feat: added basic state machine system & Engine.Systems class library

Engine.Systems/StateMachine/StateBehaviourBase.cs

@@ -0,0 +1,37 @@
+using Syntriax.Engine.Core;
+
+namespace Syntriax.Engine.StateMachine;
+
+public abstract class StateBehaviourBase : Behaviour, IState
+{
+    public event IState.StateUpdateEventHandler? OnStateUpdate = null;
+    public event IState.StateTransitionedFromEventHandler? OnStateTransitionedFrom = null;
+    public event IState.StateTransitionedToEventHandler? OnStateTransitionedTo = null;
+
+    public abstract event IState.StateTransitionReadyEventHandler? OnStateTransitionReady;
+
+    public abstract string Name { get; }
+
+    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, from);
+    }
+
+    protected virtual void OnTransitionedFromState(IState to) { }
+    public void TransitionFrom(IState to)
+    {
+        OnTransitionedFromState(to);
+        OnStateTransitionedFrom?.Invoke(this, to);
+    }
+
+    public abstract IState? GetNextState();
+}