ECSatize AlertsSystem (#5559)

Content.Shared/Alert/AlertKey.cs

@@ -0,0 +1,62 @@
+using System;
+using Robust.Shared.Serialization;
+using Robust.Shared.Serialization.Manager;
+
+namespace Content.Shared.Alert;
+
+/// <summary>
+/// Key for an alert which is unique (for equality and hashcode purposes) w.r.t category semantics.
+/// I.e., entirely defined by the category, if a category was specified, otherwise
+/// falls back to the id.
+/// </summary>
+[Serializable, NetSerializable]
+public struct AlertKey : ISerializationHooks, IPopulateDefaultValues
+{
+    public AlertType? AlertType { get; private set; }
+    public readonly AlertCategory? AlertCategory;
+
+    /// NOTE: if the alert has a category you must pass the category for this to work
+    /// properly as a key. I.e. if the alert has a category and you pass only the alert type, and you
+    /// compare this to another AlertKey that has both the category and the same alert type, it will not consider them equal.
+    public AlertKey(AlertType? alertType, AlertCategory? alertCategory)
+    {
+        AlertCategory = alertCategory;
+        AlertType = alertType;
+    }
+
+    public bool Equals(AlertKey other)
+    {
+        // compare only on alert category if we have one
+        if (AlertCategory.HasValue)
+        {
+            return other.AlertCategory == AlertCategory;
+        }
+
+        return AlertType == other.AlertType && AlertCategory == other.AlertCategory;
+    }
+
+    public override bool Equals(object? obj)
+    {
+        return obj is AlertKey other && Equals(other);
+    }
+
+    public override int GetHashCode()
+    {
+        // use only alert category if we have one
+        if (AlertCategory.HasValue) return AlertCategory.GetHashCode();
+        return AlertType.GetHashCode();
+    }
+
+    public void PopulateDefaultValues()
+    {
+        AlertType = Alert.AlertType.Error;
+    }
+
+    /// <param name="category">alert category, must not be null</param>
+    /// <returns>An alert key for the provided alert category. This must only be used for
+    /// queries and never storage, as it is lacking an alert type.</returns>
+    public static AlertKey ForCategory(AlertCategory category)
+    {
+        return new(null, category);
+    }
+}