#!/usr/bin/env bash
#
# Unlimited use with this notice. (C) 2006-2023 George Georgalis <george@galis.org>
#
#:: This script automates the process of rsync snapshot backup
#:: and rotation in a push, pull or localhost configuration.
#

set -e
#set -x
#[ -t 0 ] && set -x || true # verbose if run from terminal

devnul () { return $? ;} #:> expect nothing in return
stderr () { echo "$*" 1>&2 ;} #:> return args to stderr
chkecho () { [ "$*" ] && echo "$*" || true ;} #:> echo args or no operation if none
logwrn () { [ "$*" ] && { logger -s "^^ $* ^^"   ; return $? ;} || true ;}
logerr () { [ "$*" ] && { logger -s ">>> $* <<<" ; return 1  ;} || true ;}
chkwrn () { [ "$*" ] && { stderr    "^^ $* ^^"   ; return 0 ;} || true ;} #:> if args not null, wrn stderr args return 0
chkerr () { [ "$*" ] && { stderr    ">>> $* <<<" ; return 1 ;} || true ;} #:> if args not null, err stderr args return 1
source_iff () { [ -e "$1" ] && { . "$1" && chkecho "$1" || chkerr "error: $1" ;} ;} #:> source arg1 if exists

usage () { cat <<EOF
Usage: $0
# ${0##*/} local orig prefix
   makes a local snapshot in prefix/bk/1/ of orig
# ${0##*/} (push|pull) host orig prefix
   pushes orig to host:/prefix/bk/1/ or from host:/orig to prefix/bk/1/
# ${0##*/} rotate level prefix [host]
   generates prefix/bk/level/ from prefix/bk/1/ oprionally on remote host
# ${0##*/} purge level prefix [host]
   purges excess from prefix/bk/level/ oprionally on remote host
# ${0##*/} merge prefix [host]
   merge like files (dupmerge.c) below prefix, optionally on remote host
# ${0##*/} help
   display this help message
Extra parameters are considered an error,
RSYNC_OPTS env to incert with rsync exec, eg
  RSYNC_OPTS='--include /etc --include /root --include /usr/local --exclude=/*'
orig and prefix must be full path.
EOF
# # ${0##*/} batch [include]
#    use batch mode on $HOME/.$(basename $0).rc or optionally include
# # ${0##*/} batch conf
#    display discovered include file
}

lock () { # lock to prevent multiple generating runs to
 # the same host, you can still shoot yourself in the foot
 #[ ! "$(id -u)" = "0" ] && chkerr "You must be root to lock $(basename $0) in /var/run"
 LOCK="/tmp/$(basename $0)-${USER}-${HOST}.pid"
 [ -f "$LOCK" ] && { chkerr "Lock exists: $LOCK" ; exit 1 ;} || echo "$$" >"$LOCK" ;}
unlock () { rm $LOCK ;}

locallast () { find "$PREFIX/1" -mindepth 1 -maxdepth 1 -type d | sort | tail -n1 ;}
remotelast () { ssh "$HOST" "find "$PREFIX/1" -mindepth 1 -maxdepth 1 -type d | sort | tail -n1" ;}
testlast () { [ -z "$LAST" ] && chkerr ">>> No prior backup?  mkdir -p $PREFIX/0 $PREFIX/1/$NOW $PREFIX/2 $PREFIX/3" || true ;}

localsnap () {
 mkdir -p "$LAST/$ORIG" "$PREFIX/0/$NOW/$ORIG/"
 { rsync $rsync_opt --link-dest="$LAST/$ORIG" $ORIG/ $PREFIX/0/$NOW/$ORIG/ \
  || true # files could disappear during rsync
 } | grep -v /$ || true # cleanup output, false exit expected
 mv $PREFIX/0/$NOW $PREFIX/1/
 cat >$PREFIX/1/$NOW/${NOW}-${FUNCNAME} <<EOL
RSYNC_OPT='$RSYNC_OPT' $0 $op $ORIG $PREFIX
# aka:
  rsync $rsync_opt --link-dest="$LAST/$ORIG" $ORIG/ $PREFIX/0/$NOW/$ORIG/ 
EOL
} # localsnap

