#!/bin/bash

# Postgres backup/restore hook for the discourse `db` service.

set -e

BACKUP_FILE='/var/lib/postgresql/data/backup.sql'
export PGPASSWORD=$(cat "${POSTGRES_PASSWORD_FILE:-/run/secrets/db_password}")
DB_USER="${POSTGRES_USER:-discourse}"
DB_NAME="${POSTGRES_DB:-discourse}"

function backup {
  pg_dump -U "$DB_USER" "$DB_NAME" | gzip > "$BACKUP_FILE"
}

function restore {
  cd /var/lib/postgresql/data/

  # Block all non-local connections so the running discourse app + sidekiq cannot reconnect and
  # interfere with the drop/recreate/reimport. Restored on exit.
  restore_hba() {
    cat pg_hba.conf.bak > pg_hba.conf
    rm -f pg_hba.conf.bak
    su postgres -c 'pg_ctl reload'
  }
  cp pg_hba.conf pg_hba.conf.bak
  echo 'local all all trust' > pg_hba.conf
  su postgres -c 'pg_ctl reload'
  trap restore_hba EXIT INT TERM

  # terminate any lingering local sessions before recreate
  # see https://stackoverflow.com/questions/5108876/kill-a-postgresql-session-connection
  psql -U "$DB_USER" -d postgres -c \
    "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname='${DB_NAME}' AND pid<>pg_backend_pid();"

  # drop database and then recreate it
  psql -U "$DB_USER" -d postgres -c "DROP DATABASE ${DB_NAME} WITH (FORCE);"
  createdb -U "$DB_USER" "$DB_NAME"

  # reimport data 
  gunzip -c "$BACKUP_FILE" | psql -U "$DB_USER" -d "$DB_NAME" -1 -v ON_ERROR_STOP=1 -f -
}

$@