#include <bh/internal/thread.h>

static unsigned __stdcall bh_thread_run(void *arg)
{
    bh_tls_t *tls;
    bh_thread_data_t data;

    /* Fetch thread data, store it on stack and free from heap */
    data = *(bh_thread_data_t *)arg;
    free(arg);

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

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

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

    /* Destroy our TLS */
    bh_tls_cleanup();

    /* Call thread specific end function (deallocate libc TLS) */
    data.end(0);

    return 0;
}

int bh_thread_init_base(bh_thread_t *thread,
                        bh_task_t *task,
                        bh_thread_begin_cb_t begin,
                        bh_thread_end_cb_t end)
{
    bh_thread_data_t *data;

    /* Allocate thread specific data */
    data = malloc(sizeof(*data));
    if (!data)
        return BH_OOM;

    /* Setup thread specific data */
    data->task = task;
    data->end = end;

    /* Create and setup thread (relative to the callers libc) */
    thread->allocated = 0;
    thread->handle = (HANDLE)_beginthreadex(NULL, 0, bh_thread_run, data, 0, NULL);

    /* Check for errors */
    if (!thread->handle)
    {
        free(data);
        return BH_ERROR;
    }

    return BH_OK;
}

bh_thread_t *bh_thread_new_base(bh_task_t *task,
                                bh_thread_begin_cb_t begin,
                                bh_thread_end_cb_t end)
{
    bh_thread_t *result;

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

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

    return result;
}

int bh_thread_sleep(unsigned long timeout)
{
    Sleep(timeout);
    return BH_OK;
}

int bh_thread_join(bh_thread_t *thread)
{
    /* Join the thread */
    WaitForSingleObject(thread->handle, INFINITE);
    CloseHandle(thread->handle);

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

    return BH_OK;
}

int bh_thread_detach(bh_thread_t *thread)
{
    /* Detach from thread */
    CloseHandle(thread->handle);

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

    return BH_OK;
}

int bh_mutex_init(bh_mutex_t *mutex)
{
    /* TODO: Is this spincount needed or sane? */
    if (!InitializeCriticalSectionAndSpinCount(&mutex->handle, 0x400))
        return BH_ERROR;
    return BH_OK;
}

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

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

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

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

int bh_semaphore_init(bh_semaphore_t *semaphore, int count)
{
    /* Create semaphore with max value of 32767 (to match POSIX) */
    semaphore->handle = CreateSemaphore(NULL, count, 0x7FFF, NULL);
    if (!semaphore->handle)
        return BH_ERROR;

    return BH_OK;
}

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

int bh_semaphore_post(bh_semaphore_t *semaphore)
{
    if (!ReleaseSemaphore(semaphore->handle, 1, NULL))
        return BH_ERROR;
    return BH_OK;
}

int bh_semaphore_wait(bh_semaphore_t *semaphore)
{
    if (WaitForSingleObject(semaphore->handle, INFINITE))
        return BH_ERROR;
    return BH_OK;
}

int bh_semaphore_wait_for(bh_semaphore_t *semaphore,
                          unsigned long timeout)
{
    /* FIXME: Check if we timed out or errored out */
    if (WaitForSingleObject(semaphore->handle, timeout))
        return BH_TIMEOUT;
    return BH_ERROR;
}

int bh_semaphore_try_wait(bh_semaphore_t *semaphore)
{
    if (WaitForSingleObject(semaphore->handle, 0))
        return BH_ERROR;
    return BH_OK;
}

#if WINVER >= _WIN32_WINNT_VISTA
int bh_cond_init(bh_cond_t *cond)
{
    InitializeConditionVariable(&cond->handle);
    return BH_OK;
}

void bh_cond_destroy(bh_cond_t *cond)
{
    (void)cond;
}

int bh_cond_wait(bh_cond_t *cond,
                 bh_mutex_t *mutex)
{
    return bh_cond_wait_for(cond, mutex, INFINITE);
}

int bh_cond_wait_for(bh_cond_t *cond,
                     bh_mutex_t *mutex,
                     unsigned long timeout)
{
    /* FIXME: Check if we timed out or errored out */
    if (!SleepConditionVariableCS(&cond->handle, &mutex->handle, timeout))
        return BH_TIMEOUT;
    return BH_OK;
}

