/**
 * Types and guards the rows of `notifications`, and converts them to the
 * {@link Notification} that `GET /api/notifications` answers.
 *
 * @module
 */

import type { SQLOutputValue } from "node:sqlite";
import type {
  Notification,
  NotificationData,
  NotificationType,
} from "../../shared/notification.ts";

/**
 * Stored by the triggers of `notification-service.ts`, and read back by
 * `getNotificationsForUser`.
 */
export interface NotificationRow {
  id: string;
  user_id: string;
  /** A {@link NotificationType}, not checked by the guard. */
  type: string;
  /** The {@link NotificationData} as JSON, not checked by the guard. */
  data: string;
  /** 0 or 1. */
  read: number;
  created_at: string;
  /**
   * Names the event that caused the notification. A unique index keeps a
   * second row with the same `(user_id, source_key)` out; null allows
   * duplicates.
   */
  source_key: string | null;
  [key: string]: SQLOutputValue;
}

/**
 * Checks whether `obj`, a row `getNotificationsForUser` selected, is a
 * {@link NotificationRow}.
 */
export function isNotificationRow(
  obj: unknown,
): obj is NotificationRow {
  return !!obj && typeof obj === "object" &&
    "id" in obj && typeof obj.id === "string" &&
    "user_id" in obj && typeof obj.user_id === "string" &&
    "type" in obj && typeof obj.type === "string" &&
    "data" in obj && typeof obj.data === "string" &&
    "read" in obj && typeof obj.read === "number" &&
    "created_at" in obj && typeof obj.created_at === "string" &&
    "source_key" in obj &&
    (typeof obj.source_key === "string" || obj.source_key === null);
}

/**
 * Converts a row to the {@link Notification} the client gets.
 *
 * @throws {SyntaxError} When `data` isn't valid JSON.
 */
export function notificationRowToApi(row: NotificationRow): Notification {
  return {
    id: row.id,
    userId: row.user_id,
    type: row.type as NotificationType,
    data: JSON.parse(row.data) as NotificationData,
    read: Boolean(row.read),
    createdAt: new Date(row.created_at),
  };
}