package com.iluwatar.command;

/**

*

* The Command pattern is a behavioral design pattern in which an object is used to encapsulate all information

* needed to perform an action or trigger an event at a later time. This information includes the method name,

* the object that owns the method and values for the method parameters.

* <p>

* Four terms always associated with the command pattern are command, receiver, invoker and client. A command

* object (spell) knows about the receiver (target) and invokes a method of the receiver. Values for parameters of

* the receiver method are stored in the command. The receiver then does the work. An invoker object (wizard)

* knows how to execute a command, and optionally does bookkeeping about the command execution. The invoker

* does not know anything about a concrete command, it knows only about command interface. Both an invoker object

* and several command objects are held by a client object (app). The client decides which commands to execute at

* which points. To execute a command, it passes the command object to the invoker object.

* <p>

* In other words, in this example the wizard casts spells on the goblin. The wizard keeps track of the previous

* spells cast, so it is easy to undo them. In addition, the wizard keeps track of the spells undone, so they

* can be redone.

*

*

*/

public class App {

/**

* Program entry point

* @param args command line args

*/

public static void main(String[] args) {

Wizard wizard = new Wizard();

Goblin goblin = new Goblin();

goblin.printStatus();

wizard.castSpell(new ShrinkSpell(), goblin);

goblin.printStatus();

wizard.castSpell(new InvisibilitySpell(), goblin);

goblin.printStatus();

wizard.undoLastSpell();

goblin.printStatus();

wizard.undoLastSpell();

goblin.printStatus();

wizard.redoLastSpell();

goblin.printStatus();

wizard.redoLastSpell();

goblin.printStatus();

}

}