Changeling last resort (#43820)

* Changeling-LastResort-Stasis

* Update changeling_catalog.yml

* fix

* Merge fix

* fix

* Update ChangelingLastResortSystem.cs

* ConfirmableAction

* fix 2

* Merge

* Update ChangelingLastResortSystem.cs

* review

* sprite

* Update icon.png

* fix

* NightVision

* review

* Interaction

* review review

* misc cleaning

- Moved some components around
- Lowered price of biodegrade and voice mimic
- Updated store locale to make the warning more clear
- Unpredicted "Take Over Body"
- Made cloning copy over entity descriptions

* abstract

* fix

* stuff

* move to API

* fix MobLing

* review

* docs

---------

Co-authored-by: ScarKy0 <scarky0@onet.eu>

Content.Client/Changeling/Systems/ChangelingLastResortSystem.cs

@@ -0,0 +1,5 @@
+using Content.Shared.Changeling.Systems;
+
+namespace Content.Client.Changeling.Systems;
+
+public sealed partial class ChangelingLastResortSystem : SharedChangelingLastResortSystem;

Content.Server/Antag/AntagSelectionSystem.API.Assignment.cs

@@ -497,4 +497,26 @@ public sealed partial class AntagSelectionSystem
         GameTicker.StartGameRule(ruleEnt);
         return (ruleEnt, antag);
     }
+
+    /// <summary>
+    /// Assigns components to an entity based on a <see cref="AntagSpecifierPrototype"/>
+    /// </summary>
+    /// <param name="entity">The entity to give the components.</param>
+    /// <param name="antag">The prototype to apply the components from.</param>
+    [PublicAPI]
+    public void AssignAntagComponents(EntityUid entity, ProtoId<AntagSpecifierPrototype> antag)
+    {
+        // The following is where we apply components, equipment, and other changes to our antagonist entity.
+        if (!ProtoMan.Resolve(antag, out var antagPrototype))
+            return;
+
+        AssignAntagComponents(entity, antagPrototype);
+    }
+
+    /// <inheritdoc cref="AssignAntagComponents(EntityUid,ProtoId{AntagSpecifierPrototype})"/>
+    [PublicAPI]
+    public void AssignAntagComponents(EntityUid entity, AntagSpecifierPrototype antag)
+    {
+        EntityManager.AddComponents(entity, antag.Components);
+    }
 }

Content.Server/Antag/AntagSelectionSystem.cs

@@ -26,6 +26,7 @@ using Content.Shared.GameTicking.Components;
 using Content.Shared.Random.Helpers;
 using Content.Shared.Roles;
 using Content.Shared.Whitelist;
+using JetBrains.Annotations;
 using Robust.Server.Audio;
 using Robust.Server.GameObjects;
 using Robust.Server.Player;
@@ -780,7 +781,7 @@ public sealed partial class AntagSelectionSystem : GameRuleSystem<AntagSelection
             $"Game rule {ToPrettyString(gameRule)}, failed to pre-assign {player.Name} to antag {prototype.ID}");
 
         // The following is where we apply components, equipment, and other changes to our antagonist entity.
-        EntityManager.AddComponents(antag, prototype.Components);
+        AssignAntagComponents(antag, prototype);
 
         // Equip the entity's RoleLoadout and LoadoutGroup
         List<ProtoId<StartingGearPrototype>> gear = new();

