#include "util.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>

static num num_cos_dl(num a)
{
    num u = 1.0;
    int p = 7;
    for(p = 2 * p - 1; p >= 1; p -= 2)
        u = num(1) - a * a / (p * p + p) * u;
    return u;
}

num num_cos(num a)
{
    if(a < 0) a = -a;
    a = a % num(6.28319);
    if(a > num(3.14159)) a -= num(6.28319);
    return num_cos_dl(a);
}

num num_sin(num a)
{
    return num_cos(a - num(1.57080));
}

num num_clamp(num t, num lower, num upper)
{
    if(t < lower)
        return lower;
    if(t > upper)
        return upper;
    return t;
}

num num_rand(void)
{
    num r;
    r.v = rand() & 0xffff;
    return r;
}

num num_rand_between(num low, num high)
{
    num width = high - low;
    if(width <= 0)
        return low;

    num r;
    r.v = rand() % width.v;
    return r + low;
}

vec3 vec_rotate_around_z(vec3 v, vec2 rotator)
{
    num c = rotator.x;
    num s = rotator.y;
    return vec3(
        c * v.x - s * v.y,
        c * v.y + s * v.x,
        v.z);
}

static char strings[8][64];
static int strings_next = 0;

static char const *do_str(char const *fmt, ...)
{
    char *s = strings[strings_next];
    strings_next = (strings_next + 1) % 8;

    va_list args;
    va_start(args, fmt);
    vsnprintf(s, sizeof strings[0], fmt, args);
    va_end(args);

    return s;
}

char const *str(num x)
{
    return do_str("%g", (float)x);
}

char const *str(vec2 u)
{
    return do_str("[%g %g]", (float)u.x, (float)u.y);
}

char const *str(vec3 u)
{
    return do_str("[%g %g %g]", (float)u.x, (float)u.y, (float)u.z);
}