import UIKit

extension FloatingPoint {
    var degreesToRadians: Self { self * .pi / 180 }
    var radiansToDegrees: Self { self * 180 / .pi }
}

@IBDesignable class ArcView: UIView {

    @IBInspectable var arcRadius: CGFloat = 40 {
        didSet {
            drawShap()
        }
    }

    @IBInspectable var fillColor:UIColor = .white {
        didSet {
            drawShap()
        }
    }

    @IBInspectable var strokeColor:UIColor = UIColor.red {
        didSet {
            drawShap()
        }
    }

    @IBInspectable var lineWidth:CGFloat = 2 {
        didSet {
            drawShap()
        }
    }

    @IBInspectable var cornerRadius:CGFloat = 0 {
        didSet {
            drawShap()
        }
    }

    override class var layerClass: AnyClass {
        CAShapeLayer.self
    }

    private var shapeLayer: CAShapeLayer {
        self.layer as! CAShapeLayer
    }

    private func drawShap() {
        shapeLayer.path = getBezierPath()
        shapeLayer.fillColor = fillColor.resolvedColor(with: traitCollection).cgColor
        shapeLayer.strokeColor = strokeColor.resolvedColor(with: traitCollection).cgColor
        shapeLayer.lineWidth = lineWidth

        shapeLayer.shadowColor = UIColor.black.cgColor
        shapeLayer.shadowOpacity = 0.15
        shapeLayer.shadowOffset = CGSize(width: 0, height: 0)
        shapeLayer.masksToBounds = false
    }

    private func getBezierPath() -> CGPath {

        let radius: CGFloat = arcRadius
        let s_radious: CGFloat = 8
        let alpha = asin(s_radious/radius).radiansToDegrees
        let path = UIBezierPath()
        let halfWidth = self.frame.width / 2

        path.move(to: CGPoint(x: cornerRadius, y: 0))
        path.addLine(to: CGPoint(x: (halfWidth - radius - s_radious), y: 0))

        path.addArc(withCenter: .init(x: halfWidth-(radius+s_radious), y: s_radious),
                    radius: s_radious,
                    startAngle: CGFloat(-90).degreesToRadians,
                    endAngle: CGFloat(0).degreesToRadians,
                    clockwise: true)

        path.addArc(withCenter: CGPoint(x: halfWidth, y: 0),
                    radius: radius + s_radious/6,
                    startAngle: CGFloat(180 - alpha).degreesToRadians,
                    endAngle: CGFloat(0+alpha).degreesToRadians,
                    clockwise: false)

        path.addArc(withCenter: .init(x: halfWidth+radius+s_radious, y: s_radious),
                    radius: s_radious,
                    startAngle: CGFloat(180).degreesToRadians,
                    endAngle: CGFloat(270).degreesToRadians,
                    clockwise: true)
        print("\(halfWidth-(radius+s_radious))")
        print("\(halfWidth), \(radius), \(s_radious)")

        path.addLine(to: CGPoint(x: self.frame.width - cornerRadius, y: 0))
        path.addArc(withCenter: CGPoint(x: frame.width - cornerRadius, y: frame.height - cornerRadius), radius: cornerRadius, startAngle: CGFloat(-90).degreesToRadians, endAngle: CGFloat(90).degreesToRadians, clockwise: true)
        path.addLine(to: CGPoint(x: cornerRadius, y: self.frame.height))
        path.addArc(withCenter: CGPoint(x: cornerRadius, y: frame.height/2), radius: cornerRadius, startAngle: CGFloat(90).degreesToRadians, endAngle: CGFloat(-90).degreesToRadians, clockwise: true)
        path.close()
        return path.cgPath
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        drawShap()
    }

    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)
        if traitCollection.hasDifferentColorAppearance(comparedTo: previousTraitCollection) {
            drawShap()
        }
    }
}