#!/bin/bash

function findGetorb(){
 #this function is used to find the location of real getorb.
 wgetorbPath="$(cd "${0%/*}" 2>/dev/null; echo "$PWD"/"${0##*/}")"
 which -a getorb | grep -v ${wgetorbPath} | head -n1
}

function helpMsg(){
cat << _EOF
wgetorb -- a program to interpolate the ODR files

usage: wgetorb [t=|ymd=|mjd=|doy=|sec=]t0[,t1,dt] [lon=lon0,lon1] [lat=lat0,lat1] [+]path

where:

  t0      Epoch for the orbit interpolation in various formats:
          ymd=t0: [YY]YYMMDD.DDD or [YY]YYMMDDHHMMSS.SSS
          mjd=t0: Modified Julian Dates (MJD.DDD)
          doy=t0: Year and day-of-year ([YY]YYDDD.DDD)
          sec=t0: UTC seconds since 1 Jan 1985
          t=t0: best guess between ymd= and mjd=
          t0: best guess between ymd= and mjd=
                                             
  t0,t1,dt  Interpolation for a time range (t0 to t1) requested
            (formats as above) with step size dt (in seconds)
            
  lon0,lon1 longitude range (deg)
  lat0,lat1 latitude range (deg)
  
  path    path name of directory or URL in which ODR files are stored
 +path    path name of a single ODR file to be used (Local only)
     
  Examples:
  wgetorb mjd=50001.500 /home/ers2/ODR  
  wgetorb ymd=991231235959,000101000159,60 .
  wgetorb 910809.1244,910809.1245,1 ftp://dutlru2.lr.tudelft.nl/pub/orbits/ODR.ERS-1/dgm-e04  
_EOF
}

function whichODR(){
orbitTime=${1}
arcListFile=${2}

arcs=0
while read LINE; do
  if [ "${LINE}" == "Arc# ------- Arc interval ------ -SLR-xover-altim  Repeat Ver  ---- Begin ----" ]; then
    arcs=1
  elif [ ${arcs} -eq 1 ]; then
    arc=`echo ${LINE} | awk '{print $1}'`
    arcStart=`echo ${LINE} | awk '{print $2}'`
    arcEnd=`echo ${LINE} | awk '{print $5}'`
    if [ ${arcStart} -lt ${orbitTime} ] && [ ${arcEnd} -gt ${orbitTime} ]; then
      echo ${arc}
      break
    fi
  fi
done < ${arcListFile}
}

#main 
[ $# -eq 0 ] && helpMsg && exit 0

#this script can be named as getorb and placed ahead of real getorb in path. 
#In this case we need to find real getorb
getorbPath=`findGetorb`

arcListLocation="${!#}" #last option, can be local folder or wget URL
if [ ${arcListLocation:0:1} == "+" ]; then 
  if [ -f ${arcListLocation:1} ]; then
    # if regular file run getorb
    ${getorbPath} ${@}
    exit $?
  fi
fi
if [ ! -d ${arcListLocation} ] ; then
  timeInput="${1}" 
  timeFormat=`echo ${timeInput%%=*}`
  t0=`echo ${timeInput##*=}| cut -d"," -f1`
  case ${timeFormat} in
    ymd)
      orbitStartDate=`mdate -y ${t0} | tail -n1 | awk '{print $4}'`
    ;;
    mjd)
      orbitStartDate=`mdate -m ${t0} | tail -n1 | awk '{print $4}'`
    ;;
    doy)
      orbitStartDate=`mdate -d ${t0} | tail -n1 | awk '{print $4}'`
    ;;
    sec)
      orbitStartDate=`mdate -s ${t0} | tail -n1 | awk '{print $4}'`
    ;;
    *) #either t or nothing specified. guess between ymd or mjd
      orbitStartDate=`mdate ${t0} | tail -n1 | awk '{print $4}'`
    ;;
  esac

  #remove last parameter (the URL will be replaced with ODR file)
  length=$(($#-1))
  parameters=${@:1:$length}

  #get arclist
  wget -q "${arcListLocation}/arclist" -O arclist -o wgetorb.log
  arc=`whichODR "${orbitStartDate}" ./arclist`
  wget -q "${arcListLocation}/ODR.${arc}" -O ODR.${arc} -a wgetorb.log

  ${getorbPath} ${parameters} +ODR.${arc}
  exit $?
else
  ${getorbPath} $@
  exit $?
fi