#!/bin/bash
# Copyright 2002  Patrick J. Volkerding, Concord, CA, USA
# Copyright 2018  Patrick J. Volkerding, Sebeka, Minnesota, USA
# All rights reserved.
#
# Redistribution and use of this script, with or without modification, is
# permitted provided that the following conditions are met:
#
# 1. Redistributions of this script must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
#
#  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
#  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
#  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
#  EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
#  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
#  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
#  OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
#  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
#  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
#  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

CWD=$(pwd)

# Display usage for basic usage errors:
usage() {
  cat << EOF
pkgdiff: missing file arguments
Try 'pkgdiff --help' for more information.
EOF
}

# Display full --help if requested:
helpme() {
  cat << EOF
Usage: pkgdiff [OPTION] FILE1 FILE2
Show which files are new and which are removed between two tar archives.
The tar archives may be uncompressed, or compressed with gzip, bzip2,
xz, or lzip. Also works with .rpm and .deb.

  --help           display this help and exit
  -c               use ANSI color with default tree mode
  -a               show simple text (ASCII) diff of package file lists

By default, the trees are drawn with in crude ASCII with no color. For
the full-color effect, try something like this:

  pkgdiff -c package1 package2 | less -r

EOF
  # --help doesn't return
  exit 22
}

# How the heck do I open this?
explode() {
  tar xf $1 1> /dev/null 2> /dev/null
  # Check for common extensions and do additional magic:
  if [ ! "$(basename $1)" = "$(basename $1 .zip)" ]; then
    unzip $1 1> /dev/null 2> /dev/null
  fi
  if [ ! "$(basename $1)" = "$(basename $1 .rpm)" ]; then
    cp $1 .
    rpm2tgz $(basename $1) 1> /dev/null 2> /dev/null
    rm -f $(basename $1)
    tar xzf $(basename $1 .rpm).tgz 1> /dev/null 2> /dev/null
    rm -f $(basename $1 .rpm).tgz
  fi
  if [ ! "$(basename $1)" = "$(basename $1 .deb)" ]; then
    cp $1 .
    ar x $(basename $1) 1> /dev/null 2> /dev/null
    tar xf data.tar.xz 1> /dev/null 2> /dev/null
    rm -f * 2> /dev/null
  fi
  # Diffs for other archive formats are welcome.
}

# Parse options.
# -c turns on colorization ala dircolors:
unset COLOR
if [ "$1" = "-c" ]; then
  COLOR="-C"
  shift 1
fi
if [ "$1" = "-a" ]; then
  ASCII=true
  shift 1
fi
if [ "$1" = "--help" ]; then
  helpme
fi

TMPDIR=$(mktemp -d)
cd $TMPDIR

if [ ! -r "$1" ]; then
  if [ -d "$CWD/$1" ]; then
    usage
    exit 99
  else
    PKG1="$CWD/$1"
  fi
else
  PKG1="$1"
fi

if [ ! -r "$2" ]; then
  if [ -d "$CWD/$2" ]; then
    usage
    #echo "pkgdiff -- find the difference between two tar archives"
    #echo "usage: pkgdiff [ -C ] pkg1 pkg2"
    exit 99
  else
    PKG2="$CWD/$2"
  fi
else
  PKG2="$2"
fi

# We have to account for the possibility that the packages have the
# same name, but different contents...
if [ "$(basename $PKG1)" = "$(basename $PKG2)" ]; then
  PKG1=${PKG1}.orig
fi

# This will be mighty safe even if we ended up in /tmp.
PKG=.pkgdiff.$(mcookie)

( mkdir -p $TMPDIR/$PKG/1
  cd $TMPDIR/$PKG/1
  if [ -r $PKG1 ]; then
    explode $PKG1
  elif [ -r $(dirname $PKG1)/$(basename $PKG1 .orig) ]; then
    explode $(dirname $PKG1)/$(basename $PKG1 .orig)
  fi
  if [ ! "$ASCII" = "true" ]; then
    tree $COLOR -a --noreport > ../$(basename $PKG1)
  else
    find ./ | sed '2,$s,^\./,,' | tar --no-recursion -T - -cf - | tar tf - | sort > ../$(basename $PKG1)
  fi
)
( mkdir -p $TMPDIR/$PKG/2
  cd $TMPDIR/$PKG/2
  explode $PKG2
  if [ ! "$ASCII" = "true" ]; then
    tree $COLOR -a --noreport > ../$(basename $PKG2)
  else
    find ./ | sed '2,$s,^\./,,' | tar --no-recursion -T - -cf - | tar tf - | sort > ../$(basename $PKG2)
  fi
)

# Always going that extra mile... ;)
if [ -r $PKG1 ]; then
  touch -r $PKG1 $TMPDIR/$PKG/$(basename $PKG1)
elif [ -r $(dirname $PKG1)/$(basename $PKG1 .orig) ]; then
  touch -r $(dirname $PKG1)/$(basename $PKG1 .orig) $TMPDIR/$PKG/$(basename $PKG1)
fi
touch -r $PKG2 $TMPDIR/$PKG/$(basename $PKG2)

rm -rf $TMPDIR/$PKG/{1,2}
( cd $TMPDIR/$PKG ; diff -d -u $(basename $PKG1) $(basename $PKG2) )

# cleanup:
rm -rf $PKG $TMPDIR