#!/bin/bash
# program: lfilesearch
# by Andrew Newman
# last modified: Tue Sep 19 14:00:38 EDT 2006
# program will search default or input lfile for
# stations that are either within a certain distance of a point
# or within a rectangular range

LFILE=/home/anewman/gg/tables/lfile.spherical
USAGE=~/$$.usage
# create a usage display that will be shown if command is run with no arguements
       printf "Usage: `basename $0` [-CLON/LAT/RAD] [-RLONMIN/LONMAX/LATMIN/LATMAX] [-L lfile]
        Program will search default or input lfile for stations that are either within a certain distance of a point
        or within a rectangular area.
          One of the two options is required:
           -C will search the LFILE for stations within the circular radius [km] from CLON, CLAT
           -R will search the LFILE for stations within rectangular region between LONMIN/LONMAX 
	       and LATMIN/LATMAX. distance output will be from center of rectangle.
	  Option:
	   -L will use the input LFILE rather than default 
	  Caveat:
	   + This program _will_ fail if search is across the international date-line or poles. 
	   + search assumes a useful range between -180/180 and -90/90.
	    For example: `basename $0` -C-107/35/1000  
	             or: `basename $0` -R-120/-100/10/40 \n " >$USAGE
 if  [ ${#} -lt "1" ] ; then
   cat $USAGE  # display usage
   rm $USAGE
   exit 1 # exit with error after removing temp file
 fi

while getopts ":C:R:L:" OPT
do
   case ${OPT} in
       C) CLON=`echo $OPTARG | awk -F"/" '{print $1}'`
          CLAT=`echo $OPTARG | awk -F"/" '{print $2}'`
          CRAD=`echo $OPTARG | awk -F"/" '{print $3}'`
	  CSEARCH=1; # flag for radial search, else do a rectangular search
        ;;
       R) LONMIN=`echo $OPTARG | awk -F"/" '{print $1}'`
          LONMAX=`echo $OPTARG | awk -F"/" '{print $2}'`
          LATMIN=`echo $OPTARG | awk -F"/" '{print $3}'`
          LATMAX=`echo $OPTARG | awk -F"/" '{print $4}'`
	  CLON=`echo $OPTARG | awk -F"/" '{print ($1+$2)/2}'` # Get central point
	  CLAT=`echo $OPTARG | awk -F"/" '{print ($3+$4)/2}'` #  of rectangle
        ;;
       L) LFILE=$OPTARG
         ;;

       *) echo "ERROR: unknown modifier flag used (${OPT}), exiting."  # if a bad modifier is used
           rm $USAGE   
	   exit 1 ;; # exit with error after removing temp file
   esac
done

# check to see if LFILE exists
if [ ! -e $LFILE ] ; then  # does $LFILE exist?
	echo "ERROR: $LFILE doesn't exist.  Exiting."
	rm $USAGE
	exit 1   # exit with error after removing temp file
fi

#                       1 2  3 4 5 6 7 8 91011 12  
awk 'BEGIN{FIELDWIDTHS="4 13 1 2 3 9 1 1 3 3 9 43" }
     BEGIN{print "# STAT   LON           LAT             RAD"}
       (NR>1){ {LAT=$4+$5/60+$6/3600; LON=$9+$10/60+$11/3600}                        # convert deg min and sec to deg.decimal
           {if ($3=="S") LAT=0-LAT}{if ($8=="W") LON=0-LON}                          # correct for S and W as negatives
           {RAD=(((LAT-CLAT)**2+(LON-CLON)**2)**.5)*111.15}                          # calculate distance
           if (CSEARCH==1) {                                                         # if using circular search
             if (CRAD>RAD) printf " %4s %13.8f %13.8f  %13.6f\n", $1, LON, LAT, RAD} # only stations closer than CRAD
           else {                                                                    # otherwise, a rectangular search
             if (LAT>LATMIN && LAT<LATMAX && LON >LONMIN && LON <LONMAX)             # only stations within range
             printf "  %4s %13.8f %13.8f  %13.6f\n", $1, LON, LAT, RAD}        
    }' CSEARCH=$CSEARCH CLAT=$CLAT CLON=$CLON LONMIN=$LONMIN LONMAX=$LONMAX LATMIN=$LATMIN LATMAX=$LATMAX CRAD=$CRAD $LFILE 

# remove temporary usage file
 rm $USAGE 
# exit cleanly
 exit 0