Content.Server/Changeling/Systems/ChangelingLastResortSystem.cs

@@ -0,0 +1,109 @@
+using Content.Server.Antag;
+using Content.Shared.Administration.Systems;
+using Content.Shared.Antag;
+using Content.Shared.Changeling.Components;
+using Content.Shared.Changeling.Systems;
+using Content.Shared.DoAfter;
+using Content.Shared.Humanoid;
+using Content.Shared.Mind;
+using Content.Shared.Mobs.Systems;
+using Content.Shared.Popups;
+using Robust.Shared.Prototypes;
+
+namespace Content.Server.Changeling.Systems;
+
+public sealed partial class ChangelingLastResortSystem : SharedChangelingLastResortSystem
+{
+    private static readonly ProtoId<AntagSpecifierPrototype> ChangelingAntag = "Changeling";
+
+    [Dependency] private RejuvenateSystem _rejuvenate = default!;
+    [Dependency] private SharedMindSystem _mind = default!;
+    [Dependency] private MobStateSystem _mobState = default!;
+    [Dependency] private SharedPopupSystem _popup = default!;
+    [Dependency] private SharedDoAfterSystem _doAfter = default!;
+    [Dependency] private AntagSelectionSystem _antag = default!;
+
+    [SubscribeLocalEvent]
+    private void OnTakeOverCorpseAction(Entity<ChangelingSlugComponent> ent,
+        ref ChangelingTakeOverCorpseActionEvent args)
+    {
+        // CanTakeOver checks for the existence of ChangelingIdentityComponent on the target.
+        // As such it cannot be predicted as that component is not networked to sessions other than the owner
+        // Unless we do fucky networking magic
+        if (args.Handled || !CanTakeOver(ent.Owner, args.Target))
+            return;
+
+        args.Handled = true;
+
+        Audio.PlayPvs(ent.Comp.Sound, ent.Owner);
+        _popup.PopupEntity(Loc.GetString("changeling-takeover-start-others", ("user", ent.Owner)),
+            ent.Owner,
+            PopupType.MediumCaution);
+
+        var doAfter = new DoAfterArgs(EntityManager,
+            ent.Owner,
+            ent.Comp.TakeOverDuration,
+            new ChangelingTakeOverCorpseDoAfterEvent(),
+            ent,
+            target: args.Target)
+        {
+            BreakOnDamage = true,
+            BreakOnMove = true,
+            DuplicateCondition = DuplicateConditions.None,
+            RequireCanInteract = false,
+        };
+
+        _doAfter.TryStartDoAfter(doAfter);
+    }
+
+    /// <summary>
+    /// Checks whether a changeling slug can take over the <paramref name="target"/> body.
+    /// </summary>
+    private bool CanTakeOver(EntityUid user, EntityUid target, bool showPopups = true)
+    {
+        if (!HasComp<HumanoidProfileComponent>(target))
+            return false;
+
+        if (HasComp<ChangelingIdentityComponent>(target))
+        {
+            if (showPopups)
+                _popup.PopupEntity(Loc.GetString("changeling-takeover-is-changeling"), user);
+            return false;
+        }
+
+        if (_mobState.IsDead(target))
+            return true;
+
+        if (showPopups)
+            _popup.PopupEntity(Loc.GetString("changeling-takeover-not-dead"), user);
+        return false;
+    }
+
+    [SubscribeLocalEvent]
+    private void OnTakeOverCorpseDoAfter(Entity<ChangelingSlugComponent> ent,
+        ref ChangelingTakeOverCorpseDoAfterEvent args)
+    {
+        args.Handled = true;
+
+        if (args.Cancelled || args.Target is not { } target || !CanTakeOver(args.User, target, showPopups: false))
+            return;
+
+        if (!_mind.TryGetMind(args.User, out var mindId, out var mind))
+            return;
+
+        TakeOverCorpse(args.User, target, mindId, mind);
+
+        _popup.PopupEntity(Loc.GetString("changeling-takeover-success-self"), target, target, PopupType.Large);
+    }
+
+    private void TakeOverCorpse(EntityUid user, EntityUid target, EntityUid mindId, MindComponent mind)
+    {
+        // TODO: delete this after adding the stasis.
+        _rejuvenate.PerformRejuvenate(target);
+        _mind.TransferTo(mindId, target, mind: mind);
+
+        _antag.AssignAntagComponents(target, ChangelingAntag);
+
+        QueueDel(user);
+    }
+}

Content.Server/Cloning/CloningSystem.cs

@@ -88,6 +88,7 @@ public sealed partial class CloningSystem : SharedCloningSystem
 
         // Set the clone's name. The raised events will also adjust their PDA and ID card names.
         _metaData.SetEntityName(clone.Value, originalName, raiseEvents: settings.RaiseEntityRenamedEvent);
+        _metaData.SetEntityDescription(clone.Value, Description(original));
         _identity.QueueIdentityUpdate(clone.Value); // We have to manually refresh the identity in case we did not raise events.
 
