/*!
 * Original code by Remix Sofware Inc
 * MIT Licensed, Copyright(c) 2021 Remix software Inc, see LICENSE.remix.md for details
 * 
 * Credits to the Remix team:
 * https://github.com/remix-run/remix/blob/main/packages/remix-server-runtime/memoryStorage.ts
 */
import type {
  CreateSessionStorageFunction,
  SessionData,
  SessionIdStorageStrategy,
  SessionStorage
} from "./sessions";

interface MemorySessionStorageOptions {
  /**
   * The Cookie used to store the session id on the client, or options used
   * to automatically create one.
   */
  cookie?: SessionIdStorageStrategy["cookie"];
}

export type CreateMemorySessionStorageFunction = (
  options?: MemorySessionStorageOptions
) => SessionStorage;

/**
 * Creates and returns a simple in-memory SessionStorage object, mostly useful
 * for testing and as a reference implementation.
 *
 * Note: This storage does not scale beyond a single process, so it is not
 * suitable for most production scenarios.
 *
 * @see https://remix.run/api/remix#creatememorysessionstorage
 */
export const createMemorySessionStorageFactory =
  (createSessionStorage: CreateSessionStorageFunction): CreateMemorySessionStorageFunction =>
  ({ cookie } = {}) => {
    let uniqueId = 0;
    let map = new Map<string, { data: SessionData; expires?: Date }>();

    return createSessionStorage({
      cookie,
      async createData(data, expires) {
        let id = (++uniqueId).toString();
        map.set(id, { data, expires });
        return id;
      },
      async readData(id) {
        if (map.has(id)) {
          let { data, expires } = map.get(id)!;

          if (!expires || expires > new Date()) {
            return data;
          }

          // Remove expired session data.
          if (expires) map.delete(id);
        }

        return null;
      },
      async updateData(id, data, expires) {
        map.set(id, { data, expires });
      },
      async deleteData(id) {
        map.delete(id);
      }
    });
  };