#!/bin/sh

# pdfcrush -- Optimize the use of the fonts in a PDF file by using ps2pdfwr.
# Copyright (C) 2005-2024 Vincent Lefevre
#
# Warning! pdfcrush overwrites the files given in argument, and
# in some cases, the result can be bigger than the original PDF
# file (and sometimes look different).
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 3
# of the License, or (at your option) any later version.
#
# 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, see <https://www.gnu.org/licenses/>.
#
# History:
#   2024-09-01: Updated copyright notice.
#   2024-03-20: Added a comment about Ghostscript's AutoRotatePages option.
#   2023-11-24:
#     * Abort with some Ghostscript versions (ToUnicode CMap issue).
#     * Use ps2pdfwr (for the latest PDF version) rather than ps2pdf
#       (which just executes "ps2pdfwr -dCompatibilityLevel=1.4").
#   2022-12-04: Use the -dAutoRotatePages=/None gs option with ps2pdf.
#   2021-01-17: Bug fix: do not restore the PageMedia data.
#   2011-04-30: Added support for pdftk 1.44 and later.
#   2011-02-21: Space normalization.
#   2010-03-04: Decode more entities.
#   2010-01-12: Bug fix.
#   2009-10-25: No longer test the pdftk version (not reliable).
#   2009-10-02:
#     * Decode entities (for non-ASCII characters).
#     * Output version information.
#   2009-09-25:
#     * Secure temporary files.
#     * CreationDate and Creator restored if pdftk 1.41+ is available.
#     * Make sure that no data are lost.
#     * Cleanup of temporary files in case of error.
#   2007-05-17:
#     * No longer convert into PS as an intermediate format.
#     * The input file is replaced by the output.
#     * New usage: each argument is a PDF file to process.
#   2005-12-14: Initial version.

echo 'This is $Id: pdfcrush 171414 2024-09-01 12:33:49Z vinc17/qaa $' | \
  sed -e 's/.Id: //;s/Z .*//'

if [ $# -eq 0 ]; then
  echo "Usage: pdfcrush <file.pdf> ..." >&2
  exit 1
fi

set -e
err=0

gsv=`gs --version`
if [ "x$gsv" = x10.00.0 ] || \
   [ "x$gsv" = x10.02.0 ]; then
  printf >&2 "%s\n"                                                \
    "Ghostscript $gsv may regenerate an incorrect ToUnicode CMap:" \
    "  https://bugs.ghostscript.com/show_bug.cgi?id=707237"        \
    "It must not be used. Aborting."
  exit 1
fi

# Directory for temporary files. Note: to avoid data loss in case of
# problem (e.g. reboot at the wrong time), this directory should not
# be relative to /tmp; so, let's use /var/tmp (the current directory
# may be a bad idea and may not be writable).
tmpdir=`mktemp -d /var/tmp/pdfcrush-XXXXXXXX`

trap 'rm -rf $tmpdir' 0
tmpinfo="$tmpdir/info"
tmppdf1="$tmpdir/crushed.pdf"
tmppdf2="$tmpdir/final.pdf"

keys='Creator|CreationDate|Title|Subject|Keywords|Author'

# pdftk will be used to restore the metadata, if available.
# Warning! The official pdftk 1.41 version is broken; you may
# need the handle_utf8_data_in_update_info patch from Debian.
pdftkv=`pdftk --version 2> /dev/null || true`

for i in "$@"
do
  if file "$i" | grep -q 'PDF document'; then
    if [ -n "$pdftkv" ]; then
      printf "Getting metadata of file %s\n" "$i"
      if pdftk --help | grep -q dump_data_utf8; then
        pdftk "$i" dump_data_utf8 > "$tmpinfo"
        update=update_info_utf8
      else
        pdftk "$i" dump_data | perl > "$tmpinfo" -CO -ne \
          "/^InfoKey: ($keys)\$/ or next; print; \$_ = <>;
           /^InfoValue: / or die; s/&#(\\d+);/chr\$1/eg;
           s/&gt;/>/g; s/&lt;/</g; s/&amp;/&/g; tr/ //s; print"
        update=update_info
      fi
    fi
    printf "Crushing file %s\n" "$i"
    # The -dAutoRotatePages=/None gs option is needed to avoid any change
    # of orientation, as the goal is just to reduce the PDF file size.
    # Note that Ghostscript's AutoRotatePages heuristic does not work well
    # in practice (see Ghostscript bug 706119), but even if it were really
    # good, we do not want to change the orientation as we do not know the
    # intent of the author of the document. If needed, auto-rotating could
    # ideally be done by the PDF viewer.
    ps2pdfwr -dAutoRotatePages=/None "$i" "$tmppdf1"
    if [ -n "$pdftkv" ]; then
      printf "Restoring metadata of file %s\n" "$i"
      # Since ps2pdfwr may change the PageMedia data, do not restore them.
      # For instance, if PageMediaRotation is not 0, ps2pdfwr handles the
      # rotation and changes the PageMedia data accordingly; restoring
      # these data yields an incorrect rotation of the contents.
      perl -ni -e 'print unless /^PageMedia/' "$tmpinfo"
      printf >> "$tmpinfo" "InfoKey: ModDate\nInfoValue: D:%s\n" \
        $(date +%Y%m%d%H%M%S%z | sed "s/\([-+]..\)\(..\)/\1'\2'/")
      pdftk "$tmppdf1" $update "$tmpinfo" output "$tmppdf2"
    else
      echo "pdftk not found; metadata not modified."
      mv "$tmppdf1" "$tmppdf2"
    fi
    trap 'if [ $? = 0 ]; then rm -rf $tmpdir; \
                         else echo "Backup in $tmpdir"; fi' 0
    mv -f "$tmppdf2" "$i"
    trap 'rm -rf $tmpdir' 0
    printf "Successfully processed file %s\n" "$i"
  else
    printf "Skipping %s (not a PDF file)\n" "$i" >&2
    err=2
  fi
done

exit $err