package class8_Lab_RemoteControl_Invoker.other;


import java.util.Deque;
import java.util.LinkedList;

/**
 * This is a "helper" class that handles the details of invocation of specific commands
 * @author hornick
 *
 */
public class Invoker {

    private Deque<Command> stack = new LinkedList<Command>();

    /**
	 * constructor
	 */
	public Invoker() {
	}
	
	/**
	 * tells this to execute its Command immediately
	 */
	public boolean invoke( Command command ) {
        if(null == command) {
            System.out.println("Errro!!!!");
        }

        boolean status;
        status = command.execute();
        if(status) {
            stack.push(command);
        }
		return status;
	}

//	/**
//	 * tells this to undo the last Command (if possible)
//	 */
//	public boolean undo() {
//		return false;
//	}

    /**
     * This method creates a command to undo things.
     * This command actually manipulates the internal
     * stacks of this class as needed to perform
     * the operation.
     * @return the undo command.
     */
    public Command getUndoCommand() {
        return new Command() {
            @Override
            public boolean execute() {
                boolean status;
                Command lastCommand = stack.pollFirst();
                if(null != lastCommand) {
                    status = lastCommand.unexecute();
                } else {
                    status = false;
                }
                return false; // dilemma: If we return true, (e.g. status)
                // THIS gets pushed onto the UNDO stack
                // If we return "false", the command "fails"
            }

            @Override
            public boolean unexecute() {
                return false;  //To change body of implemented methods use File | Settings | File Templates.
            }

            @Override
            public String getCommandName() {
                return "Undo";
            }
        };
    }

}