//
//  Created by Tom Baranes on 23/08/16.
//  Copyright (c) 2016 IBAnimatable. All rights reserved.
//

import UIKit

public class ActivityIndicatorAnimationLineSpinFadeLoader: ActivityIndicatorAnimating {

  // MARK: Properties

  fileprivate let duration: CFTimeInterval = 1.2
  fileprivate let timingFunction: TimingFunctionType = .easeInOut

  // MARK: ActivityIndicatorAnimating

  public func configureAnimation(in layer: CALayer, size: CGSize, color: UIColor) {
    let lineSpacing: CGFloat = 2
    let lineSize = CGSize(width: (size.width - 4 * lineSpacing) / 5, height: (size.height - 2 * lineSpacing) / 3)
    let x = (layer.bounds.size.width - size.width) / 2
    let y = (layer.bounds.size.height - size.height) / 2
    let beginTime = layer.currentMediaTime
    let beginTimes: [CFTimeInterval] = [0.12, 0.24, 0.36, 0.48, 0.6, 0.72, 0.84, 0.96]
    let animation = defaultAnimation

    for i in 0 ..< 8 {
      let line = makeLineLayer(angle: CGFloat.pi / 4 * CGFloat(i),
                               size: lineSize,
                               origin: CGPoint(x: x, y: y),
                               containerSize: size,
                               color: color)
      animation.beginTime = beginTime + beginTimes[i]
      line.add(animation, forKey: "animation")
      layer.addSublayer(line)
    }
  }

}

// MARK: - Setup

private extension ActivityIndicatorAnimationLineSpinFadeLoader {

  var defaultAnimation: CAKeyframeAnimation {
    let animation = CAKeyframeAnimation(keyPath: .opacity)
    animation.keyTimes = [0, 0.5, 1]
    animation.timingFunctionsType = [timingFunction, timingFunction]
    animation.values = [1, 0.3, 1]
    animation.duration = duration
    animation.repeatCount = .infinity
    animation.isRemovedOnCompletion = false
    return animation
  }

  func makeLineLayer(angle: CGFloat, size: CGSize, origin: CGPoint, containerSize: CGSize, color: UIColor) -> CALayer {
    let radius = containerSize.width / 2 - max(size.width, size.height) / 2
    let lineContainerSize = CGSize(width: max(size.width, size.height), height: max(size.width, size.height))
    let lineContainer = CALayer()
    let lineContainerFrame = CGRect(
      x: origin.x + radius * (cos(angle) + 1),
      y: origin.y + radius * (sin(angle) + 1),
      width: lineContainerSize.width,
      height: lineContainerSize.height)
    let line = ActivityIndicatorShape.line.makeLayer(size: size, color: color)
    let lineFrame = CGRect(
      x: (lineContainerSize.width - size.width) / 2,
      y: (lineContainerSize.height - size.height) / 2,
      width: size.width,
      height: size.height)

    lineContainer.frame = lineContainerFrame
    line.frame = lineFrame
    lineContainer.addSublayer(line)
    lineContainer.sublayerTransform = CATransform3DMakeRotation(CGFloat.pi / 2 + angle, 0, 0, 1)
    return lineContainer
  }

}