Cleanup factions code (#11075)

Co-authored-by: Kara <lunarautomaton6@gmail.com>

Content.Server/NPC/Components/AiFactionPrototype.cs

@@ -1,17 +0,0 @@
-using Robust.Shared.Prototypes;
-
-namespace Content.Server.NPC.Components
-{
-    [Prototype("aiFaction")]
-    public sealed class AiFactionPrototype : IPrototype
-    {
-        // These are immutable so any dynamic changes aren't saved back over.
-        // AiFactionSystem will just read these and then store them.
-        [ViewVariables]
-        [IdDataField]
-        public string ID { get; } = default!;
-
-        [DataField("hostile")]
-        public IReadOnlyList<string> Hostile { get; private set; } = new List<string>();
-    }
-}

Content.Server/NPC/Components/AiFactionTagComponent.cs

@@ -1,11 +0,0 @@
-using Content.Server.NPC.Systems;
-
-namespace Content.Server.NPC.Components
-{
-    [RegisterComponent]
-    public sealed class AiFactionTagComponent : Component
-    {
-        [DataField("factions")]
-        public Faction Factions { get; set; } = Faction.None;
-    }
-}

Content.Server/NPC/Components/FactionComponent.cs

@@ -0,0 +1,29 @@
+using Content.Server.NPC.Systems;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Prototype.Set;
+
+namespace Content.Server.NPC.Components
+{
+    [RegisterComponent]
+    [Access(typeof(FactionSystem))]
+    public sealed class FactionComponent : Component
+    {
+        /// <summary>
+        /// Factions this entity is a part of.
+        /// </summary>
+        [ViewVariables(VVAccess.ReadWrite),
+         DataField("factions", customTypeSerializer:typeof(PrototypeIdHashSetSerializer<FactionPrototype>))]
+        public HashSet<string> Factions = new();
+
+        /// <summary>
+        /// Cached friendly factions.
+        /// </summary>
+        [ViewVariables]
+        public readonly HashSet<string> FriendlyFactions = new();
+
+        /// <summary>
+        /// Cached hostile factions.
+        /// </summary>
+        [ViewVariables]
+        public readonly HashSet<string> HostileFactions = new();
+    }
+}

Content.Server/NPC/Components/FactionPrototype.cs

@@ -0,0 +1,23 @@
+using Robust.Shared.Prototypes;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Prototype.List;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Prototype.Set;
+
+namespace Content.Server.NPC.Components
+{
+    /// <summary>
+    /// Contains data about this faction's relations with other factions.
+    /// </summary>
+    [Prototype("faction")]
+    public sealed class FactionPrototype : IPrototype
+    {
+        [ViewVariables]
+        [IdDataField]
+        public string ID { get; } = default!;
+
+        [ViewVariables(VVAccess.ReadWrite), DataField("friendly", customTypeSerializer:typeof(PrototypeIdListSerializer<FactionPrototype>))]
+        public List<string> Friendly = new();
+
+        [ViewVariables(VVAccess.ReadWrite), DataField("hostile", customTypeSerializer:typeof(PrototypeIdListSerializer<FactionPrototype>))]
+        public List<string> Hostile = new();
+    }
+}