import UIKit

extension UIColor {
    convenience init?(unsafeHex: String?) {
        guard let unsafeHex = unsafeHex else { return nil }
        if unsafeHex.isEmpty {
            return nil
        } else if unsafeHex.hasPrefix("#") {
            self.init(hex: unsafeHex)
        } else {
            self.init(hex: "#\(unsafeHex)")
        }
    }

    convenience init?(hex: String) {
        let r, g, b, a: CGFloat

        if hex.hasPrefix("#") {
            let start = hex.index(hex.startIndex, offsetBy: 1)
            let hexColor = String(hex[start...])

            if hexColor.count == 8 {
                let scanner = Scanner(string: hexColor)
                var hexNumber: UInt64 = 0

                if scanner.scanHexInt64(&hexNumber) {
                    r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
                    g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
                    b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
                    a = CGFloat(hexNumber & 0x000000ff) / 255

                    self.init(red: r, green: g, blue: b, alpha: a)
                    return
                }
            }

            if hexColor.count == 6 {
                let scanner = Scanner(string: hexColor)
                var hexNumber: UInt64 = 0

                if scanner.scanHexInt64(&hexNumber) {
                    r = CGFloat((hexNumber & 0xff0000) >> 16) / 255
                    g = CGFloat((hexNumber & 0x00ff00) >> 8) / 255
                    b = CGFloat(hexNumber & 0x0000ff) / 255

                    self.init(red: r, green: g, blue: b, alpha: 1.0)
                    return
                }
            }
        }

        return nil
    }
}