#!/bin/bash

set -e
set -o pipefail
set -u

usage() {
  echo "Usage: $0 [-n <node-list>] [-f] [ -M <newmaster> ] [up|down]"
  echo " -M is for internal use only (used in n>2 clusters if we want to reboot the master first)"
}
error_usage() {
  usage >&2
  exit 1
}

nodelist="node-list"
newmaster=""
force="0"

while getopts "fhn:M:" OPTION; do
  case "$OPTION" in
    f)
      force="1"
      ;;
    h)
      usage
      exit 0
      ;;
    M)
      newmaster="$OPTARG"
      ;;
    n)
      nodelist="$OPTARG"
      if ! [  -e "$nodelist" ]; then
        echo >&2 "nodelist $nodelist not found."
        exit 1
      fi
      ;;
    *)
      error_usage
  esac
done
shift $(($OPTIND - 1))

direction="${1:-up}"
[ "$#" -ge 1 ] && shift
case "$direction" in
  up)   print_list=tac;;
  down) print_list=cat;;
  *) error_usage;;
esac

[ "$#" -gt 0 ] && error_usage

count_instances() {
  gnt-instance list --no-headers -o status --filter '(pnode == "'"$1"'")' | grep -c -v ADMIN_down
}
has_instances() {
  if [ "$(count_instances "$1")" != 0 ]; then
    return 0
  else
    return 1
  fi
}

reboot_host() {
  local tgt
  local max_wait
  local wait_until
  local sleep_time

  tgt="$1"

  if has_instances "$tgt"; then
    echo >&2 "$tgt not empty."
    exit 1
  fi

  ssh -n -l root "$tgt" shutdown -r 1 "'reboot requested by $0 on $(hostname -f)'"

  # wait for target to go down:
  max_wait='300 seconds'
  wait_until=$(date -d "now +$max_wait" +%s)
  while ping -c 5 -q "$tgt" > /dev/null; do
    echo "[$(date)] $tgt is still up (will wait until $(date -d "@$wait_until")."
    sleep 10
    if [ "$(date +%s)" -gt "$wait_until" ]; then
      echo >&2 "Giving up on waiting for $tgt to go down."
      exit 1
    fi
  done

  sleep_time=30
  echo "[$(date)] $tgt is down.  Pausing for $sleep_time seconds"
  sleep "$sleep_time"

  max_wait='15 minutes'
  wait_until=$(date -d "now +$max_wait" +%s)
  while ! ping -c 5 -q "$tgt" > /dev/null; do
    echo "[$(date)] $tgt is still down (will wait until $(date -d "@$wait_until")."
    if [ "$(date +%s)" -gt "$wait_until" ]; then
      echo >&2 "Giving up on waiting for $tgt to come back."
      exit 1
    fi
    sleep 10
  done

  sleep_time=30
  echo "[$(date)] $tgt is up.  Pausing for $sleep_time seconds"
  sleep "$sleep_time"

  max_wait='180 minutes'
  wait_until=$(date -d "now +$max_wait" +%s)
  while ! ssh -n -l root "$tgt" systemctl is-system-running; do
    echo "[$(date)] $tgt is still booting up (will wait until $(date -d "@$wait_until")."
    if [ "$(date +%s)" -gt "$wait_until" ]; then
      echo >&2 "Giving up on waiting for $tgt to come back."
      exit 1
    fi
    sleep 10
  done

  sleep_time=30
  echo "[$(date)] $tgt has finished booting.  Pausing for $sleep_time seconds"
  sleep "$sleep_time"
}

# move down, i.e. from 2 to 1, ..., 14 to 13.
moveupdown() {
  first_tgt="$(${print_list} "$nodelist" | head -n1 | awk '{print $1}')"
  last_node="$(${print_list} "$nodelist" | tail -n1 | awk '{print $1}')"
  me=$(hostname -f)

  if has_instances "$first_tgt"; then
    echo "$first_tgt not empty."
    exit 1
  fi

  if [ "$me" != "$last_node" ]; then
    echo "Making $last_node the new master"
    ssh -n -l root "$last_node" gnt-cluster master-failover
    echo "relaunching reboot-cluster on $last_node"
    tmp="$(ssh -n -l root -t "$last_node" tempfile)"
    scp "$nodelist" "$last_node:$tmp"
    ssh -l root -t "$last_node" screen -S reboot-cluster -m sh -c "\"echo Relaunched on $last_node; ganeti-reboot-cluster -f -n '$tmp' -M '$me' '$direction'; echo ganeti-reboot-cluster exited with \$?.; sleep 12h\""
    echo >&1 "fell through!"
    exit 1
  fi