pushsnap () {
cat >"/tmp/${NOW}-${op}" <<EOL
RSYNC_OPTS="$RSYNC_OPTS" $0 $op $HOST $ORIG $PREFIX
## ${hostname}:rsync $rsync_opt --link-dest="$LAST/$ORIG" $ORIG/ ${HOST}:$PREFIX/0/$NOW/$ORIG/
EOL
 ssh $HOST "mkdir -p '$LAST/$ORIG' '$PREFIX/0/$NOW/$ORIG/'"
 { rsync $rsync_opt --link-dest="$LAST/$ORIG" $ORIG/ ${HOST}:$PREFIX/0/$NOW/$ORIG/ 2>&1 | tee /tmp/${NOW}-${op}-errout \
  || true # false exit not unusual, files could disappear or not have read perms, check log
 } | grep -Ev '(/$| -> )' || true # rm dir and symlink creation from output, false exit not unusual
ssh $HOST "mv $PREFIX/0/$NOW $PREFIX/1/" \
 && ssh $HOST "cat >$PREFIX/1/$NOW/${NOW}-${op}-errout" </tmp/${NOW}-${op}-errout && rm /tmp/${NOW}-${op}-errout \
 && ssh $HOST "cat >$PREFIX/1/$NOW/${NOW}-${op}" <"/tmp/${NOW}-${op}" \
 && rm -f "/tmp/${NOW}-${op}-errout" "/tmp/${NOW}-${op}"
} # pushsnap

pullsnap () {
 mkdir -p  "$LAST/$ORIG" "$PREFIX/0/$NOW/$ORIG/"
 {
   rsync $rsync_opt --link-dest="$LAST/$ORIG" $HOST:$ORIG/ $PREFIX/0/$NOW/$ORIG/ 2>&1 | tee /tmp/${NOW}-${op}-errout \
  || true # false exit not unusual, files could disappear or not have read perms, check log
 } | grep -Ev '(/$| -> )' || true # rm dir and symlink creation from output, false exit not unusual
 mv $PREFIX/0/$NOW $PREFIX/1/
 mv /tmp/${NOW}-${op}-errout $PREFIX/1/$NOW/${NOW}-${op}-errout
 cat >"$PREFIX/1/$NOW/${NOW}-${op}" <<EOL
 RSYNC_OPT='$RSYNC_OPT' $0 $op $HOST $ORIG $PREFIX
 ## ${hostname}:rsync $rsync_opt --link-dest="$LAST/$ORIG" $ORIG/ ${HOST}:$PREFIX/0/$NOW/$ORIG/
EOL
} # pullsnap

rotlocal () {
 case $LEVEL in
  2|3)
   mkdir -p "$PREFIX/$LEVEL/"
   mv "$LAST" "$PREFIX/$LEVEL/"
  ;;
  *)
   chkerr "$0 : invalid rotate level."
  ;;
 esac
} # rotlocal

rotremote () {
 case $LEVEL in
  2|3) ssh $HOST "mkdir -p '$PREFIX/$LEVEL/' && mv '$LAST' '$PREFIX/$LEVEL/'"
  ;;
  *)
   chkerr "$0 : invalid rotate level."
  ;;
 esac
} # rotremote

# below the PREFIX
# 	./bk/0 is in process snapshot
# 	./bk/1 is completed first interval
#	./bk/2 is completed second interval, daily
#	./bk/3 is completed third interval, weekly

purglocal () {
 case $LEVEL in
  1) # dispose snapshots older than 4 days, but keep at least 50
   # (sed expression suppresses 40 lines from tail of input)
   chkerr $( ls -d $PREFIX/1/* 2>/dev/null | sed -n -e :a -e '$q;N;2,50ba' -e 'P;D' \
              | while read dir; do
                  find $dir -maxdepth 0 -mtime +4 -exec rm -rf \{\} \;
                  done 2>&1 )
  ;;
  2) # dispose of dailies older than 14 days but keep at least 20
   # (sed expression suppresses 20 lines from tail of input)
   chkerr $( ls -d $PREFIX/2/* 2>/dev/null | sed -n -e :a -e "\$q;N;2,20ba" -e "P;D" \
              | while read dir; do
                  find $dir -maxdepth 0 -mtime +14 -exec rm -rf \{\} \;
                  done 2>&1 )
  ;;
  *) chkerr "Undefined level for purge: $0 $*" ;;
 esac
} # purgelocal

