#!/bin/bash
# Constants
re=6371
mu=398600.5
pi=$(echo "scale=10; 4*a(1)" | bc -l) 
# Regexes
satnore="^[1-9]{1}[0-9]{4}$"                # Regex for 5-digit SATNO
paddedsatnore="^[0| ]{1}[0-9| ]{3}[1-9]$"   # Regex for padded satno
shortintdesre="^[0-9]{5}[A-Za-z]+$"         # Regex for short int-des (98067A, 98067ABCD)

# Math functions
cuberoot() {
  echo "e(l($1)/3)" | bc -l
}

# Main functions
settlefile() {
  #workingdir=$(pwd)
  #tlefile=$workingdir/tle
  tlefile=/usr/local/share/tle/tle
}

update() {
  # Maybe have a .csv file listing a saved account?
  echo "Updating local spacetrack catalog."
  case "$1" in
    auto) username="" && password="" ;;
  esac
  [ -z "$1" ] && read -p "Enter space-track.org username: " username && read -s -p "Enter space-track.org password: " password
  query="https://www.space-track.org/basicspacedata/query/class/tle_latest/ORDINAL/1/EPOCH/%3Enow-30/format/tle"
  #query="https://www.space-track.org/basicspacedata/query/class/tle_latest/30/orderby/NORAD_CAT_ID/format/tle"
  curl https://www.space-track.org/ajaxauth/login -c /usr/local/share/tle/cookies.txt -d "identity=$username&password=$password&query=$query" > /usr/local/share/tle/tle
  exit 0
}

readplaces() {
  placefile=/usr/local/share/tle/places.csv
}

getplace() {
  placeline=$(sed -n "/^$1/p" $placefile)
  name=$(echo $placeline | cut -f1 -d",")
  fullname=$(echo $placeline | cut -f2 -d",")
  lat=$(echo $placeline | cut -f3 -d",")
  lon=$(echo $placeline | cut -f4 -d",")
  elevation=$(echo $placeline | cut -f5 -d",")
  azleft=$(echo $placeline | cut -f6 -d",")
  azright=$(echo $placeline | cut -f7 -d",")
  elmin=$(echo $placeline | cut -f8 -d",")
  elmax=$(echo $placeline | cut -f9 -d",")
  rangemin=$(echo $placeline | cut -f10 -d",")
  rangemax=$(echo $placeline | cut -f11 -d",")
}

showplace() {
  echo "Place: $fullname"
  echo "Latitude (N): $lat"
  echo "Longitude (W): $lon"
  echo "Elevation (km): $elevation"
  echo "Left-hand azimuth extent (deg): $azleft"
  echo "Right-hand azimuth extent (deg): $azright"
  echo "Minimum elevation angle (deg): $elmin"
  echo "Maximum elevation angle (deg): $elmax"
  echo "Minimum range (km): $rangemin"
  echo "Maximum range (km): $rangemax"
}

padtime() {
  read input
  if [ ${#input} -eq 1 ]; then
	  echo 0$input
  elif [ ${#input} -gt 1 ]; then
	  echo $input 
  else 
	  echo "0"
  fi
}

getseconds() {
  echo "(86400*$1)+(3600*$2)+(60*$3)+$4" | bc -l
}

getage() {
  days=$(echo "$1/86400" | bc -l)
  dayfraction=0.$(echo $days | cut -f2 -d".")
  hours=$(echo "(86400/3600)*$dayfraction" | bc -l)
  hourfraction=0.$(echo $hours | cut -f2 -d".")
  minutes=$(echo "3600*$hourfraction/60" | bc -l)
  minutesfraction=0.$(echo $minutes | cut -f2 -d".")
  seconds=$(echo "60*$minutesfraction" | bc -l)
  days=$(echo $days | cut -f1 -d".")
  days=$(echo $(echo $days | cut -f1 -d".") | padtime)d
  hours=$(echo $(echo $hours | cut -f1 -d".") | padtime)h
  minutes=$(echo $(echo $minutes | cut -f1 -d".") | padtime)m
  seconds=$(echo $(echo $seconds | cut -f1 -d".") | padtime)s
  echo "$days $hours $minutes $seconds"
}

