#!/bin/bash
# Copyright (C) 2016 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


# todo: if we cancel in the middle of a btrfs send, then run again immediately, the received subvolume doesn't get a Received UUID: field, and we won't mount it. Need to figure out a solution that will fix this.


[[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"

source /usr/local/lib/err

usage() {
  cat <<'EOF'
btrbk-run [OPTIONS]
usually -t TARGET_HOST or -s SOURCE_HOST

Note, at source location, intentionally not executable, run and read
install-my-scripts.

EOF
  echo "top of script file:"
  sed -n '1,/^[# ]*end command line/{p;b};q' "$0"
  exit $1
}

rsync-dirs() {
  local host=$1
  local path=$2
  m rsync $dry_run_arg -ahi --relative --delete "$path" "root@$host:/"
}


pre="${0##*/}: "
m() { if $verbose; then printf "$pre%s\n"  "$*"; fi;  "$@"; }
e() { printf "$pre%s\n"  "$*"; }
die() { printf "$pre%s\n" "$*" >&2;  exit 1; }

# latest $MAIL_HOST
if [[ -e /b/bash_unpublished/source-state ]]; then
  source /b/bash_unpublished/source-state
fi

# note q is owned by root:1000

mountpoints=()

rsync_mountpoint=/q

# default options
conf_only=false
dry_run=false # mostly for testing
rate_limit=no
verbose=true; verbose_arg=-v
progress_arg="--progress"
pull_reexec=false

default_args_file=/etc/btrbk-run.conf
if [[ -s $default_args_file ]]; then
  set -- $(< $default_args_file) "$@"
  # i havent used this feature yet, so warn about it
  echo "$0: warning: default btrbk-run options set in $default_args_file (sleeping 5 seconds):"
  cat $default_args_file
  sleep 5
fi

cron=false
orig_args=("$@")
temp=$(getopt -l cron,pull-reexec,help cl:m:npqs:t:vh "$@") || usage 1
eval set -- "$temp"
while true; do
  case $1 in
    --cron)
      cron=true
      pre=
      shift
      ;;
    # only creates the config file, does not run btrbk
    -c) conf_only=true; shift ;;
    # bytes per second, suffix k m g
    -l) rate_limit=$2; shift 2 ;;
    # Comma separated mountpoints to backup. This has defaults set below.
    -m) IFS=, mountpoints=($2); unset IFS; shift 2 ;;
    -n) dry_run=true; dry_run_arg=-n; shift ;;
    -p) progress_arg="--progress"; shift ;;
    --pull-reexec) pull_reexec=true; shift ;;
    -q) verbose=false; verbose_arg=; progress_arg=; shift ;;
    # source host to receive a backup from
    -s) source=$2; shift 2 ;;
    # target hosts to send to. empty is valid for just doing local
    # snapshot. we have default hosts we will populate.
    -t) IFS=, targets=($2); unset IFS; shift 2 ;;
    -v) verbose=true; verbose_arg=-v; shift ;;
    -h|--help) usage ;;
    --) shift; break ;;
    *) die "Internal error!" ;;
  esac
done

# only tested commands are resume and archive
cmd_arg=${1:-run}

case $cmd_arg in
  run|resume|archive) : ;;
  *) die "untested command arg" ;;
esac

if (( $# > 1 )); then
  die: "only 1 nonoption arg is supported"
fi

if [[ -v targets && $source ]]; then
  die "error: -t and -s are mutually exclusive"
fi

if $verbose; then
  printf "options: conf_only=%s\ndry_run=%s\nrate_limit=%s\nverbose=%s\ncmd_arg=%s" "$conf_only" "$dry_run" "$rate_limit" "$verbose" "$cmd_arg"
fi
### end options parsing

# TODO: i wonder if there should be an option to send to the default
# targets, plus any given on the command line.

# set default targets
if [[ ! -v targets && ! $source ]]; then
  if [[ $HOSTNAME != "$MAIL_HOST" ]] && $cron ; then
    echo "MAIL_HOST=$MAIL_HOST, nothing to do"
    exit 0
  fi

