#!/bin/bash

function g_backup {

  #### Config defaults
  # dir(s) to backup (: separated)
  local BACKUPDIRS=""
  # Excludefile für rsync
  local BACKUPEXCLUDES=""
  # Backup-Server (Backup-Destination)
  local BACKUPSRV=""
  # SSH Port
  local BACKUPSRVPORT="22"
  # SSH User
  local BACKUPSRVUSER=""
  # Destination path on Backup-Server
  local BACKUPSRVPATH=""
  # run optional command on server and start backup only on success
  local BACKUPSRVTESTCMD=""
  # Copy only without hostname/backup-date Structure
  local NODIRSTRUCT=""

  g_tries=5
  g_tries_delay=120

  # Config files for custom vars
  [ -r /usr/local/etc/g_backup.conf ] && . /usr/local/etc/g_backup.conf
  [ -r ~/.config/g_backup.conf ] && . ~/.config/g_backup.conf

  # Use CMD-line args
  [ -n "$1" ] && BACKUPDIRS=$1
  [ -n "$2" ] && BACKUPSRVPATH=$2
  [ -n "$3" ] && BACKUPEXCLUDES=$3
  [ -n "$4" ] && BACKUPSRV=$4
  [ -n "$5" ] && BACKUPSRVPORT=$5
  [ -n "$6" ] && BACKUPSRVUSER=$6
  [ -n "$7" ] && BACKUPSRVTESTCMD=$7
  [ -n "$8" ] && NODIRSTRUCT=$8

  local usage="
  $0 BACKUPDIR1[:BACKUPDIR2:BACKUPDIR3] BACKUPPATH [BACKUPEXCLUDES BACKUPSRV BACKUPSRVPORT BACKUPSRVUSER BACKUPSRVTESTCMD NODIRSTRUCT]"

  [ -z "$BACKUPDIRS" ] && g_echo_error "No Directory to Backup (BACKUPDIR) given $usage" && return 1
  [ -z "$BACKUPSRVPATH" ] && g_echo_error "No path to put the Backup (BACKUPPATH) given $usage" && return 1

  if [ "$BACKUPEXCLUDES" == "default" ]
  then
    BACKUPEXCLUDES="$g_tmp/default-excludes"
    echo '.local/share/gvfs-metadata
.local/share/Trash
.unison*
unison.log
.unison.sh.log
.local/share/Steam/
dwhelper
*cache*
*tmp*
*temp*
*.log
*.log.*
*.del
*.bak
*.old
*backup*
.var/app/org.signal.Signal
vpn
.config/Nextcloud/
nextcloud-test.*/
.VirtualBox/
DMS/
tmp
.zoom/
.steam/
pagefile.sys
.config/Signal/
.var/app/com.microsoft.Teams
GTC/
Eingang/
_neu
_nru_pre
.xsession-errors*
part.dd
.local/share/Steam
/Nextcloud/
var-lib-docker
/proc/
/sys/
/dev/
/run/
/mnt/' >$g_tmp/default-excludes
  fi

  if [ -n "$BACKUPSRV" ] 
  then
    [ -z "$BACKUPSRVPORT" ] && g_echo_error "No SSH-Port given $usage" && return 1
    local sshopts="g_retrycmd ssh -n -p $BACKUPSRVPORT -o BatchMode=yes -o StrictHostKeyChecking=accept-new  $BACKUPSRVUSER@$BACKUPSRV"
    local sshoptsnoretry="ssh -n -p $BACKUPSRVPORT -o BatchMode=yes -o StrictHostKeyChecking=accept-new  $BACKUPSRVUSER@$BACKUPSRV"
  fi

  rsyncopts="-aXAH --no-inc-recursive --timeout=180 --force -yy --one-file-system --open-noatime --delete-after --ignore-missing-args --partial"
  [ -n "$BACKUPEXCLUDES" ] && rsyncopts="$rsyncopts --delete-excluded --exclude-from=$BACKUPEXCLUDES"
  [ -n "$BACKUPSRV" ] && rsyncopts="$rsyncopts -e 'ssh -p $BACKUPSRVPORT'"
  [ "$BACKUPSRVUSER" == "root" ] && syncopts="$rsyncopts --numeric-ids"

  local ORIGIFS="$IFS"
  IFS=':'
  # Prepare Dest-Dir on Backup-Server
  local CMDS="mkdir -p ${BACKUPSRVPATH}/$(hostname):chmod 700 ${BACKUPSRVPATH}/$(hostname)"
  [ -n "$NODIRSTRUCT" ] && CMDS="mkdir -p ${BACKUPSRVPATH}"
  [ -n "$BACKUPSRVTESTCMD" ] && CMDS="$BACKUPSRVTESTCMD:$CMDS"
  for CMD in $CMDS
  do
    IFS="$ORIGIFS"
    g_runcmd $sshopts $CMD || return $?
  done

