#!/bin/bash
ver=20
#-----------------------------------------------------------------------#
#
# customizepkg-patching
# Applies a patch to PKGBUILD before building.
#
#  Maintainer: Michael Duell <michael.duell@rub.de>
#
#  Old maintainer:
#  Daniel Oertwig <Daniel.Oertwig@googlemail.com>
#  homepage: http://www.proggen.org
#
# A modification of the original customizepkg from
# <wain@archlinux.fr>
# homepage: http://archlinux.fr
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
#-----------------------------------------------------------------------#



#-----------------------------------------------------------------------#
## Some help ...
#-----------------------------------------------------------------------#
print_usage()
{
  echo "customizepkg - patching version $ver"
  echo
  echo "Without any option, this script reads files from the current directory and shows a diff"
  echo "between the original and the customized version of the files."
  echo "The patch to apply the changes is read from /etc/customizepkg.d/\$pkgname"
  echo
  echo "usage: customizepkg <option>"
  echo
  echo "customizepkg --version, -V       Shows version"
  echo "customizepkg --help, -h          Shows this help"
  echo "customizepkg --edit, -e          Edit files marked for customization"
  echo "                                 (add -v to edit with vimdiff)"
  echo "customizepkg --patch, -p         Review patch (add -m to save)"
  echo "customizepkg --modify, -m        Apply the saved modifications"
  echo "customizepkg --vimdiff, -v       Show diff using vimdiff"
  echo
  echo "To customize a file, use:"
  echo "$ cp file file.original"
  echo "then edit file."
  echo
  echo "To add a file, create and edit it, then use:"
  echo "$ touch file.original"
  echo
  echo "To remove a file, use:"
  echo "$ mv file file.original"
  echo
  echo "Written by Daniel Oertwig <Daniel.Oertwig@googlemail.com>"
  echo "      homepage: http://www.proggen.org"
  echo " as a modification of the original customizepkg from"
  echo " <wain@archlinux.fr>"
  echo "  homepage: http://archlinux.fr"
  echo
}



print_version()
{
  echo "customizepkg - patching version $ver"
}



#-----------------------------------------------------------------------#
## MAIN PROGRAMM
#-----------------------------------------------------------------------#
shopt -s nullglob
VIMDIFF=0
MODIFY=0
PATCH=0
EDIT=0



# Parse commandline options. Modifications are made only
# if the option -m or --modify are given!
while [[ "$#" != "0" ]]; do
  case $1 in
    -h|--help)
      print_usage
      exit 0
      ;;
    --version|-V)
      print_version
      exit 0
      ;;
    -e|--edit)
      EDIT=1
      ;;
    -p|--patch)
      PATCH=1
      ;;
    -m|--modify)
      MODIFY=1
      ;;
    --vimdiff|-v)
      VIMDIFF=1
      ;;
  esac
  shift
done



# Ensure the PKGBUILD file is there and read it to
# get the pkgname variable!
if [[ ! -r ./PKGBUILD ]]; then
  echo "PKGBUILD not found!"
  exit 1
fi
source ./PKGBUILD || exit 1



# Perform an action on each pair of original and
# changed files.
for_changes_do() {
  for f in ./*.original; do
    "$@" "$f" "${f%.original}"
  done
}



# Edit customized files, with vimdiff if the VIMDIFF
# option was given, or with the editor specified by
# EDITOR (falling back on vi) otherwise.
if [[ "$EDIT" == "1" ]]; then
  if [[ "$VIMDIFF" == "1" ]]; then
    edit="vim -d"
  else
    edit="${EDITOR:-vi}"
  fi
  for_changes_do $edit
  exit 0
fi



# Show a patch with the current modifications.
# If the MODIFY option was given, also write it to the
# configdir.
if [[ "$PATCH" == "1" ]]; then
  for_changes_do diff -upN |
    if [[ "$MODIFY" == "1" ]]; then
      tee "/etc/customizepkg.d/$pkgname"
    else
      cat
    fi
  exit 0
fi



# Ensure there is a patch available in the configdir!
if [[ ! -r "/etc/customizepkg.d/$pkgname" ]]; then
  echo "No configuration for $pkgname in /etc/customizepkg.d"
  exit 1
fi



# Apply the patch. Exit if something goes wrong.
patch -b -z .original -i "/etc/customizepkg.d/$pkgname"
if [[ "$?" -gt "1" ]]; then
  echo "Patching failed!"
  for f in *.rej; do
    echo "$f"
    cat "$f"
  done
  exit 1
fi



# Show the diffs
if [[ "$VIMDIFF" == "1" ]]; then
  for_changes_do vim -d
else
  for_changes_do diff -upN
fi



# Revert a modification.
# If the original file is empty, it means that
# a new file was created by the patch, so remove it.
revert() {
  mv -f "$1" "$2"
  [[ -s "$2" ]] || rm "$2"
}



# Only if the MODIFY option was given the 
# modified file stays. Otherwise, the original
# file is used.
if [[ "$MODIFY" == "0" ]]; then
  for_changes_do revert
  rm -f *.rej
fi



# Exit gracefully :)
exit 0