Syntriax.Engine/Engine.Systems/StateMachine/StateBehaviourBase.cs

using Syntriax.Engine.Core;

namespace Syntriax.Engine.Systems.StateMachine;

public abstract class StateBehaviourBase : Behaviour, IState
{
    public Event<IState> OnStateUpdate { get; } = new();
    public Event<IState, IState.StateTransitionedFromArguments> OnStateTransitionedFrom { get; } = new();
    public Event<IState, IState.StateTransitionedToArguments> OnStateTransitionedTo { get; } = new();
    public Event<IState, IState.StateTransitionReadyArguments> OnStateTransitionReady { get; } = new();
    public Event<INameable, INameable.NameChangedArguments> OnNameChanged { get; } = new();

    private string _name = string.Empty;
    public string Name
    {
        get => _name;
        set
        {
            if (_name.CompareTo(value) == 0)
                return;

            string previousName = _name;
            _name = value;
            OnNameChanged?.Invoke(this, new(previousName));
        }
    }

    protected virtual void OnUpdateState() { }
    public void Update()
    {
        OnUpdateState();
        OnStateUpdate?.Invoke(this);
    }

    protected virtual void OnTransitionedToState(IState from) { }
    public void TransitionTo(IState from)
    {
        OnTransitionedToState(from);
        OnStateTransitionedTo?.Invoke(this, new(from));
    }

    protected virtual void OnTransitionedFromState(IState to) { }
    public void TransitionFrom(IState to)
    {
        OnTransitionedFromState(to);
        OnStateTransitionedFrom?.Invoke(this, new(to));
    }

    public abstract IState? GetNextState();
}