; time.pro
; ========
; Author: R.J.Barnes
; 
; $License$
;
; TimeYrsectoYMDHMS         Convert seconds of year to YMDHMS
; TimeYMDHMStoYrsec         Convert YMDHMS to seconds of year
; TimeEpochtoYMDHMS         Convert seconds of epoch to YMDHMS
; TimeYMDHMStoEpoch         Convert YMDHMS to seconds of epoch
; TimeJuliantoYMDHMS        Convert Julian time to YMDHMS
; TimeYMDHMStoJulian        Convert YMDHMS to Julian time
;
; ---------------------------------------------------------------



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;+
; NAME:
;       TimeYrsectoYMDHMS
;
; PURPOSE:
;       Convert seconds of year to YMDHMS.
;       
;
; CALLING SEQUENCE:
;       status = TimeYrsecToYMDHMS(yr,mo,dy,hr,mt,sc,yrsec)
;
;       All the arguments must be given. 
;
;       The returned value is zero for success, or -1 for failure
;
;-----------------------------------------------------------------
;


function TimeYrsecToYMDHMS,yr,mo,dy,hr,mt,sc,yrsec

  nday=[0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365]
  lday=[0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366]

  if ((yr mod 4) eq 0) and (((yr mod 100) ne 0) or ((yr mod 400) eq 0)) then $
  jday=lday else jday=nday

  yd=fix(yrsec/(24L*60L*60L));

  n=0
  while ((n lt 12) and (yd ge jday[n])) do n=n+1

  mo=n
  if (n gt 0) then dy=1+yd-jday[n-1] else dy=yd+1
   
  dt=yrsec mod (24L*60L*60L)
  hr=fix(dt/(60L*60L)) 
  mt=fix((dt mod (60L*60L))/60L) 
  ;sc=fix(dt mod 60L)
  sc=(dt mod 60L)
 
  return, 0
end

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;+
; NAME:
;       TimeYMDHMSToYrsec
;
; PURPOSE:
;       Convert YMDHMS to seconds of year.
;       
;
; CALLING SEQUENCE:
;       yrsec = TimeYMDHMSToYrSec(yr,mo,dy,hr,mt,sc)
;
;       All the arguments must be given. 
;
;       The returned value is the number of seconds past the
;       start of the year for success, or -1 for failure
;
;-----------------------------------------------------------------
;

function TimeYMDHMSToYrsec,yr,mo,dy,hr,mt,sc

  jday=[0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334]
  mday=[31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

  if ( (mo lt 1) or (mo gt 12) or (hr lt 0) or (hr gt 23) or $ 
       (dy lt 1) or (mt lt 0) or (mt ge 60) or (sc lt 0) or $
       (sc ge 60) ) then return, -1

  if (dy gt mday[mo-1]) then begin
    if (mo ne 2) then return, -1 $
    else if (dy ne (mday[1] +1) or ((yr mod 4) ne 0)) then return, -1
  endif

  t = jday[mo-1] + dy - 1

  if ( (mo gt 2) and ((yr mod 4) eq 0) and $ 
       (((yr mod 100) ne 0) or ((yr mod 400) eq 0))) then t=t+1

  ;return, (((t*24L + hr)*60L + mt)*60L)+sc
  return, (((t*24D + hr)*60D + mt)*60D)+sc
end


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;+
; NAME:
;       TimeYMDHMSToEpoch
;
; PURPOSE:
;       Convert YMDHMS to seconds of epoch.
;       
;
; CALLING SEQUENCE:
;       epoch = TimeYMDHMSToEpoch(yr,mo,dy,hr,mt,sc)
;
;       All the arguments must be given. 
;
;       The returned value is the number of seconds since 0:00UT
;       January 1, 1970 for success, or -1 for failure
;
;-----------------------------------------------------------------
;

function TimeYMDHMSToEpoch,yr,mo,dy,hr,mt,sc

  YEAR_SEC=365.0D*24.0D*3600.0D
  LYEAR_SEC=366.0D*24.0D*3600.0D

  if (yr lt 1970) then return, -1

  yrsec=TimeYMDHMSToYrsec(yr,mo,dy,hr,mt,sc);
  if (yrsec eq -1) then return, -1
  ;tme=double(yrsec)
  tme=yrsec
   
