/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */


#include <langinfo.h>
#include <locale.h>
#include <nl_types.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

static int number(char *);
static int jan1(const int);
static void badmonth(void);
static void badyear(void);
static void usage(void);
static void cal(const int, const int, char *, const int);
static void load_months(void);
static void pstr(char *, const int);

#define DAYW    " S  M Tu  W Th  F  S"
#define TITLE   "   %s %u\n"
#define YEAR    "\n\n\n\t\t\t\t%u\n\n"
#define MONTH   "\t%4.3s\t\t\t%.3s\t\t%10.3s\n"

static char *months[] = {
        "January", "February", "March", "April",
        "May", "June", "July", "August",
        "September", "October", "November", "December",
};

static char *short_months[] = {
        "Jan", "Feb", "Mar", "Apr",
        "May", "Jun", "Jul", "Aug",
        "Sep", "Oct", "Nov", "Dec",
};

static char mon[] = {
        0,
        31, 29, 31, 30,
        31, 30, 31, 31,
        30, 31, 30, 31,
};

static char *myname;
static char string[432];
static struct tm *thetime;
static time_t timbuf;

int
main(int argc, char *argv[])
{
        int y, i, j;
        int m;
        char *time_locale;
        char    *ldayw;

        myname = argv[0];

        (void) setlocale(LC_ALL, "");
#if !defined(TEXT_DOMAIN)
#define TEXT_DOMAIN     "SYS_TEST"
#endif
        (void) textdomain(TEXT_DOMAIN);


        while (getopt(argc, argv, "") != EOF)
                usage();

        argc -= optind;
        argv  = &argv[optind];

        time_locale = setlocale(LC_TIME, NULL);
        if ((time_locale[0] != 'C') || (time_locale[1] != '\0'))
                load_months();

        /*
         * TRANSLATION_NOTE
         * This message is to be used for displaying
         * the names of the seven days, from Sunday to Saturday.
         * The length of the name of each one should be two or less.
         */
        ldayw = dcgettext(NULL, DAYW, LC_TIME);

        switch (argc) {
        case 0:
                timbuf = time(&timbuf);
                thetime = localtime(&timbuf);
                m = thetime->tm_mon + 1;
                y = thetime->tm_year + 1900;
                break;
        case 1:
                goto xlong;
        case 2:
                m = number(argv[0]);
                y = number(argv[1]);
                break;
        default:
                usage();
        }

/*
 *      print out just month
 */

        if (m < 1 || m > 12)
                badmonth();
        if (y < 1 || y > 9999)
                badyear();
        /*
         * TRANSLATION_NOTE
         * This message is to be used for displaying
         * specified month and year.
         */
        (void) printf(dcgettext(NULL, TITLE, LC_TIME), months[m-1], y);
        (void) printf("%s\n", ldayw);
        cal(m, y, string, 24);
        for (i = 0; i < 6*24; i += 24)
                pstr(string+i, 24);
        return (0);

/*
 *      print out complete year
 */

xlong:
        y = number(argv[0]);
        if (y < 1 || y > 9999)
                badyear();
        /*
         * TRANSLATION_NOTE
         * This message is to be used for displaying
         * specified year.
         */
        (void) printf(dcgettext(NULL, YEAR, LC_TIME), y);
        for (i = 0; i < 12; i += 3) {
                for (j = 0; j < 6*72; j++)
                        string[j] = '\0';
                /*
                 * TRANSLATION_NOTE
                 * This message is to be used for displaying
                 * names of three months per a line and should be
                 * correctly translated according to the display width
                 * of the names of months.
                 */
                (void) printf(
                        dcgettext(NULL, MONTH, LC_TIME),
                        short_months[i], short_months[i+1], short_months[i+2]);
                (void) printf("%s   %s   %s\n", ldayw, ldayw, ldayw);
                cal(i+1, y, string, 72);
                cal(i+2, y, string+23, 72);
                cal(i+3, y, string+46, 72);
                for (j = 0; j < 6*72; j += 72)
                        pstr(string+j, 72);
        }
        (void) printf("\n\n\n");
        return (0);
}

static int
number(char *str)
{
        int n, c;
        char *s;

        n = 0;
        s = str;
        /*LINTED*/
        while (c = *s++) {
                if (c < '0' || c > '9')
                        return (0);
                n = n*10 + c-'0';
        }
        return (n);
}

static void
pstr(char *str, const int n)
{
        int i;
        char *s;

        s = str;
        i = n;
        while (i--)
                if (*s++ == '\0')
                        s[-1] = ' ';
        i = n+1;
        while (i--)
                if (*--s != ' ')
                        break;
        s[1] = '\0';
        (void) printf("%s\n", str);
}

static void
cal(const int m, const int y, char *p, const int w)
{
        int d, i;
        char *s;

        s = (char *)p;
        d = jan1(y);
        mon[2] = 29;
        mon[9] = 30;

        switch ((jan1(y+1)+7-d)%7) {

        /*
         *      non-leap year
         */
        case 1:
                mon[2] = 28;
                break;

        /*
         *      1752
         */
        default:
                mon[9] = 19;
                break;

        /*
         *      leap year
         */
        case 2:
                ;
        }
        for (i = 1; i < m; i++)
                d += mon[i];
        d %= 7;
        s += 3*d;
        for (i = 1; i <= mon[m]; i++) {
                if (i == 3 && mon[m] == 19) {
                        i += 11;
                        mon[m] += 11;
                }
                if (i > 9)
                        *s = i/10+'0';
                s++;
                *s++ = i%10+'0';
                s++;
                if (++d == 7) {
                        d = 0;
                        s = p+w;
                        p = s;
                }
        }
}

/*
 *      return day of the week
 *      of jan 1 of given year
 */

static int
jan1(const int yr)
{
        int y, d;

/*
 *      normal gregorian calendar
 *      one extra day per four years
 */

        y = yr;
        d = 4+y+(y+3)/4;

/*
 *      julian calendar
 *      regular gregorian
 *      less three days per 400
 */

        if (y > 1800) {
                d -= (y-1701)/100;
                d += (y-1601)/400;
        }

/*
 *      great calendar changeover instant
 */

        if (y > 1752)
                d += 3;

        return (d%7);
}

static void
load_months(void)
{
        int month;

        for (month = MON_1; month <= MON_12; month++)
                months[month - MON_1] = nl_langinfo(month);
        for (month = ABMON_1; month <= ABMON_12; month++)
                short_months[month - ABMON_1] = nl_langinfo(month);
}

static void
badmonth()
{
        (void) fprintf(stderr, gettext("%s: bad month\n"), myname);
        usage();
}

static void
badyear()
{
        (void) fprintf(stderr, gettext("%s: bad year\n"), myname);
        usage();
}

static void
usage(void)
{
        (void) fprintf(stderr, gettext("usage: %s [ [month] year ]\n"), myname);
        exit(1);
}