wallets.ts

// A Singleton Dictionary of User Wallets

import Reports from './reports';

export default class Wallets {
  static instance: Wallets;
  #wallets: { [id: string]: number } = {};
  #reports = new Reports();

  constructor() {
    if (Wallets.instance) {
      return Wallets.instance;
    }
    Wallets.instance = this;
  }

  createWallet(userId: string): boolean {
    // A method to initialize a users wallet
    if (!(userId in this.#wallets)) {
      this.#wallets[userId] = 0;
      this.#reports.logEvent(`wallet for '${userId}' created and set to 0`);
      return true;
    }
    return false;
  }

  getBalance(userId: string): number {
    // A method to check a users balance
    this.#reports.logEvent(
      `Balance check for '${userId}' = ${this.#wallets[userId]}`
    );
    return this.#wallets[userId];
  }

  adjustBalance(userId: string, amount: number): number {
    // A method to adjust a user balance up or down
    this.#wallets[userId] = this.#wallets[userId] + amount;
    this.#reports.logEvent(
      `Balance adjustment for '${userId}'. New balance = ${
        this.#wallets[userId]
      }`
    );
    return this.#wallets[userId];
  }
}