#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <pthread.h>
#include <sched.h>
#include <errno.h>

#include "malloc.h"
#include "mutex.h"
#include "macro.h"
#include "thread.h"

struct sa_thread {
    pthread_t id;
    sa_thread_func_t thread_func;
    void *userdata;
    int running;
    sa_mutex *mutex;
};

struct sa_tls {
    pthread_key_t key;
};

static pthread_once_t tid_once = PTHREAD_ONCE_INIT;
static sa_tls *tid_tls = NULL;

static void tid_free_cb(void *p) {
    sa_thread *t = p;

    sa_assert(t);

    if (!t->thread_func) {
        /* This is a foreign thread, we need to free the struct */
        sa_mutex_free(t->mutex);
        sa_free(t);
    }
}

static void tid_init(void) {
    tid_tls = sa_tls_new(tid_free_cb);
}

static void* internal_thread_func(void *userdata) {
    sa_thread *t = userdata;
    sa_assert(t);

    t->id = pthread_self();
    sa_tls_set(tid_tls, t);

    sa_mutex_lock(t->mutex);
    t->running++;
    sa_mutex_unlock(t->mutex);

    t->thread_func(t->userdata);

    sa_mutex_lock(t->mutex);
    t->running -= 2;
    sa_mutex_unlock(t->mutex);

    return NULL;
}

sa_thread* sa_thread_new(sa_thread_func_t thread_func, void *userdata) {
    sa_thread *t;

    sa_assert(thread_func);

    pthread_once(&tid_once, tid_init);

    if (!tid_tls)
        return NULL;

    if (!(t = sa_new(sa_thread, 1)))
        return NULL;

    t->thread_func = thread_func;
    t->userdata = userdata;
    t->running = 1;

    if (!(t->mutex = sa_mutex_new(FALSE, FALSE))) {
        sa_free(t);
        return NULL;
    }

    if (pthread_create(&t->id, NULL, internal_thread_func, t) < 0) {
        sa_mutex_free(t->mutex);
        sa_free(t);
        return NULL;
    }

    return t;
}

sa_bool_t sa_thread_is_running(sa_thread *t) {
    sa_bool_t b;
    sa_assert(t);

    /* Unfortunately there is no way to tell whether a "foreign"
     * thread is still running. See
     * http://udrepper.livejournal.com/16844.html for more
     * information */
    sa_assert(t->thread_func);

    sa_mutex_lock(t->mutex);
    b = t->running > 0;
    sa_mutex_unlock(t->mutex);

    return b;
}

void sa_thread_free(sa_thread *t) {
    sa_assert(t);

    /* Only allowed when this is not a foreign thread */
    sa_assert(t->thread_func);

    sa_thread_join(t);
    sa_mutex_free(t->mutex);
    sa_free(t);
}

int sa_thread_join(sa_thread *t) {
    sa_assert(t);

    /* Only allowed when this is not a foreign thread */
    sa_assert(t->thread_func);

    return pthread_join(t->id, NULL);
}

sa_thread* sa_thread_self(void) {
    sa_thread *t;

    pthread_once(&tid_once, tid_init);

    if (!tid_tls)
        return NULL;

    if ((t = sa_tls_get(tid_tls)))
        return t;

    /* This is a foreign thread, let's create a pthread structure to
     * make sure that we can always return a sensible pointer */

    if (!(t = sa_new(sa_thread, 1)))
        return NULL;

    t->id = pthread_self();
    t->thread_func = NULL;
    t->userdata = NULL;
    t->running = 2;
    t->mutex = sa_mutex_new(FALSE, FALSE);

    sa_tls_set(tid_tls, t);

    return t;
}

void* sa_thread_get_data(sa_thread *t) {
    sa_assert(t);

    return t->userdata;
}

void sa_thread_set_data(sa_thread *t, void *userdata) {
    sa_assert(t);

    t->userdata = userdata;
}

void sa_thread_yield(void) {
#ifdef HAVE_PTHREAD_YIELD
    pthread_yield();
#else
    sa_assert_se(sched_yield() == 0);
#endif
}

sa_tls* sa_tls_new(sa_free_cb_t free_cb) {
    sa_tls *t;

    if (!(t = sa_new(sa_tls, 1)))
        return NULL;

    if (pthread_key_create(&t->key, free_cb) < 0) {
        sa_free(t);
        return NULL;
    }

    return t;
}

void sa_tls_free(sa_tls *t) {
    sa_assert(t);

    sa_assert_se(pthread_key_delete(t->key) == 0);
    sa_free(t);
}

void *sa_tls_get(sa_tls *t) {
    sa_assert(t);

    return pthread_getspecific(t->key);
}

void *sa_tls_set(sa_tls *t, void *userdata) {
    void *r;

    sa_assert(t);
    r = pthread_getspecific(t->key);
    sa_assert_se(pthread_setspecific(t->key, userdata) == 0);
    return r;
}