#include <bh/internal/thread.h>
#include <string.h>
#include <stdlib.h>

static void *bh_thread_run(void *arg)
{
    bh_tls_t *tls;
    bh_task_t *task;

    /* Fetch thread data */
    task = (bh_task_t *)arg;

    /* Setup TLS */
    tls = bh_tls_fetch();

    /* Do the task, mark as done, and if required free it */
    task->func(task->data);
    task->flags |= BH_THREAD_DONE;

    if (task->flags & BH_THREAD_CLEANUP)
        bh_task_free(task);

    /* Destroy TLS */
    bh_tls_cleanup();

    return NULL;
}

int bh_thread_init(bh_thread_t *thread,
                   bh_task_t *task)
{
    thread->allocated = 0;
    if (pthread_create(&thread->handle, NULL, bh_thread_run, task))
        return BH_ERROR;

    return BH_OK;
}

bh_thread_t *bh_thread_new(bh_task_t *task)
{
    bh_thread_t *result;

    /* Allocate thread object */
    result = malloc(sizeof(*result));
    if (result && bh_thread_init(result, task))
    {
        free(result);
        result = NULL;
    }

    /* Mark thread as allocated for deallocation in join/detach */
    if (result)
        result->allocated = 1;

    return result;
}

int bh_thread_join(bh_thread_t *thread)
{
    /* Join the thread */
    if (pthread_join(thread->handle, NULL))
        return BH_ERROR;

    /* If thread is allocated, deallocate it */
    if (thread->allocated)
        free(thread);

    return BH_OK;
}

int bh_thread_detach(bh_thread_t *thread)
{
    /* Detach the thread */
    if (pthread_detach(thread->handle))
        return BH_ERROR;

    /* If thread is allocated, deallocate it */
    if (thread->allocated)
        free(thread);

    return BH_OK;
}

int bh_mutex_init(bh_mutex_t *mutex)
{
    if (pthread_mutex_init(&mutex->handle, NULL))
        return BH_ERROR;
    return BH_OK;
}

void bh_mutex_destroy(bh_mutex_t *mutex)
{
    pthread_mutex_destroy(&mutex->handle);
}

int bh_mutex_lock(bh_mutex_t *mutex)
{
    if (pthread_mutex_lock(&mutex->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_mutex_try_lock(bh_mutex_t *mutex)
{
    if (pthread_mutex_trylock(&mutex->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_mutex_unlock(bh_mutex_t *mutex)
{
    if (pthread_mutex_unlock(&mutex->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_semaphore_init(bh_semaphore_t *semaphore, int count)
{
    if (sem_init(&semaphore->handle, 0, count))
        return BH_ERROR;
    return BH_OK;
}

void bh_semaphore_destroy(bh_semaphore_t *semaphore)
{
    sem_destroy(&semaphore->handle);
}

int bh_semaphore_post(bh_semaphore_t *semaphore)
{
    if (sem_post(&semaphore->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_semaphore_wait(bh_semaphore_t *semaphore)
{
    if (sem_wait(&semaphore->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_semaphore_wait_for(bh_semaphore_t *semaphore,
                          unsigned long timeout)
{
    struct timespec ts;

    ts.tv_sec = timeout / 1000;
    ts.tv_nsec = (timeout - ts.tv_sec * 1000) * 1000000;

    if (sem_timedwait(&semaphore->handle, &ts))
        return BH_TIMEOUT;
    return BH_OK;
}

int bh_semaphore_try_wait(bh_semaphore_t *semaphore)
{
    if (sem_trywait(&semaphore->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_cond_init(bh_cond_t *cond)
{
    if (pthread_cond_init(&cond->handle, NULL))
        return BH_ERROR;
    return BH_OK;
}

void bh_cond_destroy(bh_cond_t *cond)
{
    pthread_cond_destroy(&cond->handle);
}

int bh_cond_wait(bh_cond_t *cond,
                 bh_mutex_t *mutex)
{
    if (pthread_cond_wait(&cond->handle, &mutex->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_cond_wait_for(bh_cond_t *cond,
                     bh_mutex_t *mutex,
                     unsigned long timeout)
{
    struct timespec ts;

    ts.tv_sec = timeout / 1000;
    ts.tv_nsec = (timeout - ts.tv_sec * 1000) * 1000000;

    if (pthread_cond_timedwait(&cond->handle, &mutex->handle, &ts))
        return BH_TIMEOUT;
    return BH_OK;
}

int bh_cond_signal(bh_cond_t *cond)
{
    if (pthread_cond_signal(&cond->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_cond_broadcast(bh_cond_t *cond)
{
    if (pthread_cond_broadcast(&cond->handle))
        return BH_ERROR;
    return BH_OK;
}

int bh_thread_pool_init(bh_thread_pool_t *pool,
                        size_t size)
{
    size_t i;
    static bh_task_t pool_task;
    static int pool_task_init = 0;

