//********************************** Banshee Engine (www.banshee3d.com) **************************************************//
//**************** Copyright (c) 2016 Marko Pintera (marko.pintera@gmail.com). All rights reserved. **********************//
#pragma once

#include "Prerequisites/BsPrerequisitesUtil.h"
#include "Math/BsMath.h"

namespace bs
{
	/** @addtogroup Math
	 *  @{
	 */

	/** A two dimensional vector. */
    class BS_UTILITY_EXPORT Vector2
    {
    public:
        float x, y;

    public:
		Vector2()
		{ }

        Vector2(BS_ZERO zero)
			:x(0.0f), y(0.0f)
        { }

        Vector2(float x, float y)
            :x(x), y(y)
        { }

		/** Exchange the contents of this vector with another. */
		void swap(Vector2& other)
		{
			std::swap(x, other.x);
			std::swap(y, other.y);
		}

		float operator[] (UINT32 i) const
        {
            assert(i < 2);

            return *(&x+i);
        }

		float& operator[] (UINT32 i)
        {
            assert(i < 2);

            return *(&x+i);
        }
		
		/** Pointer accessor for direct copying. */
		float* ptr()
		{
			return &x;
		}

		/** Pointer accessor for direct copying. */
		const float* ptr() const
		{
			return &x;
		}

        Vector2& operator= (const Vector2& rhs)
        {
            x = rhs.x;
            y = rhs.y;

            return *this;
        }

		Vector2& operator= (float rhs)
		{
			x = rhs;
			y = rhs;

			return *this;
		}

        bool operator== (const Vector2& rhs) const
        {
            return (x == rhs.x && y == rhs.y);
        }

        bool operator!= (const Vector2& rhs) const
        {
            return (x != rhs.x || y != rhs.y);
        }

        Vector2 operator+ (const Vector2& rhs) const
        {
            return Vector2(x + rhs.x, y + rhs.y);
        }

        Vector2 operator- (const Vector2& rhs) const
        {
            return Vector2(x - rhs.x, y - rhs.y);
        }

        Vector2 operator* (const float rhs) const
        {
            return Vector2(x * rhs, y * rhs);
        }

        Vector2 operator* (const Vector2& rhs) const
        {
            return Vector2(x * rhs.x, y * rhs.y);
        }

        Vector2 operator/ (const float rhs) const
        {
            assert(rhs != 0.0);

            float fInv = 1.0f / rhs;

            return Vector2(x * fInv, y * fInv);
        }

        Vector2 operator/ (const Vector2& rhs) const
        {
            return Vector2(x / rhs.x, y / rhs.y);
        }

        const Vector2& operator+ () const
        {
            return *this;
        }

        Vector2 operator- () const
        {
            return Vector2(-x, -y);
        }

        friend Vector2 operator* (float lhs, const Vector2& rhs)
        {
            return Vector2(lhs * rhs.x, lhs * rhs.y);
        }

        friend Vector2 operator/ (float lhs, const Vector2& rhs)
        {
            return Vector2(lhs / rhs.x, lhs / rhs.y);
        }

        friend Vector2 operator+ (Vector2& lhs, float rhs)
        {
            return Vector2(lhs.x + rhs, lhs.y + rhs);
        }

        friend Vector2 operator+ (float lhs, const Vector2& rhs)
        {
            return Vector2(lhs + rhs.x, lhs + rhs.y);
        }

        friend Vector2 operator- (const Vector2& lhs, float rhs)
        {
            return Vector2(lhs.x - rhs, lhs.y - rhs);
        }

        friend Vector2 operator- (const float lhs, const Vector2& rhs)
        {
            return Vector2(lhs - rhs.x, lhs - rhs.y);
        }

        Vector2& operator+= (const Vector2& rhs)
        {
            x += rhs.x;
            y += rhs.y;

            return *this;
        }

        Vector2& operator+= (float rhs)
        {
            x += rhs;
            y += rhs;

            return *this;
        }

        Vector2& operator-= (const Vector2& rhs)
        {
            x -= rhs.x;
            y -= rhs.y;

            return *this;
        }

        Vector2& operator-= (float rhs)
        {
            x -= rhs;
            y -= rhs;

            return *this;
        }

        Vector2& operator*= (float rhs)
        {
            x *= rhs;
            y *= rhs;

            return *this;
        }

        Vector2& operator*= (const Vector2& rhs)
        {
            x *= rhs.x;
            y *= rhs.y;

            return *this;
        }

        Vector2& operator/= (float rhs)
        {
            assert(rhs != 0.0f);

            float inv = 1.0f / rhs;

            x *= inv;
            y *= inv;

            return *this;
        }

        Vector2& operator/= (const Vector2& rhs)
        {
            x /= rhs.x;
            y /= rhs.y;

            return *this;
        }

        /** Returns the length (magnitude) of the vector. */
        float length() const
        {
            return Math::sqrt(x * x + y * y);
        }

