Add utility AI (#806)

Co-authored-by: Pieter-Jan Briers <pieterjan.briers@gmail.com>
Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>
Co-authored-by: Pieter-Jan Briers <pieterjan.briers+git@gmail.com>

Content.Server/AI/Operators/Combat/Ranged/ShootAtEntityOperator.cs

@@ -0,0 +1,100 @@
+using Content.Server.GameObjects;
+using Content.Server.GameObjects.Components.Mobs;
+using Content.Server.GameObjects.Components.Movement;
+using Content.Server.GameObjects.Components.Weapon.Ranged;
+using Robust.Shared.Interfaces.GameObjects;
+
+
+namespace Content.Server.AI.Operators.Combat.Ranged
+{
+    public class ShootAtEntityOperator : AiOperator
+    {
+        private IEntity _owner;
+        private IEntity _target;
+        private float _accuracy;
+
+        private float _burstTime;
+
+        private float _elapsedTime;
+
+        public ShootAtEntityOperator(IEntity owner, IEntity target, float accuracy, float burstTime = 0.5f)
+        {
+            _owner = owner;
+            _target = target;
+            _accuracy = accuracy;
+            _burstTime = burstTime;
+        }
+
+        public override bool TryStartup()
+        {
+            if (!base.TryStartup())
+            {
+                return true;
+            }
+            
+            if (!_owner.TryGetComponent(out CombatModeComponent combatModeComponent))
+            {
+                return false;
+            }
+
+            if (!combatModeComponent.IsInCombatMode)
+            {
+                combatModeComponent.IsInCombatMode = true;
+            }
+
+            return true;
+        }
+
+        public override void Shutdown(Outcome outcome)
+        {
+            base.Shutdown(outcome);
+            if (_owner.TryGetComponent(out CombatModeComponent combatModeComponent))
+            {
+                combatModeComponent.IsInCombatMode = false;
+            }
+        }
+
+        public override Outcome Execute(float frameTime)
+        {
+            // TODO: Probably just do all the checks on first try and then after that repeat the fire.
+            if (_burstTime <= _elapsedTime)
+            {
+                return Outcome.Success;
+            }
+
+            _elapsedTime += frameTime;
+
+            if (_target.TryGetComponent(out DamageableComponent damageableComponent))
+            {
+                if (damageableComponent.IsDead())
+                {
+                    return Outcome.Success;
+                }
+            }
+            
+            if (!_owner.TryGetComponent(out HandsComponent hands) || hands.GetActiveHand == null)
+            {
+                return Outcome.Failed;
+            }
+
+            var equippedWeapon = hands.GetActiveHand.Owner;
+
+            if ((_target.Transform.GridPosition.Position - _owner.Transform.GridPosition.Position).Length >
+                _owner.GetComponent<AiControllerComponent>().VisionRadius)
+            {
+                // Not necessarily a hard fail, more of a soft fail
+                return Outcome.Failed;
+            }
+
+            // Unless RangedWeaponComponent is removed from hitscan weapons this shouldn't happen
+            if (!equippedWeapon.TryGetComponent(out RangedWeaponComponent rangedWeaponComponent))
+            {
+                return Outcome.Failed;
+            }
+
+            // TODO: Accuracy
+            rangedWeaponComponent.AiFire(_owner, _target.Transform.GridPosition);
+            return Outcome.Continuing;
+        }
+    }
+}