#!/bin/bash

# check if inside git repository
has_git=$(git rev-parse --is-inside-work-tree 2> /dev/null)

# if we are in repository
if [[ "$has_git" == "true" ]]
then
  label=$(git describe --tags)

# if we are not in repository, but an old version file exist
elif test -f version.f90
then
  label=$(awk -F\' '/git_describe/{ print $2 }' version.f90)

# not in a repository and no old version file
else
  label="unknown"

fi

# write label into file version.f90.tmp
cat version.f90.in | sed 's/unknown/'$label'/' > version.f90.tmp

# check if a previous version.f90 file exists
if test -f version.f90 ; then

# version.f90 existing: check if new and previous files differ
   diff -wib version.f90.tmp version.f90  2> /dev/null > /dev/null

   if [ $? = 1 ] ; then 
# they differ: update file version.f90
      mv version.f90.tmp version.f90
   fi
# do not update if files are the same (prevents useless recompilation)

else

# file version.f90 not existing: create one
   mv version.f90.tmp version.f90

fi