         _adminLogger.Add(LogType.Chat, LogImpact.Medium, $"The body of {original:player} was cloned as {clone.Value:player}");

Content.Shared/Changeling/Components/ChangelingLastResortAbilityComponent.cs

@@ -0,0 +1,30 @@
+using Content.Shared.Actions;
+using Robust.Shared.Audio;
+using Robust.Shared.GameStates;
+using Robust.Shared.Prototypes;
+
+namespace Content.Shared.Changeling.Components;
+
+/// <summary>
+/// Allows a changeling to gib their current body and escape as a head slug.
+/// </summary>
+[RegisterComponent, NetworkedComponent]
+public sealed partial class ChangelingLastResortAbilityComponent : Component
+{
+    /// <summary>
+    /// The prototype ID of the slug to spawn.
+    /// </summary>
+    [DataField]
+    public EntProtoId SlugPrototype = "MobHeadSlug";
+
+    /// <summary>
+    /// The sound to play when the changeling gibbs.
+    /// </summary>
+    [DataField]
+    public SoundSpecifier Sound = new SoundCollectionSpecifier("gib", AudioParams.Default.WithVariation(0.025f));
+}
+
+/// <summary>
+/// Action event for Last Resort.
+/// </summary>
+public sealed partial class ChangelingLastResortActionEvent : InstantActionEvent;

Content.Shared/Changeling/Components/ChangelingSlugComponent.cs

@@ -0,0 +1,51 @@
+using Content.Shared.Actions;
+using Content.Shared.DoAfter;
+using Robust.Shared.Audio;
+using Robust.Shared.GameStates;
+using Robust.Shared.Prototypes;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.Changeling.Components;
+
+/// <summary>
+/// Allows a changeling slug to take over a corpse and become a full changeling again.
+/// </summary>
+[RegisterComponent, NetworkedComponent, AutoGenerateComponentState]
+public sealed partial class ChangelingSlugComponent : Component
+{
+    /// <summary>
+    /// The action granted for taking over a corpse.
+    /// </summary>
+    [DataField]
+    public EntProtoId? Action = "ActionChangelingTakeOverCorpse";
+
+    /// <summary>
+    /// The action entity associated with taking over a corpse.
+    /// </summary>
+    [DataField, AutoNetworkedField]
+    public EntityUid? ActionEntity;
+
+    /// <summary>
+    /// How long it takes to take over a corpse.
+    /// </summary>
+    [DataField]
+    public TimeSpan TakeOverDuration = TimeSpan.FromSeconds(5);
+
+    /// <summary>
+    /// The sound to play when starting the takeover.
+    /// </summary>
+    [DataField]
+    public SoundSpecifier? Sound = new SoundPathSpecifier("/Audio/Effects/Fluids/splat.ogg");
+}
+
+/// <summary>
+/// Action event for taking over a corpse.
+/// </summary>
+[ByRefEvent]
+public sealed partial class ChangelingTakeOverCorpseActionEvent : EntityTargetActionEvent;
+
+/// <summary>
+/// DoAfter event for the takeover process.
+/// </summary>
+[Serializable, NetSerializable]
+public sealed partial class ChangelingTakeOverCorpseDoAfterEvent : SimpleDoAfterEvent;

Content.Shared/Changeling/Systems/ChangelingTransformSystem.cs

@@ -195,6 +195,7 @@ public sealed partial class ChangelingTransformSystem : EntitySystem
             _adminLogger.Add(LogType.Action, LogImpact.High, $"{ToPrettyString(ent.Owner):player} successfully transformed into \"{Name(targetIdentity)}\"");
 
         _metaData.SetEntityName(ent, Name(targetIdentity), raiseEvents: false); // Don't raise events because we don't want to rename the ID card.
+        _metaData.SetEntityDescription(ent, Description(targetIdentity));
         _identity.QueueIdentityUpdate(ent); // We have to manually refresh the identity because we did not raise events.
 
