/*      $OpenBSD: runq.c,v 1.5 2023/05/31 16:51:46 op Exp $     */

/*
 * Copyright (c) 2013,2019 Eric Faurot <eric@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdlib.h>
#include <time.h>

#include "smtpd.h"

struct job {
        TAILQ_ENTRY(job)         entry;
        time_t                   when;
        void                    *arg;
};

struct runq {
        TAILQ_HEAD(, job)        jobs;
        void                    (*cb)(struct runq *, void *);
        struct event             ev;
};

static void runq_timeout(int, short, void *);

static struct runq *active;

static void
runq_reset(struct runq *runq)
{
        struct timeval   tv;
        struct job      *job;
        time_t           now;

        job = TAILQ_FIRST(&runq->jobs);
        if (job == NULL)
                return;

        now = time(NULL);
        if (job->when <= now)
                tv.tv_sec = 0;
        else
                tv.tv_sec = job->when - now;
        tv.tv_usec = 0;
        evtimer_add(&runq->ev, &tv);
}

static void
runq_timeout(int fd, short ev, void *arg)
{
        struct runq     *runq = arg;
        struct job      *job;
        time_t           now;

        active = runq;
        now = time(NULL);

        while((job = TAILQ_FIRST(&runq->jobs))) {
                if (job->when > now)
                        break;
                TAILQ_REMOVE(&runq->jobs, job, entry);
                runq->cb(runq, job->arg);
                free(job);
        }

        active = NULL;
        runq_reset(runq);
}

int
runq_init(struct runq **runqp, void (*cb)(struct runq *, void *))
{
        struct runq     *runq;

        runq = malloc(sizeof(*runq));
        if (runq == NULL)
                return (0);

        runq->cb = cb;
        TAILQ_INIT(&runq->jobs);
        evtimer_set(&runq->ev, runq_timeout, runq);

        *runqp = runq;

        return (1);
}

int
runq_schedule(struct runq *runq, time_t delay, void *arg)
{
        time_t t;

        time(&t);
        return runq_schedule_at(runq, t + delay, arg);
}

int
runq_schedule_at(struct runq *runq, time_t when, void *arg)
{
        struct job      *job, *tmpjob;

        job = malloc(sizeof(*job));
        if (job == NULL)
                return (0);

        job->arg = arg;
        job->when = when;

        TAILQ_FOREACH(tmpjob, &runq->jobs, entry) {
                if (tmpjob->when > job->when) {
                        TAILQ_INSERT_BEFORE(tmpjob, job, entry);
                        goto done;
                }
        }
        TAILQ_INSERT_TAIL(&runq->jobs, job, entry);

    done:
        if (runq != active && job == TAILQ_FIRST(&runq->jobs)) {
                evtimer_del(&runq->ev);
                runq_reset(runq);
        }
        return (1);
}

int
runq_cancel(struct runq *runq, void *arg)
{
        struct job      *job, *first;

        first = TAILQ_FIRST(&runq->jobs);
        TAILQ_FOREACH(job, &runq->jobs, entry) {
                if (job->arg == arg) {
                        TAILQ_REMOVE(&runq->jobs, job, entry);
                        free(job);
                        if (runq != active && job == first) {
                                evtimer_del(&runq->ev);
                                runq_reset(runq);
                        }
                        return (1);
                }
        }

        return (0);
}

int
runq_pending(struct runq *runq, void *arg, time_t *when)
{
        struct job      *job;

        TAILQ_FOREACH(job, &runq->jobs, entry) {
                if (job->arg == arg) {
                        if (when)
                                *when = job->when;
                        return (1);
                }
        }

        return (0);
}