import Foundation
import UIKit

public class AvatarGenerator {

    public static func avatar(for name: String, size: CGSize, backColor: UIColor? = nil) -> UIImage? {
        let back = backColor ?? color(for: name)
        let text = displayString(for: name, fontSize: size.height / 3)

        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        let context = UIGraphicsGetCurrentContext()

        let rect = CGRect(origin: CGPoint.zero, size: size)


        context?.setFillColor(back.cgColor)
        context?.fill(rect)

        let textSize = text.size()

        let centerRect = CGRect(x: (size.width - textSize.width) / 2,
                                y: (size.height - textSize.height) / 2,
                                width: textSize.width,
                                height: textSize.height)
        text.draw(in: centerRect)

        let image = UIGraphicsGetImageFromCurrentImageContext()

        UIGraphicsEndImageContext()

        return image

    }

    public static func color(for name: String) -> UIColor {
        if name.trimmingCharacters(in: .whitespaces).utf8.count == 0 {
            return UIColor.slm_paleGrayColor()
        }
        // TODO: hash not guarantie that value be same after relaunch
        // check for string caus it seams not the case
        let idx = abs(name.hashValue) % saveColors.count
        let color = saveColors[idx]

        return color
    }

    public static let saveColors: [UIColor] = [UIColor(red:0.93, green:0.29, blue:0.16, alpha:1.00),
                                                UIColor(red:0.25, green:0.66, blue:0.01, alpha:1.00),
                                                UIColor(red:0.88, green:0.59, blue:0.01, alpha:1.00),
                                                UIColor(red:0.06, green:0.58, blue:0.93, alpha:1.00),
                                                UIColor(red:0.56, green:0.23, blue:0.97, alpha:1.00),
                                                UIColor(red:0.99, green:0.26, blue:0.50, alpha:1.00),
                                                UIColor(red:0.00, green:0.63, blue:0.77, alpha:1.00),
                                                UIColor(red:0.92, green:0.44, blue:0.01, alpha:1.00)]

    static private func displayString(for name: String, fontSize: CGFloat) -> NSAttributedString {
        let attributes = [
            NSFontAttributeName : UIFont.slm_font(withSize: fontSize, weight: UIFontWeightBold),
            NSForegroundColorAttributeName: UIColor.white
        ]

        var result = ""

        let words = name.components(separatedBy: CharacterSet.whitespaces)
        for word in words.prefix(2) {
            if word.utf8.count == 0 {
                continue
            }
            let toIndex = word.index(word.startIndex, offsetBy: 1)
            let firstLetter = word.substring(to: toIndex).uppercased()

            result += firstLetter
        }
        return NSAttributedString(string: result, attributes: attributes)
    }
}