#!/system/bin/sh
#
# Andbackup performs Android backups and restores.
#
# Copyright (C) 2017  Aaron Ball <nullspoon@oper.io>
#
# 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 <http://www.gnu.org/licenses/>.
#
set -u

backups=/sdcard/andbackup
#backups=/storage/ext_sd/bk/andbackup/andbackupBK
flag_delimiter="-"

export ANDROID_DATA='/data/data'
export ANDROID_CODE='/data/app'
export ANDROID_SYSTEM='/system'

usage() {
  # NOTE: The maximum width of this text should be 65 chars. This
  #       will ensure it displays properly on most devices without
  #       strange wrapping.
  #       If using vim to reflow, execute ':set tw=65'
  out="
Andbackup is a basic Android application (or package) backup and
restore script. It can backup a single application, or a list
of applications provided in a text file (one application name per
line). It can do the same for application restore.

The default backup path is '/sdcard/andbackup/'.

Usage:
  andbackup.sh <command> [opts]

Commands:
  help                    Print this help text
  backup      <app_name>  Back up a single package
  restore     <app_name>  Restore a single package
  list                    List installed packages
  listbackup  <list_file> Backup packages using a list text file
  listrestore <list_file> Restore packages from a list text file

"
  printf "${out}"
}


log() {
  logtype=${1:-}
  logmsg=${2:-}
  logdate=$(date '+%T %F')

  printf "%s   %s   %s\n" "${logdate}" "${logtype}" "${logmsg}"
}

# Some useful macros
linfo() {
  log "info " "${1:-}"
}

lerror() {
  log "error" "${1:-}"
}

lwarn() {
  log "warn " "${1:-}"
}

lfatal() {
  log "fatal" "${1:-}"
}


backup_app() {
  local app="${1:-}"
  local args="${2:-}"
  local preserve_cache=0 # Whether to preserve cache in the backup. Can yield
                         # notably larger backups for some applications
  local origifs=${IFS}   # Input field seperator at runtime. Useful for
                         # reverting

  # Make sure app is specified
  if [[ -z ${app} ]]; then
    lerror "Application name required."
    return 1
  fi

  # Handle passed arguments
  IFS=' ' 
  for arg in ${args}; do
    # Don't clean up the cache if preserveCache is specified
    if [ "${arg}" = 'preserveCache' ]; then
      preserve_cache=true
    else
      # Do nothing with unknown arguments
      lwarn "${app}: Unknown backup argument '${arg}'"
    fi
  done
  IFS=${origifs}

  # Make sure app is installed
  if [ ! -d "${ANDROID_DATA}/${app}" ]; then
    lerror "Package ${app} appears to not be installed."
    return 2
  fi

  linfo "Backing up ${app}"
  local apk="$(find ${ANDROID_CODE}/${app}-*/base.apk | head -n1)"
  local data="${ANDROID_DATA}/${app}"

  # No need to stop the application because we're in recovery mode

  # Create backup destination if not exist
  [ ! -d "${backups}/${app}" ] && mkdir -p "${backups}/${app}"

  # Backup the apk file if it exists
  if [ ! -z "${apk}" ] && [ -f "${apk}" ]; then
    # Delete the old backup first
    # There is a permissions issue querk when the backup was originally taken in
    # recovery mode, but later is taken in android (Permission denied for no
    # apparent reason)
    [ -f "${backups}/${app}/base.apk" ] && rm -f "${backups}/${app}/base.apk"
    # Copy the installer to the backup dir
    cp -p "${apk}" "${backups}/${app}/base.apk"
  else
    linfo "${app} apk file could not be found. Skipping apk installer backup."
  fi

  # If the data directory is not found or the data variable is empty, skip
  # backup. This covers a weird edge case where an application is installed but
  # hasn't been launched (I think?). The data variable would be empty, causing
  # this script to backup /*.
  if [ -z "${data}" ] || [ ! -d "${data}" ]; then
    lwarn "No data directory for application '${app}' found. Skipping backup."
    return 2
  fi

  # Stop the application if it is running
  # Don't try to stop it if the twrp binary is found. If we're in recovery
  # mode, the application already isn't running.
  if [ ! -f /sbin/twrp ]; then
    linfo "Stopping application ${app}"
    am force-stop "${app}"
  else
    linfo "Skipping application force stop while booted to recovery mode."
  fi

  taropts=" -C ${data} -c "
  # Decide if excluding cache or preserving
  if [[ ! -d "${data}/cache" ]]; then
    linfo "Cache doesn't exist for ${app}"
  elif [ "$preserve_cache" -eq 0 ]; then
    linfo "Excluding cache for ${app}"
    taropts="${taropts} --exclude=cache"
  else
    linfo "Preserving cache for ${app}"
  fi

