#ifndef VEC_H

#include "util.h"
#include <cmath>


// STRUCTURE
struct Vector
{
    inline Vector(void) : x(0), y(0), z(0), w(0) {}
    inline Vector(float x, float y, float z) : x(x), y(y), z(z), w(0) {}

    union
    {
        float e[4];

        struct
        {
            float x, y, z, w;
        };
    };
};


// OPERATORS
// -v
inline Vector operator-(Vector const &v)
{
    Vector result;

    result.x = -v.x;
    result.y = -v.y;
    result.z = -v.z;

    return result;
}

// v1 - v2
inline Vector operator-(Vector const &v1, Vector const &v2)
{
    Vector result;

    result.x = v1.x - v2.x;
    result.y = v1.y - v2.y;
    result.z = v1.z - v2.z;

    return result;
}

// v1 + v2
inline Vector operator+(Vector const &v1, Vector const &v2)
{
    Vector result;

    result.x = v1.x + v2.x;
    result.y = v1.y + v2.y;
    result.z = v1.z + v2.z;

    return result;
}

// v1 += v2
inline Vector &operator+=(Vector &v1, Vector const &v2)
{
    v1 = v1 + v2;

    return v1;
}

// f * v
inline Vector operator*(float f, Vector const &v)
{
    Vector result;

    result.x = v.x * f;
    result.y = v.y * f;
    result.z = v.z * f;

    return result;
}

// v / f
inline Vector operator/(Vector const &v, float f)
{
    Vector result;

    float inverse = 1.0f / f;

    result.x = v.x * inverse;
    result.y = v.y * inverse;
    result.z = v.z * inverse;

    return result;
}

// v /= f
inline Vector &operator/=(Vector &v, float f)
{
    v = v / f;

    return v;
}


// PUBLIC FUNCTIONS
inline float VectorLength(Vector &v)
{
    float result = sqrtf(v.x * v.x + v.y * v.y + v.z * v.z);

    // zero length
    if (result < EPSILON_E3)
    {
        result = 0.0f;
    }

    return result;
}

inline void VectorNormalize(Vector &v)
{
    float length = VectorLength(v);

    // zero length
    if (length == 0.0f)
    {
        v.x = 0.0f;
        v.y = 0.0f;
        v.z = 0.0f;
    }
    else
    {
        float lengthInv = 1.0f / length;

        v.x *= lengthInv;
        v.y *= lengthInv;
        v.z *= lengthInv;
    }
}

inline Vector VectorCross(Vector &v1, Vector &v2)
{
    Vector result;

    result.x = (v1.y * v2.z) - (v1.z * v2.y);
    result.y = (v1.z * v2.x) - (v1.x * v2.z);
    result.z = (v1.x * v2.y) - (v1.y * v2.x);

    return result;
}

inline float VectorDot(Vector &v1, Vector &v2)
{
    float result;

    result = (v1.x * v2.x) + (v1.y * v2.y) + (v1.z * v2.z);

    return result;
}


#define VEC_H
#endif