source: buchla-68k/orig/DATE/DATEBOOK.C@ b8080f6

/*
   =============================================================================
        datebook.c -- F A S T    C A L E N D A R
        Version 11 -- 1989-02-06 -- D.N. Lynx Crowe

        Adapted from public domain source code retrieved from Usenet.

        This C program is a faster,  more general version of the
        standard UNIX utility CALENDAR(1), only modified for GEMDOS
        and with a few kinks added...

        It recognizes the following formats for dates:

        numeric/numeric                     As in:  1/12, 01/12, 12/1, ...
                                                                                        month/day format

        3-charmonth[any chars] numeric      As in:  January 12, Jan. 12,
                                            jan. 12, JAN. 12, ...

        3-charweekday[any chars]            As in:  Friday, Monday, MON.,
                                            mon., tue, wed, ...

        numeric month                       A month from 1 to 12 as in:
                                            1, 2, 04, 12, ...

    Any lines, following a line that is matched, that have "whitespace"
    in the first column will be printed along with the matched line.
   =============================================================================
*/

#define HASARGS         0               /* define non-zero to allow file arg */

#include "stdio.h"
#include "ctype.h"

#include "types.h"
#include "time.h"
#include "math.h"

#include "stddefs.h"

#define CALFILE "c:\\datebook.dat"      /* default name for datebook file */

#define DAY     (24*3600)               /*  Number of seconds in a day.  */

#define EPOCH   1985
#define EPSILONg 279.611371     /* solar ecliptic long at EPOCH */
#define RHOg     282.680403     /* solar ecliptic long of perigee at EPOCH */
#define e          0.01671542   /* solar orbit eccentricity */
#define lzero     18.251907     /* lunar mean long at EPOCH */
#define Pzero    192.917585     /* lunar mean long of perigee at EPOCH */
#define Nzero     55.204723     /* lunar mean long of node at EPOCH */

/*  Remove this for SYS5 machines, or others with strchr instead of index.  */
/*  #define     strchr  index   */

/* 

*/

char mstring[128];

char datebuf[300];              /*  Global input line.  */

char *months[] = {              /*  Month definitions.  */

        "JAN", "FEB", "MAR",
        "APR", "MAY", "JUN",
        "JUL", "AUG", "SEP",
        "OCT", "NOV", "DEC"
};

char    *nm_mon[] = {

        "January", "February", "March",
        "April", "May", "June",
        "July", "August", "September",
        "October", "November", "December"
};

char *weekdays[] = {            /*  Weekday definitions.  */

        "SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"
};

char    *nm_day[] = {

        "Sunday" , "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
        "Saturday"
};

short   tisnow;
short   seen;

FILE    *outfp = stdout;

int
ly(yr)
int yr;
{
        /* returns 1 if leapyear, 0 otherwise */

        return (yr % 4 == 0 && yr % 100 != 0 || yr % 400 == 0);
}

double
dtor(deg)
double deg;
{
        /* convert degrees to radians */

        return (deg * PI / 180);
}

double
adj360(deg)
double *deg;
{
        /* adjust value so 0 <= deg <= 360 */

        do {

                if (*deg < 0)
                        *deg += 360;
                else if (*deg > 360)
                        *deg -= 360;

        } while (*deg < 0 || *deg > 360);
}

double
potm(days)
double days;
{
        double N;
        double Msol;
        double Ec;
        double LambdaSol;
        double l;
        double Mm;
        double Ev;
        double Ac;
        double A3;
        double Mmprime;
        double A4;
        double lprime;
        double V;
        double ldprime;
        double D;
        double Nm;

        N = 360 * days / 365.2422;  /* sec 42 #3 */
        adj360(&N);

        Msol = N + EPSILONg - RHOg; /* sec 42 #4 */
        adj360(&Msol);

        Ec = 360 / PI * e * sin(dtor(Msol)); /* sec 42 #5 */

        LambdaSol = N + Ec + EPSILONg;       /* sec 42 #6 */
        adj360(&LambdaSol);

        l = 13.1763966 * days + lzero;       /* sec 61 #4 */
        adj360(&l);

        Mm = l - (0.1114041 * days) - Pzero; /* sec 61 #5 */
        adj360(&Mm);

        Nm = Nzero - (0.0529539 * days);     /* sec 61 #6 */
        adj360(&Nm);

