// Shape with indented Notched Tab View
// based on: DuncanMC's https://github.com/DuncanMC/ShapeWithTab

class ShapeWithNotchedTabView: UIView {
	
	var cornerRadius: CGFloat = 20
	var tabRadius: CGFloat = 60
	
	var roundedCorners: Bool = true { didSet { setNeedsLayout() } }
	
	var shapeLayer = CAShapeLayer()
	
	func buildShapeLayerPath() -> CGPath {
		let boxWidth = bounds.size.width
		let boxHeight = bounds.size.height
		
		// These are the corners of the view's primary rectangle
		// top-right
		let point1 = CGPoint(x: boxWidth, y: 0)
		// bottom-right
		let point2 = CGPoint(x: boxWidth, y: boxHeight)
		// bottom-left
		let point3 = CGPoint(x: 0, y: boxHeight)
		// top-left
		let point4 = CGPoint(x: 0, y: 0)
		
		// These are the corners of the "tab notch" that is inset from the top of the view
		let tabPoint1 = CGPoint(x: boxWidth / 2 - tabRadius, y: 0)
		let tabPoint2 = CGPoint(x: boxWidth / 2, y: tabRadius * 2)
		let tabPoint3 = CGPoint(x: boxWidth / 2 + tabRadius , y: 0)
		
		let path = CGMutablePath()
		
		// if we want rounded corners
		if roundedCorners {
			path.move(to: CGPoint(x: boxWidth, y: boxHeight - cornerRadius))
			
			path.addArc(tangent1End: point2,
						tangent2End: point3,
						radius: cornerRadius)
			path.addArc(tangent1End: point3,
						tangent2End: point4,
						radius: cornerRadius)
			path.addArc(tangent1End: point4,
						tangent2End: tabPoint1,
						radius: cornerRadius)
		} else {
			path.move(to: point1)
			path.addLine(to: point2)
			path.addLine(to: point3)
			path.addLine(to: point4)
			
		}
		
		// Draw the corner that curves around to our
		//	indented "circle tab notch" at the top
		// of the shape
		path.addArc(tangent1End: tabPoint1,
					tangent2End: tabPoint2,
					radius: cornerRadius)
		
		// Draw the "circle tab notch"
		path.addArc(tangent1End: tabPoint2,
					tangent2End: tabPoint3,
					radius: tabRadius)
		
		// Draw the corner from the circle tab notch back to the top of the rect
		path.addArc(tangent1End: tabPoint3,
					tangent2End: point1,
					radius: cornerRadius)
		
		if roundedCorners {
			// Draw the rest of the rounded rectangle
			path.addArc(tangent1End: point1,
						tangent2End: point2,
						radius: cornerRadius)
		} else {
			// Draw the rest of the rectangle
			path.addLine(to: point1)
		}
		
		path.closeSubpath()
		
		return path
	}
	
	func doInitSetup() {
		self.layer.addSublayer(shapeLayer)
		
		// Configure a shape layer to draw an outline
		shapeLayer.fillColor = UIColor.white.cgColor
		shapeLayer.strokeColor = UIColor.blue.cgColor
		shapeLayer.lineWidth = 2
	}
	
	override init(frame: CGRect) {
		super.init(frame: frame)
		self.doInitSetup()
	}
	
	required init?(coder: NSCoder) {
		super.init(coder: coder)
		self.doInitSetup()
	}
	
	public func updateShapeLayerPath() {
		let path = buildShapeLayerPath()
		shapeLayer.path =  path
	}
	
	override func layoutSubviews() {
		super.layoutSubviews()
		shapeLayer.frame = bounds
		updateShapeLayerPath()
	}
}

// example controller

class ViewController: UIViewController {

	override func viewDidLoad() {
		super.viewDidLoad()
		view.backgroundColor = UIColor(white: 0.95, alpha: 1.0)

		let v = ShapeWithNotchedTabView()
		v.translatesAutoresizingMaskIntoConstraints = false
		view.addSubview(v)
		
		NSLayoutConstraint.activate([
			v.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20.0),
			v.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20.0),
			v.centerYAnchor.constraint(equalTo: view.centerYAnchor),
			v.heightAnchor.constraint(equalToConstant: 120.0),
		])

		let label = UILabel()
		label.translatesAutoresizingMaskIntoConstraints = false
		label.textAlignment = .center
		label.numberOfLines = 0
		label.text = "Tap anywhere to toggle rounded corners"
		view.addSubview(label)
		
		NSLayoutConstraint.activate([
			label.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 40.0),
			label.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -40.0),
			label.topAnchor.constraint(equalTo: v.bottomAnchor, constant: 20.0),
		])
	}

	override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
		if let v = view.subviews.first as? ShapeWithNotchedTabView {
			v.roundedCorners.toggle()
		}
	}
}