#pragma once

#include <optional>


namespace cru::ui
{
    struct Point
    {
        constexpr static Point Zero()
        {
            return Point(0, 0);
        }

        constexpr Point() = default;
        constexpr Point(const float x, const float y) : x(x), y(y) { }

        float x = 0;
        float y = 0;
    };

    constexpr bool operator==(const Point& left, const Point& right)
    {
        return left.x == right.x && left.y == right.y;
    }

    constexpr bool operator!=(const Point& left, const Point& right)
    {
        return !(left == right);
    }

    struct Size
    {
        constexpr static Size Zero()
        {
            return Size(0, 0);
        }

        constexpr Size() = default;
        constexpr Size(const float width, const float height) : width(width), height(height) { }

        float width = 0;
        float height = 0;
    };

    constexpr Size operator + (const Size& left, const Size& right)
    {
        return Size(left.width + right.width, left.height + right.height);
    }

    constexpr Size operator - (const Size& left, const Size& right)
    {
        return Size(left.width - right.width, left.height - right.height);
    }

    constexpr bool operator==(const Size& left, const Size& right)
    {
        return left.width == right.width && left.height == right.height;
    }

    constexpr bool operator!=(const Size& left, const Size& right)
    {
        return !(left == right);
    }

    struct Thickness
    {
        constexpr static Thickness Zero()
        {
            return Thickness(0);
        }

        constexpr Thickness() : Thickness(0) { }

        constexpr explicit Thickness(const float width)
            : left(width), top(width), right(width), bottom(width) { }

        constexpr explicit Thickness(const float horizontal, const float vertical)
            : left(horizontal), top(vertical), right(horizontal), bottom(vertical) { }

        constexpr Thickness(const float left, const float top, const float right, const float bottom)
            : left(left), top(top), right(right), bottom(bottom) { }

        float GetHorizontalTotal() const
        {
            return left + right;
        }

        float GetVerticalTotal() const
        {
            return top + bottom;
        }

        float Validate() const
        {
            return left >= 0.0 && top >= 0.0 && right >= 0.0 && bottom >= 0.0;
        }

        float left;
        float top;
        float right;
        float bottom;
    };

    struct Rect
    {
        constexpr Rect() = default;
        constexpr Rect(const float left, const float top, const float width, const float height)
            : left(left), top(top), width(width), height(height) { }
        constexpr Rect(const Point& lefttop, const Size& size)
            : left(lefttop.x), top(lefttop.y), width(size.width), height(size.height) { }

        constexpr static Rect FromVertices(const float left, const float top, const float right, const float bottom)
        {
            return Rect(left, top, right - left, bottom - top);
        }

        constexpr float GetRight() const
        {
            return left + width;
        }

        constexpr float GetBottom() const
        {
            return top + height;
        }

        constexpr Point GetLeftTop() const
        {
            return Point(left, top);
        }

        constexpr Point GetRightBottom() const
        {
            return Point(left + width, top + height);
        }

        constexpr Size GetSize() const
        {
            return Size(width, height);
        }

        constexpr Rect Shrink(const Thickness& thickness) const
        {
            return Rect(left + thickness.left, top + thickness.top, width - thickness.GetHorizontalTotal(), height - thickness.GetVerticalTotal());
        }

        constexpr bool IsPointInside(const Point& point) const
        {
            return
                point.x >= left &&
                point.x < GetRight() &&
                point.y >= top &&
                point.y < GetBottom();
        }

        float left = 0.0f;
        float top = 0.0f;
        float width = 0.0f;
        float height = 0.0f;
    };

    enum class MouseButton
    {
        Left,
        Right,
        Middle
    };

    struct TextRange
    {
        constexpr static std::optional<TextRange> FromTwoSides(unsigned first, unsigned second)
        {
            if (first > second)
                return std::make_optional<TextRange>(second, first - second);
            if (first < second)
                return std::make_optional<TextRange>(first, second - first);
            return std::nullopt;
        }

        constexpr static std::pair<unsigned, unsigned> ToTwoSides(std::optional<TextRange> text_range, unsigned default_position = 0)
        {
            if (text_range.has_value())
                return std::make_pair(text_range.value().position, text_range.value().position + text_range.value().count);
            return std::make_pair(default_position, default_position);
        }

        constexpr TextRange() = default;
        constexpr TextRange(const unsigned position, const unsigned count)
            : position(position), count(count)
        {

        }

        unsigned position = 0;
        unsigned count = 0;
    };

    bool IsKeyDown(int virtual_code);
    bool IsKeyToggled(int virtual_code);
    bool IsAnyMouseButtonDown();
}