namespace Chernobyl.DesignPatterns.Command
{
    /// <summary>
    /// An interface for working with types that use the command design pattern 
    /// (see http://en.wikipedia.org/wiki/Command_pattern). 
    /// </summary>
    public interface ICommand
    {
        /// <summary>
        /// Performs the command in question.
        /// </summary>
        void Execute();

        /// <summary>
        /// Causes the command to be reverted if it was previously executed. This 
        /// method only works if <see cref="CanUndo"/> is equal to <c>true</c>.
        /// </summary>
        /// <exception cref="CannotUndoException">Thrown if this 
        /// <see cref="ICommand"/> does not support undo (i.e., 
        /// <see cref="CanUndo"/> is false).</exception>
        void Undo();

        /// <summary>
        /// True if this <see cref="ICommand"/> can be reverted after a call to 
        /// <see cref="Execute()"/>, false if otherwise.
        /// </summary>
        bool CanUndo { get; }
    }
}