#!/bin/sh

# Author: Khalid Baheyeldin http://2bits.com
# Based on Artisan Numerique http://artisan.karma-lab.net/node/1240
#
TMP=/tmp

PROG=`basename $0`
if [ $# != 3 ]; then
  echo "Usage: $PROG old_version new_version drupal_directory\ne.g. $PROG 5.5 5.6 /var/www"
  exit
fi

VER_OLD=$1
VER_NEW=$2
DRUPAL_DIR=$3

# Change that to the directory where Drupal is installed
PATCH_FILE=$TMP/drupal-$VER_OLD-to-$VER_NEW.patch
cd $TMP

rm -rf drupal-*

for VER in $VER_OLD $VER_NEW
do
  # Download the tar ball
  TAR_GZ=drupal-$VER.tar.gz
  wget http://ftp.drupal.org/files/projects/$TAR_GZ
  if [ -r $TAR_GZ ]; then 
    # Extract it
    tar -xzf $TAR_GZ
    if [ $? != 0 ]; then
      echo "Could not extract $TAR_GZ"
      exit 
    fi
  else 
    echo "Could not download $TAR_GZ"
    exit
  fi
done

# Now create the diff file
diff -Naur drupal-$VER_OLD drupal-$VER_NEW > $PATCH_FILE
# Now change to the directory where your Drupal installation is
cd $DRUPAL_DIR
# Check that the patch would apply without errors
patch -p1 --dry-run < $PATCH_FILE
# Assuming there are no error from the previous step, you can
echo "Please review the messages above, then answer the following question!"
# now apply the patch for real
echo "Do you want to proceed with the patch? (y/n) \c"
read ANS

case $ANS in
y) echo "Applying patch ..."
   patch -p1 -b < $PATCH_FILE
   ;;
*) echo "Patching cancelled ..."
   ;;
esac