#!/bin/sh

_get_unpack_package()
{
  PACKAGE=$1

  if [ "x$PACKAGE" = "x" ];
  then
    echo "Argument missing."
    return 1
  fi

  FILEPATH=$(apt-cache show $PACKAGE | grep ^Filename | cut -d ' ' -f 2-)

  if [ "x$FILEPATH" = "x" ];
  then
    echo "Package '$PACKAGE' does not exist."
    return 1
  fi

  ARCHIVE=$(basename $FILEPATH)

  wget -q -nc -c $DEBIANMIRROR/$FILEPATH -P $CACHEDIR && \
    ([ -d $TEMPDIR/$PACKAGE ] || mkdir $TEMPDIR/$PACKAGE) && \
    dpkg -x $CACHEDIR/$ARCHIVE $TEMPDIR/$PACKAGE
}

_do_etcdiff()
{
  ETCBASEDIR=$1
  PREFIX=$2

  if [ "x$ETCBASEDIR" = "x" ];
  then
    echo "Argument missing."
    return 1
  fi

  REPORT_NAME=$(basename $ETCBASEDIR)

  # Report diff between debian conf and our local one
  rm -f $REPORTDIR/$REPORT_NAME.diff
  [ -d $PREFIX/etc ] && find $PREFIX/etc -type f | \
  while read file;
  do
    diff -ruN $ETCBASEDIR/${file#$PREFIX/} ${file#$PREFIX} >> $REPORTDIR/$REPORT_NAME.diff
  done

  # Report symlinks in /etc
  rm -f $REPORTDIR/$REPORT_NAME.symlinks
  [ -d $PREFIX/etc ] && find $PREFIX/etc -type l | \
  while read file;
  do
    stat -c '%N' $file >> $REPORTDIR/$REPORT_NAME.symlinks
  done
}

etcdiff_system()
{
  PACKAGES=$(dpkg --get-selections | grep 'install$' | cut -f 1 -d '	')

  rm $PROMPT_RM -rf $TEMPDIR/__debian_etc  && mkdir $TEMPDIR/__debian_etc

  for p in $PACKAGES;
  do

    # Skip packages which don't put anything in /etc
    if ! dpkg -L $p | grep -q '/etc/';
    then
      continue
    fi

    echo "Getting package $p..."
    if ! _get_unpack_package $p;
    then
      continue
    fi

    # save the original etc dir for later processing
    if [ ! -d $TEMPDIR/$p/etc ];
    then
      echo "Warning: package $p does not have any /etc, but 'dpkg -L' shows it"
      continue
    else
      cp -ir $TEMPDIR/$p/etc $TEMPDIR/__debian_etc
    fi
  done

  _do_etcdiff $TEMPDIR/__debian_etc

  rm -rf $TEMPDIR/__debian_etc
}

etcdiff_by_package()
{
  PACKAGE=$1

  if [ "x$PACKAGE" = "x" ];
  then
    echo "Argument missing."
    return 1
  fi

  if dpkg --status $PACKAGE | grep -q 'not-installed';
  then
    echo "Package '$PACKAGE' not installed"
    return 1
  fi

  # Skip packages which don't put anything in /etc
  if ! dpkg -L $PACKAGE | grep -q '/etc/';
  then
    echo "$PACKAGE does not put any file in /etc"
    return 1
  fi

  if ! _get_unpack_package $PACKAGE;
  then
    return 1
  fi

  if [ ! -d $TEMPDIR/$PACKAGE/etc ];
  then
    echo "Warning: package $p does not have any /etc, but 'dpkg -L' shows it"
    return 1
  fi

  if ! _do_etcdiff $TEMPDIR/$PACKAGE $TEMPDIR/$PACKAGE;
  then
    return 1
  fi

  return 0
}

etcdiff_by_file()
{
  FILE=$1

  if [ "x$FILE" = "x" ];
  then
    echo "Argument missing."
    return 1
  fi

  if [ ! -e $FILE ];
  then
    echo "ERROR, file $FILE does not exist."
    return 1;
  fi

  if [ ! -f $FILE ];
  then
    echo "ERROR, file $FILE is not a regular file."
    return 1;
  fi

  if [ $FILE = ${FILE#/etc/} ];
  then
    echo "ERROR, file path must begin with /etc/."
    return 1;
  fi

  # Find out which installed package provides the config file
  PACKAGE=$(dpkg-query -S "$FILE" | cut -d ':' -f 1 | uniq 2> /dev/null)

  REPORT_NAME=$(basename $FILE)

  if [ "x$PACKAGE" = "x" ];
  then
    diff -ruN /dev/null $FILE > $REPORTDIR/$REPORT_NAME.diff
  else
    if ! _get_unpack_package $PACKAGE;
    then
      return 1
    fi
    diff -ruN $FILE $TEMPDIR/$PACKAGE/$FILE > $REPORTDIR/$REPORT_NAME.diff
  fi

  if [ $(stat -c '%s' $REPORTDIR/$REPORT_NAME.diff) -eq 0 ];
  then
    rm -f $REPORTDIR/$REPORT_NAME.diff
  fi
}