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

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

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

struct sa_thread {
    pthread_t id;
    sa_thread_func_t thread_func;
    void *userdata;
    int running;
    pthread_mutex_t running_mutex;
};

struct sa_tls {
    pthread_key_t key;
};

static sa_tls_t *thread_tls;
static sa_once_t thread_tls_once = SA_ONCE_INIT;

static void tls_free_cb(void *p) {
    sa_thread_t *t = p;

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

static void thread_tls_once_func(void) {
    thread_tls = sa_tls_new(tls_free_cb);
}

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

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

    t->thread_func(t->userdata);

    sa_assert_success(pthread_mutex_lock(&t->running_mutex));
    t->running = 0;
    sa_assert_success(pthread_mutex_unlock(&t->running_mutex));
    
    return NULL;
}

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

    sa_assert(thread_func);
    
    if (sa_once(&thread_tls_once, thread_tls_once_func) < 0 || !thread_tls)
        return NULL;

    if (!(t = sa_new(sa_thread_t, 1)))
        return NULL;
    
    t->thread_func = thread_func;
    t->userdata = userdata;

    sa_assert_success(pthread_mutex_init(&t->running_mutex, NULL));
    t->running = 1;
    
    if (pthread_create(&t->id, NULL, internal_thread_func, t) < 0) {
        sa_assert_success(pthread_mutex_destroy(&t->running_mutex));
        sa_free(t);
        return NULL;
    }

    return t;
}

int sa_thread_is_running(sa_thread_t *t) {
    int b;
    sa_assert(t);

    if (!t->thread_func) {
        /* Mhmm, this is a foreign thread, t->running is not
         * necessarily valid. We misuse pthread_getschedparam() to
         * check if the thread is valid. This might not be portable. */

        int policy;
        struct sched_param param;
        
        return pthread_getschedparam(t->id, &policy, &param) >= 0 || errno != ESRCH;
    }

    sa_assert_success(pthread_mutex_lock(&t->running_mutex));
    b = t->running;
    sa_assert_success(pthread_mutex_unlock(&t->running_mutex));
    
    return !!b;
}

void sa_thread_free(sa_thread_t *t) {
    sa_assert(t);
    
    sa_thread_join(t);
    sa_assert_success(pthread_mutex_destroy(&t->running_mutex));
    sa_free(t);
}

int sa_thread_join(sa_thread_t *t) {
    sa_assert(t);
    
    return pthread_join(t->id, NULL);
}

sa_thread_t* sa_thread_self(void) {
    sa_thread_t *t;
    
    if (sa_once(&thread_tls_once, thread_tls_once_func) < 0 || !thread_tls)
        return NULL;

    if ((t = sa_tls_get(thread_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_t, 1)))
        return NULL;
    
    t->id = pthread_self();
    t->thread_func = NULL;
    t->userdata = NULL;
    t->running = 1;

    sa_tls_set(thread_tls, t);
    
    return t;
}

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

    return t->userdata;
}

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

    t->userdata = userdata;
}

void sa_thread_yield(void) {
#ifdef HAVE_PTHREAD_YIELD
    pthread_yield();
#else
    sa_assert_success(sched_yield());
#endif
}

sa_tls_t* sa_tls_new(sa_free_func_t free_cb) {
    sa_tls_t *t;

    if (!(t = sa_new(sa_tls_t, 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 *t) {
    sa_assert(t);

    sa_assert_success(pthread_key_delete(t->key));
    sa_free(t);
}

void *sa_tls_get(sa_tls_t *t) {
    sa_assert(t);
    
    return pthread_getspecific(t->key);
}

void *sa_tls_set(sa_tls_t *t, void *userdata) {
    void *r;
    
    r = pthread_getspecific(t->key);
    sa_assert_success(pthread_setspecific(t->key, userdata));
    return r;
}