  at_work=false

  case $HOSTNAME in
    kw)
      at_work=true
      ;;&
    x2|x3)
      if ping -q -c1 -w1 hal.office.fsf.org \
              && ip n show 192.168.0.26 | grep . &>/dev/null; then
      at_work=true
      fi
      ;;&
    kw|x2|x3)
      if $at_work && ping -q -c1 -w1 iank.vpn.office.fsf.org &>/dev/null; then
        home=iank.vpn.office.fsf.org
      else
        home=b8.nz
      fi
      ;;&
    kw)
      targets=($home x2)
      ;;
    x2|x3)
      targets=($home kw)
      ;;
    tp)
      # kd disabled temporarily while its hot and i plan to work on it.
      #targets=(frodo kd)
      targets=(frodo x3.b8.nz)
      # might not be connected to the vpn
      if timeout -s 9 10 ssh kw :; then
        targets+=(kw)
      fi
      ;;
    kd)
      targets=(frodo tp)
      # might not be connected to the vpn
      if timeout -s 9 10 ssh kw :; then
        targets+=(kw)
      fi
      ;;
    *)
      die "error: no default targets for this host, use -t"
      ;;
  esac
fi

if [[ -v targets ]]; then
  echo "targets: ${targets[*]}"
fi

if [[ $source ]]; then
  echo "source: $source"
fi


if [[ $mountpoints ]]; then
  for mp in ${mountpoints[@]}; do # default mountpoints to sync
    if [[ -e /nocow/btrfs-stale/$mp ]]; then
      die "error: $mp is stale, mount-latest-subvol first"
    fi
  done
else
  # set default mountpoints
  case $HOSTNAME in
    # no remote backups atm. note, if we do enable this, configuration below will need some changes.
    #  frodo)
    #    prospective_mps=(/i)
    #    ;;
    *)
      prospective_mps=(/a /q)
      if [[ $source ]]; then
        source_state="$(ssh $source cat /a/bin/bash_unpublished/source-state)"
        eval "$source_state"
        source_host="$(ssh $source cat /etc/hostname)"
        if [[ $source_host == "$MAIL_HOST" ]]; then
          prospective_mps+=(/o)
        fi
      else
        if [[ $HOSTNAME == "$MAIL_HOST" ]]; then
          prospective_mps+=(/o)
        fi
      fi
      ;;
  esac
  for mp in ${prospective_mps[@]}; do # default mountpoints to sync
    if [[ -e /nocow/btrfs-stale/$mp ]]; then
      e "warning: $mp stale, not adding to default mountpoints"
      continue
    fi
    if awk '{print $2}' /etc/fstab | grep -xF $mp &>/dev/null; then
      mountpoints+=($mp)
    fi
  done
fi

echo "mountpoints: ${mountpoints[*]}"

##### end command line parsing ########

if [[ $source ]]; then
  if [[ $(ssh $source systemctl is-active btrbk.service) != inactive ]]; then
    echo "$0: error: cron btrbk is running on source. exiting out of caution"
    exit 1
  fi
fi

# pull_reexec stops us from getting into an infinite loop if there is some
# kind of weird problem
pulla=false
for m in "${mountpoints[@]}"; do
  if [[ $m == /a ]]; then
    pulla=true
    break
  fi
done
if ! $pull_reexec && [[ $source ]] && $pulla ; then
  tmpf=$(mktemp)
  scp $source:/a/bin/distro-setup/btrbk-run $tmpf
  if ! diff -q $tmpf $BASH_SOURCE; then
    e "found newer version on host $source. reexecing"
    install -T $tmpf /usr/local/bin/btrbk-run
    m /usr/local/bin/btrbk-run --pull-reexec "${orig_args[@]}"
    exit
  fi
fi





if ! which btrbk &>/dev/null; then
  die "error: no btrbk binary found"
fi
# if our mountpoints are from stale snapshots,
# it doesn't make sense to do a backup.
check-subvol-stale ${mountpoints[@]} || die "found stale mountpoints in ${mountpoints[*]}"

# for an initial run, btrbk requires the dir to exist.
mkdir -p /mnt/root/btrbk
local_zone=$(date +%z)

if [[ $source ]]; then
  if ! zone=$(ssh root@$source date +%z); then
    die failed to ssh to root@$source
  fi
  if [[ $zone != $local_zone ]]; then
    die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
  fi

else

  sshable=()
  sshfail=()
  min_idle_ms=$((1000 * 60 * 15))
  for h in ${targets[@]}; do
    if zone=$(ssh root@$h "mkdir -p /mnt/root/btrbk && date +%z"); then
      # This is a separate ssh because xprintidle can fail and thats ok.
      if $cron && idle_ms=$(ssh $h DISPLAY=:0 xprintidle); then
        if (( idle_ms < min_idle_ms )); then

