// 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 att;
using System.Globalization;
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}";
        }
    }
}