#!/bin/bash

# Postgres backup/restore hook for the `postgres` service. Invoked by backupbot-two via:
#   backupbot.backup.pre-hook     = "/pg_backup.sh backup"
#   backupbot.backup.volumes.postgres_data.path = "backup.sql"
#   backupbot.restore.post-hook   = "/pg_backup.sh restore"
# Backup dumps the DB to backup.sql (gzip) inside the postgres volume; backupbot archives it.
# Restore reimports it. The mattermost app keeps TCP connections open to the DB, so restore must
# terminate them and FORCE-drop before recreating, then reimport the dump deterministically — the
# previous recipe shipped no restore hook (file-level PGDATA restore did not reload into the running
# postgres), so a restored backup silently kept the live (un-restored) state.

set -e

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

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

function restore {
  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();"
  psql -U "$DB_USER" -d postgres -c "DROP DATABASE ${DB_NAME} WITH (FORCE);"
  createdb -U "$DB_USER" "$DB_NAME"
  gunzip -c "$BACKUP_FILE" | psql -U "$DB_USER" -d "$DB_NAME" -1 -v ON_ERROR_STOP=1 -f -
}

$@