#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>

#include <hexagram/schedule.h>

static inline hexagram_schedule_timer *_timer(hexagram_schedule *schedule, size_t i) {
    return &((hexagram_schedule_timer *)(schedule + 1))[i];
};

static int _timer_cmp(const void *item_a, const void *item_b) {
    hexagram_schedule_timer *a = (hexagram_schedule_timer *)item_a,
                            *b = (hexagram_schedule_timer *)item_b;

    return a->slot->interval_us < b->slot->interval_us? -1:
           a->slot->interval_us > b->slot->interval_us?  1: 0;
}

static inline int _timer_set(hexagram_schedule_timer *timer, time_t nsec) {
    timer->ts.it_value.tv_sec     = 0;
    timer->ts.it_value.tv_nsec    = nsec;
    timer->ts.it_interval.tv_sec  = 0;
    timer->ts.it_interval.tv_nsec = nsec;

    return timer_settime(timer->id, 0, &timer->ts, NULL);
}

static inline int _timer_stop(hexagram_schedule_timer *timer) {
    return _timer_set(timer, 0);
}

static void _ev_notify(union sigval sv) {
    hexagram_schedule_timer *timer = sv.sival_ptr;
    hexagram_schedule_slot *slot   = timer->slot;

    if (slot->handler(&slot->frame, timer->ctx) < 0) {
        timer->error = errno;

        _timer_stop(timer);
    }
}

hexagram_schedule *hexagram_schedule_create(hexagram_schedule_slot *table,
                                            size_t count,
                                            void *ctx) {
    hexagram_schedule *schedule;
    size_t i;

    if ((schedule = malloc(sizeof(*schedule) + count * sizeof(hexagram_schedule_timer))) == 0) {
        goto error_malloc_schedule;
    }

    schedule->table = table;
    schedule->count = count;

    for (i=0; i<count; i++) {
        hexagram_schedule_timer *timer = _timer(schedule, i);

        memset(&timer->ev, '\0', sizeof(struct sigevent));

        timer->ev.sigev_notify          = SIGEV_THREAD;
        timer->ev.sigev_notify_function = _ev_notify;
        timer->ev.sigev_value.sival_ptr = timer;

        timer->slot  = &table[i];
        timer->ctx   = ctx;
        timer->error = 0;

        if (timer_create(CLOCK_REALTIME, &timer->ev, &timer->id) < 0) {
            goto error_timer_create;
        }
    }

    qsort(schedule + 1, count, sizeof(hexagram_schedule_timer), _timer_cmp);

    return schedule;

error_timer_create:
    while (--i) {
        hexagram_schedule_timer *timer = _timer(schedule, i);

        timer_delete(timer->id);
    }

    free(schedule);

error_malloc_schedule:
    return NULL;
}

void hexagram_schedule_destroy(hexagram_schedule *schedule) {
    size_t i;

    for (i=0; i<schedule->count; i++) {
        hexagram_schedule_timer *timer = _timer(schedule, i);

        _timer_stop(timer);

        timer_delete(timer->id);
    }

    free(schedule);
}

int hexagram_schedule_run(hexagram_schedule *schedule) {
    size_t i;

    for (i=0; i<schedule->count; i++) {
        hexagram_schedule_timer *timer = _timer(schedule, i);

        if (_timer_set(timer, 1000 * timer->slot->interval_us) < 0) {
            goto error_timer_set;
        }
    }

    return 0;

error_timer_set:
    return -1;
}

int hexagram_schedule_stop(hexagram_schedule *schedule) {
    size_t i;

    for (i=0; i<schedule->count; i++) {
        hexagram_schedule_timer *timer = _timer(schedule, i);

        if (_timer_stop(timer) < 0) {
            goto error_timer_stop;
        }
    }

    return 0;

error_timer_stop:
    return -1;
}

int hexagram_schedule_error(hexagram_schedule *schedule) {
    size_t i;

    for (i=0; i<schedule->count; i++) {
        hexagram_schedule_timer *timer = _timer(schedule, i);

        if (timer->error != 0) {
            return timer->error;
        }
    }

    return 0;
}