Facade

// The subsystem: correct, but each class must be used in a specific order with matching config.
class VideoCodec {
  encode(file, format, bitrateKbps) {
    console.log(`Encoding ${file} to ${format} at ${bitrateKbps}kbps`);
    return `${file}.${format}`;
  }
}

class AudioMixer {
  normalize(file) {
    console.log(`Normalizing audio levels for ${file}`);
  }
}

class MetadataWriter {
  writeMetadata(file, title, durationSeconds) {
    console.log(`Writing metadata to ${file}: title="${title}", duration=${durationSeconds}s`);
  }
}

// The Facade: one simple method, correct call order and config handled internally.
class VideoConverterFacade {
  constructor() {
    this.codec = new VideoCodec();
    this.mixer = new AudioMixer();
    this.metadata = new MetadataWriter();
  }

  convertVideo(file, format, title, durationSeconds) {
    const output = this.codec.encode(file, format, 5000);
    this.mixer.normalize(output);
    this.metadata.writeMetadata(output, title, durationSeconds);
    return output;
  }
}

// Simple case: one call, no need to know the subsystem exists.
const converter = new VideoConverterFacade();
converter.convertVideo("vacation.mov", "mp4", "Summer Vacation", 245);

// Advanced case: a caller who needs a custom bitrate still reaches the subsystem directly.
const codec = new VideoCodec();
codec.encode("vacation.mov", "mp4", 12000);

package smarthome

import "fmt"

// The subsystem: independent services, each with their own API.
type Lights struct{}

func (l Lights) TurnOn(room string) {
	fmt.Printf("Lights: turning on in %s\n", room)
}

type Thermostat struct{}

func (t Thermostat) SetTemperature(celsius int) {
	fmt.Printf("Thermostat: setting to %d°C\n", celsius)
}

type SecuritySystem struct{}

func (s SecuritySystem) Disarm() {
	fmt.Println("Security: disarming")
}

// The Facade: one high-level method coordinating three subsystems in the right order.
type SmartHomeFacade struct {
	lights  Lights
	thermo  Thermostat
	arm     SecuritySystem
}

func NewSmartHomeFacade() *SmartHomeFacade {
	return &SmartHomeFacade{}
}

func (f *SmartHomeFacade) GoodMorning() {
	f.arm.Disarm()
	f.lights.TurnOn("kitchen")
	f.thermo.SetTemperature(21)
}

// Usage: one call replaces manually sequencing three subsystems correctly every morning.
func main() {
	home := NewSmartHomeFacade()
	home.GoodMorning()
}