        Ev = 1.2739 * sin(dtor(2*(l - LambdaSol) - Mm)); /* sec 61 #7 */

        Ac = 0.1858 * sin(dtor(Msol));       /* sec 61 #8 */
        A3 = 0.37 * sin(dtor(Msol));

        Mmprime = Mm + Ev - Ac - A3;         /* sec 61 #9 */

        Ec = 6.2886 * sin(dtor(Mmprime));    /* sec 61 #10 */

        A4 = 0.214 * sin(dtor(2 * Mmprime)); /* sec 61 #11 */

        lprime = l + Ev + Ec - Ac + A4;      /* sec 61 #12 */

        V = 0.6583 * sin(dtor(2 * (lprime - LambdaSol))); /* sec 61 #13 */

        ldprime = lprime + V;                /* sec 61 #14 */

        D = ldprime - LambdaSol;             /* sec 63 #2 */

        return((double)(50 * (1 - cos(dtor(D)))));    /* sec 63 #3 */
}

moontxt(buf)
char buf[];
{
        char *cp = buf;
        long *lo;       /* used by time calls */
        long curtime;
        double days;   /* days since EPOCH */
        double phase;  /* percent of lunar surface illuminated */
        double phase2; /* percent of lunar surface illuminated one day later */
        int i = EPOCH;
        struct tm *pt; /* ptr to time structure */

        lo = &curtime;
        time(lo);               /* get system time */
        pt = gmtime(lo);        /* get ptr to gmt time struct */

        /* calculate days since EPOCH */

        days = (pt->tm_yday +1) + ((pt->tm_hour + (pt->tm_min / 60.0)
                + (pt->tm_sec / 3600.0)) / 24.0);

        while (i < pt->tm_year + 1900)
                days = days + 365 + ly(i++);

        phase = potm(days);
        sprintf(cp,"The Moon is ");
        cp += strlen(buf);

        if ((int)(phase + .5) == 100)
                sprintf(cp,"Full");
        else if ((int)(phase + 0.5) == 0) 
                sprintf(cp,"New");
        else if ((int)(phase + 0.5) == 50)  {

                phase2 = potm(++days);

                if (phase2 > phase)
                        sprintf(cp,"at the First Quarter");
                else 
                        sprintf(cp,"at the Last Quarter");

        } else if ((int)(phase + 0.5) > 50) {

                phase2 = potm(++days);

                if (phase2 > phase)
                        sprintf(cp,"Waxing ");
                else 
                        sprintf(cp,"Waning ");

                cp = buf + strlen(buf);
                sprintf(cp,"Gibbous (%1.0f%% of Full)", phase);

        } else if ((int)(phase + 0.5) < 50) {

                phase2 = potm(++days);

                if (phase2 > phase)
                        sprintf(cp,"Waxing ");
                else
                        sprintf(cp,"Waning ");

                cp = buf + strlen(buf);
                sprintf(cp,"Crescent (%1.0f%% of Full)", phase);
        }
}

/* 

*/

/* 
   =============================================================================
        chinayr() -- returns a pointer to a static string for the Chinese year
   =============================================================================
*/

char *
chinayr(year)
register int year;
{
        static  char    *chyrs[] = {    /* Chinese Year cycle */

                "Rat",          /* 0 */
                "Ox",           /* 1 */
                "Tiger",        /* 2 */
                "Rabbit",       /* 3 */
                "Dragon",       /* 4 */
                "Snake",        /* 5 */
                "Horse",        /* 6 */
                "Ram",          /* 7 */
                "Monkey",       /* 8 */
                "Cock",         /* 9 */
                "Dog",          /* 10 */
                "Boar"          /* 11 */
        };

        year -= 4;

        if (year < 0)
                return((char *)"?????");
        else
                return(chyrs[year % 12]);
}

/* 

*/

/*
   =============================================================================
        getdate() -- Check the input line, and get only the lines without
        leading "whitespace".  Conditionally print those lines with leading
        blanks, based on the "success" flag.
   =============================================================================
*/

char *
getdate(fp, success)
char *success;
register FILE *fp;
{
        register int c;
        static char inbuf[300];
        register char *t, *s;

        t = inbuf;
        s = datebuf;

        while ((c = getc(fp)) LE ' ' AND c NE EOF) {    /*  Skip leading space.  */

                ungetc(c, fp);
                fgets(inbuf, 300, fp);

