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

Engine.Systems/StateMachine/State.cs

@@ -0,0 +1,52 @@
+namespace Syntriax.Engine.StateMachine;
+
+public class State : IState
+{
+    public event IState.StateUpdateEventHandler? OnStateUpdate = null;
+    public event IState.StateTransitionedFromEventHandler? OnStateTransitionedFrom = null;
+    public event IState.StateTransitionedToEventHandler? OnStateTransitionedTo = null;
+    public event IState.StateTransitionReadyEventHandler? OnStateTransitionReady = null;
+
+    private readonly List<StateTransition> transitions = [];
+    private readonly Dictionary<string, StateTransition> possibleTransitions = [];
+
+    public string Name { get; set; } = "Default State Name";
+    public IReadOnlyList<StateTransition> Transitions => transitions;
+    public IReadOnlyDictionary<string, StateTransition> PossibleTransitions => possibleTransitions;
+
+    public void RemoveTransition(string name)
+    {
+        if (!possibleTransitions.TryGetValue(name, out StateTransition stateTransition))
+            return;
+
+        transitions.Remove(stateTransition);
+        possibleTransitions.Remove(name);
+    }
+
+    public void AddTransition(string name, StateTransition stateTransition)
+    {
+        if (transitions.Contains(stateTransition))
+            return;
+
+        transitions.Add(stateTransition);
+        possibleTransitions.Add(name, stateTransition);
+    }
+
+    public void Update()
+    {
+        if (GetNextState() is IState transitionState)
+            OnStateTransitionReady?.Invoke(this, transitionState);
+        OnStateUpdate?.Invoke(this);
+    }
+
+    public void TransitionTo(IState from) => OnStateTransitionedTo?.Invoke(this, from);
+    public void TransitionFrom(IState to) => OnStateTransitionedFrom?.Invoke(this, to);
+
+    public IState? GetNextState()
+    {
+        foreach (StateTransition stateTransition in transitions)
+            if (stateTransition.CanTransition)
+                return stateTransition.State;
+        return null;
+    }
+}