#!/bin/bash
# This script is executed by "recovery_1st_stage" to recovery a Standby node.

set -o xtrace

PRIMARY_NODE_PGDATA="$1"
DEST_NODE_HOST="$2"
DEST_NODE_PGDATA="$3"
PRIMARY_NODE_PORT="$4"
DEST_NODE_ID="$5"
DEST_NODE_PORT="$6"

PRIMARY_NODE_HOST=$(hostname)
PGHOME=/usr/pgsql-13
ARCHIVEDIR=/var/lib/pgsql/archivedir
REPLUSER=repl
REPL_SLOT_NAME=$(echo ${DEST_NODE_HOST,,} | tr -- -. _)
POSTGRESQL_STARTUP_USER=postgres
SSH_KEY_FILE=id_rsa_pgpool
SSH_OPTIONS="-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -i ~/.ssh/${SSH_KEY_FILE}"

echo recovery_1st_stage: start: pg_basebackup for Standby node $DEST_NODE_ID

## Test passwordless SSH
ssh -T ${SSH_OPTIONS} ${POSTGRESQL_STARTUP_USER}@${DEST_NODE_HOST} ls /tmp > /dev/null

if [ $? -ne 0 ]; then
    echo recovery_1st_stage: passwordless SSH to ${POSTGRESQL_STARTUP_USER}@${DEST_NODE_HOST} failed. Please setup passwordless SSH.
    exit 1
fi

## Get PostgreSQL major version
PGVERSION=`${PGHOME}/bin/initdb -V | awk '{print $3}' | sed 's/\..*//' | sed 's/\([0-9]*\)[a-zA-Z].*/\1/'`
if [ $PGVERSION -ge 12 ]; then
    RECOVERYCONF=${DEST_NODE_PGDATA}/myrecovery.conf
else
    RECOVERYCONF=${DEST_NODE_PGDATA}/recovery.conf
fi

## Create replication slot "${REPL_SLOT_NAME}"
${PGHOME}/bin/psql -h ${PRIMARY_NODE_HOST} -p ${PRIMARY_NODE_PORT} postgres \
    -c "SELECT pg_create_physical_replication_slot('${REPL_SLOT_NAME}');"  >/dev/null 2>&1

if [ $? -ne 0 ]; then
    echo ERROR: recovery_1st_stage: create replication slot \"${REPL_SLOT_NAME}\" failed. You may need to create replication slot manually.
fi

## Execute pg_basebackup to recovery Standby node
ssh -T ${SSH_OPTIONS} ${POSTGRESQL_STARTUP_USER}@$DEST_NODE_HOST "

    set -o errexit

    rm -rf $DEST_NODE_PGDATA
    rm -rf $ARCHIVEDIR/*

    ${PGHOME}/bin/pg_basebackup -h $PRIMARY_NODE_HOST -U $REPLUSER -p $PRIMARY_NODE_PORT -D $DEST_NODE_PGDATA -X stream

    cat > ${RECOVERYCONF} << EOT
primary_conninfo = 'host=${PRIMARY_NODE_HOST} port=${PRIMARY_NODE_PORT} user=${REPLUSER} application_name=${DEST_NODE_HOST} passfile=''/var/lib/pgsql/.pgpass'''
recovery_target_timeline = 'latest'
primary_slot_name = '${REPL_SLOT_NAME}'
EOT

    if [ ${PGVERSION} -ge 12 ]; then
        sed -i -e \"\\\$ainclude_if_exists = '$(echo ${RECOVERYCONF} | sed -e 's/\//\\\//g')'\" \
               -e \"/^include_if_exists = '$(echo ${RECOVERYCONF} | sed -e 's/\//\\\//g')'/d\" ${DEST_NODE_PGDATA}/postgresql.conf
        touch ${DEST_NODE_PGDATA}/standby.signal
    else
        echo \"standby_mode = 'on'\" >> ${RECOVERYCONF}
    fi

    sed -i \
        -e \"s/#*port = .*/port = ${DEST_NODE_PORT}/\" \
        -e \"s@#*archive_command = .*@archive_command = 'cp \\\"%p\\\" \\\"${ARCHIVEDIR}/%f\\\"'@\" \
        ${DEST_NODE_PGDATA}/postgresql.conf
"

if [ $? -ne 0 ]; then

    ${PGHOME}/bin/psql -h ${PRIMARY_NODE_HOST} -p ${PRIMARY_NODE_PORT} postgres \
        -c "SELECT pg_drop_replication_slot('${REPL_SLOT_NAME}');"  >/dev/null 2>&1

    if [ $? -ne 0 ]; then
        echo ERROR: recovery_1st_stage: drop replication slot \"${REPL_SLOT_NAME}\" failed. You may need to drop replication slot manually.
    fi

    echo ERROR: recovery_1st_stage: end: pg_basebackup failed. online recovery failed
    exit 1
fi

echo recovery_1st_stage: end: recovery_1st_stage is completed successfully
exit 0