        /** Returns the square of the length(magnitude) of the vector. */
        float squaredLength() const
        {
            return x * x + y * y;
        }

        /** Returns the distance to another vector. */
        float distance(const Vector2& rhs) const
        {
            return (*this - rhs).length();
        }

        /** Returns the square of the distance to another vector. */
        float sqrdDistance(const Vector2& rhs) const
        {
            return (*this - rhs).squaredLength();
        }

        /** Calculates the dot (scalar) product of this vector with another. */
        float dot(const Vector2& vec) const
        {
            return x * vec.x + y * vec.y;
        }

        /** Normalizes the vector. */
        float normalize()
        {
            float len = Math::sqrt(x * x + y * y);

            // Will also work for zero-sized vectors, but will change nothing
            if (len > 1e-08)
            {
                float invLen = 1.0f / len;
                x *= invLen;
                y *= invLen;
            }

            return len;
        }

        /** Generates a vector perpendicular to this vector. */
        Vector2 perpendicular() const
        {
            return Vector2 (-y, x);
        }

        /**
		 * Calculates the 2 dimensional cross-product of 2 vectors, which results in a single floating point value which 
		 * is 2 times the area of the triangle.
         */
        float cross(const Vector2& other) const
        {
            return x * other.y - y * other.x;
        }

        /** Sets this vector's components to the minimum of its own and the ones of the passed in vector. */
        void floor(const Vector2& cmp)
        {
            if(cmp.x < x) x = cmp.x;
            if(cmp.y < y) y = cmp.y;
        }

        /** Sets this vector's components to the maximum of its own and the ones of the passed in vector. */
        void ceil(const Vector2& cmp)
        {
            if(cmp.x > x) x = cmp.x;
            if(cmp.y > y) y = cmp.y;
        }

        /** Returns true if this vector is zero length. */
        bool isZeroLength() const
        {
            float sqlen = (x * x) + (y * y);
            return (sqlen < (1e-06 * 1e-06));
        }

        /** Calculates a reflection vector to the plane with the given normal. */
        Vector2 reflect(const Vector2& normal) const
        {
            return Vector2(*this - (2 * this->dot(normal) * normal));
        }

		/** Performs Gram-Schmidt orthonormalization. */
		static void orthonormalize(Vector2& u, Vector2& v)
		{
			u.normalize();

			float dot = u.dot(v); 
			v -= u*dot;
			v.normalize();
		}

		/** Normalizes the provided vector and returns a new normalized instance. */
		static Vector2 normalize(const Vector2& val)
		{
			float len = Math::sqrt(val.x * val.x + val.y * val.y);

			// Will also work for zero-sized vectors, but will change nothing
			Vector2 normalizedVec = val;
			if (len > 1e-08)
			{
				float invLen = 1.0f / len;
				normalizedVec.x *= invLen;
				normalizedVec.y *= invLen;
			}

			return normalizedVec;
		}

		/** Checks are any of the vector components NaN. */
		bool isNaN() const
		{
			return Math::isNaN(x) || Math::isNaN(y);
		}

		/** Returns the minimum of all the vector components as a new vector. */
		static Vector2 min(const Vector2& a, const Vector2& b)
		{
			return Vector2(std::min(a.x, b.x), std::min(a.y, b.y));
		}

		/** Returns the maximum of all the vector components as a new vector. */
		static Vector2 max(const Vector2& a, const Vector2& b)
		{
			return Vector2(std::max(a.x, b.x), std::max(a.y, b.y));
		}

        static const Vector2 ZERO;
		static const Vector2 ONE;
		static const Vector2 UNIT_X;
		static const Vector2 UNIT_Y;
    };

	/** @} */

	/** @cond SPECIALIZATIONS */
	BS_ALLOW_MEMCPY_SERIALIZATION(Vector2);
	/** @endcond */
}