purgremote () {
 case $LEVEL in
  1) # dispose snapshots older than 3 days, but keep at least 40
   # (sed expression suppresses 40 lines from tail of input)
   chkerr $(ssh $HOST "ls -d $PREFIX/1/* 2>/dev/null | sed -n -e :a -e '\$q;N;2,40ba' -e 'P;D' \
    | while read dir; do
     find \$dir -maxdepth 0 -mtime +3 -exec rm -rf \{\} \;
    done" 2>&1 )
  ;;
  2) # dispose of dailies older than 14 days but keep at least 20
   # (sed expression suppresses 20 lines from tail of input)
   chkerr $(ssh $HOST 'ls -d '$PREFIX'/2/* 2>/dev/null | sed -n -e :a -e "$q;N;2,20ba" -e "P;D" \
    | while read dir; do
     find $s -maxdepth 0 -mtime +14 -exec rm -rf \{\} \;
    done' 2>&1 )
  ;;
 esac
} # purgremote

merge () {
 chkerr run dupemerge binary
}

_logger () { logger "$*" ; [ -t 1 ] && chkwrn "$*" || true ;}

now () { date +%Y%m%d_%H%M%S ;}

op="$1" # operation
case "$op" in
 local)
  [ $# = 3 ] || chkerr "local : not 3 args : $(usage)"
  ORIG="$2" ; PREFIX="$3"/bk
 ;;
 push|pull)
  [ $# = 4 ] || chkerr "(push|pull) : not 4 args : $(usage)"
  HOST="$2" ; ORIG="$3" ; PREFIX="$4"/bk
 ;;
 rotate)
  [ $# = 3 -o $# = 4 ] || chkerr "rotate : not 3 or 4 args : $(usage)"
  LEVEL="$2" ; PREFIX="$3"/bk ; [ -n "$4" ] && HOST="$4" \
   && { op=rotremote ;} \
   || { op=rotlocal ;}
 ;;
 purge)
  [ $# = 3 -o $# = 4 ] || chkerr "purge : not 3 or 4  args : $(usage)"
  LEVEL="$2" ; PREFIX="$3"/bk ; [ -n "$4" ] && HOST="$4" \
   && { op=purgremote ;} \
   || { op=purglocal ;}
 ;;
 merge)
  [ $# = 2 -o $# = 4 ] || chkerr "merge : not 2 or 4 args : $(usage)"
  PREFIX="$2" ; [ -n "$3" ] && HOST="$3" \
   && op=mergeremote \
   || op=mergelocal
 ;;
#  batch|conf)
#   [ -n "$3" ] && chkerr $(usage) # extra arg
#   while read include
#    do # assign INCLUDE as last existing in list, and check exec
#     [ -e "$include" ] && INCLUDE="$include"
#    done <<EOF
# /etc/backlinkrc
# /usr/local/etc/backlinkrc
# $HOME/.backlinkrc
# $2
# EOF
#   [ -x "$INCLUDE" ] && true \
#    || { [ -e "$INCLUDE" ] \
#     && chkerr "$0 $1 : $INCLUDE is not exec" \
#     || chkerr "$0 $1 : no include for exec" ;}
#  ;;
 help)
  usage ; exit 0
 ;;
  *) chkerr "$(usage)"
 ;;
esac # $op

case "$op" in # set LAST
 local|pull|rotlocal) LAST="$(locallast)"
  testlast
 ;;
 push|rotremote)      LAST="$(remotelast)"
  testlast
 ;;
esac # set LAST

NOW=$(now)