  lpyear=(yr-1969)/4;
  ryear=(yr-1970)-lpyear;

  tme=tme+(lpyear*LYEAR_SEC)+(ryear*YEAR_SEC) 
 
  return, tme
end


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;+
; NAME:
;       TimeEpochToYMDHMS
;
; PURPOSE:
;       Convert seconds of epoch to YMDHMS.
;       
;
; CALLING SEQUENCE:
;       status = TimeEpochToYMDHMS(yr,mo,dy,hr,mt,sc,epoch)
;
;       All the arguments must be given. 
;
;       The returned value is zero for success, or -1 for failure
;
;-----------------------------------------------------------------
;

function TimeEpochToYMDHMS,yr,mo,dy,hr,mt,sc,tme

  i=0
  yrsec=0.0D
  YEAR_SEC=365.0D*24.0D*3600.0D
  LYEAR_SEC=366.0D*24.0D*3600.0D
  

  while (yrsec le tme) and (i lt 10000) do begin
     if ((i mod 4) eq 2) then yrsec=yrsec+LYEAR_SEC $
     else yrsec=yrsec+YEAR_SEC
     i=i+1
    
  endwhile

  if (((i-1) mod 4) eq 2) then tmptme=tme-(yrsec-LYEAR_SEC) $
  else tmptme=tme-(yrsec-YEAR_SEC)
  yr=i+1969
  return, TimeYrsecToYMDHMS(yr,mo,dy,hr,mt,sc,tmptme)
end


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;+
; NAME:
;       TimeYMDHMSToJulian
;
; PURPOSE:
;       Convert YMDHMS to Julian date.
;       
;
; CALLING SEQUENCE:
;       julian = TimeYMDHMStoJulian(yr,mo,dy,hr,mt,sc)
;
;       All the arguments must be given. 
;
;       The returned value is the julian time for success, 
;       or -1 for failure
;
;-----------------------------------------------------------------
;


function TimeYMDHMSToJulian,yr,mo,dy,hr,mt,sc

  DAY_SEC=24.0D*3600.0D

  yr=yr-1

  i=fix(yr/100)

  A=i

  i=fix(A/4)
  B=fix(2-A+i)
  
  i=floor(365.25*yr)
 
  i+=floor(30.6001*14)
 
  jdoy=i+B+1720994.5D
  
  dfrac=1.0+TimeYMDHMSToYrsec(yr+1,mo,dy,hr,mt,sc)/DAY_SEC;
   
  return,jdoy+dfrac
end


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;+
; NAME:
;       TimeJulianToYMDHMS
;
; PURPOSE:
;       Convert Julian date to YMDHMS.
;       
;
; CALLING SEQUENCE:
;       status = TimeJulianToYMDHMS(yr,mo,dy,hr,mt,sc,epoch)
;
;       All the arguments must be given. 
;
;       The returned value is zero for success, or -1 for failure
;
;-----------------------------------------------------------------
;

function TimeJulianToYMDHMS,yr,mo,dy,hr,mt,sc,jd

  DAY_SEC=24.0D*3600.0D

  factor=0.5/DAY_SEC/1000; 

  F=(jd+0.5)-floor(jd+0.5)

  if ((F+factor) ge 1.0) then begin
    jd=jd+factor;
    F=0.0;
  endif

  Z=floor(jd+0.5);

  if (Z lt 2299161) then A=Z $
  else begin 
    alpha=floor((Z-1867216.25)/36524.25)
    A=Z+1+alpha-floor(alpha/4)
  endelse

  B=A+1524;
  C=floor((B-122.1)/365.25)
  D=floor(365.25*C)
  E=floor((B-D)/30.6001)
  day=B-D-floor(30.6001*E)+F

  if (E lt 13.5) then month=floor(E-0.5) $
  else month=floor(E-12.5)
  if (month gt 2.5) then year=C-4716 $
  else year=C-4715
  

  yr=fix(floor(year))
  mo=fix(month)
  dy=fix(floor(day))

  A=(day-floor(day))*DAY_SEC;

  hr=fix(floor(A/3600.0))
  mt=fix(floor((A-hr*3600.0D)/60.0))

  sc=A-hr*3600.0-mt*60.0

end