Predict EMPs (#39802)

* predicted emps

* fixes

* fix

* review

Content.Shared/Power/EntitySystems/SharedBatterySystem.cs

@@ -0,0 +1,44 @@
+using Content.Shared.Emp;
+using Content.Shared.Power.Components;
+
+namespace Content.Shared.Power.EntitySystems;
+
+public abstract class SharedBatterySystem : EntitySystem
+{
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<BatteryComponent, EmpPulseEvent>(OnEmpPulse);
+    }
+
+    private void OnEmpPulse(EntityUid uid, BatteryComponent component, ref EmpPulseEvent args)
+    {
+        args.Affected = true;
+        UseCharge(uid, args.EnergyConsumption, component);
+        // Apply a cooldown to the entity's self recharge if needed to avoid it immediately self recharging after an EMP.
+        TrySetChargeCooldown(uid);
+    }
+
+    public virtual float UseCharge(EntityUid uid, float value, BatteryComponent? battery = null)
+    {
+        return 0f;
+    }
+
+    public virtual void SetMaxCharge(EntityUid uid, float value, BatteryComponent? battery = null) { }
+
+    public virtual float ChangeCharge(EntityUid uid, float value, BatteryComponent? battery = null)
+    {
+        return 0f;
+    }
+
+    /// <summary>
+    /// Checks if the entity has a self recharge and puts it on cooldown if applicable.
+    /// </summary>
+    public virtual void TrySetChargeCooldown(EntityUid uid, float value = -1) { }
+
+    public virtual bool TryUseCharge(EntityUid uid, float value, BatteryComponent? battery = null)
+    {
+        return false;
+    }
+}