Allow solutions to store extra reagent data (#19323)

Content.Shared/Chemistry/Reagent/ReagentId.cs

@@ -0,0 +1,93 @@
+using Content.Shared.FixedPoint;
+using Robust.Shared.Serialization;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Prototype;
+
+namespace Content.Shared.Chemistry.Reagent;
+
+/// <summary>
+/// Struct used to uniquely identify a reagent. This is usually just a ReagentPrototype id string, however some reagents
+/// contain additional data (e.g., blood could store DNA data).
+/// </summary>
+[Serializable, NetSerializable]
+[DataDefinition]
+public partial struct ReagentId : IEquatable<ReagentId>
+{
+    // TODO rename data field.
+    [DataField("ReagentId", customTypeSerializer: typeof(PrototypeIdSerializer<ReagentPrototype>), required: true)]
+    public string Prototype { get; private set; }
+
+    /// <summary>
+    /// Any additional data that is unique to this reagent type. E.g., for blood this could be DNA data.
+    /// </summary>
+    [DataField("data")]
+    public ReagentData? Data { get; private set; }
+
+    public ReagentId(string prototype, ReagentData? data)
+    {
+        Prototype = prototype;
+        Data = data;
+    }
+
+    public ReagentId()
+    {
+        Prototype = default!;
+    }
+
+    public bool Equals(ReagentId other)
+    {
+        if (Prototype != other.Prototype)
+            return false;
+
+        if (Data == null)
+            return other.Data == null;
+
+        if (other.Data == null)
+            return false;
+
+        if (Data.GetType() != other.Data.GetType())
+            return false;
+
+        return Data.Equals(other.Data);
+    }
+
+    public bool Equals(string prototype, ReagentData? otherData = null)
+    {
+        if (Prototype != prototype)
+            return false;
+
+        if (Data == null)
+            return otherData == null;
+
+        return Data.Equals(otherData);
+    }
+
+    public override bool Equals(object? obj)
+    {
+        return obj is ReagentId other && Equals(other);
+    }
+
+    public override int GetHashCode()
+    {
+        return HashCode.Combine(Prototype, Data);
+    }
+
+    public string ToString(FixedPoint2 quantity)
+    {
+        return Data?.ToString(Prototype, quantity) ?? $"{Prototype}:{quantity}";
+    }
+
+    public override string ToString()
+    {
+        return Data?.ToString(Prototype) ?? Prototype;
+    }
+
+    public static bool operator ==(ReagentId left, ReagentId right)
+    {
+        return left.Equals(right);
+    }
+
+    public static bool operator !=(ReagentId left, ReagentId right)
+    {
+        return !(left == right);
+    }
+}