#!/usr/bin/nawk -f
# SccsId[] = "@(#)epoch_time_awk.awk 1.3 08/03/04"
BEGIN \
{
  for (n=1; n<ARGC; n++)
  {
    if (ARGV[1] == "-z")
    {
      if (ARGV[2] !~ /^-?[0-9]+$/)
        Usage_and_exit("Time zone must be integer (represents hours)!")
      tz_adj  = ARGV[2] * 3600
      ARGV[2] = ""
      ARGV[1] = ""
      shift_ARGV()
    }
    else if (ARGV[1] == "-h")
      Usage_and_exit()
  }
  if (ARGV[1] == "")
  {
    print secs_since_epoch()
    exit 0
  }
  julian_table()
  if (ARGV[1] ~ /[0-9][0-9][0-9][0-9][0-1][0-9][0-3][0-9][0-2][0-9][0-5][0-9][0-5][0-9]/)
  {
    print secs_since_epoch()
    exit 0
  }
  epoch_sss = ARGV[1] + tz_adj
  days = sprintf("%d",(epoch_sss / 86400))
  sss  = sprintf("%d",(epoch_sss % 86400))
  sub(/^-/,"",sss)
  int(sss)
  ddddd = (basedate(1970,01,01) + days)
  yyyymmdd = ddddd_to_yyyymmdd(ddddd)
  hh  =  (sss / 3600.000000)
  sss =  (sss % 3600.000000)
  mm  =  (sss / 60.000000)
  ss  =  (sss % 60)
  printf("%8s%02d%02d%02d\n", yyyymmdd, hh, mm, ss)
  exit 0
}
function basedate(YYYY,MM,DD, yyyy,cc,ddddd,leapdays,cc_leapdays,accum_days)
{
  julian_table()
  yyyy = YYYY
  if ((yyyy - 1) > 0)
  {
    yyyy--
    cc          = int(yyyy / 100)
    ddddd       = yyyy * 365
    leapdays    = int(yyyy / 4)
    cc_leapdays = (cc > 0) ? (int(cc / 4)) : 0
    ddddd       = ddddd + leapdays - cc + cc_leapdays
    yyyy++
  }
  ddddd += DD
  if (leap_year(yyyy))
    for (i=0; i<13; i++) accum_days[i] = julian_leap[i]
  else
    for (i=0; i<13; i++) accum_days[i] = julian_days[i]
  ddddd += accum_days[MM += 0]
  return (ddddd)
}
function ddddd_to_yyyymmdd(DDDDD, ddddd,yyyy,mmdd,i)
{
  yyyy = ddddd = reduce(DDDDD)
  sub(/-.*$/,"", yyyy); yyyy  += 0
  sub(/^.*-/,"",ddddd); ddddd += 0

  if (leap_year(yyyy))
    for (i in julian_leap)
      julian[i] = julian_leap[i]
  else
    for (i in julian_days)
      julian[i] = julian_days[i]
  for (i=13; i>0; i--)
  {
    if (julian[i] < ddddd)
    {
    # if (leap_year(yyyy) && i > 2) ddddd++
      ddddd -= julian[i]
      mmdd = sprintf("%02d%02d", i, ddddd)
      break
    }
  }
  return (yyyy""mmdd)
}
function julian_table()
{
  split("0 31 59 90 120 151 181 212 243 273 304 334 365", julian_days)
  split("0 31 60 91 121 152 182 213 244 274 305 335 366", julian_leap)
}
function leap_year(YYYY)
{
  return (((YYYY%4 == 0 && YYYY%100 != 0) || (YYYY%400 == 0)) ? 1 : 0)
}
function reduce(DDDDD, yyyy,ddddd,cc,leapdays,cc_leapdays,i)
{
  for (i=1; ; i++)
  {
    yyyy        = int(DDDDD / 365) - i
    ddddd       = DDDDD - yyyy * 365
    cc          = int(yyyy / 100)
    leapdays    = int(yyyy / 4)
    cc_leapdays = (cc > 0) ? (int(cc / 4)) : 0
    leapdays    = leapdays - cc + cc_leapdays
    ddddd      -= leapdays
    yyyy++
    if (ddddd > 0) break
  }
  return yyyy"-"ddddd
}
function secs_since_epoch(ddddd,ddddd_yyyy,sss)
{
  if (ARGV[1] == "")
    "date +\%Y\%m\%d\%H\%M\%S" | getline yyyymmddhhmiss
  else
    yyyymmddhhmiss = sprintf("%14s",substr(ARGV[1]"00000000000000",1,14))
  yyyy = substr(yyyymmddhhmiss, 1,4)
  mm   = substr(yyyymmddhhmiss, 5,2)
  dd   = substr(yyyymmddhhmiss, 7,2)
  hh   = substr(yyyymmddhhmiss, 9,2)
  mi   = substr(yyyymmddhhmiss,11,2)
  ss   = substr(yyyymmddhhmiss,13,2)
  ddddd = basedate(yyyy,mm,dd)
  ddddd_yyyy = basedate(1970,01,01)
  ddddd -= ddddd_yyyy
  sss = (ddddd * 86400) + (hh * 3600) + (mi * 60) + ss
  sss += tz_adj
  return sss
}
function shift_ARGV(i,j,k)
{
  k = ARGC
  for (i=1; i<=ARGC; i++)
  {
    if (ARGV[i] == "")
    {
      for (j=i+1; j<=k; j++)
      {
        if (ARGV[j] == "")
          continue
        ARGV[i] = ARGV[j]
        ARGV[j] = ""
        break
      }
    }
  }
  for (i=1; i<=k; i++)
    if (ARGV[i] == "")
      ARGC--
  return ARGC
}
function Usage_and_exit(SPECIFIC_ERROR)
{
  if (SPECIFIC_ERROR) print "\n"SPECIFIC_ERROR
  print "\nPurpose: Return current Unix Epoch time (ssssssssss) or",
      "\n         convert specified Unix Epoch time to yyyymmddhhmiss",
      "\n         datetime, or convert yyyymmddhhmiss datetime to",
      "\n         Unix Epoch seconds.\n",
      "\n  Usage: epoch_time.awk -h -z [-]hh [yyyymmddhhmiss|ssssssssss]",
      "\n    e.g. epoch_time.awk [no options or arguments]",
      "\n         epoch_time.awk 20070121132053",
      "\n         epoch_time.awk 1169385653"
  exit 1
}