remote_and_television_command_pattern.rb

# frozen_string_literal: true


# The command pattern is useful in situations where you want to decouple the requester of an action
# from the object that performs the action, need to support undo/redo functionality, require
# flexibility to dynamically change or extend commands, or aim to encapsulate requests as objects
# for easier management and organization in a software system.

# This pattern can be split in three main components: The receiver, the invoker and the command

# Receiver
class Television
  def turn_on
    puts "#{self.class.name} turned on"
  end

  def change_channel
    puts "#{self.class.name} channel changed"
  end
end

# Command "Interface"
class Command
  def initialize(receiver)
    @receiver = receiver
  end

  def execute
    raise NotImplementedError, 'This is an Abstract class - Subclasses must implement this method'
  end
end

# Command used to turn on a receiver. It can be used with different receivers, such as a television
# or a light, for example
class TurnOnCommand < Command
  def execute
    @receiver.turn_on
  end
end

# Command used to turn off a receiver. It can be used with different receivers, such as a television
# or a light, for example
class ChangeChannelCommand < Command
  def execute
    @receiver.change_channel
  end
end

# Invoker
class RemoteControl
  def initialize
    @commands = {}
  end

  def add_command(key, command)
    @commands[key] = command
  end

  def press_button(key)
    return @commands[key].execute if @commands.key?(key)

    puts 'Command not found'
  end
end

television = Television.new
turn_on_command = TurnOnCommand.new(television)
change_channel_command = ChangeChannelCommand.new(television)

remote_control = RemoteControl.new
remote_control.add_command(:turn_on, turn_on_command)
remote_control.add_command(:change_channel, change_channel_command)

remote_control.press_button(:turn_on) # Same as execute command
remote_control.press_button(:change_channel) # Same as execute command