Facade

• It's a high level API to hide other unnecessary details

class PlumbingSystem {
  // low level access to plumbing system
  setPressure(v: number) {}
  turnOn() {}
  turnOff() {}
}

class ElectricalSystem {
  // low level access to electrical system
  setVoltage(v: number) {}
  turnOn() {}
  turnOff() {}
}

// Facade Class
class House {
  private plumbing = new PlumbingSystem();
  private electrical = new ElectricalSystem();

  // simplify the operation of the internal systems
  public turnOnSystems() {
    this.electrical.setVoltage(120);
    this.electrical.turnOn();
    this.plumbing.setPressure(500);
    this.plumbing.turnOn();
  }

  public shutDown() {
    this.plumbing.turnOff();
    this.electrical.turnOff();
  }
}

const client = new House();
client.turnOnSystems();
client.shutDown();