Add extension methods to get a player's id and tests (#3630)

* Add extension methods to get a player's id and tests

* More extensive tests

* Make inventory check for ids first

* Rename to GetHeldId and TryGetHeldId

Content.Server/GameObjects/Components/PDA/PDAExtensions.cs

@@ -0,0 +1,80 @@
+#nullable enable
+using System.Diagnostics.CodeAnalysis;
+using Content.Server.GameObjects.Components.Access;
+using Content.Server.GameObjects.Components.GUI;
+using Content.Server.Interfaces.GameObjects.Components.Items;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.GameObjects.Components.PDA
+{
+    public static class PdaExtensions
+    {
+        /// <summary>
+        ///     Gets the id that a player is holding in their hands or inventory.
+        ///     Order: Hands > ID slot > PDA in ID slot
+        /// </summary>
+        /// <param name="player">The player to check in.</param>
+        /// <returns>The id card component.</returns>
+        public static IdCardComponent? GetHeldId(this IEntity player)
+        {
+            IdCardComponent? firstIdInPda = null;
+
+            if (player.TryGetComponent(out IHandsComponent? hands))
+            {
+                foreach (var item in hands.GetAllHeldItems())
+                {
+                    if (firstIdInPda == null &&
+                        item.Owner.TryGetComponent(out PDAComponent? pda) &&
+                        pda.ContainedID != null)
+                    {
+                        firstIdInPda = pda.ContainedID;
+                    }
+
+                    if (item.Owner.TryGetComponent(out IdCardComponent? card))
+                    {
+                        return card;
+                    }
+                }
+            }
+
+            if (firstIdInPda != null)
+            {
+                return firstIdInPda;
+            }
+
+            IdCardComponent? firstIdInInventory = null;
+
+            if (player.TryGetComponent(out InventoryComponent? inventory))
+            {
+                foreach (var item in inventory.GetAllHeldItems())
+                {
+                    if (firstIdInInventory == null &&
+                        item.TryGetComponent(out PDAComponent? pda) &&
+                        pda.ContainedID != null)
+                    {
+                        firstIdInInventory = pda.ContainedID;
+                    }
+
+                    if (item.TryGetComponent(out IdCardComponent? card))
+                    {
+                        return card;
+                    }
+                }
+            }
+
+            return firstIdInInventory;
+        }
+
+        /// <summary>
+        ///     Gets the id that a player is holding in their hands or inventory.
+        ///     Order: Hands > ID slot > PDA in ID slot
+        /// </summary>
+        /// <param name="player">The player to check in.</param>
+        /// <param name="id">The id card component.</param>
+        /// <returns>true if found, false otherwise.</returns>
+        public static bool TryGetHeldId(this IEntity player, [NotNullWhen(true)] out IdCardComponent? id)
+        {
+            return (id = player.GetHeldId()) != null;
+        }
+    }
+}