#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'

if [ -r /etc/crypted-backups ]; then
  . /etc/crypted-backups
else
  echo "Configuration file (/etc/crypted-backups) not readable! Aborting!"
  exit 1
fi
user_mode=""
source_mode=""
verbose=''

function notification_source_to_destination () {
  local source_directory=$1
  local destination_directory=$2
  if [ $source_directory != "" -a $destination_directory != "" ];then
    echo "$source_directory -> $destination_directory"
    return 0
  else
    echo "Source ($source_directory) or destination ($destination_directory) directory not given!"
    return 1
  fi
}

function generate_timestamp () {
  local timestamp="$(date +"%Y%m%d-%H%M%S")-"
  echo ${timestamp}
  return 0
}

# Adds trailing slash, if missing
# Fails when path is not absolute, or not within user home, when not root
function sanitize_pathname () {
  local path=$1
  if [ ${#path} -ne 0 ]; then
    if [ ${path:0:1} = "/" -o ${path:0:2} = "~/" -a $(id -u) -ne 0 ]; then
      if [ ${path:${#path}-1} != "/" ]; then
        echo "$path/"
        return 0
      else
        echo "$path"
        return 0
      fi
    else
      echo "Directory must be absolute!"
      return 1
    fi
  else
    echo "Directory can not be empty!"
    return 1
  fi
}

function check_database_server () {
  if [ ! -x /usr/bin/mysql ]; then
    echo "/usr/bin/mysql is not available. Is MariaDB or MySQL actually installed?"
    return 1
  elif [ !$(systemctl is-active mysqld) = "active" ]; then
    echo "No MariaDB or MySQL service is currently running. Start it with 'systemctl start mysqld'."
    return 1
  fi
}

function check_database_settings () {
  if [ -z "$database_destination" ]; then
    echo "The \"database_destination\" variable can not be empty."
    return 1
  elif [ -z "$database_user" ]; then
    echo "The \"database_user\" variable can not be empty."
    return 1
  elif [ -z "$database_password" ]; then
    echo "The \"database_password\" variable can not be empty."
    return 1
  fi
  return 0
}

function check_directory_exists () {
  local destination=$1
  if [ ! -d $destination ]; then
    echo "Directory \"$destination\" does not exist!"
    return 1
  else
    return 0
  fi
}

function check_directory_exists_and_autocreate () {
  local destination=$1
  if [ ! -d $destination ]; then
    echo "Directory \"$destination\" does not exist yet. Creating..."
    mkdir -p $destination
  else
    return 0
  fi
}

function check_directory_permission_root () {
  if [ -w $1 ]; then
    return 0
  else
    echo "Directory not writable: $1."
    return 1
  fi
}

function check_directory_writable_user () {
  if [ -w $1 ]; then
    return 0
  else
    echo "Directory not writable: $1."
    return 1
  fi
}

function check_directory_owner_user() {
  if [ ! -O $1 ]; then
    echo "Directory not owned by user $(whoami): $1"
    return 1
  else
    return 0
  fi
}

function check_user_directory () {
  local directory=$1
  echo "Checking directory \"$directory\"."
  check_directory_exists_and_autocreate $directory
  check_directory_writable_user $directory
  return 0
}

function check_root_directory () {
  local directory=$1
  check_directory_exists_and_autocreate $directory
  check_directory_permission_root $directory
  return 0
}

function get_parent_directory () {
  local directory=$1
  local parent=""
  parent=$(dirname $directory)
  parent=$(sanitize_pathname $parent)
  echo "$parent"
  return 0
}

function get_basename_directory () {
  local directory=$1
  local base=$(basename $directory)
  echo "$base"
  return 0
}

function compress_to_tmp_file () {
  local source_file=$1
  local tmp_file=$2
  echo "Compressing source ($source_file) to temporary file ($tmp_file)."
  case $tar_suffix in
    ".tar.tbz")
      tar cfj "$tmp_file" $source_file
      ;;
    ".tar.tgz")
      tar cfz "$tmp_file" $source_file
      ;;
    ".tar.tlz")
      tar --lzma -cf "$tmp_file" $source_file
      ;;
    ".tar.xz")
      tar cfJ "$tmp_file" $source_file
      ;;
    *)
      echo "Using \"$tar_suffix\" as \$tar_suffix is not supported."
      return 1
      ;;
  esac
  return 0
}

function encrypt_tmp_file () {
  local tmp_file=$1
  local destination_file=$2
  local encrypt_return=-1
  echo "Encrypting $tmp_file to $destination_file."
  set +eu
  gpg -e \
    -r "$gpg_public_key" \
    -o "$destination_file" \
    "$tmp_file"
  encrypt_return=$?
  set -eu
  if [ $encrypt_return -gt 0 ];then
    echo "GnuPG encryption returns with: $encrypt_return"
    echo "Removing $tmp_file."
    rm -f "$tmp_file"
    return 1
  fi
  echo "Removing $tmp_file."
  rm -f "$tmp_file"
  return 0
}

function backup_single_directory () {
  local source_directory=$1
  local source_directory_basename=$(get_basename_directory $source_directory)
  local source_parent_directory=$(get_parent_directory $source_directory)
  local tmp_directory=$(sanitize_pathname $tmp)
  local destination_directory=$(sanitize_pathname $2)
  local timestamp=$(generate_timestamp)
  local tmp_file="$tmp_directory$timestamp$source_directory_basename$tar_suffix"
  local destination_file="$destination_directory$timestamp$source_directory_basename$tar_suffix$gpg_suffix"
  notification_source_to_destination "$source_parent_directory$source_directory_basename" $destination_file
  echo "Going to $source_directory_basename's parent directory: $source_parent_directory."
  cd $source_parent_directory
  check_directory_exists $source_directory
  "check_"$user_mode"_directory" $tmp_directory
  "check_"$user_mode"_directory" $destination_directory
  compress_to_tmp_file $source_directory_basename $tmp_file
  encrypt_tmp_file $tmp_file $destination_file
}

