Privado-iOS/iOS/Privado/Sources/Common/View/GradientView.swift

//
//  GradientView.swift
//  PrivadoVPN
//
//  Created by Zhandos Bolatbekov on 25.03.2021.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import UIKit

struct GradientStop {
    var color: UIColor
    var location: Double
}

public class GradientView: UIView {
    
    var stops: [GradientStop] = [] {
        didSet {
            self.updateColors()
            self.updateLocations()
        }
    }
    
    var horizontalMode: Bool = false { didSet { self.updatePoints() } }
    var diagonalMode: Bool = false { didSet { self.updatePoints() } }
    
    public var cornerRadius: CGFloat = 0 {
        didSet {
            self.layer.cornerRadius = self.cornerRadius
        }
    }
    
    public var shadowColor: UIColor = .clear {
        didSet {
            self.layer.shadowColor = self.shadowColor.cgColor
        }
    }
    
    public var shadowRadius: CGFloat = 0 {
        didSet {
            self.layer.shadowRadius = self.shadowRadius
        }
    }
    
    public var shadowOpacity: CGFloat = 0 {
        didSet {
            self.layer.shadowOpacity = Float(self.shadowOpacity)
        }
    }
    
    public var shadowOffsetY: CGFloat = 0 {
        didSet {
            self.layer.shadowOffset.height = self.shadowOffsetY
        }
    }
    
    override public class var layerClass: AnyClass {
        return CAGradientLayer.self
    }
    
    var gradientLayer: CAGradientLayer? {
        return self.layer as? CAGradientLayer
    }
    
    func updatePoints() {
        if self.horizontalMode {
            self.gradientLayer?.startPoint = self.diagonalMode ? CGPoint(x: 1, y: 0) : CGPoint(x: 0, y: 0.5)
            self.gradientLayer?.endPoint   = self.diagonalMode ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0.5)
        } else {
            self.gradientLayer?.startPoint = self.diagonalMode ? CGPoint(x: 0, y: 0) : CGPoint(x: 0.5, y: 0)
            self.gradientLayer?.endPoint   = self.diagonalMode ? CGPoint(x: 1, y: 1) : CGPoint(x: 0.5, y: 1)
        }
    }
    
    func updateLocations() {
        self.gradientLayer?.locations = self.stops.map { $0.location as NSNumber }
    }
    
    func updateColors() {
        self.gradientLayer?.colors = self.stops.map { $0.color.cgColor }
    }
    
    override public func layoutSubviews() {
        super.layoutSubviews()
        updatePoints()
        updateLocations()
        updateColors()
    }
}