#!/data/data/com.termux/files/usr/bin/sh
#
# Copyright (C) 2023 Bacula Systems SA
# License: BSD 2-Clause; see file LICENSE-FOSS
#
# This script setup a "master-key" for the volume encryption on the SD
#

# tell where GNUPG will work (usually in /opt/bacula/etc/gnupg)
GNUPGHOME="/data/data/com.termux/files/usr/etc/bacula/gnupg"
KEYMAN_CONF="/data/data/com.termux/files/usr/etc/bacula/key-manager.conf"

#############################################################################
#
# usage
#
#############################################################################
usage()
{
   echo "$0 [ check | install ]"
   echo "setup a master key for the key-manager"
   exit 1
}

#############################################################################
#
# check_gnupg
#
#############################################################################
check_gnupg()
{
   # Check if GnuPG is installed
   GNUPGBIN=`which gpg`
   if [ -z "$GNUPGBIN" ] ; then
      echo "GnuPG is not found or not installed" >&2
      exit 1
   fi
}

#############################################################################
#
# check
#
#############################################################################
check_python_gnupg()
{
   # Check if the python3 API is installed for GnuPG
   PYTHON3=`which python3`
   if [ -z "$PYTHON3" ] ; then
      echo "python3 is not found or not installed" >&2
      exit 1
   fi
   OUT=`mktemp`
   $PYTHON3 -c 'import gnupg;print("OK" if gnupg.GPG else "KO")' >$OUT 2>/dev/null
   out=`cat $OUT`
   if [ "$out" != "OK" ] ; then
      echo "python3 gnupg module is not found" >&2
      echo "try: pip3 install gnupg" >&2
      exit 1
   fi
}

#############################################################################
#
# check
#
#############################################################################
check()
{
   check_gnupg
   check_python_gnupg

   if [ -e $GNUPGHOME ] ; then
      echo "Directory \"$GNUPGHOME\" exists"
   else
      echo "Directory \"$GNUPGHOME\" doesn't exist"
   fi
   exit 0
}

#############################################################################
#
# install
#
#############################################################################
install()
{
   check_gnupg

   # Don't overwrite an existing configuration
   if [ -e "$GNUPGHOME" ] ; then
      echo "Directory \"$GNUPGHOME\" already exists, abort" >&2
      exit 1
   fi

   mkdir $GNUPGHOME
   chmod go-rwx $GNUPGHOME
   export GNUPGHOME

   PASSPHRASE=`openssl rand -base64 10`

   GNUPG_SCRIPT=`mktemp`
   cat > $GNUPG_SCRIPT <<EOF
Key-Type: RSA
Subkey-Type: RSA
Key-length: 2048
Subkey-Length: 2048
Name-Real: Bacula
Name-Email: bacula@localhost
Expire-Date: 0
Passphrase: $PASSPHRASE
%commit
%echo done
EOF

   GNUPG_OUT=`mktemp`
   $GNUPGBIN --batch --full-gen-key $GNUPG_SCRIPT >$GNUPG_OUT 2>&1
   if [ $? != 0 ] ; then
      cat $GNUPG_OUT
      rm $GNUPG_OUT
      echo "Error with gpg" >&2
      exit 1
   fi
   rm $GNUPG_SCRIPT

   # retrieve the fingerprint of the key
   fpr=`$GNUPGBIN -k --with-colons | awk -F : '$1 ~/fpr/ { print $10;exit }'`

   cat >$KEYMAN_CONF <<EOF
[DEFAULT]
gnupghome="$GNUPGHOME"

[$fpr]
#volume_regex=Volume[0-9]+|TestVolume[0-9]+
uid=bacula@localhost
passphrase=$PASSPHRASE
stealth=off
EOF
   if [ "$USER" = root ] || [ "$(id -u)" = 0  ]; then
      echo change ownership to user bacula
      chown -R bacula:bacula $KEYMAN_CONF $GNUPGHOME
   fi
   echo "public and private keys have been created in $GNUPGHOME"
   echo "the key-manager configuration file is in $KEYMAN_CONF"
   exit 0
}

operation=$1
shift

case $operation in
   "check")
      check
      ;;
   "install")
      install
      ;;
   *)
      usage
      ;;
esac
