using System;

namespace Chernobyl.Mathematics.Mechanics
{
    /// <summary>
    /// A mechanism that is either up (off) or down (on).
    /// </summary>
    public interface IButton
    {
        /// <summary>
        /// True if the button was down, false if otherwise (set to the previous 
        /// value of IButton.IsDown).
        /// </summary>
        bool WasDown { get; }

        /// <summary>
        /// True if the button is down, false if otherwise.
        /// </summary>
        bool IsDown { get; }

        /// <summary>
        /// An event that is raised when this button is pushed down or turned 
        /// on.
        /// </summary>
        event EventHandler OnDown;

        /// <summary>
        /// An event that is raised when this button has stopped being pushed 
        /// down or is off.
        /// </summary>
        event EventHandler OnUp;

        /// <summary>
        /// An event that is raised when the button's state has changed, i.e. 
        /// the button has gone from up to down or down to up.
        /// </summary>
        event EventHandler OnChange;
    }
}