epochtime () {
  # date +%Y-%j-%H-%M-%S
  tle=$(getsatno $1 $2)
  epochyear=${tle:18:2}
  if [ $epochyear -le 57 ]; then
	  epochyear="20$epochyear"
  elif [ $epochyear -gt 57 ]; then
	  epochyear="19$epochyear"
  fi
  epochday=${tle:20:12}
  jday=${epochday:0:3}
  jdayfraction=0.${epochday:4}
  hours=$(echo "$jdayfraction*24" | bc -l)
  hoursfraction=0.$(echo $hours | cut -f2 -d".")
  minutes=$(echo "$hoursfraction*60" | bc -l)
  minutesfraction=0.$(echo $minutes | cut -f2 -d".")
  seconds=$(echo "scale=3; ($minutesfraction*60)/1" | bc -l)
  secondsfraction=$(echo $seconds | cut -f2 -d".")
  seconds=$(echo $(echo $seconds | cut -f1 -d".") | padtime)
  seconds=$(echo $seconds.$secondsfraction)
  hours=$(echo $(echo $hours | cut -f1 -d".") | padtime)
  minutes=$(echo $(echo $minutes | cut -f1 -d".") | padtime)
  echo "$epochyear $jday $hours:$minutes:$seconds UTC"
}

age() {
  read inputtime
  epochyear=$(echo $inputtime | cut -f1 -d" ")
  epochday=$(echo $inputtime | cut -f2 -d" ") 
  hours=$(echo $inputtime | cut -f1 -d":")
  hours=$(echo $hours | cut -f3 -d" ")
  minutes=$(echo $inputtime | cut -f2 -d":")
  seconds=$(echo $inputtime | cut -f3 -d":")
  seconds=$(echo $seconds | cut -f1 -d".")
  now=$(date -u +%s)
  then=$(getseconds $(echo "$epochday-1" | bc) $hours $minutes $seconds)
  datecmd="date --date=$epochyear-01-01 -u +%s"
  then1970=`$datecmd`
  then=$(echo "$then+$then1970" | bc)
  diff=$(echo "$now-$then" | bc)
  elsetage=$(getage $diff)
  echo $elsetage
}

gettle() {
  sed -n "/^[12] $1/p" $2
}

getsatno() {
  [[ $1 =~ $satnore ]] && gettle $1 $2 && exit 0
  [[ $1 =~ $paddedsatnore ]] && correctedsatno=$(echo "$1" | sed "s/^0/ /;: loop s/ 0/  /;t loop") && sed -n "/^[12] $correctedsatno/p" $2 && exit 0
  [[ $1 =~ $shortintdesre ]] && line1=$(sed -n "/^1.\{8\}$1/p" $2) && gettle "${line1:2:5}" $2 && exit 0
}

printsatno() {
  [[ $1 =~ $satnore ]] && echo $1 && exit 0
  [[ $1 =~ $shortintdesre ]] && line1=$(sed -n "/^1.\{8\}$1/p" $2)
  echo ${line1:2:5}
}


decodetle() {
  read line1
  read line2
  # Line 1
  satno=${line1:2:5}
  classification=${line1:7:1}
  if [ $classification == "U" ]; then
	 classification="UNCLASSIFIED"
  fi
  if [ $classification == "S" ]; then
	  classification="SECRET"
  fi
  intdes=${line1:9:7}
  if [ ${intdes:0:1} -ge "5" ]; then
    intdes=19$intdes
  else
    intdes=20$intdes
  fi
  intdes=${intdes:0:4}-${intdes:4:100}
  epochyear=${line1:18:2}
  if [ ${epochyear:0:1} -ge "5" ]; then
    epochyear=19$epochyear
  else
    epochyear=20$epochyear
  fi
  epochday=${line1:20:12}
  mmprime=${line1:33:11}
  mmdoubleprime=${line1:44:9}
  dragterm=${line1:53:9}
  ephtype=${line1:62:1}
  elsetnumber=${line1:65:3}
  checksum1=${line1:68:1}
  
  # Line 2
  inclination=${line2:8:8}
  raan=${line2:17:8}
  eccentricity=0.${line2:26:7}
  argofperigee=${line2:34:8}
  meananomaly=${line2:43:8}
  meanmotion=${line2:52:11}
  period=$(echo "scale=2; 1440/$meanmotion" | bc -l)
  revnumber=${line2:63:5}
  checksum2=${line2:68:1}

  # Other
  T=$(echo "scale=2; $period * 60" | bc -l)
  a=$(cuberoot $(echo "($mu * $T^2)/(4*$pi^2)" | bc -l))
  apogee=$(echo "scale=2; $a*(1+$eccentricity)/1" | bc -l)
  apogeealt=$(echo "$apogee - $re" | bc -l)
  perigee=$(echo "scale=2; $a*(1-$eccentricity)/1" | bc -l)
  perigeealt=$(echo "$perigee - $re" | bc -l)

