#ifndef VEC3H
#define VEC3H

#include <math.h>
#include <stdlib.h>

class vec3
{
public:
    vec3() {}
    vec3(float e0, float e1, float e2) { e[0] = e0; e[1] = e1; e[2] = e2; }
    inline float x() const { return e[0]; }
    inline float y() const { return e[1]; }
    inline float z() const { return e[2]; }
    inline float r() const { return e[0]; }
    inline float g() const { return e[1]; }
    inline float b() const { return e[2]; }

    inline const vec3& operator+() const { return *this; }
    inline vec3 operator-() const { return vec3(-e[0], -e[1], -e[2]); }
    inline float operator[](int i) const { return e[i]; }
    inline float& operator[](int i) { return e[i]; }

    inline vec3& operator+=(const vec3 &v2);
    inline vec3& operator-=(const vec3 &v2);
    inline vec3& operator*=(const vec3 &v2);
    inline vec3& operator/=(const vec3 &v2);
    inline vec3& operator*=(const float t);
    inline vec3& operator/=(const float t);

    inline float length() const
    {
        return sqrt(e[0] * e[0] + e[1] * e[1] + e[2] * e[2]);
    }

    inline float squared_length() const
    {
        return e[0] * e[0] + e[1] * e[1] + e[2] * e[2];
    }

    inline void make_unit_vector();

    float e[3];
};

// inline std::istream& operator>>(std::istream &is, vec3 &t)
// {
//     is >> t.e[0] >> t.e[1] >> t.e[2];
//     return is;
// }

// inline std::ostream& operator<<(std::ostream &os, const vec3 &t)
// {
//     os << t.e[0] << " " << t.e[1] << " " << t.e[2];
//     return os;
// }

inline void vec3::make_unit_vector()
{
    float k = 1.0 / sqrt(e[0] * e[0] + e[1] * e[1] + e[2] * e[2]);
    e[0] *= k;
    e[1] *= k;
    e[2] *= k;
}

inline vec3 operator+(const vec3 &v1, const vec3 &v2)
{
    return vec3(v1.e[0] + v2.e[0], v1.e[1] + v2.e[1], v1.e[2] + v2.e[2]);
}

inline vec3 operator-(const vec3 &v1, const vec3 &v2)
{
    return vec3(v1.e[0] - v2.e[0], v1.e[1] - v2.e[1], v1.e[2] - v2.e[2]);
}

inline vec3 operator*(const vec3 &v1, const vec3 &v2)
{
    return vec3(v1.e[0] * v2.e[0], v1.e[1] * v2.e[1], v1.e[2] * v2.e[2]);
}

inline vec3 operator/(const vec3 &v1, const vec3 &v2)
{
    return vec3(v1.e[0] / v2.e[0], v1.e[1] / v2.e[1], v1.e[2] / v2.e[2]);
}

inline vec3 operator*(float t, const vec3 &v)
{
    return vec3(t * v.e[0], t * v.e[1], t * v.e[2]);
}

inline vec3 operator/(vec3 v, float t)
{
    return vec3(v.e[0] / t, v.e[1] / t, v.e[2] / t);
}

inline vec3 operator*(const vec3 &v, float t)
{
    return vec3(t * v.e[0], t * v.e[1], t * v.e[2]);
}

inline float dot(const vec3 &v1, const vec3 &v2)
{
    return v1.e[0] * v2.e[0] + v1.e[1] * v2.e[1] + v1.e[2] * v2.e[2];
}

inline vec3 cross(const vec3 &v1, const vec3 &v2)
{
    return vec3( (v1.e[1] * v2.e[2] - v1.e[2] * v2.e[1]),
                 (- (v1.e[0] * v2.e[2] - v1.e[2] * v2.e[0])),
                 (v1.e[0] * v2.e[1] - v1.e[1] * v2.e[0]) );
}

inline vec3& vec3::operator+=(const vec3 &v)
{
    e[0] += v.e[0];
    e[1] += v.e[1];
    e[2] += v.e[2];

    return *this;
}

inline vec3& vec3::operator*=(const vec3 &v)
{
    e[0] *= v.e[0];
    e[1] *= v.e[1];
    e[2] *= v.e[2];

    return *this;
}

inline vec3& vec3::operator/=(const vec3 &v)
{
    e[0] /= v.e[0];
    e[1] /= v.e[1];
    e[2] /= v.e[2];

    return *this;
}

inline vec3& vec3::operator-=(const vec3 &v)
{
    e[0] -= v.e[0];
    e[1] -= v.e[1];
    e[2] -= v.e[2];

    return *this;
}

inline vec3& vec3::operator/=(const float t)
{
    float k = 1.0 / t;

    e[0] *= k;
    e[1] *= k;
    e[2] *= k;

    return *this;
}

inline vec3 unit_vector(vec3 v)
{
    return v / v.length();
}

#endif