         Dirty(ent);

Content.Shared/Changeling/Systems/SharedChangelingLastResortSystem.cs

@@ -0,0 +1,49 @@
+using Content.Shared.Mind;
+using Content.Shared.Actions;
+using Content.Shared.Changeling.Components;
+using Content.Shared.Gibbing;
+using Robust.Shared.Audio.Systems;
+using Robust.Shared.Network;
+
+namespace Content.Shared.Changeling.Systems;
+
+public abstract partial class SharedChangelingLastResortSystem : EntitySystem
+{
+    [Dependency] private INetManager _net = default!;
+    [Dependency] private GibbingSystem _gibbing = default!;
+    [Dependency] private SharedMindSystem _mind = default!;
+    [Dependency] private SharedActionsSystem _actions = default!;
+    [Dependency] protected SharedAudioSystem Audio = default!;
+
+    [SubscribeLocalEvent]
+    private void OnTakeOverMapInit(Entity<ChangelingSlugComponent> ent, ref MapInitEvent args)
+    {
+        _actions.AddAction(ent, ref ent.Comp.ActionEntity, ent.Comp.Action);
+    }
+
+    [SubscribeLocalEvent]
+    private void OnTakeOverShutdown(Entity<ChangelingSlugComponent> ent, ref ComponentShutdown args)
+    {
+        if (ent.Comp.ActionEntity != null)
+            _actions.RemoveAction(ent.Owner, ent.Comp.ActionEntity);
+    }
+
+    [SubscribeLocalEvent]
+    private void OnLastResortAction(Entity<ChangelingLastResortAbilityComponent> ent,
+        ref ChangelingLastResortActionEvent args)
+    {
+        if (args.Handled || !_mind.TryGetMind(args.Performer, out var mindId, out var mind))
+            return;
+
+        args.Handled = true;
+
+        Audio.PlayPredicted(ent.Comp.Sound, args.Performer, args.Performer);
+
+        if (!_net.IsServer)
+            return; // Transfer Mind is unpredictable.
+
+        var slug = PredictedSpawnAtPosition(ent.Comp.SlugPrototype, Transform(args.Performer).Coordinates);
+        _mind.TransferTo(mindId, slug, mind: mind);
+        _gibbing.Gib(args.Performer);
+    }
+}

Resources/Locale/en-US/changeling/changeling.ftl

@@ -42,6 +42,12 @@ changeling-flesh-clothing-alert-desc = Whether clothing transformation is enable
 changeling-biodegrade-used-popup = {CAPITALIZE(THE($user))} vomits acid over {POSS-ADJ($user)} {$restraint}!
 changeling-biodegrade-used-popup-self = We vomit acid over our {$restraint}!
 
+# last resort
+changeling-takeover-not-dead = This body yet lives! We cannot infest it alive.
+changeling-takeover-is-changeling = This body rejects our attempts to take over!
+changeling-takeover-start-others = {CAPITALIZE(THE($user))} begins to crawl inside the corpse!
+changeling-takeover-success-self = We have successfully infested the body and assumed its form.
+
 # stings
 changeling-sting-success = We silently sting {THE($target)}!
 

Resources/Locale/en-US/store/changeling-catalog.ftl

@@ -24,3 +24,8 @@ changeling-catalog-lethal-sting-desc = Causes very slow damage to the target. Us
 
 changeling-catalog-hallucinogenic-sting-name = Hallucinogenic Sting
 changeling-catalog-hallucinogenic-sting-desc = Causes the target to get high and have difficulty speaking. Causes confusion among the crew. Can be used on self.
+
+changeling-catalog-last-resort-name = Last Resort
+changeling-catalog-last-resort-desc = Gib your current body and escape as a weak head slug. If you infest a humanoid corpse, you can return to a full changeling body.
+
+                                      Warning! This resets your progress as a changeling, removing your store purchases and absorbed identities!

