using System;

namespace RgbConverter
{
    public static class Rgb
    {
        /// <summary>
        /// Gets hexadecimal representation source RGB decimal values.
        /// </summary>
        /// <param name="red">The valid decimal value for RGB is in the range 0-255.</param>
        /// <param name="green">The valid decimal valu for RGB is in the range 0-255.</param>
        /// <param name="blue">The valid decimal val for RGB is in the range 0-255.</param>
        /// <returns>Returns hexadecimal representation source RGB decimal values.</returns>
        public static string GetHexRepresentation(int red, int green, int blue)
        {
            if (red > 255)
            {
                red = 255;
            }

            if (red < 0)
            {
                red = 0;
            }

            if (green > 255)
            {
                green = 255;
            }

            if (green < 0)
            {
                green = 0;
            }

            if (blue > 255)
            {
                blue = 255;
            }

            if (blue < 0)
            {
                blue = 0;
            }

            static string DigitToHex(int color)
            {
                return color switch
                {
                    0 => "0",
                    1 => "1",
                    2 => "2",
                    3 => "3",
                    4 => "4",
                    5 => "5",
                    6 => "6",
                    7 => "7",
                    8 => "8",
                    9 => "9",
                    10 => "A",
                    11 => "B",
                    12 => "C",
                    13 => "D",
                    14 => "E",
                    15 => "F",
                    _ => "-1"
                };
            }

            return DigitToHex((red / 16) % 16) + DigitToHex(red % 16) + DigitToHex((green / 16) % 16) + DigitToHex(green % 16) + DigitToHex((blue / 16) % 16) + DigitToHex(blue % 16);
        }
    }
}