#!/bin/bash
Version=1.0.6

# Usage: failover_p4d_from_this_host.sh SDP_INSTANCE Style Type BackupHost NO_OP
# This is intended to be called by 'hms', not directly by a human.

# Micro-functions.
function msg () { echo -e "$*"; }
function bail () { msg "\nError: ${1:-Unknown Error}\n"; exit ${2:-1}; }
function usage () { msg "Usage:\n\t$UsageSummary\n"; exit 2; }
function cmd () {
   if [[ $NO_OP -eq 0 ]]; then
      msg "Running: $*"
      $*
      return $?
   else
      msg "NO_OP: Would run: $*"
   fi
}

# Do nothing unless usage is correct.
export SDP_INSTANCE=${1:-Unset}
declare Style=${2:-Unset}
declare Type=${3:-Unset}
declare BackupHost=${4:-Unset}
declare NO_OP=${5:-Unset}
declare ThisScript=${0##*/}
declare UsageSummary="$ThisScript SDP_INSTANCE Style Type BackupHost NO_OP"
declare P4DInitScript=/p4/$SDP_INSTANCE/bin/p4d_${SDP_INSTANCE}_init

[[ $# -eq 5 ]] || bail "Bad Usage!  Usage:\n\t$UsageSummary\n"

msg "Starting $ThisScript v$Version on ${HOSTNAME%%.*} at $(date)."
msg "Args: I=$SDP_INSTANCE S=$Style T=$Type BH=$BackupHost NO_OP=$NO_OP"

# Load SDP controlled shell environment.
source /p4/common/bin/p4_vars "$SDP_INSTANCE" || \
   bail "Failed to load SDP environment for instance $SDP_INSTANCE."

[[ $(id -u -n) == $OSUSER ]] || bail "$0 can only be run by $OSUSER"

[[ $NO_OP -eq 1 ]] && msg "NO_OP: Preview Mode Enabled."

[[ -x $P4DInitScript ]] || bail "$P4DInitScript is not executable."

# For unscheduled failover, we attempt to top the server to prevent
# split brain, and nothing more.  The host alias must be also be
# changed externally to this automation.
cmd $P4DInitScript stop

[[ ${SERVERID^^} == *"MASTER"* || "${SERVERID^^} == *"_EDGE_"* ]] ||\
   bail "Instance $SDP_INSTANCE ServerID ($SERVERID) indicates it not a master or edge server! Aborting further failover processing on host ${HOSTNAME%%.*}."

# For scheduled failover, we go further and preserve the original journal
# file verbatim.

if [[ $Style == Scheduled ]]; then
   cmd scp -q -p $P4JOURNAL $BackupHost:$P4JOURNAL.from_old_master ||\
      bail "Failed to scp $P4JOURNAL to backup host $BackupHost:$P4JOURNAL.from_old_master."
fi