// Copyright (c) Xenko contributors (https://xenko.com) and Silicon Studio Corp. (https://www.siliconstudio.co.jp)
// Distributed under the MIT license. See the LICENSE.md file in the project root for more information.
using System.Globalization;
using Xenko.Core.Annotations;
using System.Runtime.Serialization;

namespace math
{
    /// <summary>
    /// A class containing extension methods for processing colors.
    /// </summary>
    public static class ColorExtensions
    {
        /// <summary>
        /// Indicates if the given string can be converted to an <see cref="uint"/> RGBA value using <see cref="StringToRgba"/>.
        /// </summary>
        /// <param name="stringColor">The string to convert.</param>
        /// <returns>True if the string can be converted, false otherwise.</returns>
        public static bool CanConvertStringToRgba([CanBeNull] string stringColor)
        {
            return stringColor?.StartsWith("#") ?? false;
        }

        /// <summary>
        /// Converts the given string to an <see cref="uint"/> RGBA value.
        /// </summary>
        /// <param name="stringColor">The string to convert.</param>
        /// <returns>The converted RGBA value.</returns>
        public static uint StringToRgba([CanBeNull] string stringColor)
        {
            var intValue = 0xFF000000;
            if (stringColor != null)
            {
                if (stringColor.StartsWith("#"))
                {
                    if (stringColor.Length == "#000".Length && uint.TryParse(stringColor.Substring(1, 3), NumberStyles.HexNumber, null, out intValue))
                    {
                        intValue = ((intValue & 0x00F) << 16)
                                   | ((intValue & 0x00F) << 20)
                                   | ((intValue & 0x0F0) << 4)
                                   | ((intValue & 0x0F0) << 8)
                                   | ((intValue & 0xF00) >> 4)
                                   | ((intValue & 0xF00) >> 8)
                                   | (0xFF000000);
                    }
                    if (stringColor.Length == "#000000".Length && uint.TryParse(stringColor.Substring(1, 6), NumberStyles.HexNumber, null, out intValue))
                    {
                        intValue = ((intValue & 0x000000FF) << 16)
                                   | (intValue & 0x0000FF00)
                                   | ((intValue & 0x00FF0000) >> 16)
                                   | (0xFF000000);
                    }
                    if (stringColor.Length == "#00000000".Length && uint.TryParse(stringColor.Substring(1, 8), NumberStyles.HexNumber, null, out intValue))
                    {
                        intValue = ((intValue & 0x000000FF) << 16)
                                   | (intValue & 0x0000FF00)
                                   | ((intValue & 0x00FF0000) >> 16)
                                   | (intValue & 0xFF000000);
                    }
                }
            }
            return intValue;
        }

        /// <summary>
        /// Converts the given RGB value to a string.
        /// </summary>
        /// <param name="value">The RGB value to convert.</param>
        /// <returns>The converted string.</returns>
        [NotNull]
        public static string RgbToString(int value)
        {
            var r = (value & 0x000000FF);
            var g = (value & 0x0000FF00) >> 8;
            var b = (value & 0x00FF0000) >> 16;
            return $"#{r:X2}{g:X2}{b:X2}";
        }

        /// <summary>
        /// Converts the given RGBA value to a string.
        /// </summary>
        /// <param name="value">The RGBA value to convert.</param>
        /// <returns>The converted string.</returns>
        [NotNull]
        public static string RgbaToString(int value)
        {
            var r = (value & 0x000000FF);
            var g = (value & 0x0000FF00) >> 8;
            var b = (value & 0x00FF0000) >> 16;
            var a = (value & 0xFF000000) >> 24;
            return $"#{a:X2}{r:X2}{g:X2}{b:X2}";
        }
    }
}