// STEREOsecs.c
//
// Originated and maintained by
// 
//		Tycho von Rosenvinge
//		Laboratory for High Energy Astrophysics
//		NASA/Goddard Space Flight Center
//		Greenbelt, MD  20771
//  
//		Tel. 301-286-6721   
//		e-mail tycho@milkyway.gsfc.nasa.gov
//
// See STEREOtime.h for a description of each function

// STEREOsecs is a subset of STEREOtime

// #define TEST__  // define to include main() at the end
				// of this file to test STEREOtime.c;
				// comment this out when linking to
				// user program

#define SID    86400L     // number of seconds in a day
#define SECONDS_OFFSET  -378691200L  
     // 1958 Jan 1 00:00:00 relative to 
	 // 1970 Jan 1 00:00:00
#define DAYS_OFFSET     -4383
	 // 1958 Jan 1 relative to 1970 Jan 1

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
// #include <conio.h>  DOS only
#include <math.h>

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

static int maxday[]={0,31,28,31,30,31,30,31,31,30,31,30,31};


char *pass_bl(char *str);      // Pass blanks,/,tabs,FF,LF or \n in string
char *pass_fld(char *str);     // Pass next field in string

// 24 hour clock
// 1958 Jan 1=> DOY=1 (not 0!) 

void sec58_ymdhms(long sec58,int *piyear,int *pimon,int *piday,int *pihour,int *pimin,int *pisec);

int ymd_doy58(int iyear,int imon,int iday);
   
void doy58_ymd(int doy58,int *piyear,int *pimon,int *piday);

// char *dayofwk(int iday,int imon,int iyear);

long ts_sec58(char *str,char **end);
	// Scan date/time string to obtain seconds of 1958
	// e.g. 1997 Nov 11 00:00:00
    // returns pointer to end of string in case there is
	// another time to scan (e.g. when you have a start
	// and end date/time in one string);
	// Must supply proper char **end even if you aren't
	// going to use this feature because the routine
	// will set *end equal to a pointer value

// int ds_doy58(char *ds);  // date string -> doy58

// void doy58_ds(int doy58,char *ds); // doy58 -> date string

void sec58_ts(long sec58,char *ts);

// long sec58_sec70(long sec58);  // changes seconds of 1958 to seconds of 1970

// int doy58_doyxx(int doy58,int yrxx );

// int doyxx_doy58(int doyxx, int yrxx);

char *month(int imon);

// void day_fraction_hms(double day_fraction,int *phour,int *pmin,int *psec);

// void DDOY_ts(int year,double DDOY,char *ts);  // Decimal DOY -> time string


char *pass_bl(char *str)      // Pass blanks,/,tabs,FF,LF or \n in string
{
        while (*str && (isspace(*str) || *str=='/'))
               str++;
// debug
// printf("\npass_bl:");
// printf("\n  str:    .%s",str);
// printf("\nCR to cont");
// getch();

        return str;
}


char *pass_fld(char *str)    // Pass next field in string
{
        while (*str && (isspace(*str) || *str=='/'))
                str++;
        while (*str && !(isspace(*str) || *str=='/'))
                str++;
// debug
// printf("\npass_fld:");
// printf("\n  str:    .%s",str);
// printf("\nCR to cont");
// getch();
        return str;
}


void sec58_ymdhms(long sec58,int *piyear,int *pimon,int *piday,int *phour,int *pmin,int *psec)
// Converts seconds of 1958 to iyear,imon,iday,...
// time= 0 seconds at 00:00:00 on 1958 Jan 1
// Hour based on 24 hour clock
{
long d70,sec70; // 1970 Jan 1=> d70=0! (vs doy70=1)

sec70=sec58 + SECONDS_OFFSET;

d70=sec70/SID;
sec70-=d70*SID;
if(sec70<0)
  {
   sec70+=SID;
   d70--;
  }

doy58_ymd(d70+1-DAYS_OFFSET,piyear,pimon,piday);

*phour=(int)(sec70/3600L);
*pmin=(int)((sec70-*phour*3600L)/60L);
*psec=(int)(sec70-*phour*3600L-*pmin*60L);
// Be careful: *phour*3600 can evaluate to a negative integer!