Resources/Prototypes/Actions/changeling.yml

@@ -202,3 +202,39 @@
     - !type:AddReagentToBloodstream
       reagent: Cryptobiolin
       quantity: 10 # About 20s of your speech being scrambled
+
+- type: entity
+  parent: BaseAction
+  id: ActionChangelingLastResort
+  name: "[color=red]Last Resort[/color]"
+  description: We sacrifice our current body in a moment of need, violently expanding to break through obstacles and reforming as a headslug.
+  components:
+  - type: ConfirmableAction
+    popup: suicide-action-popup
+  - type: Action
+    raiseOnAction: true
+    checkCanInteract: false # You can transform if you are killed
+    checkConsciousness: false
+    itemIconStyle: BigAction
+    icon:
+      sprite: Interface/Actions/changeling2.rsi
+      state: last_resort
+  - type: InstantAction
+    event: !type:ChangelingLastResortActionEvent
+  - type: ChangelingLastResortAbility
+
+- type: entity
+  parent: BaseAction
+  id: ActionChangelingTakeOverCorpse
+  name: Take Over Corpse
+  description: Infest a corpse to return to your true form.
+  components:
+  - type: Action
+    useDelay: 10
+    itemIconStyle: BigAction
+    icon:
+      sprite: Interface/Actions/changeling2.rsi
+      state: take_over_corpse
+  - type: EntityTargetAction
+    event: !type:ChangelingTakeOverCorpseActionEvent
+  - type: TargetAction

Resources/Prototypes/Catalog/changeling_catalog.yml

@@ -34,7 +34,7 @@
   description: changeling-catalog-voice-mimic-desc
   icon: { sprite: /Textures/Interface/Actions/changeling2.rsi, state: mimicry}
   cost:
-    ChangelingDNA: 20
+    ChangelingDNA: 10
   categories:
   - ChangelingStoreUtility
   conditions:
@@ -49,7 +49,7 @@
   icon: { sprite: /Textures/Interface/Actions/changeling2.rsi, state: biodegrade }
   applyToMob: true
   cost:
-    ChangelingDNA: 20
+    ChangelingDNA: 10
   categories:
   - ChangelingStoreUtility
   conditions:
@@ -130,3 +130,17 @@
   - !type:ListingLimitedStockCondition
     stock: 1
   productAction: ActionChangelingStingHallucinogenic
+
+- type: listing
+  id: ChangelingLastResort
+  name: changeling-catalog-last-resort-name
+  description: changeling-catalog-last-resort-desc
+  applyToMob: true
+  cost:
+    ChangelingDNA: 20
+  categories:
+  - ChangelingStoreUtility
+  conditions:
+  - !type:ListingLimitedStockCondition
+    stock: 1
+  productAction: ActionChangelingLastResort

Resources/Prototypes/Entities/Mobs/Player/changeling.yml

@@ -14,6 +14,53 @@
     balance:
       ChangelingDNA: 60
 
+- type: entity
+  parent: [ SimpleSpaceMobBase, MobNightVision ]
+  id: MobHeadSlug
+  name: headslug
+  description: A small, slug-like creature with a large, gaping maw. It's covered in a thick, slimy mucus.
+  components:
+  - type: Fixtures
+    fixtures:
+      fix1:
+        shape:
+          !type:PhysShapeCircle
+          radius: 0.2
+        density: 15
+        mask:
+        - SmallMobMask
+        layer:
+        - SmallMobLayer
+  - type: Sprite
+    drawdepth: SmallMobs
+    layers:
+    - map: ["enum.DamageStateVisualLayers.Base"]
+      state: slug
+      sprite: Mobs/Animals/headslug.rsi
+  - type: DamageStateVisuals
+    states:
+      Alive:
+        Base: slug
+      Dead:
+        Base: slug_dead
+  - type: MobThresholds
+    thresholds:
+      0: Alive
+      50: Dead
+  - type: MovementSpeedModifier # Slightly faster than regular mobs
+    baseWalkSpeed: 3
+    baseSprintSpeed: 5
+  - type: MeleeWeapon
+    altDisarm: false
+    damage:
+      types:
+        Blunt: 5
+        Structural: 15 # to destroy lockers in which bodies could be hidden
+  - type: ChangelingSlug
+  - type: Tag # Removes DoorBumpOpener
+    tags:
+      []
+
 - type: entity # dummy prototype for the store listing
   id: ChangelingFleshClothingAbilityStoreDummy
   categories: [ HideSpawnMenu ]

