/*
 * datetime.c - parameter and command interface to date and time utilities
 *
 * This file is part of zsh, the Z shell.
 *
 * Copyright (c) 2002 Peter Stephenson, Clint Adams
 * All rights reserved.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and to distribute modified versions of this software for any
 * purpose, provided that the above copyright notice and the following
 * two paragraphs appear in all copies of this software.
 *
 * In no event shall Peter Stephenson, Clint Adams or the Zsh Development Group
 * be liable to any party for direct, indirect, special, incidental, or
 * consequential damages arising out of the use of this software and its
 * documentation, even if Peter Stephenson, Clint Adams and the Zsh
 * Development Group have been advised of the possibility of such damage.
 *
 * Peter Stephenson, Clint Adams and the Zsh Development Group specifically
 * disclaim any warranties, including, but not limited to, the implied
 * warranties of merchantability and fitness for a particular purpose.
 * The software provided hereunder is on an "as is" basis, and Peter
 * Stephenson, Clint Adams and the Zsh Development Group have no obligation
 * to provide maintenance, support, updates, enhancements, or modifications.
 *
 */

#include "datetime.mdh"
#include "datetime.pro"
#include <time.h>

#ifndef HAVE_MKTIME
#ifdef HAVE_TIMELOCAL
#define	mktime(x)	timelocal(x)
#define HAVE_MKTIME	1
#endif
#endif

static int
reverse_strftime(char *nam, char **argv, char *scalar, int quiet)
{
#if defined(HAVE_STRPTIME) && defined(HAVE_MKTIME)
    struct tm tm;
    zlong mytime;
    char *endp;

    /*
     * Initialise all parameters to zero; there's no floating point
     * so memset() will do the trick.  The exception is that tm_isdst
     * is set to -1 which, if not overridden, will cause mktime()
     * to use the current timezone.  This is probably the best guess;
     * it's the one that will cause dates and times output by strftime
     * without the -r option and without an explicit timezone to be
     * converted back correctly. Additionally, tm_mday is set to 1
     * as that and not 0 corresponds to the first of the month.
     */
    (void)memset(&tm, 0, sizeof(tm));
    tm.tm_isdst = -1;
    tm.tm_mday = 1;
    endp = strptime(argv[1], argv[0], &tm);

    if (!endp) {
	/* Conversion failed completely. */
	if (!quiet)
	    zwarnnam(nam, "format not matched");
	return 1;
    }

    mytime = (zlong)mktime(&tm);

    if (scalar)
	setiparam(scalar, mytime);
    else {
	char buf[DIGBUFSIZE];
	convbase(buf, mytime, 10);
	printf("%s\n", buf);
    }

    if (*endp && !quiet) {
	/*
	 * Not everything in the input string was converted.
	 * This is probably benign, since the format has been satisfied,
	 * but issue a warning unless the quiet flag is set.
	 */
	zwarnnam(nam, "warning: input string not completely matched");
    }

    return 0;
#else
    if (!quiet)
	zwarnnam(nam, "not implemented on this system");
    return 2;
#endif
}

static int
output_strftime(char *nam, char **argv, Options ops, UNUSED(int func))
{
    int bufsize, x, len;
    char *endptr = NULL, *scalar = NULL, *buffer;
    struct tm *tm;
    struct timespec ts;

    if (OPT_ISSET(ops,'s')) {
	scalar = OPT_ARG(ops, 's');
	if (!isident(scalar)) {
	    zwarnnam(nam, "not an identifier: %s", scalar);
	    return 1;
	}
    }
    if (OPT_ISSET(ops, 'r')) {
	if (!argv[1]) {
	    zwarnnam(nam, "timestring expected");
	    return 1;
	}
	return reverse_strftime(nam, argv, scalar, OPT_ISSET(ops, 'q'));
    }

    if (!argv[1]) {
	zgettime(&ts);
	tm = localtime(&ts.tv_sec);
    } else {
	errno = 0;

	ts.tv_sec = (time_t)strtoul(argv[1], &endptr, 10);
	if (errno != 0) {
	    zwarnnam(nam, "%s: %e", argv[1], errno);
	    return 1;
	} else if (*argv[1] == '\0' || *endptr != '\0') {
	    zwarnnam(nam, "%s: invalid decimal number", argv[1]);
	    return 1;
	}

	tm = localtime(&ts.tv_sec);
	if (!tm) {
	    zwarnnam(nam, "%s: unable to convert to time", argv[1]);
	    return 1;
	}