return;
}


int ymd_doy58(int iyear,int imon,int iday)
  // function to convert date of Gregorian              
  // calendar (iyear,imon,iday) to day of year 1958     
  // 1958 Jan 1 = doy58 #1 (not 0!);
  // iyear must be 4 digits-e.g. 1979, not 79           
{
long c;
if(imon>2){
    imon -=3;
    }
else{
    imon +=9;
    iyear -=1;
    }
c=iyear/100;
iyear=iyear-c*100;

return (int)((long)(146097L*c)/4+(1461L*iyear)/4+(153*imon+2)/5+iday-719469L-DAYS_OFFSET+1L);
}


void doy58_ymd(int doy58,int *piyear,int *pimon,int *piday)
   // converts doy58 to iyear,imon,iday
   // 1958 Jan 1 = doy58 #1 (not 0!)
{
long d,m,y,j;
j=(doy58+719469L+DAYS_OFFSET-1L)*4-1;
y=j/146097;
j=j-y*146097;
d=(j/4)*4+3;
j=d/1461;
d=((d+4-j*1461)/4)*5-3;
m=d/153;
d=(d+5-153*m)/5;
y=100*y+j;
if(m<10)
  m+=3;
else{
  m-=9;
  y+=1;
  }
*piday=d;
*pimon=m;
*piyear=y;
}


long ts_sec58(char *str,char **end)
// Scan date/time string to obtain seconds of 1958;
// string in [YY]YY Mon DD HH[:]MM[:][SS] format,
// where [] imply optional parameters;
//
//   [YY]YY/MM/DD HH[:]MM[:][SS] also works.
//   [YY]YY DOY   HH[:]MM[:][SS] also works
//   [YY]YY DecimalDoy           also works (e.g. 1998 33.5 = 1998 Feb 2 12:00)
//
// e.g.00 Nov 1 0410 is recognised as 2000 Nov 1 04:10:00 
//
// ts_sec58 returns pointer to the point after the time
// scanned (a useful feature if there is another time
// to scan e.g., when you have a start and end date/time
// in one string); you must supply a proper char **end
// argument even if you aren't going to use this feature
// since the routine will set *end to equal a pointer
// value

{
        char *ptr;
        char buf[4],sZmon[4];
        long sec58;
        int i,doy58,doy,year,mon,day,hour,mins,sec;
		double DDOY,frac;

        ptr=str;
        *end=ptr;     // gets reset at end upon successful scan

        year=atoi(ptr);

        if(year>36 && year<100)
             year+=1900;
        else if (year<26)
             year+=2000;
		if(!(year>1936 && year<2026))
		{
			printf("\n\007ERROR in ts_sec58:\n  %s; CR to cont",str);
			getchar();
			return 0L;
		}

// debug
// printf("\nts_sec58(): %s",ptr);
// printf("\n            year=%d",year);
// printf("\nCR to cont ");
// getch();


        ptr=pass_fld(ptr); // skip ptr over year
        ptr=pass_bl(ptr);  // skip to start of month or DOY

// debug
// printf("\nptr=%ld,strchr=%ld; CR to continue ",ptr,strchr(ptr,'.'));
// getch();

		if(strchr(ptr,'.') && strchr(ptr,'.')-ptr <5)
		{  // Decimal DOY
			sscanf(ptr,"%lf",&DDOY);
			frac=DDOY-(int)DDOY;
			hour=(int)(frac*SID/3600.);
			mins=(int)((frac*SID-hour*3600.)/60.);    // important to have '.' in hour*3600.
			sec=(int)(frac*SID-hour*3600.-mins*60.);  // because hour*3600 can evaluate to a
													  // negative integer!
			doy58=ymd_doy58(year,1,1)+(long)DDOY-1;     // DDOY starts with 1 on Jan 1 instead of 0
			doy58_ymd(doy58,&year,&mon,&day);
// debug
// printf("\nts_sec58() encountered a decimal doy:");
// printf("\n  %s",ptr);
// printf("\n  %8.4lf: %d %d/%d %2d:%2d:%2d",DDOY,year,mon,day,hour,mins,sec);
// printf("\nCR to cont ");
// getch();
			ptr=pass_fld(ptr);    // unnecessary, but leaves ptr at same point as other formats
		}
		else 
		{  // (DOY or MM/DD or Mon DD) + HH[:]MM[:][SS]	
			if(isdigit(ptr[0]) && (strchr(ptr,'/')==NULL || strchr(ptr,'/')-ptr>4))
			{ // DOY
				doy=atoi(ptr);
				doy58=ymd_doy58(year,1,1)+(long)doy-1; // DOY starts with 1 on Jan 1 instead of 0
				doy58_ymd(doy58,&year,&mon,&day);
				ptr=pass_fld(ptr); 
				ptr=pass_bl(ptr);  // ptr at start of time
			}
			else if(isdigit(ptr[0]) && strchr(ptr,'/')!=NULL && (strchr(ptr,'/')-ptr)<3)
			{ // MM/DD
				mon=atoi(ptr);
				if(mon<1 || mon>12)
				{
					printf("\n\007ERROR in ts_sec58:\n%s ??; CR to cont",ptr);
					getchar();
					return 0L;
				}
				ptr=pass_fld(ptr); 
				ptr=pass_bl(ptr);  // skip to start of DD

