/***
  This file is part of eudev, forked from systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

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

#include "time-util.h"
#include "macro.h"

usec_t now(clockid_t clock_id) {
        struct timespec ts;

        assert_se(clock_gettime(clock_id, &ts) == 0);

        return timespec_load(&ts);
}

usec_t timespec_load(const struct timespec *ts) {
        assert(ts);

        if (ts->tv_sec == (time_t) -1 &&
            ts->tv_nsec == (long) -1)
                return USEC_INFINITY;

        if ((usec_t) ts->tv_sec > (UINT64_MAX - (ts->tv_nsec / NSEC_PER_USEC)) / USEC_PER_SEC)
                return USEC_INFINITY;

        return
                (usec_t) ts->tv_sec * USEC_PER_SEC +
                (usec_t) ts->tv_nsec / NSEC_PER_USEC;
}

char *format_timespan(char *buf, size_t l, usec_t t, usec_t accuracy) {
        static const struct {
                const char *suffix;
                usec_t usec;
        } table[] = {
                { "y", USEC_PER_YEAR },
                { "month", USEC_PER_MONTH },
                { "w", USEC_PER_WEEK },
                { "d", USEC_PER_DAY },
                { "h", USEC_PER_HOUR },
                { "min", USEC_PER_MINUTE },
                { "s", USEC_PER_SEC },
                { "ms", USEC_PER_MSEC },
                { "us", 1 },
        };

        unsigned i;
        char *p = buf;
        bool something = false;

        assert(buf);
        assert(l > 0);

        if (t == USEC_INFINITY)
                return NULL;

        if (t <= 0) {
                snprintf(p, l, "0");
                p[l-1] = 0;
                return p;
        }

        /* The result of this function can be parsed with parse_sec */

        for (i = 0; i < ELEMENTSOF(table); i++) {
                int k = 0;
                size_t n;
                bool done = false;
                usec_t a, b;

                if (t <= 0)
                        break;

                if (t < accuracy && something)
                        break;

                if (t < table[i].usec)
                        continue;

                if (l <= 1)
                        break;

                a = t / table[i].usec;
                b = t % table[i].usec;

                /* Let's see if we should shows this in dot notation */
                if (t < USEC_PER_MINUTE && b > 0) {
                        usec_t cc;
                        int j;

                        j = 0;
                        for (cc = table[i].usec; cc > 1; cc /= 10)
                                j++;

                        for (cc = accuracy; cc > 1; cc /= 10) {
                                b /= 10;
                                j--;
                        }

                        if (j > 0) {
                                k = snprintf(p, l,
                                             "%s"USEC_FMT".%0*llu%s",
                                             p > buf ? " " : "",
                                             a,
                                             j,
                                             (unsigned long long) b,
                                             table[i].suffix);

                                t = 0;
                                done = true;
                        }
                }

                /* No? Then let's show it normally */
                if (!done) {
                        k = snprintf(p, l,
                                     "%s"USEC_FMT"%s",
                                     p > buf ? " " : "",
                                     a,
                                     table[i].suffix);

                        t = b;
                }

                n = MIN((size_t) k, l);

                l -= n;
                p += n;

                something = true;
        }

        *p = 0;

        return buf;
}