#!/bin/bash

# Postgres backup/restore hook for the immich `database` service (VectorChord/pgvecto.rs). Restore
# follows the same pattern as the (green) matrix-synapse recipe — a local-trust `pg_hba` lockout so
# the app can't reconnect and race the reimport — plus the `search_path` rewrite from immich's docs
# (https://docs.immich.app/administration/backup-and-restore) so the vector/vchord types resolve.

set -e

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

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

function restore {
  # Reload pg_hba WITHOUT depending on a client connection — SIGHUP the postmaster directly. This is
  # what guarantees the app is re-admitted at the end even if a psql connection isn't available.
  reload_pg() {
    local pid
    pid=$(head -1 "${PGDATA_DIR}/postmaster.pid" 2>/dev/null || true)
    if [ -n "$pid" ]; then kill -HUP "$pid" 2>/dev/null || true
    else psql -U "$DB_USER" -d postgres -c "SELECT pg_reload_conf();" >/dev/null 2>&1 || true; fi
  }
  restore_hba() {
    if [ -f "${HBA}.ccci.bak" ]; then
      cat "${HBA}.ccci.bak" > "$HBA"
      rm -f "${HBA}.ccci.bak"
      reload_pg
    fi
  }
  # Always re-admit the app, even if any step below fails or the hook is signalled.
  trap restore_hba EXIT INT TERM

  # Lock the networked app out for the duration of the restore: a local-trust-only pg_hba + reload
  # makes postgres reject every TCP connection, so immich-server can't reconnect and re-run its own
  # migrations concurrently with (and conflicting with) the import. Then terminate the connections it
  # already holds so DROP DATABASE can proceed.
  cp "$HBA" "${HBA}.ccci.bak"
  printf 'local all all trust\n' > "$HBA"
  reload_pg
  psql -U "$DB_USER" -d postgres -c \
    "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname='${DB_NAME}' AND pid<>pg_backend_pid();" >/dev/null

  psql -U "$DB_USER" -d postgres -c "DROP DATABASE ${DB_NAME} WITH (FORCE);" >/dev/null
  createdb -U "$DB_USER" "$DB_NAME"
  # Rewrite the empty search_path the VectorChord dump sets so vector/vchord type + operator
  # references resolve during the import (immich upstream restore procedure), then import alone.
  gunzip -c "$BACKUP_FILE" \
    | sed "s/SELECT pg_catalog.set_config('search_path', '', false);/SELECT pg_catalog.set_config('search_path', 'public, pg_catalog', true);/g" \
    | psql -U "$DB_USER" -d "$DB_NAME" --single-transaction --set ON_ERROR_STOP=on >/dev/null

  restore_hba
  trap - EXIT INT TERM
}

$@