Add prediction to electric grills (#36241)

* Prediction for EntityHeaterSystem

* Switch to Entity<T>

* meh

* Move popup inside ChangeSetting

* Fix grill visually turning on when changing setting while power is off

* Add note about my failed quest

* Why isn't this an IDE warning?

* Move comment above switch expression in SettingPower

Content.Shared/Temperature/Systems/SharedEntityHeaterSystem.cs

@@ -0,0 +1,97 @@
+using Content.Shared.Examine;
+using Content.Shared.Popups;
+using Content.Shared.Power;
+using Content.Shared.Power.EntitySystems;
+using Content.Shared.Temperature.Components;
+using Content.Shared.Verbs;
+using Robust.Shared.Audio.Systems;
+
+namespace Content.Shared.Temperature.Systems;
+
+/// <summary>
+/// Handles <see cref="EntityHeaterComponent"/> events.
+/// </summary>
+public abstract partial class SharedEntityHeaterSystem : EntitySystem
+{
+    [Dependency] private readonly SharedAppearanceSystem _appearance = default!;
+    [Dependency] private readonly SharedPopupSystem _popup = default!;
+    [Dependency] private readonly SharedPowerReceiverSystem _receiver = default!;
+    [Dependency] private readonly SharedAudioSystem _audio = default!;
+
+    private readonly int _settingCount = Enum.GetValues<EntityHeaterSetting>().Length;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<EntityHeaterComponent, ExaminedEvent>(OnExamined);
+        SubscribeLocalEvent<EntityHeaterComponent, GetVerbsEvent<AlternativeVerb>>(OnGetVerbs);
+        SubscribeLocalEvent<EntityHeaterComponent, PowerChangedEvent>(OnPowerChanged);
+    }
+
+    private void OnExamined(Entity<EntityHeaterComponent> ent, ref ExaminedEvent args)
+    {
+        if (!args.IsInDetailsRange)
+            return;
+
+        args.PushMarkup(Loc.GetString("entity-heater-examined", ("setting", ent.Comp.Setting)));
+    }
+
+    private void OnGetVerbs(Entity<EntityHeaterComponent> ent, ref GetVerbsEvent<AlternativeVerb> args)
+    {
+        if (!args.CanAccess || !args.CanInteract)
+            return;
+
+        var nextSettingIndex = ((int)ent.Comp.Setting + 1) % _settingCount;
+        var nextSetting = (EntityHeaterSetting)nextSettingIndex;
+
+        var user = args.User;
+        args.Verbs.Add(new AlternativeVerb()
+        {
+            Text = Loc.GetString("entity-heater-switch-setting", ("setting", nextSetting)),
+            Act = () =>
+            {
+                ChangeSetting(ent, nextSetting, user);
+            }
+        });
+    }
+
+    private void OnPowerChanged(Entity<EntityHeaterComponent> ent, ref PowerChangedEvent args)
+    {
+        // disable heating element glowing layer if theres no power
+        // doesn't actually change the setting since that would be annoying
+        var setting = args.Powered ? ent.Comp.Setting : EntityHeaterSetting.Off;
+        _appearance.SetData(ent, EntityHeaterVisuals.Setting, setting);
+    }
+
+    protected virtual void ChangeSetting(Entity<EntityHeaterComponent> ent, EntityHeaterSetting setting, EntityUid? user = null)
+    {
+        // Still allow changing the setting without power
+        ent.Comp.Setting = setting;
+        _audio.PlayPredicted(ent.Comp.SettingSound, ent, user);
+        _popup.PopupClient(Loc.GetString("entity-heater-switched-setting", ("setting", setting)), ent, user);
+        Dirty(ent);
+
+        // Only show the glowing heating element layer if there's power
+        if (_receiver.IsPowered(ent.Owner))
+            _appearance.SetData(ent, EntityHeaterVisuals.Setting, setting);
+    }
+
+    protected float SettingPower(EntityHeaterSetting setting, float max)
+    {
+        // Power use while off needs to be non-zero so powernet doesn't consider the device powered
+        // by an unpowered network while in the off state. Otherwise, when we increase the load,
+        // the clientside APC receiver will think the device is powered until it gets the next
+        // update from the server, which will cause the heating element to glow for a moment.
+        // I spent several hours trying to figure out a better way to do this using PowerDisabled
+        // or something, but nothing worked as well as this.
+        // Just think of the load as a little LED, or bad wiring, or something.
+        return setting switch
+        {
+            EntityHeaterSetting.Low => max / 3f,
+            EntityHeaterSetting.Medium => max * 2f / 3f,
+            EntityHeaterSetting.High => max,
+            _ => 0.01f,
+        };
+    }
+}