#ifndef _AL_RANDOM_H
#define _AL_RANDOM_H

#include "lib.h"
#include "macros.h"

#define AL_RAND_MAX RAND_MAX
#define AL_RAND_INIT_SEED 1738

extern u32 al_rand_seed;

extern __thread bool al_rand_set;
#ifndef AL_SRAND_THREAD_LOCAL
extern __thread u32 al_rand_state;
#endif

static inline void al_random_init(u32 seed)
{
    al_rand_seed = seed;
}

// @TODO: Replace this with an implementation of any PRNG algorithm where
//  we can control the state and make it thread-local. Trying to predict the
//  state in libc is pretty dumb.
// al_rand() is equivalent to libc rand(), as such there is no expectation
// of it being an actually good random number generator.
#ifdef AL_SRAND_THREAD_LOCAL
#define rrand() rand()
#else
#define rrand() rand_r(&al_rand_state)
#endif
static inline s32 al_rand(void)
{
    if (UNLIKELY(!al_rand_set)) {
#ifdef AL_SRAND_THREAD_LOCAL
        srand(al_rand_seed);
#else
        al_rand_state = al_rand_seed;
#endif
        // Call rand() once after setting the seed incase it returns the seed
        // on the first call, like on Windows. Having the first result potentially
        // be so similar run-to-run would no longer even be pseudo-random.
        // https://stackoverflow.com/a/76676396
        rrand();
        al_rand_set = true;
    }
    return rrand();
}
#undef rrand

// https://c-faq.com/lib/randrange.html
static inline s32 al_random_int(s32 min, s32 max) // [MIN, MAX]
{
    return min + al_rand() / (AL_RAND_MAX / (max - min + 1) + 1);
}

static inline void al_random_hex_chars(char *buf)
{
    al_snprintf(buf, 9, "%08X", al_rand());
}

#endif // _AL_RANDOM_H