#pragma once

#include <math.h>

typedef float choice_t;

#define do_op(o, r, i)							\
    inline void operator o##= (const r & rhs) { for(unsigned n=0; n<(i); n++) c[n] o##= rhs.c[n]; } \
    inline void operator o##= (choice_t d) { for(unsigned n=0; n<(i); n++) c[n] o##= d; } \
    inline r operator o (const r & rhs) const { r tmp(*this); tmp o##= rhs; return tmp; } \
    inline r operator o (choice_t d) const { r tmp(*this); tmp o##= d; return tmp; }

#define do_ops(c, i)		\
    do_op(*, c, i);		\
    do_op(/, c, i);		\
    do_op(+, c, i);		\
    do_op(-, c, i);


struct v3 {
    union {
	choice_t c[4];
	struct {
	    choice_t x, y, z, w;
	};
    };

    v3(choice_t x, choice_t y, choice_t z) : c{x,y,z} {}
    v3(choice_t f) : v3(f,f,f) {}
    v3() : v3(0,0,0) {}

    do_ops(v3, 3);

    inline v3 operator-(void) const { return {-x, -y, -z}; }

    inline choice_t operator^(const v3& rhs) const
    { return x * rhs.x + y * rhs.y + z * rhs.z; }

    /* Return normalised (unit) vector. */
    inline v3 norm() const
    { return *this / len(); }

    inline choice_t len() const
    { return sqrtf(x*x + y*y + z*z); }

    inline choice_t lensquared() const
    { return x*x + y*y + z*z; }

    /* Return vector reflected around `n'. Expects `this' and `n' to be unit. */
    inline v3 ref(const v3& n) const
    { return n * ((*this ^ n) * 2) - *this;}

    /* Cross product. */
    inline v3 cross(const v3& b) const
    { return { y*b.z - z*b.y,
	       x*b.z - z*b.x,
	       x*b.y - y*b.x }; }

    inline v3 refract(const v3& n, choice_t ior_ratio) const
    {
	return n * sqrtf(1 - powf(ior_ratio, 2) * (1 - powf(*this ^ n, 2))) + (*this - n * (*this ^ n)) * ior_ratio;
    }

    inline v3 refract(const v3& n, choice_t ior_incident, choice_t ior_refract) const
    { return refract(n, ior_incident / ior_refract); }

    inline v3 clamp(const v3& from, const v3& to) const
    { return { fmin(fmax(x, from.x), to.x),
	       fmin(fmax(y, from.y), to.y),
	       fmin(fmax(z, from.z), to.z) }; }

    inline v3 exp() const
    { return { ::exp(x), ::exp(y), ::exp(z) }; }

    inline v3 htan(choice_t exposure = 0) const
    {
	return { powf((tanh(x + exposure) + 1) / 2, 2.2), powf((tanh(y + exposure) + 1) / 2, 2.2), powf((tanh(z + exposure) + 1) / 2, 2.2) };
	return { tanh(x + exposure), tanh(y + exposure), tanh(z + exposure) };
    }
};

#undef do_ops
#undef do_op

#define V3_FMT "v3(%.2f, %.2f, %.2f)"
#define V3_ARG(v) (v).x, (v).y, (v).z

struct Matrix
{
    v3 m[4];
    void init_rotate(const v3& angle)
    {
        choice_t Cx = cos(angle.c[0]), Cy = cos(angle.c[1]), Cz = cos(angle.c[2]);
        choice_t Sx = sin(angle.c[0]), Sy = sin(angle.c[1]), Sz = sin(angle.c[2]);
        choice_t sxsz = Sx*Sz, cxsz = Cx*Sz;
        choice_t cxcz = Cx*Cz, sxcz = Sx*Cz;
        Matrix result = {{ { Cy*Cz, Cy*Sz, -Sy },
                           { sxcz*Sy - cxsz, sxsz*Sy + cxcz, Sx*Cy },
                           { cxcz*Sy + sxsz, cxsz*Sy - sxcz, Cx*Cy } }};
        *this = result;
    }

    v3 transform(const v3& vec) const
    { return { m[0] ^ vec, m[1] ^ vec, m[2] ^ vec }; }
};