#include "runtime.h"
#include "threading.h"

#ifdef _WIN32
    #define WIN32_LEAN_AND_MEAN
    #include <Windows.h>

struct vy_mutex_s {
    HANDLE handle;
    ptrdiff_t next_reusable;
};

    #define MAX_MUTEX 1024
static vy_mutex _mutex[MAX_MUTEX];
static ptrdiff_t _first_reusable = MAX_MUTEX;
static ptrdiff_t _next           = 0;

VY_DLLEXPORT vy_mutex *vyCreateMutex(void) {
    if (_first_reusable < MAX_MUTEX) {
        vy_mutex *mtx   = &_mutex[_first_reusable];
        _first_reusable = mtx->next_reusable;
        return mtx;
    } else if (_next < MAX_MUTEX) {
        vy_mutex *mtx = &_mutex[_next];
        mtx->handle   = CreateMutexW(NULL, FALSE, NULL);
        if (!mtx->handle) {
            vyLog("core", "Mutex creation failed: %u", GetLastError());
            return NULL;
        }
        mtx->next_reusable = MAX_MUTEX;
        ++_next;
        return mtx;
    }
    vyReportError("core", "Ran out of mutex objects");
    return NULL;
}

VY_DLLEXPORT void vyDestroyMutex(vy_mutex *mutex) {
    ptrdiff_t index      = mutex - &_mutex[0];
    mutex->next_reusable = _first_reusable;
    _first_reusable      = index;
}

VY_DLLEXPORT bool vyLockMutex(vy_mutex *mutex) {
    return WaitForSingleObject(mutex->handle, INFINITE) == WAIT_OBJECT_0;
}
v VY_DLLEXPORT bool vyUnlockMutex(vy_mutex *mutex) {
    return ReleaseMutex(mutex->handle) != 0;
}

#elif defined(__linux__)

    #include <pthread.h>
struct vy_mutex_s {
    pthread_mutex_t handle;
    ptrdiff_t next_reusable;
};

    #define MAX_MUTEX 1024
static vy_mutex _mutex[MAX_MUTEX];
static ptrdiff_t _first_reusable = MAX_MUTEX;
static ptrdiff_t _next           = 0;
static pthread_mutex_t _guard    = PTHREAD_MUTEX_INITIALIZER;

VY_DLLEXPORT vy_mutex *vyCreateMutex(void) {
    pthread_mutex_lock(&_guard);
    if (_first_reusable < MAX_MUTEX) {
        vy_mutex *mtx   = &_mutex[_first_reusable];
        _first_reusable = mtx->next_reusable;
        pthread_mutex_unlock(&_guard);
        return mtx;
    } else if (_next < MAX_MUTEX) {
        vy_mutex *mtx = &_mutex[_next];
        if (pthread_mutex_init(&mtx->handle, NULL) != 0) {
            vyLog("core", "Mutex creation failed");
            pthread_mutex_unlock(&_guard);
            return NULL;
        }
        mtx->next_reusable = MAX_MUTEX;
        ++_next;
        pthread_mutex_unlock(&_guard);
        return mtx;
    }
    vyReportError("core", "Ran out of mutex objects");
    pthread_mutex_unlock(&_guard);
    return NULL;
}

VY_DLLEXPORT void vyDestroyMutex(vy_mutex *mutex) {
    ptrdiff_t index = mutex - &_mutex[0];
    pthread_mutex_lock(&_guard);
    mutex->next_reusable = _first_reusable;
    _first_reusable      = index;
    pthread_mutex_unlock(&_guard);
}

VY_DLLEXPORT bool vyLockMutex(vy_mutex *mutex) {
    return pthread_mutex_lock(&mutex->handle) == 0;
}

VY_DLLEXPORT bool vyUnlockMutex(vy_mutex *mutex) {
    return pthread_mutex_unlock(&mutex->handle) == 0;
}

#endif