#!/usr/bin/env bash
set -euo pipefail

PATH="/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:${PATH:-}"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
ROOT_DIR="$(cd "${SCRIPT_DIR}/../.." && pwd)"
ENV_FILE="${ROOT_DIR}/.env"
BACKUP_DIR="${BACKUP_DIR:-/volume1/naurua_db_backups/dev}"
FILE_PREFIX="${FILE_PREFIX:-erpnaurua_dev}"
PG_DUMP_BIN="${PG_DUMP_BIN:-$(command -v pg_dump || true)}"
PSQL_BIN="${PSQL_BIN:-$(command -v psql || true)}"

if [[ ! -f "${ENV_FILE}" ]]; then
  echo "Missing environment file: ${ENV_FILE}" >&2
  exit 1
fi

set -a
# shellcheck disable=SC1090
. "${ENV_FILE}"
set +a

for required_var in DB_HOST DB_PORT DB_NAME DB_USER DB_PASSWORD; do
  if [[ -z "${!required_var:-}" ]]; then
    echo "Missing required database setting: ${required_var}" >&2
    exit 1
  fi
done

if [[ -z "${PG_DUMP_BIN}" || ! -x "${PG_DUMP_BIN}" ]]; then
  echo "Compatible pg_dump is required. Set PG_DUMP_BIN to a PostgreSQL client binary." >&2
  exit 1
fi
if [[ -z "${PSQL_BIN}" || ! -x "${PSQL_BIN}" ]]; then
  echo "psql is required." >&2
  exit 1
fi

export PGPASSWORD="${DB_PASSWORD}"
server_version_num="$("${PSQL_BIN}" -h "${DB_HOST}" -p "${DB_PORT}" -U "${DB_USER}" -d "${DB_NAME}" -X -Atqc 'SHOW server_version_num')"
client_version="$("${PG_DUMP_BIN}" --version | sed -E 's/.*PostgreSQL\)?[[:space:]]+([0-9]+).*/\1/')"
server_major="${server_version_num:0:${#server_version_num}-4}"

if [[ -z "${server_major}" || -z "${client_version}" || "${server_major}" != "${client_version}" ]]; then
  echo "pg_dump major version mismatch: server=${server_major:-unknown}, client=${client_version:-unknown}" >&2
  exit 1
fi

mkdir -p "${BACKUP_DIR}"
timestamp="$(date +%Y%m%d_%H%M%S)"
output_file="${BACKUP_DIR}/${FILE_PREFIX}_${DB_NAME}_${timestamp}.dump"
temporary_file="${output_file}.tmp"

cleanup() { rm -f "${temporary_file}"; }
trap cleanup EXIT

"${PG_DUMP_BIN}" -h "${DB_HOST}" -p "${DB_PORT}" -U "${DB_USER}" -d "${DB_NAME}" \
  --format=custom --no-owner --no-privileges > "${temporary_file}"

if [[ ! -s "${temporary_file}" ]]; then
  echo "Backup failed: dump file is empty." >&2
  exit 1
fi

mv -f "${temporary_file}" "${output_file}"
trap - EXIT

find "${BACKUP_DIR}" -maxdepth 1 -type f -name "${FILE_PREFIX}_${DB_NAME}_*.dump" \
  -printf '%T@ %p\n' | sort -nr | tail -n +21 | cut -d' ' -f2- | xargs -r rm -f

printf '%s\n' "Backup created: ${output_file}"