                /*  Print the line if we previously printed a match.  */

                if (*success)
                        fprintf(outfp,"%s\t%s", (tisnow ? ">" : " "), inbuf);
        }

        *success = 1;                   /*  Assume success for now.  */

        if (c EQ EOF)                   /*  Return EOF if we are there.  */
                return((char *)0);

        ungetc(c, fp);                  /*  Unget the character.  */
        fgets(t, 300, fp);              /*  Get the input line.  */
        strcpy(s, t);                   /*  Make a copy of it.  */

        return(inbuf);
}

/* 

*/

/*
   =============================================================================
        isnow() -- See if the passed string has a "NOW" date in it.
   =============================================================================
*/

int
isnow(datebuf)
char *datebuf;
{
        char *s, *t;
        long l;
        register int before, after, offset, month, day;
        register struct tm *tmptr;
        long timenow;

        time(&timenow);         /*  Get the current time.  */
        tmptr = localtime(&timenow);

        before = 0;
        after  = 0;

        t = datebuf;

/* 

*/
        /*  Is the first character a digit in a Month?  */

        if (isdigit(*t) AND (month = getnum(&t) - 1) GE 0 AND month < 12) {

                tisnow = (tmptr->tm_mon EQ month);

                /*  Find the separating slash.  */

                if (s = (char *)strchr(t, '/'))
                        t = s + 1;
                else if (tmptr->tm_mon EQ month)
                        return(1);
                else
                        return(0);

        /*  Is the string a month name?  */

        } else if ((month = ischmonth(t)) GE 0) {

                /*  Skip till while space.  */

                while (!isspace(*t) AND *t)
                        ++t;

                /*  Skip to first NON-white space.  */

                while (isspace(*t) AND *t)
                        ++t;

        /*  Not a month, so try a DAY as in Friday, Saturday, etc...  */

        } else if ((day = ischday(datebuf)) GE 0) {

                tisnow = (day EQ tmptr->tm_wday);

                /*  Is this today?  */

                if (day EQ tmptr->tm_wday OR ((day + 6)%7) EQ tmptr->tm_wday)
                        return(1);
                else
                        return(0);

        } else {

                /*  Fail to recognize any other data as a valid date.  */

                return(0);
        }
/* 

*/
        /*  Is there only what looks to be a month?  If so, then OK.  */

        if (! *t OR ! isdigit(*t)) {

                /*  Is it this month?  */

                if (tmptr->tm_mon EQ month)
                        return(1);

                return(0);
        }

        /*  Calculate the value of the day.  */

        day = getnum(&t);

        /*  Check for *w or *W extended week specifiers.  */

        if (*t EQ '*') {

                if (t[1] EQ 'w')
                        ++before;

                if (t[1] EQ 'W')
                        ++after;

                if (t[2] EQ 'W')
                        ++after;

                if (t[2] EQ 'w')
                        ++before;
        }

/* 

*/            
        offset = 1;                     /*  Set weekend offset.  */

        switch (tmptr->tm_wday) {       /*  Get offset based on the weekend.  */

        case 5:         ++offset;

        case 6:         ++offset;

        default:        ++offset;

        }

        tisnow = istoday(timenow, month, day);
                
        /*  Step through all dates by DAY.  */

        l = timenow - (after * 7 * DAY);

        while (l < timenow + (before * 7 * DAY) + (offset * DAY)) {

                if (istoday(l, month, day))
                        return(1);

                l += DAY;
        }

        return(0);              /*  Return failure.  */
}

/* 

*/

/*
   =============================================================================
        ischday() -- Check if the string s is a DAY of the week as in monday,
        tues, wed, THU., or any derivative thereof.
   =============================================================================
*/

int
ischday(s)
register char *s;
{
        register char *tt;
        register int i, found = 0, c;
        register char t[30];

        /*  Copy the input, and capitalize it.  */

        for (tt = t, i=0; isalpha(*s) AND i < 28; ++i)
                *tt++ = islower(c = *s++) ? toupper(c) : c;

        *tt = '\0';