				day=atoi(ptr);
				ptr=pass_fld(ptr); 
				ptr=pass_bl(ptr);  // ptr at start of time
			}	
			else
			{ // Mon DD
			
				sZmon[0]=toupper(ptr[0]);
				sZmon[1]=tolower(ptr[1]);
				sZmon[2]=tolower(ptr[2]);
				sZmon[3]='\0';

				for(i=0;i<12;i++)
				if(!strcmp(sZmon,Months[i]))
				{
					mon=i+1;
					break;
				}

				if(i==12)
				{
					printf("\n\007ERROR in ts_sec58:\nmonth = %s ???; CR to cont",sZmon);
					getchar();
					return 0L;
				}

				ptr=pass_fld(ptr);
				ptr=pass_bl(ptr);

				day=atoi(ptr);
				ptr=pass_fld(ptr);
				ptr=pass_bl(ptr);  // ptr at start of time
			}  
		
			if((year%4==0&&(year%100!=0))||(year%400==0))
				maxday[2]=29;
			else
				maxday[2]=28;
			if(day<1||day>maxday[mon])
			{
				printf("\n\007ERROR in ts_sec58:\nmonth = %s, day = %d ???; CR to cont",sZmon,day);
				getchar();
				return 0L;
			}

			// note:  12:10 = 12:10:00 = 1210; need to be careful!

			buf[0]=*ptr++;
			if(*ptr==':')
				buf[1]='\0';
			else
			{
				buf[1]=*ptr++;
				buf[2]='\0';
			}
			hour=atoi(buf);                // Hrs
			if(*ptr==':')
				ptr++;
			buf[0]=*ptr++;
			if(*ptr==':')
				buf[1]='\0';
			else
			{
				buf[1]=*ptr++;
				buf[2]='\0';
			}
			mins=atoi(buf);                 // Minutes ... lint didn't like min
			if(*ptr==':')
				ptr++;
			if(isdigit(*ptr))
			{
				sec=atoi(ptr);             // Secs
				ptr=pass_fld(ptr);
			}
			else
				sec=0;

// debug
// printf("\nts_sec58(): YY=%d,MM=%d,DD=%d,HH=%d, MM=%d, SS=%d",
//                           year,mon,day,hour,mins,sec);

		}  

        if(hour<0||hour>23)
          {
           if(hour==24 && mins==0 && sec==0)
             ;  // 24:00:00 allowed
           else
             return 0L;
          }
        if(mins<0||mins>59)
          return 0L;
        if(sec<0||sec>59)
          return 0L;

// debug
// printf("\nts_sec58(): YY=%d,MM=%d,DD=%d,HH=%d, MM=%d, SS=%d",
//                          year,mon,day,hour,mins,sec);

        sec58=(ymd_doy58(year,mon,day)-1)*SID+hour*3600L+mins*60L+sec;
// Be careful: hour*3600 can evaluate to a negative integer!