  # Compress the backup
  linfo "Compressing userdata for ${app}"
  eval tar ${taropts} . | gzip -c > "${backups}/${app}/data.tar.gz"
}


list_apps() {
  for i in $(ls /data/app); do
    printf "%s\n" "${i%-*}"
  done
}


restore_app() {
  local app=${1:-}

  # Make sure app is specified
  if [ -z "${app}" ]; then
    lerror "Please specify an app to restore."
    return 1
  fi

  # If twrp binary is found on the filesystem, do not attempt restore as
  # restores cannot be done without a running system (the various android
  # binaries don't work right).
  if [ -f /sbin/twrp ]; then
    printf "Cannot perform a %s while in recovery mode.\n" "${app}"
    return 128
  fi

  # When restoring something with flags need to restore app alone
  if [[ 0 = $(echo ${app} | grep -q [${flag_delimiter}]; echo $?) ]]; then
    linfo "This app $app had passed in options"
    #Need to get app back to std naming (without params)
    app=`echo ${app} | grep -o ^.*- | sed s/-//g | cat -`
    linfo "Restoring to std name \"${app}\" while we restore"
  fi

  # Check that backup exists to be restored
  if [[ ! -d ${backups}/${app} ]]; then
    lerror "No backup for ${app} exists."
    return 1
  fi

  linfo "Restoring ${app}"

  # Install app if it is not yet installed
  if [[ ! -f "${backups}/${app}/base.apk" ]]; then
    linfo "Installer for ${app} not found. Only restoring data."
  elif [[ $(dumpsys package ${app} | grep -c userId) -eq 0 ]]; then
    linfo "Installer detected but package ${app} is not installed. Installing"
    pm install ${backups}/${app}/base.apk
  fi

  # Stop the application if it is running
  am force-stop ${app}

  # Get pertinent metadata
  local owner=$(dumpsys package ${app} | grep userId | cut -d'=' -f2 | head -n1)
  local data="/data/data/${app}"

  # Decompress data backup
  linfo "Decompressing user data for ${app}."
  gzip -d -c ${backups}/${app}/data.tar.gz | tar -x -C "${data}"

  # Fix data permissions
  chown -R ${owner}:${owner} "${data}"
  # Fix selinux labels
  linfo "Restoring SELinux contexs for ${app}"
  restorecon -R "${data}" 2>/dev/null
}


backup_apps() {
  local apps=${@}
  [ -z "${apps}" ] && lerror "At least one app is required." && return 1

  IFS=' '
  for app in ${apps}; do
    backup_app "${app}"
  done
}


restore_apps() {
  local apps=${@}
  [ -z "${apps}" ] && log error "At least one app is required.\n" && return 1

  IFS=' '
  for app in ${apps}; do
    restore_app "${app}"
  done
}


list_backup_apps() {
  local list=${1:-}
  [ -z "${list}" ] && printf "A backup list is required." && return 1

  local app  # Application mame
  local args # Application arguments

  export IFS=$'\n'
  for line in $(cat ${list}); do
    # Parse out the app name
    app="$(echo ${line} | tr -s ' ' | cut -d ' ' -f 1)"
    # Parse out the arguments (if any)
    args="$(echo ${line} | tr -s ' ' | cut -s -d ' ' -f 2-)"
    # Execute the backup
    backup_app "${app}" "${args}"
  done
}


list_restore_apps() {
  local list=${1}
  [[ -z ${list} ]] && printf "A backup list is required.\n" && return 1

  for app in $(cat ${list}); do
    restore_app ${app}
  done
}


verify_system() {
  if [ ! -d "${ANDROID_DATA}" ]; then
    printf "Data directory (%s) not found.\n" ${ANDROID_DATA} >&2
    printf "Is it mounted?\n" >&2
    return 1
  fi
  if [ ! -d "${ANDROID_CODE}" ]; then
    printf "Application code directory (%s) not found.\n" ${ANDROID_CODE} >&2
    printf "Is it mounted?\n" >&2
    return 1
  fi
  if [ ! -d "${ANDROID_SYSTEM}/etc" ]; then
    printf "System partition (%s) is not mounted.\n" ${ANDROID_SYSTEM} >&2
    return 1
  fi
  return 0
}


main() {
  local cmd="${1:-}"

  if [ -z "${cmd:-}" ]; then
    printf "Action required (backup, listbackup, restore, listrestore)\n"
    return 1
  fi

  shift

  if [ "${cmd}" = 'help' ]; then
    usage
    return 0
  fi

  # Ensure root is running this script
  if [ $(id -u) -gt 0 ]; then
    lerror "Script must be run as root (uid 0)."
    return 1
  fi

  verify_system || return 1

  if [ "${cmd}" = 'backup' ]; then
    backup_apps ${@}
  elif [ "${cmd}" = 'listbackup' ]; then
    list_backup_apps ${@}
  elif [ "${cmd}" = 'restore' ]; then
    restore_apps ${@}
  elif [ "${cmd}" = 'listrestore' ]; then
    list_restore_apps ${@}
  elif [ "${cmd}" = 'ls' ] || [ "${cmd}" = 'list' ]; then
    list_apps
  else
    lerror "Unknown command '${cmd}'"
    usage
    return 1
  fi
}

main ${@}