New Trait: Blood Deficiency (Vault-Overseers#686)

# Description

**Blood Deficiency** is a +2 points negative Physical trait that makes
you slowly lose blood over time. When left untreated you will die from
blood loss. Inspired by the SS13 trait of the same name.

Slash/Piercing weapons and bleeding are much more lethal against you.

The moment you start taking **any** blood loss damage, you start dying
because you can't regenerate blood. Even just two consecutive kitchen
knife stabs will make you bleed enough to die slowly unless you
immediately apply gauze.

Blood packs, iron pills (or copper for Arachnids), and gauze to stop
bleeding will help you survive with this trait.

Here's how the timeline looks for untreated blood deficiency:
- ~0-21 minutes: losing blood slowly
- ~21-31 minutes: blood level below 90%, start taking bloodloss damage
- ~31-33 minutes: critical
- ~34 minutes: death

## Media

<details><summary>Expand</summary>

**Trait entry**


![image](https://github.com/user-attachments/assets/ea4a0c3c-7c05-45fc-8a32-48957701a246)


![image](https://github.com/user-attachments/assets/37398779-90a4-4f4f-a183-38d806184394)

As shown above, even just reducing the blood volume to less than 90%
means you will die a slow and painful death.

</details>

</p>
</details>

# Changelog

:cl: Skubman
- add: Add the Blood Deficiency trait, a new negative trait that makes
you slowly lose blood over time. You must routinely receive blood loss
treatment to live, and even normally non-lethal bleeding can make you
start dying slowly.

Content.Server/Body/Components/BloodstreamComponent.cs

@@ -1,5 +1,6 @@
 using Content.Server.Body.Systems;
 using Content.Server.Chemistry.EntitySystems;
+using Content.Server.Traits.Assorted;
 using Content.Shared.Chemistry.Components;
 using Content.Shared.Chemistry.Reagent;
 using Content.Shared.Damage;
@@ -11,7 +12,7 @@
 
 namespace Content.Server.Body.Components
 {
-    [RegisterComponent, Access(typeof(BloodstreamSystem), typeof(ReactionMixerSystem))]
+    [RegisterComponent, Access(typeof(BloodstreamSystem), typeof(ReactionMixerSystem), typeof(BloodDeficiencySystem))]
     public sealed partial class BloodstreamComponent : Component
     {
         public static string DefaultChemicalsSolutionName = "chemicals";
@@ -171,5 +172,17 @@ public sealed partial class BloodstreamComponent : Component
         /// </summary>
         [ViewVariables(VVAccess.ReadWrite)]
         public TimeSpan StatusTime;
+
+        /// <summary>
+        ///     If this is true, the entity will not passively regenerate blood,
+        ///     and instead will slowly lose blood.
+        /// </summary>
+        public bool HasBloodDeficiency = false;
+
+        /// <summary>
+        ///     How much reagent of blood should be removed with blood deficiency in each update interval?
+        /// </summary>
+        [DataField]
+        public FixedPoint2 BloodDeficiencyLossAmount;
     }
 }

Content.Server/Body/Systems/BloodstreamSystem.cs

@@ -118,11 +118,14 @@ public override void Update(float frameTime)
             if (!_solutionContainerSystem.ResolveSolution(uid, bloodstream.BloodSolutionName, ref bloodstream.BloodSolution, out var bloodSolution))
                 continue;
 
-            // Adds blood to their blood level if it is below the maximum; Blood regeneration. Must be alive.
-            if (bloodSolution.Volume < bloodSolution.MaxVolume && !_mobStateSystem.IsDead(uid))
-            {
-                TryModifyBloodLevel(uid, bloodstream.BloodRefreshAmount, bloodstream);
-            }
+            // Removes blood for Blood Deficiency constantly.
+            if (bloodstream.HasBloodDeficiency)
+                if (!_mobStateSystem.IsDead(uid))
+                    RemoveBlood(uid, bloodstream.BloodDeficiencyLossAmount, bloodstream);
+            // Adds blood to their blood level if it is below the maximum.
+            else if (bloodSolution.Volume < bloodSolution.MaxVolume)
+                if (!_mobStateSystem.IsDead(uid))
+                    TryModifyBloodLevel(uid, bloodstream.BloodRefreshAmount, bloodstream);
 
             // Removes blood from the bloodstream based on bleed amount (bleed rate)
             // as well as stop their bleeding to a certain extent.
@@ -472,4 +475,16 @@ public void ChangeBloodReagent(EntityUid uid, string reagent, BloodstreamCompone
         if (currentVolume > 0)
             _solutionContainerSystem.TryAddReagent(component.BloodSolution.Value, component.BloodReagent, currentVolume, out _);
     }
+
+    /// <summary>
+    ///   Remove blood from an entity, without spilling it.
+    /// </summary>
+    private void RemoveBlood(EntityUid uid, FixedPoint2 amount, BloodstreamComponent? component = null)
+    {
+        if (!Resolve(uid, ref component, logMissing: false)
+            || !_solutionContainerSystem.ResolveSolution(uid, component.BloodSolutionName, ref component.BloodSolution, out var bloodSolution))
+            return;
+
+        bloodSolution.RemoveReagent(component.BloodReagent, amount);
+    }
 }

Content.Server/Traits/BloodDeficiencyComponent.cs

@@ -0,0 +1,14 @@
+namespace Content.Server.Traits.Assorted;
+
+/// <summary>
+///     This is used for the Blood Deficiency trait.
+/// </summary>
+[RegisterComponent]
+public sealed partial class BloodDeficiencyComponent : Component
+{
+    // <summary>
+    //     How much reagent of blood should be removed in each update interval?
+    // </summary>
+    [DataField(required: true)]
+    public float BloodLossAmount;
+}

Content.Server/Traits/BloodDeficiencySystem.cs

@@ -0,0 +1,23 @@
+using Content.Server.Body.Systems;
+using Content.Server.Body.Components;
+using Content.Shared.Damage;
+
+namespace Content.Server.Traits.Assorted;
+
+public sealed class BloodDeficiencySystem : EntitySystem
+{
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<BloodDeficiencyComponent, ComponentStartup>(OnStartup);
+    }
+
+    private void OnStartup(EntityUid uid, BloodDeficiencyComponent component, ComponentStartup args)
+    {
+        if (!TryComp<BloodstreamComponent>(uid, out var bloodstream))
+            return;
+
+        bloodstream.HasBloodDeficiency = true;
+        bloodstream.BloodDeficiencyLossAmount = component.BloodLossAmount;
+    }
+}

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

@@ -23,6 +23,11 @@ trait-description-HeavyweightDrunk = Alcohol is afraid of you.
 trait-name-Muted = Muted
 trait-description-Muted = You can't speak
 
+trait-name-BloodDeficiency = Blood Deficiency
+trait-description-BloodDeficiency =
+    Your body loses more blood than it can replenish.
+    You lose blood over time, and when left untreated you will eventually die from blood loss.
+
 trait-name-Paracusia = Paracusia
 trait-description-Paracusia = You hear sounds that aren't really there
 

Resources/Prototypes/Traits/disabilities.yml

@@ -94,3 +94,17 @@
         - MedicalBorg
   components:
     - type: Snoring
+
+- type: trait
+  id: BloodDeficiency
+  category: Physical
+  points: 2
+  requirements:
+    - !type:CharacterJobRequirement
+      inverted: true
+      jobs:
+        - Borg
+        - MedicalBorg
+  components:
+    - type: BloodDeficiency  # 0.07 = start taking bloodloss damage at around ~21.4 minutes,
+      bloodLossAmount: 0.07  # then become crit ~10 minutes later