  ${print_list} "$nodelist" | (
    read tgt dummy
    while read src dummy; do
      if has_instances "$tgt"; then
        echo "$tgt not empty."
        exit 1
      fi
      reboot_host "$tgt"

      if has_instances "$src"; then
        echo "Migrating from $src to $tgt."
        if ! gnt-node migrate -f -n "$tgt" "$src"; then
          echo >&2 "gnt-node migrate exited with an error.  Bailing out."
          exit 1
        fi
      else
        echo "nothing to migrate from $src to $tgt"
      fi
      tgt="$src"
    done

    if has_instances "$tgt"; then
      echo "$tgt not empty."
      exit 1
    fi

    if ! [ "$tgt" = "$me" ]; then
      echo >&2 "I was expecting $tgt to be me ($me) here."
      exit 1
    fi

    if [ "$newmaster" != "" ]; then
      echo "Making $newmaster the new master"
      ssh -n -l root "$newmaster" gnt-cluster master-failover
    fi
    shutdown -r 1 "reboot requested by $0"
    exit
  )
}

crossmigrate() {
  me=$(hostname -f)
  if ! grep -q -F "$me" "$nodelist"; then
    echo >&2 "my hostname ($me) not found in nodelist"
    exit 1
  fi
  them="$(grep -v -F "$me" "$nodelist")"

  echo "Migrating from $them to $me."
  if ! gnt-node migrate -f -n "$me" "$them"; then
    echo >&2 "gnt-node migrate exited with an error.  Bailing out."
    exit 1
  fi
  reboot_host "$them"

  echo "Activating disks.."
  for instance in $( gnt-instance list -o name --no-headers --filter 'status == "running"' ); do
    echo " - $instance ..."
    if ! gnt-instance activate-disks "$instance"; then
      echo >&2 "gnt-instance activate-disks $instance failed.  Bailing out."
      exit 1
    fi
  done

  echo "Migrating from $me to $them."
  if ! gnt-node migrate -f -n "$them" "$me"; then
    echo >&2 "gnt-node migrate exited with an error.  Bailing out."
    exit 1
  fi

  at 'now + 30 min' << 'EOF'
screen -S hbal -d -m sh -c '
  echo "Activating disks.."
  for instance in $( gnt-instance list -o name --no-headers --filter "status == \"running\"" ); do
    echo " - $instance ..."
    if ! gnt-instance activate-disks "$instance"; then
      echo >&2 "Warning: gnt-instance activate-disks $instance failed."
    fi
  done

  hbal -L -C -v -X
  echo "done."
  sleep 1h
'
EOF
  reboot_host "$me"
}

reboot_byrd() {
  /sbin/shutdown -k 30 < /dev/null
  sleep 15m
  gnt-cluster watcher pause 30m

  for i in $(gnt-instance list --no-headers -o name); do
    gnt-instance shutdown --no-remember --submit $i
  done

  while pgrep -c '^qemu-|^kvm$' -u root ; do
    sleep 15;
    gnt-cluster watcher pause 30m
  done

  at 'now + 5 min' << EOF
sleep 4m;
gnt-cluster watcher continue
EOF

  /sbin/shutdown -c
  sleep 5
  /sbin/shutdown -r 1 </dev/null
}

if [ "${TMUX:-}" = "" ] && [ "${STY:-}" = "" ] ; then
  echo >&2 "Might want to launch me in a screen or tmux."
  exit 1
fi

if ! [ "$force" = 1 ]; then
  echo -n 'really? '
  read really
  [ "$really" = "y" ]
fi

### ensure_nodelist
###################
if ! [ -e "$nodelist" ]; then
  tmp="$(tempfile)"
  trap "rm -f '$tmp'" EXIT
  gnt-node list --no-headers -o name > "$tmp"
  nodelist="$tmp"
fi

lines=$(wc -l < "$nodelist")
case "$lines" in
  0) 
    echo >&2 "nodelist $nodelist empty."
    exit 1
    ;;
  1)
    case "$(hostname -f)" in
      byrd.debian.org)
        reboot_byrd
        ;;
      *)
        echo >&2 "Only one node."
        exit 1
    esac
    ;;
  2)
    crossmigrate
    ;;
  *)
    moveupdown
    ;;
esac