelected

            guard let scene = scene else { return }

            if newValue {

                addBorderNode(in: scene)

            }

            else if let borderNode = scene.childNode(withName: NodeName.border.rawValue) {

                scene.removeChildren(in: [borderNode])

            }

        }

        get { return super.isSelected }

    }

    func addBorderNode(in scene: SKScene) {

        // Don't do any work if the border is already visible.

        guard scene.childNode(withName: NodeName.border.rawValue) == nil else { return }

        let borderNode = SKCropNode()

        let maskNode = SKShapeNode(rectOf: bounds.size)

        maskNode.position = CGPoint(x: bounds.midX, y: bounds.midY)

        maskNode.lineWidth = 3

        maskNode.strokeColor = .blue

        maskNode.fillColor = .clear

        borderNode.maskNode = maskNode

        borderNode.addChild(maskNode)

        borderNode.name = NodeName.border.rawValue

        scene.addChild(borderNode)

    }

    // MARK: Subview Layout

    override func layoutSubviews() {

        guard self.scene == nil else { return }

        let skView = SKView(frame: bounds)

        contentView.addSubview(skView)

        skView.allowsTransparency = true

        skView.backgroundColor = .clear

        let scene = SKScene(size: bounds.size)

        scene.backgroundColor = .clear

        self.scene = scene

        addNode(for: effect, in: scene)

        if isHighlighted {

            addBorderNode(in: scene)

        }

        skView.presentScene(scene)

    }

}

extension Dream.Effect {

    /*

        Calculates where the effect node should be placed inside its `SKView`

        based on the size of the collection view cell.

    */

    fileprivate func position(in bounds: CGRect) -> CGPoint {

        var position = CGPoint(x: bounds.midX, y: bounds.midY)

        switch self {

            case .fireBreathing:

                position.x -= 30

                position.y += 30

            case .laserFocus:

                position.x -= 30

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

        }

        return position

    }

}