  # Print results
  echo "SATNO: $satno"
  echo "Classification: $classification"
  echo "International designator: $intdes"
  echo "Epoch year: $epochyear"
  echo "Epoch day: $epochday"
  echo "First derivative of mean motion: $mmprime"
  echo "Second derivative of mean motion: $mmdoubleprime"
  echo "Drag term: $dragterm"
  echo "Ephemeris type: $ephtype"
  echo "ELSET number: $elsetnumber"
  echo "Line 1 checksum: $checksum1"
  echo "Inclination (deg): $inclination"
  echo "RAAN (deg): $raan"
  echo "Eccentricity: $eccentricity"
  echo "Argument of perigee (deg): $argofperigee"
  echo "Mean anomaly (deg): $meananomaly"
  echo "Mean motion (rev/day): $meanmotion"
  echo "Period (minutes): $period"
  echo "Rev number: $revnumber"
  echo "Line 2 checksum: $checksum2"
  echo "Apogee (km): $apogee"
  echo "Perigee (km): $perigee"
  echo "Apogee altitude (km): $apogeealt"
  echo "Perigee altitude (km): $perigeealt"

  }

#while getopts 'ht' flag
#do
#  case "${flag}" in
#    h) settlefile
#       getsatno $2 $tlefile | decodetle
#       ;;
#  esac
#done

#if [ $# -eq 1 ]; then
#	settlefile
#	getsatno $1 $tlefile
#fi

case "$1" in
  sat) if [ -z "$2" ]; then echo "tle: not enough arguments."; exit 1; fi
       settlefile
	     getsatno $2 $tlefile ;;
  cron) echo "Set cron job y/n?" ;;
  decode) if [ -z "$2" ]; then echo "tle: not enough arguments."; exit 1; fi
       settlefile
	     getsatno $2 $tlefile | decodetle ;;
  looks) if [ -z "$2" ]; then echo "tle: not enough arguments."; exit 1; fi
       settlefile
	     satno=$(printsatno $2 $tlefile)
	     echo "Generating looks for "$satno"." ;;
  epochtime) if [ -z "$2" ]; then echo "tle: not enough arguments."; exit 1; fi
       settlefile
       epochtime $2 $tlefile ;;
	age) if [ -z "$2" ]; then echo "tle: not enough arguments."; exit 1; fi
       settlefile
	     epochtime $2 $tlefile | age ;;
  places) readplaces
       if [ "$2" = "edit" ]; then
         sudo $EDITOR $placefile 
         echo "If you updated places.csv, running 'sudo make install'"
         echo "from the tle repo directory will overwrite your changes!"
         echo "Ensure you copy the file on your system to share/places.csv"
         echo "in the tle repo directory if you don't want this to happen."
       exit 0
       fi
       if [ -z "$2" ]; then echo "tle: not enough arguments."; exit 1; fi
       getplace $2
       showplace ;;
  update) [ -z "$2" ] && update || update auto ;;
	     *) cat << EOF
tle - NORAD two-line element set processor. Written 2020 by Ray Patrick.

Options:
	$ tle sat [SATNO or INTDES]
		Return the TLE of the satellite specified by SATNO.
		Also accepts international designators of the form
		98067A.

        $ tle decode [SATNO or INTDES]
                Print a more human-readable list of orbital elements.

        $ tle epochtime [SATNO or INTDES]
                Print the epoch time of the given TLE in 
                YYYY DDD HH:MM:SS.MMM format.

        $ tle age [SATNO or INTDES]
                Print the age of the TLE (time elapsed since epoch).

        $ tle places [PLACE or 'edit']
                If PLACE is a place code found in share/places.csv,
                print information about the place. If the argument
                'edit' is passed, opens places.csv in \$EDITOR.

        $ tle cron
      		Set up and manage cron jobs for automatically
       		downloading new TLE files. (Coming soon)

  	$ tle looks [SATNO or INTDES] [PLACE]
       		Calculate look angles for a specific satellite.
                (Coming soon)

        $ tle update [auto]
                Updates the TLE file at /usr/local/share/tle/tle.
                (Will prompt you for your space-track.org username
                and password unless the "auto" option is given.)

NOTE: Typing "man tle" at the command line will bring up more
thorough instructions.	
EOF
esac