    /* Initialize static thread pool task */
    if (!pool_task_init)
    {
        bh_task_init(&pool_task, bh_thread_pool_worker, pool, 0);
        pool_task_init = 1;
    }

    /* Zero out pool structure */
    memset(pool, 0, sizeof(*pool));

    /* Initialize mutex and condition variables */
    if (bh_mutex_init(&pool->lock))
        goto lock_fail;

    if (bh_cond_init(&pool->new_task))
        goto task_fail;

    if (bh_cond_init(&pool->done_task))
        goto done_fail;

    /* Allocate array of threads */
    pool->threads = malloc(size * sizeof(bh_thread_t));
    pool->size = size;

    if (!pool->threads)
        goto thread_fail;

    /* Initialize queue */
    bh_queue_init(&pool->tasks);
    if (bh_queue_reserve(&pool->tasks, 64))
        goto queue_fail;

    /* Initialize threads */
    for (i = 0; i < size; i++)
    {
        if (bh_thread_init(&pool->threads[i], &pool_task))
        {
            pool->shutdown = 1;
            bh_cond_broadcast(&pool->new_task);
            for(; i; i--)
                bh_thread_join(&pool->threads[i - 1]);

            bh_queue_destroy(&pool->tasks);
            goto queue_fail;
        }
    }

    return BH_OK;

queue_fail:
    free(pool->threads);

thread_fail:
    bh_cond_destroy(&pool->done_task);

done_fail:
    bh_cond_destroy(&pool->new_task);

task_fail:
    bh_mutex_destroy(&pool->lock);

lock_fail:
    return BH_ERROR;
}

bh_thread_pool_t *bh_thread_pool_new(size_t size)
{
    bh_thread_pool_t *result;
    result = malloc(sizeof(*result));
    if (result && bh_thread_pool_init(result, size))
    {
        free(result);
        result = NULL;
    }

    return result;
}

void bh_spinlock_init(bh_spinlock_t *lock)
{
    lock->handle = 0;
}

void bh_spinlock_destroy(bh_spinlock_t *lock)
{
    (void)lock;
}

int bh_spinlock_lock(bh_spinlock_t *lock)
{
    /* TODO: Check on other OS and compilers */
#if defined(__clang__) || defined(__GNUC__)
    while (__sync_lock_test_and_set(&lock->handle, 1));
    return BH_OK;
#else
#error "Spinlocks are not supported"
    return BH_NO_IMPL;
#endif
}

int bh_spinlock_unlock(bh_spinlock_t *lock)
{
    /* TODO: Check on other OS and compilers */
#if defined(__clang__) || defined(__GNUC__)
    if (__sync_lock_test_and_set(&lock->handle, 0))
        return BH_OK;
    return BH_ERROR;
#else
#error "Spinlocks are not supported"
    return BH_NO_IMPL;
#endif
}

int bh_spinlock_try_lock(bh_spinlock_t *lock)
{
    /* TODO: Check on other OSs and compilers */
#if defined(__clang__) || defined(__GNUC__)
    if (__sync_lock_test_and_set(&lock->handle, 1))
        return BH_ERROR;
    return BH_OK;
#else
#error "Spinlocks are not supported"
    return BH_NO_IMPL;
#endif
}

bh_tls_info_t *bh_tls_info(void)
{
    static bh_tls_info_t info = { 0, 0 };

    return &info;
}

bh_tls_t *bh_tls_fetch(void)
{
    static bh_spinlock_t tls_lock = { 0 };
    static int tls_ready = 0;
    static pthread_key_t tls_key;

    bh_tls_t *tls;

    /* Protect pthread key by spinlock */
    bh_spinlock_lock(&tls_lock);

    /* Allocate pthread key if it's not allocated */
    if (tls_ready == 0)
    {
        pthread_key_create(&tls_key, NULL);
        tls_ready = 1;
    }

    /* Unlock spinlock */
    bh_spinlock_unlock(&tls_lock);

    /* Get TLS pointer and setup TLS if neccesery */
    tls = (bh_tls_t *)pthread_getspecific(tls_key);
    if (tls == NULL)
    {
        /* Allocate space for TLS */
        tls = malloc(sizeof(*tls));
        if (!tls)
            abort();

        /* Zero out TLS */
        memset(tls, 0, sizeof(*tls));

        /* Set TLS value */
        if (pthread_setspecific(tls_key, tls))
            abort();
    }

    /* Return TLS */
    return tls;
}