#!/bin/bash

# Paths
BASE=$HOME
PRIMARY=$BASE/primary
REPLICA=$BASE/replica
# Locate Postgres binaries automatically from PATH
BIN=$(pg_config --bindir)

# Clean old dirs
rm -rf $PRIMARY $REPLICA $BASE/archive

# Init primary
$BIN/initdb -D $PRIMARY
echo "archive_mode = on" >> $PRIMARY/postgresql.conf
echo "archive_command = 'cp %p $BASE/archive/%f'" >> $PRIMARY/postgresql.conf
mkdir -p $BASE/archive
$BIN/pg_ctl -D $PRIMARY -l $PRIMARY/logfile start

# Take base backup for replica
$BIN/pg_basebackup -D $REPLICA -h localhost -p 5432 -P -Xs -R

# Change port of replica to 5433
echo "port = 5433" >> $REPLICA/postgresql.conf

$BIN/pg_ctl -D $REPLICA -l $REPLICA/logfile start

# Promote replica (becomes new primary)
$BIN/pg_ctl -D $REPLICA -l $REPLICA/logfile promote

# Stop both clusters
$BIN/pg_ctl -D $PRIMARY -l $PRIMARY/logfile -m immediate stop
$BIN/pg_ctl -D $REPLICA -l $REPLICA/logfile stop

echo "restore_command = 'cp $BASE/archive/%f %p'" >> $PRIMARY/postgresql.conf

# Run pg_rewind (old primary -> follow new primary)
$BIN/pg_rewind --progress --debug -c --source-pgdata=$REPLICA --target-pgdata=$PRIMARY