SupaLidlGame/State/IState.cs

namespace SupaLidlGame.State;

public interface IState<T> where T : IState<T>
{
    /// <summary>
    /// Called when this state is entered
    /// </summary>
    /// <remarks>
    /// This returns a <c>IState</c> in case a state is being
    /// transitioned to but wants to transition to another state. For
    /// example, an attack state can return to an idle state, but that idle
    /// state can override it to the move state immediately when necessary.
    /// </remarks>
    public IState<T> Enter(IState<T> previousState);

    /// <summary>
    /// Called when the <c>Character</c> exits this <c>CharacterState</c>.
    /// </summary>
    public void Exit(IState<T> nextState);

    public IState<T> Process(double delta) => null;
}