// debug
// printf("\nts_sec58(): sec58 = %ld",sec58);

        *end=ptr;

// debug
// printf("\nLeaving ts_sec58():");
// printf("\nstr: %s",str);
// printf("\nend: %s",*end);
// printf("\nCR to cont");
// getch();

        return sec58;
}


void sec58_ts(long sec58,char *ts)
// builds time string ts as YYYY Mon DD HH:MM:SS
// time string is 21 chars including \0
{
 int year,mon,day,hour,mins,sec;

 sec58_ymdhms(sec58,&year,&mon,&day,&hour,&mins,&sec);

 sprintf(ts,"%4d %s %2d %02d:%02d:%02d",
             year,month(mon),day,hour,mins,sec);
}


char *month(int imon)
  // returns pointer to abbreviated string for month
{
static char *Months[]={"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug",
                       "Sep","Oct","Nov","Dec","???"};
if ( imon < 1 || imon > 12 )
       return(Months[12]);
else
       return(Months[imon-1]);
}


#ifdef TEST__
void main()
{
	char tstring[80], buf[80], *end;
	long tsec58;
	int year,mon,day,hour,minutes,seconds;
	int doy58;
	double ddoy;      // decimal day of year
	int ok;

	printf("\n\nCheck ymd_doy58(): 58 Jan 1= doy58 #%d",
				ymd_doy58(1958,1,1));
	printf("  \n(expect 1)\n");
	printf(  "\n                   59 Jan 1= doy58 #%d",
				ymd_doy58(1959,1,1));
	printf("  \n(expect 366)\n");

	strcpy(tstring,"1997 Dec 15 18:00");
	printf("\n\nConvert %s to seconds of 1958 and back:",
		                tstring);
	tsec58=ts_sec58(tstring,&end);
	// printf("\n%s (%ld seconds of 1958)",tstring,tsec58);
	
	sec58_ts(tsec58,buf);
	printf("\n    %s",buf);

	sec58_ymdhms(tsec58,&year,&mon,&day,&hour,&minutes,&seconds);

	doy58=ymd_doy58(year,mon,day);
	printf("\ndoy58=%d (expect 715+4383+9496 =14594)\n\n",doy58);
	printf("\nCR to continue");
	getchar();

	doy58=ymd_doy58(2000,2,1);
	printf("\n\n\ndoy58 for 2000 Feb 1: %d (expect 1493+4383+9496=15372)",doy58);

	strcpy(tstring,"2000 250.75");
	printf("\nDay 250 of year 2000 is Sep 6");
	printf("\nConvert %s to seconds of 1958 and back:",
		              tstring);
	tsec58=ts_sec58(tstring,&end);
	sec58_ts(tsec58,buf);
	printf("\n    %s\n",buf);

	strcpy(tstring,"2000 250 1820");
	printf("\nConvert %s to seconds of 1958 and back:",
		              tstring);
	tsec58=ts_sec58(tstring,&end);
	sec58_ts(tsec58,buf);
	printf("\n    %s\n",buf);


	strcpy(tstring,"2000/9/6 18:1:30");
	printf("\nConvert %s to seconds of 1958 and back:",
		              tstring);
	tsec58=ts_sec58(tstring,&end);
	sec58_ts(tsec58,buf);
	printf("\n    %s\n\n",buf);

	ok=0;
	while(!ok)
	{
	  printf("\nEnter any year as YYYY: ");
	  scanf("%d",&year);
	  if(year<1900 || year>2100)
		  continue;
	  printf("\nEnter any month number: ");
	  scanf("%d",&mon);
	  if(mon<1 || mon>12)
		  continue;
	  printf("\nEnter the day of month: ");
	  scanf("%d",&day);
	  if(day<1 || day>31)  // crude check only
		  continue;
	  ok=1;	
	}
	sprintf(tstring,"%d %s %d 00:00:00",
					 year,month(mon),day);
	tsec58=ts_sec58(tstring,&end);
	printf("\ntsec58 at start of day =%ld",tsec58);

	ok=0;
        while(!ok)
        {
          printf("\nEnter any year as YYYY: ");
          scanf("%d",&year);
          if(year<1900 || year>2100)
                  continue;
          printf("\nEnter any time as decimal DOY (Note: Noon on Jan 1 is 1.5): ");
          scanf("%lf",&ddoy);
          
		  // if(ddoy<1.0 || ddoy>366.0)  // crude check
		  //	continue;

          ok=1;
        }

		// long ts_sec58(char *str,char **end)

        sprintf(tstring,"%d %lf",year,ddoy);
        tsec58=ts_sec58(tstring,&end);
        printf("\ntsec58 =%ld",tsec58);

        sec58_ts(tsec58,buf);
        printf("\n    %s\n",buf);
}
#endif

#ifdef TEST__
#undef TEST__
#endif