# Block may be used as a template for ~/.$0.rc
##################################################
# optimized for Mac and NetBSD accounts
# rsync -a = -rlptgoD = --recursive --links --perms --times --group --owner --devices
#                -vCc = --verbose --cvs-exclude --checksum --numeric-ids
[ "$UID" = 0 ] && rsync_opt="--recursive --hard-links --links --perms --times --group         --devices --specials --numeric-ids --chmod=u=rwX" \
               || rsync_opt="--recursive --hard-links --links --perms --times --group --owner --devices --specials --numeric-ids --chmod=u=rwX"
#
# additional rsync options for terminal (non-cron) backups
[ -t 0 ] && rsync_opt="$rsync_opt --verbose --progress" || true
#
# set typical global excludes
#EXCLUDE=" tmp *.tmp *.core core .Trashes Library/Caches .Spotlight-V100"
#EXCLUDE="$EXCLUDE 2nd/ bak-*/ bk/ dist/ repo/"
#for ex in $EXCLUDE; do rsync_ex="$rsync_ex --exclude $ex" ; done
#rsync_opt="$rsync_opt $rsync_ex"
# add evn options first
rsync_opt="$rsync_opt $RSYNC_OPTS"
#
HOSTNAME=$(hostname)
#
### Example local and push batch blocks
#
#backlink.sh push host /Users/$USER/tmp /usr/local/bak-${HOSTNAME%%.*}/Users-$USER-tmp
#backlink.sh push host /Users/$USER/    /usr/local/bak-${HOSTNAME%%.*}/Users-$USER
#
#EXCLUDE= 2nd/ bak-*/ bk/ dist/ repo/ access.log data/cache/ dnscache/log/main/ tinydns/log/main/ log/default/current log/error.start/current log/error/ supervise/
#ORIG= ~geo ~root /etc /usr/local /usr/local/www /usr/pkg/etc /var/backups /var/db/pkg
#
### batch local
##lock
##NOW=$(now)
##ORIG=$HOME
##PREFIX=/usr/local/bak-${HOSTNAME%%.*}-home-$USER
##LAST="$(locallast)" ; testlast
##localsnap
##_logger "$0 $op : $PREFIX/1/$NOW$ORIG done at $(now)"
### perge
### merge
##unlock
##
### batch push
##lock
##NOW=$(now)
##HOST=host
##ORIG=$HOME
##PREFIX=/usr/local/bak-${HOSTNAME%%.*}-home-$USER
##LAST="$(locallast)" ; testlast
##pushsnap
##_logger "$0 $op : $PREFIX/1/$NOW$ORIG done at $(now)"
### perge
### merge
##unlock
#
# Block end template for ~/.$0.rc
##################################################


case $op in
 local)
  lock
  # _logger $0 $op tested 20090106 10:15:09 PM
  localsnap
  _logger "$0 $op : $PREFIX/1/$NOW/$ORIG done at $(now)"
  unlock
  exit 0
;;
  push)
  # _logger $0 $op tested 20090106 11:43:02 PM
  lock
  pushsnap
  _logger "$0 $op $HOST : $PREFIX/1/$NOW/$ORIG done at $(now)"
  unlock
  exit 0
;;
  pull)
  # _logger $0 $op 20201125_111303
  lock
  pullsnap
  _logger "$0 $op $HOST : $PREFIX/1/$NOW/$ORIG done at $(now)"
  unlock
  exit 0
;;
  rotlocal)
  #_logger $0 $op tested 20090107 12:30:51 AM
  rotlocal
  _logger "$0 rotate local : $LAST to $PREFIX/$LEVEL/ at $(now)"
  exit 0
;;
  rotremote)
  #_logger $0 $op tested 20090107 12:35:04 AM
  rotremote
  _logger "$0 rotate $HOST : $LAST to $PREFIX/$LEVEL/ at $(now)"
  exit 0
;;
  purglocal)
  #_logger $0 $op 20210402_233911_0aae0ea5
  _logger
  lock
  purglocal
# _logger "$0 purge local $LEVEL : from $NOW to $(now)"
  unlock
;;
  purgeremote)
  chkerr $0 $op is beta ready
  lock
  purgeremote
  _logger "$0 purge $HOST $LEVEL : from $NOW to $(now)"
  unlock
;;
  mergeremote)
  chkerr $0 $op is pre alpha
  lock
  mergeremote
  _logger "$0 merge $HOST $PREFIX : from $NOW to $(now)"
  unlock
;;
  mergelocal)
  chkerr $0 $op is pre alpha
  lock
  mergelocal
  _logger "$0 merge $PREFIX : from $NOW to $(now)"
  unlock
;;
  batch)
  #_logger $0 $op tested 20090107 03:26:26 PM
  . $INCLUDE
  _logger "$0 batch : $INCLUDE from $NOW to $(now)"
;;
  conf)
  echo $0 uses $INCLUDE
;;
esac

exit 0 # $0