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

int bh_cond_broadcast(bh_cond_t *cond)
{
    WakeAllConditionVariable(&cond->handle);
    return BH_OK;
}
#else
/* Condition variable implementation based on BeOS article
 * http://www-classic.be.com/aboutbe/benewsletter/volume_III/Issue40.html
 *
 * Slow, but correct implementation of CVs.
 */

int bh_cond_init(bh_cond_t *cond)
{
    if (bh_mutex_init(&cond->lock))
        return BH_ERROR;

    if (bh_semaphore_init(&cond->wait, 0))
    {
        bh_mutex_destroy(&cond->lock);
        return BH_ERROR;
    }

    if (bh_semaphore_init(&cond->done, 0))
    {
        bh_semaphore_destroy(&cond->wait);
        bh_mutex_destroy(&cond->lock);
        return BH_ERROR;
    }
    cond->waiting = 0;
    cond->signals = 0;

    return 0;
}

void bh_cond_destroy(bh_cond_t *cond)
{
    bh_semaphore_destroy(&cond->done);
    bh_semaphore_destroy(&cond->wait);
    bh_mutex_destroy(&cond->lock);
}

int bh_cond_wait(bh_cond_t *cond,
                 bh_mutex_t *mutex)
{
    int retval;

    bh_mutex_lock(&cond->lock);
    cond->waiting++;
    bh_mutex_unlock(&cond->lock);
    bh_mutex_unlock(mutex);

    retval = bh_semaphore_wait(&cond->wait);

    bh_mutex_lock(&cond->lock);
    if (cond->signals > 0)
    {
        if (retval)
            bh_semaphore_wait(&cond->wait);

        bh_semaphore_post(&cond->done);
        cond->signals--;
    }
    cond->waiting--;
    bh_mutex_unlock(&cond->lock);
    bh_mutex_lock(mutex);

    return retval;
}

int bh_cond_wait_for(bh_cond_t *cond,
                     bh_mutex_t *mutex,
                     unsigned long timeout)
{
    int retval;

    bh_mutex_lock(&cond->lock);
    cond->waiting++;
    bh_mutex_unlock(&cond->lock);
    bh_mutex_unlock(mutex);

    retval = bh_semaphore_wait_for(&cond->wait, timeout);

    bh_mutex_lock(&cond->lock);
    if (cond->signals > 0)
    {
        if (retval)
            bh_semaphore_wait(&cond->wait);

        bh_semaphore_post(&cond->done);
        cond->signals--;
    }
    cond->waiting--;
    bh_mutex_unlock(&cond->lock);
    bh_mutex_lock(mutex);

    return retval;
}

int bh_cond_signal(bh_cond_t *cond)
{
    bh_mutex_lock(&cond->lock);

    if (cond->waiting > cond->signals)
    {
        cond->signals++;

        bh_semaphore_post(&cond->wait);
        bh_mutex_unlock(&cond->lock);
        bh_semaphore_wait(&cond->done);
    }
    else
        bh_mutex_unlock(&cond->lock);

    return BH_OK;
}

int bh_cond_broadcast(bh_cond_t *cond)
{
    int i, waiting;

    bh_mutex_lock(&cond->lock);
    if (cond->waiting > cond->signals)
    {
        waiting = cond->waiting - cond->signals;
        cond->signals = cond->waiting;

        for (i = 0; i < waiting; i++)
            bh_semaphore_post(&cond->wait);

        bh_mutex_unlock(&cond->lock);

        for (i = 0; i < waiting; i++)
            bh_semaphore_wait(&cond->done);
    }
    else
        bh_mutex_unlock(&cond->lock);

    return BH_OK;
}
#endif

int bh_thread_pool_init_base(bh_thread_pool_t *pool,
                             size_t size,
                             bh_thread_begin_cb_t begin,
                             bh_thread_end_cb_t end)
{
    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_base(&pool->threads[i], &pool_task, begin, end))
        {
            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_base(size_t size,
                                          bh_thread_begin_cb_t begin,
                                          bh_thread_end_cb_t end)
{
    bh_thread_pool_t *result;

    result = malloc(sizeof(*result));
    if (result && bh_thread_pool_init_base(result, size, begin, end))
    {
        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)
{
    while (InterlockedExchange(&lock->handle, 1));
    return BH_OK;
}

int bh_spinlock_unlock(bh_spinlock_t *lock)
{
    if (InterlockedExchange(&lock->handle, 0))
        return BH_OK;
    return BH_ERROR;
}

int bh_spinlock_try_lock(bh_spinlock_t *lock)
{
    if (InterlockedExchange(&lock->handle, 1))
        return BH_ERROR;
    return BH_OK;
}

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 DWORD tls_index = TLS_OUT_OF_INDEXES;

    bh_tls_t *tls;

    /* Protect TLS index by spinlock */
    bh_spinlock_lock(&tls_lock);

    /* Allocate TLS index if it's not allocated */
    if (tls_index == TLS_OUT_OF_INDEXES)
        tls_index = TlsAlloc();

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

    /* Check that TLS index is valid */
    if (tls_index == TLS_OUT_OF_INDEXES)
        abort();

    /* Get TLS pointer and setup TLS if neccesery */
    tls = (bh_tls_t *)TlsGetValue(tls_index);
    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 (!TlsSetValue(tls_index, tls))
            abort();
    }

    /* Return TLS */
    return tls;
}