	ts.tv_nsec = 0L;
	if (argv[2]) {
	    ts.tv_nsec = (long)zstrtol(argv[2], &endptr, 10);
	    if (errno != 0) {
		zwarnnam(nam, "%s: %e", argv[2], errno);
		return 1;
	    } else if (*argv[2] == '\0' || *endptr != '\0') {
		zwarnnam(nam, "%s: invalid decimal number", argv[2]);
		return 1;
	    } else if (ts.tv_nsec < 0 || ts.tv_nsec > 999999999) {
		zwarnnam(nam, "%s: invalid nanosecond value", argv[2]);
		return 1;
	    }
	}
    }

    bufsize = strlen(argv[0]) * 8;
    buffer = zalloc(bufsize);

    len = 0;
    for (x=0; x < 4; x++) {
        if ((len = ztrftime(buffer, bufsize, argv[0], tm, ts.tv_nsec)) >= 0 ||
	    x==3)
	    break;
	buffer = zrealloc(buffer, bufsize *= 2);
    }
    if (len < 0) {
	zwarnnam(nam, "bad/unsupported format: '%s'", argv[0]);
	zfree(buffer, bufsize);
	return 1;
    }

    if (scalar) {
	setsparam(scalar, metafy(buffer, len, META_DUP));
    } else {
	fwrite(buffer, 1, len, stdout);
	putchar('\n');
    }
    zfree(buffer, bufsize);

    return 0;
}

static int
bin_strftime(char *nam, char **argv, Options ops, int func)
{
    int result = 1;
    char *tz = getsparam("TZ");

    startparamscope();
    if (tz && *tz) {
	Param pm = createparam("TZ", PM_LOCAL|PM_SCALAR|PM_EXPORTED);
	if (pm)
	    pm->level = locallevel; /* because createparam() doesn't */
	setsparam("TZ", ztrdup(tz));
    }
    result = output_strftime(nam, argv, ops, func);
    endparamscope();

    return result;
}

static zlong
getcurrentsecs(UNUSED(Param pm))
{
    return (zlong) time(NULL);
}

static double
getcurrentrealtime(UNUSED(Param pm))
{
    struct timespec now;
    zgettime(&now);
    return (double)now.tv_sec + (double)now.tv_nsec * 1e-9;
}

static char **
getcurrenttime(UNUSED(Param pm))
{
    char **arr;
    char buf[DIGBUFSIZE];
    struct timespec now;

    zgettime(&now);

    arr = (char **)zhalloc(3 * sizeof(*arr));
    sprintf(buf, "%ld", (long)now.tv_sec);
    arr[0] = dupstring(buf);
    sprintf(buf, "%ld", (long)now.tv_nsec);
    arr[1] = dupstring(buf);
    arr[2] = NULL;

    return arr;
}

static struct builtin bintab[] = {
    BUILTIN("strftime",    0, bin_strftime,    1,   3, 0, "qrs:", NULL),
};

static const struct gsu_integer epochseconds_gsu =
{ getcurrentsecs, NULL, stdunsetfn };

static const struct gsu_float epochrealtime_gsu =
{ getcurrentrealtime, NULL, stdunsetfn };

static const struct gsu_array epochtime_gsu =
{ getcurrenttime, NULL, stdunsetfn };

static struct paramdef patab[] = {
    SPECIALPMDEF("EPOCHSECONDS", PM_INTEGER|PM_READONLY,
		 &epochseconds_gsu, NULL, NULL),
    SPECIALPMDEF("EPOCHREALTIME", PM_FFLOAT|PM_READONLY,
		 &epochrealtime_gsu, NULL, NULL),
    SPECIALPMDEF("epochtime", PM_ARRAY|PM_READONLY,
		 &epochtime_gsu, NULL, NULL)
};

static struct features module_features = {
    bintab, sizeof(bintab)/sizeof(*bintab),
    NULL, 0,
    NULL, 0,
    patab, sizeof(patab)/sizeof(*patab),
    0
};

/**/
int
setup_(UNUSED(Module m))
{
    return 0;
}

/**/
int
features_(Module m, char ***features)
{
    *features = featuresarray(m, &module_features);
    return 0;
}

/**/
int
enables_(Module m, int **enables)
{
    return handlefeatures(m, &module_features, enables);
}

/**/
int
boot_(UNUSED(Module m))
{
    return 0;
}

/**/
int
cleanup_(Module m)
{
    return setfeatureenables(m, &module_features, NULL);
}

/**/
int
finish_(UNUSED(Module m))
{
    return 0;
}