#!/bin/sh

# The directory in which to find the last snapshot; must be absolute path
dir=/home/mccallum/gnu/releases

# The email addresses of people to receive mail about the new diff
diff_recipients=gnustep-dev@prep.ai.mit.edu

# The name of this module
module=gstep-base
# A regular expression for the six-digit date string "yymmdd"
yrptn='[0-9][0-9][0-9][0-9][0-9][0-9]'
# The pattern for the file containing the diff
ptn="${module}-${yrptn}"
dptn="${ptn}-${yrptn}.diff"

# Get the current date
date=`date +%y%m%d`

# Find date of the last snapshot
lastsnap=`cd $dir; ls $ptn.tar.gz 2>/dev/null |
                   sed -e "s/^.*\\(${yrptn}\\)[.a-z]*$/\\1/" |
                   sort -nr | head -1`

# Find the date of the second-to-last snapshot
secondlastsnap=`cd $dir; ls $ptn.tar.gz 2>/dev/null |
                   sed -e "s/^.*\\(${yrptn}\\)[.a-z]*$/\\1/" |
                   sort -nr | head -2 | tail -1`

# Find the date of the last diff
lastdiff=`cd $dir; ls $dptn $dptn.gz 2>/dev/null |
                    sed -e "s/^.*\\(${yrptn}\\)[.a-z]*$/\\1/" |
                    sort -nr | head -1`

echo Making diff between $secondlastsnap and $lastsnap

# The name of the diff file
diff="${module}-${secondlastsnap}-${lastsnap}.diff"

if [ -f $dir/$diff ]; then
  echo $dir/$diff already exists!  Exiting.
  exit -1
fi
echo Making $diff

# Untar the old snapshot
(cd /tmp ; tar -zvxf $dir/${module}-${secondlastsnap}.tar.gz)
# Untar the new snapshot
(cd /tmp ; tar -zvxf $dir/${module}-${lastsnap}.tar.gz)
# Make the diff
echo Diffing...
rm -f /tmp/$diff
(cd /tmp; diff -u -r ${module}-${secondlastsnap} ${module}-${lastsnap} > $diff)
# Remove the snapshot dirs
rm -rf /tmp/${module}-${secondlastsnap} /tmp/${module}-${lastsnap}

if [ -s /tmp/$diff ]; then
  # Mail a message saying the new diff is available. (Commented out for now)
  # mail -s $diff < $diff $diff_recipients
  gzip -9 /tmp/$diff && mv -f /tmp/$diff.gz $dir
else
  rm -f /tmp/$diff
fi