#!/bin/bash

NO_CLEAN=0
STATEDIR=0
UNPACK_ONLY=0
HELP=0
APPEND=1

DONE=0
while [ $DONE = 0 ]
do
  case "$1" in
      --append-args )
	  APPEND=1
	  shift
	  ;;
      --help )
	  HELP=1
	  shift
	  ;;
      --no-clean )
	  NO_CLEAN=1
	  shift
	  ;;
      --prepend-args )
	  APPEND=0
	  shift
	  ;;
      --really-clean )
	  NO_CLEAN=0
	  shift
	  ;;
      --statedir )
	  STATEDIR=1
	  NO_CLEAN=1
	  shift
	  ;;
      --unpack )
	  UNPACK_ONLY=1
	  shift
	  ;;
      * )
	  DONE=1
	  ;;
  esac
done

if ( [ $UNPACK_ONLY = 0 ] && [ "$#" -lt 1 ] ) ||
   ( [ $UNPACK_ONLY = 1 ] && [ "$#" -ne 1 ] ) ||
   [ $HELP = 1 ]
then
    echo "Usage: $0 [options] <input-file> [<program> [arguments ...]]"
    echo
    echo "This command will unpack the given archive of aptitude state"
    echo "information, then invoke the given program with the given"
    echo "list of arguments, passing appropriate -o options to cause"
    echo "aptitude to use the contents of that archive as its global"
    echo "data store."
    echo
    echo "Options:"
    echo "  --append-args    Place the generated arguments at the end of"
    echo "                   the command line (default)."
    echo "  --help           Display this message and exit."
    echo "  --no-clean       Do not remove the temporary directory after"
    echo "                   invoking aptitude."
    echo "  --prepend-args   Place the generated arguments at the beginning"
    echo "                   of the command line."
    echo "  --really-clean   Remove the state directory, even if --statedir"
    echo "                   was passed as an argument."
    echo "  --statedir       The <input-file> is an unpacked aptitude bundle,"
    echo "                   not a bundle file; implicitly sets --no-clean."
    echo "  --unpack         Just unpack the <input-file>, don't run aptitude."
    exit 1
fi

INPUTFILE="$1"
shift

if [ "$#" -lt 1 ]
then
    PROGRAM=aptitude
else
    PROGRAM="$1"
    shift
fi

if [ $STATEDIR = 0 ]
then
    tempdir=$(mktemp -p ${TMPDIR:-/tmp} -d aptitudebug.XXXXXXXXX) || exit 1
    if [ -z "$tempdir" ]
	then
	exit 1
    fi
else
    tempdir=$INPUTFILE
fi

trap '
if [ $NO_CLEAN = 1 ]
then echo "Leaving final state in $tempdir"
else echo "Removing $tempdir"; rm -fr $tempdir
fi' 0

if [ $STATEDIR = 0 ]
then
    if [ -d "$INPUTFILE" ]
    then
	echo "Can't use $INPUTFILE as the input bundle: it's a directory."
	exit 1
    fi
    if ! [ -f "$INPUTFILE" ]
    then
	echo "Can't use $INPUTFILE as the input bundle: file not found."
	exit 1
    fi

    if file "$INPUTFILE" | grep bzip2 2>/dev/null > /dev/null
    then
	DECOMPRESSOR=bunzip2
    else
	DECOMPRESSOR=gunzip
    fi

    ($DECOMPRESSOR -c < "$INPUTFILE") | (cd "$tempdir" && tar x) || exit 1
fi

if [ $UNPACK_ONLY = 1 ]
then
    exit 0
fi

if [ "$APPEND" = 1 ]
then
    "$PROGRAM" "$@" -o "Dir=$tempdir" -o "Dir::State::status=$tempdir/var/lib/dpkg/status"
else

    "$PROGRAM" -o "Dir=$tempdir" -o "Dir::State::status=$tempdir/var/lib/dpkg/status" "$@"
fi