MessageStore.ts

import FileStore from "./FileStore";
import StoreCache from "./StoreCache";
import StoreLogger from "./StoreLogger";

export default class MessageStore {
  filestore : FileStore;
  cache: StoreCache;
  logger: StoreLogger;

  constructor(directory: string) {
    this.logger = new StoreLogger();
    this.filestore = new FileStore(directory, this.logger);
    this.cache = new StoreCache(this.logger);
  }

  /**
   *
   * @param id the id of the file to save
   * @param message the text message to write to the file
   *
   * Function writes the file to disk using the id as part
   * of the filename. The id is a number and the file name is
   * formed as a .txt file using the pattern id.txt. Its saved
   * in the relative directory as set in the constructor.
   */
  public async save (id: number, message: string) {
    await this.filestore.save(id, message);
    this.cache.addOrUpdate(id, message);
  }

   /**
   *
   * @param id the id of the file to read
   *
   * Function checks if the file exists and
   * if not returns an empty string.
   * If the file does exist then the function
   * checks if the file id is in the cache and
   * if not will read the contents of the file
   * from disk and add to the cache.
   *
   * @returns message string
   */
  public read(id: number): string {
    if(!this.cache.exists(id)) {
      // Does not exist in cache so read from file
      var message = this.filestore.read(id)
      this.cache.getOrAdd(id, message)
    }
    return this.cache.getOrAdd(id)
  }
}