core/utils/Color.hpp

#ifndef CORE_COLOR_HPP
#define CORE_COLOR_HPP

namespace Core {
    using ColorChannel = unsigned char;

    template<int N>
    class Color final {
        static_assert(N >= 1 && N <= 4, "a color has 1 to 4 channels");

        ColorChannel data[static_cast<unsigned int>(N)] = {};

    public:
        Color() = default;

        template<typename OT, typename... Args>
        Color(OT a, Args&&... args) {
            init<0>(a, args...);
        }

    private:
        template<int I>
        void init() {
            static_assert(I == N,
                          "color channel parameters do not match its size");
        }

        template<int I, typename OT, typename... Args>
        void init(OT a, Args&&... args) {
            data[I] = static_cast<ColorChannel>(a);
            init<I + 1>(args...);
        }

    public:
        float asFloat(int index) const {
            return data[index] * (1.0f / 255.0f);
        }

        ColorChannel& operator[](int index) {
            return data[index];
        }

        const ColorChannel& operator[](int index) const {
            return data[index];
        }
    };

    using Color4 = Color<4>;
    using Color3 = Color<3>;
    using Color2 = Color<2>;
    using Color1 = Color<1>;
}

#endif