Utility System basics added ; however, it is currently implemented to be easy to debug / edit through the inspector, and can be improved performance wise if needed

Author: ThomasProg

Runtime/Action.cs

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+using System.Collections;
+using System.Collections.Generic;
+using Unity.Collections;
+using UnityEngine;
+using UnityEngine.Events;
+
+
+public class Action : MonoBehaviour
+{
+    [System.Serializable]
+    struct StatImportance
+    {
+        public string statName;
+
+        [SerializeField]
+        public AnimationCurve curve; // must return a value between 0 and 1.
+    }
+
+    [SerializeField]
+    float defaultImportance = 0f;
+
+    [SerializeField]
+    public int priority = 0;
+
+    [SerializeField]
+    List<StatImportance> statsImportance = new List<StatImportance>();
+
+    [SerializeField]
+    UnityEvent<Action> onStart;
+    [SerializeField]
+    UnityEvent<Action> onEnd;
+
+    [SerializeField]
+    float lastEvaluation = 0f;
+
+
+    // STATS
+    public float TotalDurationDoingAction
+    {
+        get;
+        private set;
+    }
+
+
+
+    public float EvaluateUtility(Blackboard bb)
+    {
+        float totalImportance = defaultImportance;
+
+        foreach (StatImportance statImportance in statsImportance)
+        {
+            Stat stat = bb.stats.Find((Stat s) => { return s.name == statImportance.statName; });
+            if (stat != null)
+                totalImportance += statImportance.curve.Evaluate(stat.Ratio);
+            else
+            {
+                Debug.LogWarning("Stat not found : " + statImportance.statName);
+            }
+        }
+
+        lastEvaluation = Mathf.Clamp(totalImportance, 0, 1);
+
+        return lastEvaluation;
+    }
+
+    public virtual void StartAction()
+    {
+        onStart?.Invoke(this);
+    }
+
+    public virtual void UpdateAction()
+    {
+        TotalDurationDoingAction += Time.deltaTime;
+    }
+
+    public virtual void EndAction()
+    {
+        onEnd?.Invoke(this);
+    }
+}

Runtime/Blackboard.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class Blackboard : MonoBehaviour
+{
+    [SerializeField]
+    public List<Stat> stats = new List<Stat>();
+}

Runtime/Stat.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.Events;
+
+[System.Serializable]
+public class Stat : MonoBehaviour
+{
+    [SerializeField]
+    private float ratio;
+    public float Ratio
+    {
+        get { return ratio; }
+        set 
+        {
+            ratio = Mathf.Clamp(value, 0, 1);
+        }
+    }
+};

Runtime/UtilitySystem.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+
+
+public class UtilitySystem : MonoBehaviour
+{
+    [SerializeField]
+    List<Action> actions = new List<Action>();
+    public List<Action> Actions
+    {
+        get { return actions; }
+    }
+
+
+    [SerializeField]
+    Blackboard bb;
+
+    Action currentAction = null;
+
+    public Action CurrentAction
+    {
+        get { return currentAction; }
+    }
+
+
+
+    private void Start()
+    {
+        if (currentAction != null)
+        {
+            currentAction.StartAction();
+        }
+    }
+
+    private void Update()
+    {
+        float highestUtility = 0f;
+        Action newAction = null;
+        foreach (Action action in actions)
+        {
+            float utility = action.EvaluateUtility(bb);
+            if (utility > highestUtility || (newAction != null && utility == highestUtility && action.priority > newAction.priority))
+            {
+                newAction = action;
+                highestUtility = utility;
+            }
+        }
+
+        if (newAction == null)
+        {
+            newAction = actions[Random.Range(0, actions.Count)];
+        }
+
+        if (newAction != currentAction)
+        {
+            if (currentAction  != null)
+                currentAction.EndAction();
+
+            currentAction = newAction;
+            currentAction.StartAction();
+        }
+
+        // Call update atleast 1 time, even if StartAction() has been called during the same frame
+        currentAction.UpdateAction();
+    }
+}