          # Ignore this host. i sometimes use a non-main machine for
          # testing or web browsing, knowing that everything will be wiped
          # by the next backup, but I dont want it to happen as Im using
          # it from cronjob.
          e "warning: $h: active X session in the last 15 minutes, skipping for now"
          continue
        fi
      fi
      sshable+=($h)
      if [[ $zone != $local_zone ]]; then
        die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
      fi
    else
      sshfail+=($h)
    fi
  done
  if [[ ! ${sshable[@]} ]] || { ! $cron && [[ ${sshfail[@]} ]]; }; then
    die "failed to ssh to hosts: ${sshfail[*]}"
  else
    if [[ ${sshfail[@]} ]]; then
      ret=1
      e "error: failed to ssh to ${sshfail[*]} but continuing with other hosts"
    fi
    targets=(${sshable[@]})
  fi
fi


cat >/etc/btrbk.conf <<EOF
ssh_identity /root/.ssh/home
# Just a guess that local7 is a good facility to pick.
# It's a bit odd that the transaction log has to be logged to
# a file or syslog, while other output is sent to std out.
# The man does not mention a way for them to be together, but
# I dunno if setting a log level like warn might also output
# transaction info.
transaction_syslog local7

# note, i had this because man said 20% speedup, but ran into
# this issue, https://github.com/digint/btrbk/issues/275
#stream_buffer 512m

# so we only run one at a time
lockfile                   /var/lock/btrbk.lock

# default format of short does not accomidate hourly preservation setting
timestamp_format long-iso

# only make a snapshot if things have changed
snapshot_create onchange
# I could make this different from target_preserve,
# if one disk had less space.
# for now, keeping them equal.
snapshot_preserve 36h 14d 8w 24m
snapshot_preserve_min 4h
snapshot_dir btrbk

# so, total backups = ~89
target_preserve 36h 14d 8w 24m
target_preserve_min 4h

# if something fails and it's not obvious, try doing
# btrbk -l debug -v dryrun

rate_limit $rate_limit
EOF





vol=/mnt/root
for m in ${mountpoints[@]}; do
  sub=${m##*/}
  if [[ $source ]]; then
    cat >>/etc/btrbk.conf <<EOF
volume ssh://$source$vol
subvolume $sub
target send-receive $vol/btrbk
EOF
  else
    cat >>/etc/btrbk.conf <<EOF
volume $vol
subvolume $sub
EOF
    for tg in ${targets[@]}; do
      cat >>/etc/btrbk.conf <<EOF
target send-receive ssh://$tg$vol/btrbk
EOF
    done
  fi
done


# todo: umount first to ensure we don't have any errors
# todo: do some kill fuser stuff to make umount more reliable


if $conf_only; then
  exit
fi



if $dry_run; then
  m btrbk -v -n $cmd_arg
  exit 0
elif [[ $cmd_arg == archive ]]; then
  if [[ $source ]]; then
    m btrbk $verbose_arg $progress_arg $cmd_arg ssh://$source$vol $vol
  else
    for tg in ${targets[@]}; do
      m btrbk $verbose_arg $progress_arg $cmd_arg $vol ssh://$tg$vol
    done
  fi
  exit 0
fi
# -q and just using the syslog option seemed nice,
# but it doesn't show when a send has a parent and when it doesn't.
m btrbk $verbose_arg $progress_arg $cmd_arg

# if we have it, sync to systems which don't
if mountpoint $rsync_mountpoint >/dev/null; then
  for tg in ${targets[@]}; do
    case $tg in
      li|lk)
        for x in /p/c/machine_specific/*.hosts; do
          if grep -qxF $tg $x; then
            dir=${x%.hosts}
            rsync-dirs $tg $dir
          fi
        done
        ;;
    esac
  done
fi

if [[ $source ]]; then
  m mount-latest-subvol $verbose_arg
else
  m /a/exe/mount-latest-remote ${targets[@]}
fi

exit $ret

# todo: move variable data we don't care about backing up
# to /nocow and symlink it.


# background on btrbk timezones. with short/long, timestamps use local time.
# for long, if your local time moves backwards, by moving timezones or
# for an hour when daylight savings changes it, you will temporarily get
# a more aggressive retention policy for the overlapping period, and
# vice versa for the opposite timezone move. The alternative is using
# long-iso, which puts timezone info into the timestamp, which means
# that instead of shifting time, you shift the start of day/week/month
# which is used for retention to your new local time, which means for
# example, if you moved forward by 8 hours, the daily/weekly/monthly
# retention will be 8 hours more aggressive since midnight is at a new
# time, unless you fake the timzeone using the TZ env variable.
# However, in the short term, there will be no inconsistencies.
# I don't see any problem with shifting when the day starts for
# retention, so I'm using long-iso.

# note to create a long-iso timestamp: date +%Y%m%dT%H%M%S%z