using System;
using System.Numerics;

public static class ColorConvertExtension
{
    /// <summary>
    /// 将RGB颜色转换为HSV颜色空间
    /// </summary>
    /// <param name="rgb">RGB颜色向量，X=R, Y=G, Z=B，取值范围0-1</param>
    /// <returns>HSV颜色向量，X=H(0-360), Y=S(0-1), Z=V(0-1)</returns>
    public static Vector3 RGBToHSV(this Vector3 rgb)
    {
        float r = rgb.X;
        float g = rgb.Y;
        float b = rgb.Z;
        
        float max = Math.Max(r, Math.Max(g, b));
        float min = Math.Min(r, Math.Min(g, b));
        float delta = max - min;
        
        float h = 0f;
        float s = 0f;
        float v = max;
        
        // 计算色相 (H)
        if (delta > 0f)
        {
            if (max == r)
            {
                h = (g - b) / delta;
                if (h < 0f) h += 6f;
            }
            else if (max == g)
            {
                h = 2f + (b - r) / delta;
            }
            else // max == b
            {
                h = 4f + (r - g) / delta;
            }
            
            h *= 60f; // 转换为度数
        }
        
        // 计算饱和度 (S)
        if (max > 0f)
        {
            s = delta / max;
        }
        
        return new Vector3(h, s, v);
    }

    /// <summary>
    /// 将HSV颜色转换为RGB颜色空间
    /// </summary>
    /// <param name="hsv">HSV颜色向量，X=H(0-360), Y=S(0-1), Z=V(0-1)</param>
    /// <returns>RGB颜色向量，X=R, Y=G, Z=B，取值范围0-1</returns>
    public static Vector3 HSVToRGB(this Vector3 hsv)
    {
        float h = hsv.X;
        float s = hsv.Y;
        float v = hsv.Z;
        
        // 处理色相超出范围的情况
        h = h % 360f;
        if (h < 0f) h += 360f;
        
        // 限制饱和度和明度在0-1范围内
        s = Math.Clamp(s, 0f, 1f);
        v = Math.Clamp(v, 0f, 1f);
        
        // 如果饱和度为0，直接返回灰度值
        if (s <= 0f)
        {
            return new Vector3(v, v, v);
        }
        
        // 将色相转换为0-6的范围
        float hNormalized = h / 60f;
        int sector = (int)hNormalized;
        float fractional = hNormalized - sector;
        
        float p = v * (1f - s);
        float q = v * (1f - s * fractional);
        float t = v * (1f - s * (1f - fractional));
        
        return sector switch
        {
            0 => new Vector3(v, t, p),
            1 => new Vector3(q, v, p),
            2 => new Vector3(p, v, t),
            3 => new Vector3(p, q, v),
            4 => new Vector3(t, p, v),
            _ => new Vector3(v, p, q) // 5 或 其他情况
        };
    }
}