function backup_multiple_directories () {
  local source_directory=$(sanitize_pathname $1)
  local destination_directory=$(sanitize_pathname $2)
  local layered=0
  local sub_count=0
  if [ ${#@} -gt 2 ]; then
    layered=$3
    echo "Recursive backup (depth=1) of \"$source_directory\"."
  fi
  check_directory_exists $source_directory
  "check_"$user_mode"_directory" $destination_directory
  for sub_directory in $source_directory*
  do
    if [ -d $sub_directory ];then
      sub_count=$((sub_count+1))
      "check_"$user_mode"_directory" $sub_directory
      if [ $layered -eq 1 ];then
        backup_multiple_directories $sub_directory $destination_directory$(get_basename_directory $sub_directory)
      else
        backup_single_directory $sub_directory $destination_directory
      fi
    fi
  done
  if [ $sub_count -eq 0 ]; then
    echo "There are actually no folders to backup in \"$source_directory\". Please check the configuration file!"
  fi
}

function dump_database () {
  local db=$1
  local tmp_file=$2
  mysqldump --force \
    --opt \
    -u$database_user \
    -p$database_password \
    --databases $db > $tmp_file
}

function backup_all_databases () {
  check_database_server
  check_database_settings
  local databases=( )
  local destination=$(sanitize_pathname $database_destination)
  local database
  set +eu
  databases=$(mysql -u$database_user \
    -p$database_password \
    -e "SHOW DATABASES;" \
    | grep -Ev "(Database|information_schema|performance_schema|tmp)")
  set -eu
  if [ ${#databases} -eq 0 ];then
    echo "There are actually no databases on this server. If you've set wrong user or password variables MariaDB/ MySQL will by now have complained about it."
    return 1
  else
    echo "Databases for which backups will be created: ${databases[@]}"
    for database in $databases; do
      backup_database $database $destination
    done
  fi
}

function backup_database () {
  local db=$1
  local destination_directory=$2
  local timestamp=$(generate_timestamp)
  local tmp_directory=$(sanitize_pathname $tmp)
  local sql_file="$timestamp$db$sql_suffix"
  local tmp_file="$tmp_directory$sql_file$tar_suffix"
  local destination_file="$destination_directory$timestamp$db$sql_suffix$tar_suffix$gpg_suffix"
  "check_"$user_mode"_directory" $tmp_directory
  "check_"$user_mode"_directory" $destination_directory
  echo "Going to temporary directory ($tmp_directory)."
  cd $tmp_directory
  dump_database $db $sql_file
  compress_to_tmp_file $sql_file $tmp_file
  encrypt_tmp_file $tmp_file $destination_file
}

function set_user_mode () {
  if [ $(id -u) -eq 0 ]; then
    user_mode="root"
  else
    user_mode="user"
  fi
  return 0
}

function check_gpg_set () {
  if [ -z "$gpg_public_key" ];then
    echo "Error. \"gpg_public_key\" not set!"
    exit 1
  fi
}

function print_help () {
  echo "help"
  exit 0
}

#TODO: Add function to cleanup backups
#TODO: Add function to mirror backups
#TODO: Add function to automatically add key to keyring, if not found
#TODO: Add verbose flag


check_gpg_set
set_user_mode

if [ ${#@} -gt 0 ]; then
  while getopts 'c:hr:s:v' flag; do
    case "${flag}" in
      c)
        echo "Cleanup"
        ;;
      h)
        print_help
        ;;
      r)
        echo "recall"
        ;;
      s)
        source_mode="${OPTARG}"
        ;;
      v)
        verbose='true'
        ;;
      *)
        echo "Error. Unrecognized option: ${flag}."
        exit 1
        ;;
    esac
  done
else
  print_help
fi

if [ -n "$source_mode" ];then
  case $source_mode in
    aura)
      backup_single_directory $aura_source $aura_destination
      ;;
    bitlbee)
      backup_single_directory $bitlbee_source $bitlbee_destination
      ;;
    etc)
      backup_single_directory $etc_source $etc_destination
      ;;
    git)
      backup_multiple_directories $git_source $git_destination
      ;;
    mail)
      if [ "$mail_domains_as_folders" = "yes" ]; then
        backup_multiple_directories $mail_source $mail_destination "1"
      elif [ "$mail_domains_as_folders" = "no" ]; then
        backup_multiple_directories $mail_source $mail_destination
      else
        echo "Setting \"mail_domains_as_folders\" to $mail_domains_as_folders is not supported!"
        exit 1
      fi
      ;;
    mailman)
      backup_single_directory $mailman_source $mailman_destination
      ;;
    databases)
      backup_all_databases
      ;;
    logs)
      backup_single_directory $logs_source $logs_destination
      ;;
    websites)
      backup_multiple_directories $websites_source $websites_destination
      ;;
    firefox)
      backup_single_directory $firefox_source $firefox_destination
      ;;
    thunderbird)
      backup_single_directory $thunderbird_source $thunderbird_destination
      ;;
    weechat)
      backup_single_directory $weechat_source $weechat_destination
      ;;
    *)
      echo "Error. $source_mode is not a valid backup option."
      exit 1
  esac
fi

exit 0