import Foundation
import UIKit

// Incuding at least one Objective-C class in a swift file ensures that it doesn't get stripped by the linker
private final class LinkHelperClass: NSObject {
}

public extension CALayer {
    func addShakeAnimation(amplitude: CGFloat = 3.0, duration: Double = 0.3, count: Int = 4, decay: Bool = false) {
        let k = Float(UIView.animationDurationFactor())
        var speed: Float = 1.0
        if k != 0 && k != 1 {
            speed = Float(1.0) / k
        }
                
        let animation = CAKeyframeAnimation(keyPath: "position.x")
        var values: [CGFloat] = []
        values.append(0.0)
        for i in 0 ..< count {
            let sign: CGFloat = (i % 2 == 0) ? 1.0 : -1.0
            let multiplier = decay ? 1.0 / CGFloat(i + 1) : 1.0
            values.append(amplitude * sign * multiplier)
        }
        values.append(0.0)
        animation.values = values.map { ($0 as NSNumber) as AnyObject }
        var keyTimes: [NSNumber] = []
        for i in 0 ..< values.count {
            if i == 0 {
                keyTimes.append(0.0)
            } else if i == values.count - 1 {
                keyTimes.append(1.0)
            } else {
                keyTimes.append((Double(i) / Double(values.count - 1)) as NSNumber)
            }
        }
        animation.keyTimes = keyTimes
        animation.speed = speed
        animation.duration = duration
        animation.isAdditive = true
        
        self.add(animation, forKey: "shake")
    }
    
    func addReorderingShaking() {
        func degreesToRadians(_ x: CGFloat) -> CGFloat {
            return .pi * x / 180.0
        }

        let duration: Double = 0.4
        let displacement: CGFloat = 1.0
        let degreesRotation: CGFloat = 2.0
        
        let negativeDisplacement = -1.0 * displacement
        let position = CAKeyframeAnimation.init(keyPath: "position")
        position.beginTime = 0.8
        position.duration = duration
        position.values = [
            NSValue(cgPoint: CGPoint(x: negativeDisplacement, y: negativeDisplacement)),
            NSValue(cgPoint: CGPoint(x: 0, y: 0)),
            NSValue(cgPoint: CGPoint(x: negativeDisplacement, y: 0)),
            NSValue(cgPoint: CGPoint(x: 0, y: negativeDisplacement)),
            NSValue(cgPoint: CGPoint(x: negativeDisplacement, y: negativeDisplacement))
        ]
        position.calculationMode = .linear
        position.isRemovedOnCompletion = false
        position.repeatCount = Float.greatestFiniteMagnitude
        position.beginTime = CFTimeInterval(Float(arc4random()).truncatingRemainder(dividingBy: Float(25)) / Float(100))
        position.isAdditive = true

        let transform = CAKeyframeAnimation.init(keyPath: "transform")
        transform.beginTime = 2.6
        transform.duration = 0.3
        transform.valueFunction = CAValueFunction(name: CAValueFunctionName.rotateZ)
        transform.values = [
            degreesToRadians(-1.0 * degreesRotation),
            degreesToRadians(degreesRotation),
            degreesToRadians(-1.0 * degreesRotation)
        ]
        transform.calculationMode = .linear
        transform.isRemovedOnCompletion = false
        transform.repeatCount = Float.greatestFiniteMagnitude
        transform.isAdditive = true
        transform.beginTime = CFTimeInterval(Float(arc4random()).truncatingRemainder(dividingBy: Float(25)) / Float(100))

        self.add(position, forKey: "shaking_position")
        self.add(transform, forKey: "shaking_rotation")
    }
}