//
//  SKAction+Color.swift
//  Magnetic
//
//  Created by Jesse Onolememen on 31/03/2020.
//  Copyright © 2020 efremidze. All rights reserved.
//

import Foundation
import SpriteKit

func lerp(a : CGFloat, b : CGFloat, fraction : CGFloat) -> CGFloat {
  return (b-a) * fraction + a
}

struct ColorComponents {
  var red = CGFloat(0)
  var green = CGFloat(0)
  var blue = CGFloat(0)
  var alpha = CGFloat(0)
}

extension UIColor {
  var components: ColorComponents {
    get {
      var components = ColorComponents()
      getRed(&components.red, green: &components.green, blue: &components.blue, alpha: &components.alpha)
      return components
    }
  }
}

extension SKAction {
  typealias ColorTransitionConfigure = ((_ node: SKNode) -> Void)?
  
  static func colorTransition(from fromColor: UIColor, to toColor: UIColor, duration: Double = 0.4, configure: ColorTransitionConfigure = nil) -> SKAction {
    return SKAction.customAction(withDuration: duration, actionBlock: { (node : SKNode!, elapsedTime : CGFloat) -> Void in
      let fraction = CGFloat(elapsedTime / CGFloat(duration))
      let startColorComponents = fromColor.components
      let endColorComponents = toColor.components
      let transColor = UIColor(
        red: lerp(a: startColorComponents.red, b: endColorComponents.red, fraction: fraction),
        green: lerp(a: startColorComponents.green, b: endColorComponents.green, fraction: fraction),
        blue: lerp(a: startColorComponents.blue, b: endColorComponents.blue, fraction: fraction),
        alpha: lerp(a: startColorComponents.alpha, b: endColorComponents.alpha, fraction: fraction)
      )
      
      if let configure = configure {
        configure(node)
      } else {
        if let node = node as? SKShapeNode {
          node.fillColor = transColor
        }

        if let label = node as? SKMultilineLabelNode {
          label.fontColor = transColor
        }
      }
    })
  }
}