#!/usr/bin/env bash
#  SPDX-FileCopyrightText: 2019 Max Mehl <mail [at] mehl [dot] mx>
#  SPDX-License-Identifier: GPL-3.0-or-later
########################################################################
#
#  Saves specific files and directories from a remote server via SSH.
#  Provides easy shortcuts for Uberspace.de hosts.
#  README.md provides more details.
#
########################################################################

# Fail fast on errors
set -Eeuo pipefail

# Set correct UTF-8 encoding (for FreeBSD jail)
export LC_ALL=en_US.UTF-8

CURDIR=$(dirname "$(readlink -f "$0")")
if [ ! -e "$CURDIR"/config.cfg ]; then echo "Missing config.cfg file. Edit and rename config.cfg.sample"; exit 1; fi
source "$CURDIR"/config.cfg

if [ ! -e "${HOSTS}" ]; then echo "Missing hosts file. Please set a correct value of HOSTS= in your config file. Current value: ${HOSTS}"; exit 1; fi

if [ -n "${SSH_KEY}" ]; then
  SSH_KEY_ARG="-i ${SSH_KEY}"
else
  # defaults
  SSH_KEY_ARG=""
  SSH_KEY=~/.ssh/id_rsa
fi

# Get current date
DATE=$(date +"%Y-%m-%d_%H-%M")
LOG="$CURDIR"/backup.log

function trim {
  sed -r -e 's/^[[:space:]]*//g' -e 's/[[:space:]]*$//g'
}
function pdate {
  DATE=$(date +%y-%m-%d_%H:%M:%S)
  echo "[$DATE]"
}
function logecho {
  # Echo string and copy it to log while attaching the current date
  echo "$(pdate) $*"
  echo "$(pdate) $*" >> "$LOG"
}

while read -r line; do
  # if line is a comment or blank, go to next line
  if echo "$line" | grep -qE "^\s*(#|$)"; then continue; fi

  RHOST=$(echo "$line" | cut -d";" -f1 | trim)

  # Jump to next line if this line's host does not match host of first argument (if given)
  if [[ "${1-}" != "" ]] && [[ "${1-}" != "${RHOST}" ]]; then
    continue
  fi
  # Task ssh-checker.sh to check this host
  if ! "${CURDIR}"/ssh-checker.sh "${RHOST}"; then
    logecho "${RHOST}: ERROR when connecting via SSH. Please run ssh-checker.sh to debug."
    logecho "${RHOST}: Aborting backup after an error."
    continue
  fi

  RUSER=$(echo "$RHOST" | cut -d"@" -f1)
  ALLRDIR=$(echo "$line" | cut -d";" -f2 | trim)
  US_VERSION=$(echo "$line" | cut -d";" -f3 | trim)

  # Get SSH port if needed
  if echo "$RHOST" | grep -q ":"; then
    RPORT=$(echo "$RHOST" | cut -d":" -f2)
    RHOST=$(echo "$RHOST" | cut -d":" -f1)
    RPORT_ARG="-p ${RPORT}"
  else
    # defaults
    RPORT=""
    RPORT_ARG=""
  fi

  logecho "${RHOST}: Starting backups"

  NORDIR=$(echo "$ALLRDIR" | grep -o "|" | wc -l || true)
  NORDIR=$(($NORDIR + 1))

  # Loop through all backup sources
  for ((i = 1; i <= $NORDIR; i++)); do
    RDIR=$(echo "$ALLRDIR" | cut -d"|" -f${i} | trim)

    # Set a relative destination directory
    if [ "${RDIR}" == "%virtual" ]; then
      RDIR=/var/www/virtual/${RUSER}
      DEST_REL="$RHOST/$DATE/virtual"
    elif [ "${RDIR}" == "%mysql" ]; then
      RDIR=mysql
      DEST_REL="$RHOST/$DATE/$(basename "${RDIR}")"
    elif [ "${RDIR}" == "%mails" ]; then
      RDIR=/home/${RUSER}/users
      DEST_REL="$RHOST/$DATE/mails"
    elif [ "${RDIR}" == "%home" ]; then
      RDIR=/home/${RUSER}
      DEST_REL="$RHOST/$DATE/home"
    else
      DEST_REL="$RHOST/$DATE/$(basename "${RDIR}")"
    fi

    # Define absolute temporary and final backup destination paths
    # Example:
    #   DEST=/tmp/uberspace-backup/user@example.com/2019-01-01/virtual
    #   DEST_FINAL=/media/Uberspace/user@example.com/2019-01-01/
    DEST="${TEMPDIR}/${DEST_REL}"
    DEST_FINAL="$(dirname "${BACKUPDIR}/${DEST_REL}")"

    # Set Source directory, and make exception for %mysql
    SOURCE="${RDIR}"
    if [ "${RDIR}" == "mysql" ]; then
      if [[ $US_VERSION == 6 ]]; then
        SOURCE=/mysqlbackup/latest/${RUSER}
      else
        SOURCE=/mysql_backup/current/${RUSER}
      fi
    fi

    # Create temporary and final backup destination if necessary
    if [ ! -e "${DEST}" ]; then mkdir -p "${DEST}"; fi
    if [ ! -e "${DEST_FINAL}" ]; then mkdir -p "${DEST_FINAL}"; fi

    # RSYNC
    logecho "${RHOST}: Downloading ${SOURCE} to ${DEST}"
    rsync -a -e "ssh -q -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o Compression=no -T -x ${RPORT_ARG} ${SSH_KEY_ARG}" "${RHOST}:${SOURCE}"/ "${DEST}"/

    # Pack backup directory, and delete uncompressed one
    logecho "${RHOST}: Archiving $(basename "${DEST}")"
    tar cf "${DEST}".tar -C $(echo ${DEST} | sed "s|$(basename ${DEST})$||") $(basename ${DEST}) # TODO: avoid absolute paths
    rm -rf "${DEST}"

    # Encrypt archive with GPG (it compresses at the same time)
    logecho "${RHOST}: Encrypting and compressing $(basename "${DEST}")"
    gpg --output "${DEST}".tar.gpg --encrypt --recipient ${GPG} "${DEST}".tar
    rm "${DEST}".tar

    # Push encrypted backup to final backup destination
    logecho "${RHOST}: Moving $(basename "${DEST}") to ${DEST_FINAL}"
    cp "${DEST}".tar.gpg "${DEST_FINAL}/"
    rm "${DEST}".tar.gpg

  done # End of loop through all backup sources

  # Delete all old directories except the $MAXBAK most recent
  if [ $(ls -tp "${BACKUPDIR}"/"${RHOST}"/ | grep '/$' | wc -l | tr -d ' ') -gt $MAXBAK ]; then
    oldbackups=$(ls -tp "${BACKUPDIR}"/"${RHOST}"/ | grep '/$' | tail -n +$(($MAXBAK + 1)))
    logecho "${RHOST}: Removing older backup directories: ${oldbackups}"
    ls -tpd "${BACKUPDIR}"/"${RHOST}"/* | grep '/$' | tail -n +$(($MAXBAK + 1)) | xargs -0 | xargs rm -r --
  fi

done < "$HOSTS"

logecho "Finished all operations."