Resources/Prototypes/GameRules/roundstart.yml

@@ -209,6 +209,7 @@
   id: Changeling
   parent: [BaseGameRule, BaseRoundstartAntagRule]
   components:
+  - type: ChangelingRule
   - type: GameRule
     minPlayers: 25
   - type: AntagSelection

Resources/Prototypes/Roles/Antags/changeling.yml

@@ -13,7 +13,7 @@
     text: changeling-role-greeting
     color: Red
     sound: /Audio/Ambience/Antag/changeling_start.ogg
-  components:
+  components: # When updating components, remember to copy the changes over to MobLing !!!!!
   - type: ChangelingDevour
   - type: ChangelingIdentity
   - type: ChangelingTransform

Resources/Textures/Interface/Actions/changeling2.rsi/meta.json

@@ -1,7 +1,7 @@
 {
     "version": 1,
     "license": "CC-BY-SA-3.0",
-    "copyright": "Made by ketufaispikinut from a sprite taken from tgstation at commit https://github.com/tgstation/tgstation/commit/c838ba21dae97db345e0113f99596decd1d66039 (scientist suit), a sprite taken from tgstation at commit https://github.com/tgstation/tgstation/commit/c838ba21dae97db345e0113f99596decd1d66039 (hydro suit) and the changeling ability border/background sprites created by TiniestShark. Biodegrade, Mimicry and Extract Dna On/Off, Blind, Mute, Neurodepressant, Cryogenic, Lethal and Hallucination sting by ketufaispikinut, based on TiniestShark's textures. Shop icon by ketufaispikinut, based on TiniestShark's textures.",
+    "copyright": "Made by ketufaispikinut from a sprite taken from tgstation at commit https://github.com/tgstation/tgstation/commit/c838ba21dae97db345e0113f99596decd1d66039 (scientist suit), a sprite taken from tgstation at commit https://github.com/tgstation/tgstation/commit/c838ba21dae97db345e0113f99596decd1d66039 (hydro suit) and the changeling ability border/background sprites created by TiniestShark. Biodegrade, Mimicry and Extract Dna On/Off, Blind, Mute, Neurodepressant, Cryogenic, Lethal and Hallucination sting by ketufaispikinut, based on TiniestShark's textures. Shop icon by ketufaispikinut, based on TiniestShark's textures. last_resort taken from https://github.com/tgstation/tgstation/blob/5c90546a27a1e5ea59b9f127ae274d7341acc70b/icons/mob/actions/actions_changeling.dmi and modified by Pok27 (GitHub). take_over_corpse by Pok27 (GitHub).",
     "size": {
         "x": 32,
         "y": 32
@@ -45,6 +45,12 @@
         },
         {
             "name": "shop"
+        },
+        {
+            "name": "last_resort"
+        },
+        {
+            "name": "take_over_corpse"
         }
     ]
 }

Resources/Textures/Mobs/Animals/headslug.rsi/meta.json

@@ -0,0 +1,21 @@
+{
+    "version": 1,
+    "license": "CC-BY-4.0",
+    "copyright": "Made by ketufaispikinut",
+    "size": {
+        "x": 32,
+        "y": 32
+    },
+    "states": [
+        {
+            "name": "slug",
+            "directions": 4
+        },
+        {
+            "name": "slug_dead"
+        },
+        {
+            "name": "icon"
+        }
+    ]
+}