  IFS=':'
  for BACKUPDIR in $BACKUPDIRS
  do
    IFS="$ORIGIFS"
    rsyncoptsrun="$rsyncopts"

    # prepare paths
    if [ -z "$NODIRSTRUCT" ]
    then
      # build structure
      BACKUPSRVPATH_WITH_HOST="$BACKUPSRVPATH/$(hostname)"
      BACKUPSRVPATH_WITH_DATE="$BACKUPSRVPATH_WITH_HOST/backup-$(date +%Y-%m-%d)/$BACKUPDIR"
      BACKUPSRVPATH_WITH_DATE_INCOMPLETE="$BACKUPSRVPATH_WITH_DATE-incomplete"

      # linkdest/hardlink if present
      BACKUPSRVPATH_LINK_DEST="$($sshoptsnoretry ls -d1 "$BACKUPSRVPATH_WITH_HOST/backup-*/$BACKUPDIR" 2>/dev/null | egrep -v "^backup.+-monthly/" | sort | tail -n1 | perl -pe 's/$/\//' )"
      BACKUPSRVPATH_LINK_DEST_INCOMPLETE="$($sshoptsnoretry ls -d1 "$BACKUPSRVPATH_WITH_HOST/backup-*/$BACKUPDIR-incomplete" 2>/dev/null | grep -v $BACKUPSRVPATH_WITH_HOST/backup-$(date +%Y-%m-%d) | tail -n 19 | sort | perl -pe 's/^/--link-dest=/; s/\n/\/ /g')"
      [ -n "$BACKUPSRVPATH_LINK_DEST_INCOMPLETE" ] && rsyncoptsrun="$rsyncoptsrun $BACKUPSRVPATH_LINK_DEST_INCOMPLETE"
      [ -n "$BACKUPSRVPATH_LINK_DEST" ] && rsyncoptsrun="$rsyncoptsrun --link-dest=$BACKUPSRVPATH_LINK_DEST"
      
      g_runcmd $sshopts mkdir -p "$BACKUPSRVPATH_WITH_DATE_INCOMPLETE" || continue
    else
      BACKUPSRVPATH_WITH_DATE_INCOMPLETE="$BACKUPSRVPATH"
    fi
    
    # Backup
    [ -n "$BACKUPSRV" ] && sshrsync="$BACKUPSRVUSER@$BACKUPSRV:"
    g_runcmd g_retrycmd rsync $rsyncoptsrun "$BACKUPDIR"/ "${sshrsync}$BACKUPSRVPATH_WITH_DATE_INCOMPLETE"/ || continue

    # done if no direstructure
    [ -n "$NODIRSTRUCT" ] && continue
    
    # if backups from this day already exists move it to $BACKUPSRVPATH_WITH_DATE-$$-old
    if $sshopts test -e "$BACKUPSRVPATH_WITH_DATE"
    then
      $sshopts mv "$BACKUPSRVPATH_WITH_DATE" "$BACKUPSRVPATH_WITH_DATE-$$-old"
    fi

    # move from -incomplete to default dir
    g_runcmd $sshopts mv "$BACKUPSRVPATH_WITH_DATE_INCOMPLETE" "$BACKUPSRVPATH_WITH_DATE" || continue
 
    local yearmonth="$(date +%Y-%m-)"

    # Create monthly dir if not exists
    BACKUPSRVPATH_MONTHLY="$BACKUPSRVPATH_WITH_HOST/backup-${yearmonth}monthly/$BACKUPDIR"
    if ! $sshopts test -e "$BACKUPSRVPATH_MONTHLY"
    then 
      g_echo "Creating monthly-Backup $BACKUPSRVPATH_MONTHLY"
      g_runcmd $sshopts mkdir -p "$BACKUPSRVPATH_MONTHLY" || continue
      g_runcmd $sshopts mv -T "$BACKUPSRVPATH_WITH_DATE" "$BACKUPSRVPATH_MONTHLY" || continue
      g_runcmd $sshopts ln -s "$BACKUPSRVPATH_MONTHLY" "$BACKUPSRVPATH_WITH_DATE" || continue
    fi

    # Cleanup old backups
    local yearmonthbefore="$(date +%Y-%m- --date='-1 month')"
    $sshopts find $BACKUPSRVPATH_WITH_HOST -mindepth 1 -maxdepth 1 -type d -name "backup-*" | egrep -v "backup-$yearmonth|backup-$yearmonthbefore|backup-20[0-9][0-9]-[0-9][0-9]-monthly" | while read g_toremove 
    do
      g_echo_warn "Removing old Backup $g_toremove"
      g_runcmd $sshopts chmod -R +w "$g_toremove"
      g_runcmd $sshopts rm -r "$g_toremove"
    done
  done
}