DonutView.swift

//
//  DonutView.swift
//
//  Created by jesse calkin on 3/15/16.
//  Copyright © 2016 jesse calkin. All rights reserved.
//

import UIKit

func percentToRadians(percent: CGFloat) -> CGFloat {
    return CGFloat(percent * 360) * CGFloat(M_PI) / 180.0
}

@IBDesignable class DonutView: UIView {

    //MARK: - Internal

    //MARK: _ Properties

    let numberLabel = UILabel(frame: CGRectZero)
    let percentLabel = UILabel(frame: CGRectZero)
    var percent: CGFloat = 0.45 {
        didSet {
            updateValue()
        }
    }

    //MARK: _ IB

    @IBInspectable var foregroundColor: UIColor = UIColor(red: 53.0 / 255.0, green: 63.0 / 255.0, blue: 91.0 / 255.0, alpha: 1.0)
    @IBInspectable var valueColor: UIColor = UIColor.cyanColor()

    //MARK: - Private

    //MARK: _ Properties

    //MARK: __ Layers

    private let pieLayer = CAShapeLayer()
    private let innerCircle = CAShapeLayer()
    private let outerCircle = CAShapeLayer()

    //MARK: __ Drop Shadow

    private let shadowRadius: CGFloat = 5.0
    private let shadowOpacity: Float = 0.5
    private var radius: CGFloat {
        return bounds.size.width / 3
    }

    //MARK: _ Methods

    private func updatePercentForLocation(location: CGPoint) {
        percent = min(1.0, max(0.0,location.x) / bounds.width)
    }
    
    private func updateValue() {
        let piePath = UIBezierPath()
        piePath.moveToPoint(CGPoint(x: bounds.midX, y: bounds.midY))
        piePath.addArcWithCenter(CGPoint(x: bounds.midX, y: bounds.midY), radius: radius, startAngle: 0, endAngle: percentToRadians(percent), clockwise: true)
        piePath.addLineToPoint(CGPoint(x: bounds.midX, y: bounds.midY))
        piePath.closePath()
        
        pieLayer.path = piePath.CGPath
        
        numberLabel.text = "\(Int(percent * 100.0))"
    }

    private func updateLayers() {
        let path = UIBezierPath()
        path.moveToPoint(CGPoint(x: bounds.minX, y: bounds.midX))
        path.addLineToPoint(bounds.origin)
        path.addLineToPoint(CGPoint(x: bounds.maxX, y: bounds.minY))
        path.addLineToPoint(CGPoint(x: bounds.maxX, y: bounds.midY))

        let p2 = UIBezierPath()
        p2.moveToPoint(CGPoint(x: bounds.minX, y: bounds.midX))
        p2.addLineToPoint(CGPoint(x: bounds.minX, y: bounds.maxY))
        p2.addLineToPoint(CGPoint(x: bounds.maxX, y: bounds.maxY))
        p2.addLineToPoint(CGPoint(x: bounds.maxX, y: bounds.midY))
        
        let p3 = UIBezierPath()
        p3.moveToPoint(CGPoint(x: bounds.midX + radius, y: bounds.midY))
        p3.addArcWithCenter(CGPoint(x: bounds.midX, y: bounds.midY), radius: radius, startAngle: 0, endAngle: 180 * CGFloat(M_PI) / 180.0, clockwise: false)
        path.appendPath(p3)
        
        path.appendPath(p2)
        
        let p4 = UIBezierPath()
        p4.moveToPoint(CGPoint(x: bounds.midX + radius, y: bounds.midY))
        p4.addArcWithCenter(CGPoint(x: bounds.midX, y: bounds.midY), radius: radius, startAngle: 0, endAngle: 180 * CGFloat(M_PI) / 180.0, clockwise: true)
        path.appendPath(p4)
        
        let rectForInnerCircle = CGRectInset(bounds, bounds.size.width / 4, bounds.size.height / 4)
        let pathForInnerCircle = UIBezierPath(ovalInRect: rectForInnerCircle)

        innerCircle.bounds = rectForInnerCircle

        outerCircle.path = path.CGPath
        innerCircle.path = pathForInnerCircle.CGPath
    }

    private func setupLayers() {
        layer.masksToBounds = true

        pieLayer.fillColor = valueColor.CGColor
        pieLayer.shadowRadius = shadowRadius
        pieLayer.shadowOpacity = shadowOpacity
        pieLayer.shadowColor = valueColor.CGColor
        pieLayer.bounds = bounds
        pieLayer.position = CGPoint(x: bounds.midX, y: bounds.midY)
        layer.addSublayer(pieLayer)

        outerCircle.fillColor = foregroundColor.CGColor
        outerCircle.shadowOpacity = shadowOpacity
        outerCircle.shadowOffset = CGSizeZero
        outerCircle.shadowRadius = shadowRadius
        layer.addSublayer(outerCircle)

        innerCircle.fillColor = foregroundColor.CGColor
        innerCircle.shadowOpacity = shadowOpacity
        innerCircle.shadowOffset = CGSizeZero
        innerCircle.shadowRadius = shadowRadius
        innerCircle.position = CGPoint(x: bounds.midX, y: bounds.midY)
        layer.addSublayer(innerCircle)
    }

    private func setupLabels() {
        var font = UIFont(name: "HelveticaNeue-UltraLight", size: 80.0)
        numberLabel.font = font
        numberLabel.textAlignment = NSTextAlignment.Center
        numberLabel.textColor = valueColor
        numberLabel.shadowColor = UIColor.blackColor()
        numberLabel.text = "100"
        numberLabel.sizeToFit()
        numberLabel.text = "0"
        //FIXME: Update to use NSLayoutConstraints
        numberLabel.center = CGPoint(x: bounds.midX, y: bounds.midY)
        numberLabel.layer.masksToBounds = true
        
        font = UIFont(name: "HelveticaNeue-Light", size: 16.0)
        percentLabel.font = font
        percentLabel.textAlignment = NSTextAlignment.Center
        percentLabel.textColor = valueColor
        percentLabel.shadowColor = UIColor.blackColor()
        percentLabel.text = "%"
        percentLabel.sizeToFit()
        //FIXME: Update to use NSLayoutConstraints
        percentLabel.center = CGPoint(x: bounds.midX, y: bounds.midY + 55.0)
        
        addSubview(numberLabel)
        addSubview(percentLabel)
    }

    //MARK: - Overrides

    //MARK: _ View Lifecycle

    override init(frame: CGRect) {
        super.init(frame: frame)

        setupLayers()
        setupLabels()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        setupLayers()
        setupLabels()
    }

    override func drawRect(rect: CGRect) {
        super.drawRect(rect)

        updateLayers()
    }

    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()

        setupLayers()
        setupLabels()
        percent = 0.45
    }

    //MARK: _ Touches

    override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
        super.touchesMoved(touches, withEvent: event)

        guard let location = touches.first?.locationInView(self) else { return }

        updatePercentForLocation(location)
    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        super.touchesBegan(touches, withEvent: event)

        guard let location = touches.first?.locationInView(self) else { return }
        
        updatePercentForLocation(location)
    }
}