        /*  Search the list of valid day names for the string.  */

        for (i = 0; i < 7; ++i) {

                if (strncmp(t, weekdays[i], 3) EQ 0) {

                        found++;
                        break;
                }
        }

        /*  Return the numeric equivalent if we found it.  */

        if (found)
                return(i);

        /*  Return invalid day name.  */

        return(-1);
}

/* 

*/

/*
   =============================================================================
        ischmonth() -- Check if the string s is a valid derivative of the name
        of a month as in JUNE, jun, August, etc...
   =============================================================================
*/

int
ischmonth(s)
register char *s;
{
        register char *tt;
        register int i, found = 0, c;
        register char t[30];

        /*  Copy and capitalize.  */

        for (tt = t, i=0; isalpha(*s) AND i < 28; ++i)
                *tt++ = islower(c = *s++) ? toupper(c) : c;

        *tt = '\0';

        /*  Look through the list for a match.  */

        for (i = 0; i < 12; ++i) {

                if (strncmp(t, months[i], 3) EQ 0) {

                        found++;
                        break;
                }
        }

        /*  Return the numeric equivalent if we found it.  */

        if (found)
                return(i);

        /*  Return faliure.  */

        return(-1);
}

/* 

*/

/*
   =============================================================================
        getnum() -- Scan the string *t, and evaluate any integer contained
        there.  It is assumed that at least 1 digit exists (**t).
   =============================================================================
*/

int
getnum(t)
char **t;
{
        register int i, c;
        register char *s;

        i = 0;

        /*  Get the starting address.  */
        s = *t;

        /*  Get the starting value from the first digit.  */
        i = (c = *s++) - '0';

        /*  Evaluate the rest of the digits (if any).  */

        while (isdigit(c = *s++))
                i = i * 10 + (c - '0');

        /*  Set the new address.  */
        *t = --s;

        /*  Return the value.  */
        return(i);
}

/* 

*/

/*
   =============================================================================
        istoday() -- Return whether or not the time t corresponds to
        the month and day.
   =============================================================================
*/

int
istoday(t, month, day)
long t;
register int month, day;
{
        register struct tm *tm;

        tm = localtime(&t);

        return(tm->tm_mon EQ month AND tm->tm_mday EQ day);
}

/* 

*/

/*
   =============================================================================
        main function for datebook.c
   =============================================================================
*/

main(argc, argv)
int argc;
char **argv;
{
        register char *s;
        char success;
        register char file[200];
        register FILE *fp;
        long intime;
        long *timeloc;
        int year;
        struct tm *intmp;

        /* Use file passed as an argument if it is there,
                otherwise use default file. */

#if     HASARGS
        if (argc LE 1)
#endif
                strcpy(file, CALFILE);
#if     HASARGS
        else
                strcpy(file, argv[1]);
#endif

        if ((fp = fopen(file, "r")) EQ NULL) {  /*  Open the input file.  */

                perror(file);
                exit(1);
        }

        time(timeloc = &intime);    
        intmp = localtime(timeloc);
        year = intmp->tm_year+1900;

        fprintf(outfp,"\nThe time is %02d:%02d and ",
                intmp->tm_hour, intmp->tm_min);

        fprintf(outfp,"today is %s,\n%s %d, %d - the year of the %s.\n\n",
                nm_day[intmp->tm_wday], nm_mon[intmp->tm_mon],
                intmp->tm_mday, year, chinayr(year));

        moontxt(mstring);
        fprintf(outfp, "%s\n\n", mstring);

        if ((intmp->tm_wday EQ 5) AND (intmp->tm_mday EQ 13))
                fprintf(outfp,"!\tWatch out -- It's Friday the Thirteenth!\n\n");

        success = 0;    /*  Initially, no success.  */
        seen = FALSE;

        while (s = getdate(fp, &success)) {     /*  Loop till EOF is encountered.  */

                if (isnow(datebuf)) {   /*  Check date for "NOW"  */

                        /*  Print it, it is valid.  */

                        fprintf(outfp,"%s\t%s", (tisnow ? ">" : " "), s);
                        seen = TRUE;

                } else {

                        /* Reset the "print lines with leading blanks" flag. */
                        
                        success = 0;
                }
        }

        if (NOT seen)
                fprintf(outfp, "No reminders for today.\n");

        fclose(fp);     /*  Close up and exit.  */
        exit(0);
}