#! /bin/bash

usage() {
   scriptName=$(basename $0)

   echo $1
   echo
   echo "$scriptName - ifm live view with custom editor"
   echo
   echo "usage:"
   echo "   $scriptName IMFFILE [GV_SWITCHES]"
   echo
   echo "This script requires:"
   echo "   - gv is installed"
   echo "   - your EDITOR environment variable is set"
   echo "   - ifm binaries are installed (of course)"
   echo
   echo "GV_SWITCHES is additional arguments to be sent to gv. See man 1 gv"
   echo
   echo "A useful gv switch:"
   echo "   -orientation=landscape"

   exit 1
}

ifmFile=$1
[ -f "$ifmFile" ] || usage "No ifm file given to edit"
shift
psFile="$(basename $ifmFile '.ifm').ps"

ifmBin="ifm"
[ $(which $ifmBin) ] || usage "No ifm binary found!"

[ $(which gv) ] || usage "No gv binary found!"

[ $EDITOR ] || usage "No EDITOR environment variable set!"


# How many seconds between file-changed checks
checkInterval=2


# Background a loop to watch for changes to the .ifm file
while true
do
   [ $ifmFile -nt $psFile ] &&
      $ifmBin -m -f ps -o $psFile $ifmFile

   sleep $checkInterval
done &

# Run gv with watching the state of the ps file, this is the live
# map viewer
gv -watch $psFile $* &

# Finally, leave the user in their favorite editor
$EDITOR $ifmFile

# When they are finished, kill the loop above and the viewer
kill %1
kill %2