Telecrystals (and a bit more ECS) (#4775)

Content.Server/Traitor/Uplink/Account/UplinkAccountsSystem.cs

@@ -0,0 +1,90 @@
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Content.Server.Mind.Components;
+using Content.Shared.Traitor.Uplink;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Map;
+
+namespace Content.Server.Traitor.Uplink.Account
+{
+    /// <summary>
+    ///     Manage all registred uplink accounts and their balance
+    /// </summary>
+    public class UplinkAccountsSystem : EntitySystem
+    {
+        [Dependency]
+        private readonly UplinkListingSytem _listingSystem = default!;
+
+        private readonly HashSet<UplinkAccount> _accounts = new();
+
+        public bool AddNewAccount(UplinkAccount acc)
+        {
+            return _accounts.Add(acc);
+        }
+
+
+        /// <summary>
+        /// Add TC to uplinks account balance
+        /// </summary>
+        public bool AddToBalance(UplinkAccount account, int toAdd)
+        {
+            account.Balance += toAdd;
+
+            RaiseLocalEvent(new UplinkAccountBalanceChanged(account, toAdd));
+            return true;
+        }
+
+        /// <summary>
+        /// Charge TC from uplinks account balance
+        /// </summary>
+        public bool RemoveFromBalance(UplinkAccount account, int price)
+        {
+            if (account.Balance - price < 0)
+                return false;
+
+            account.Balance -= price;
+
+            RaiseLocalEvent(new UplinkAccountBalanceChanged(account, -price));
+            return true;
+        }
+
+        /// <summary>
+        /// Force-set TC uplinks account balance to a new value
+        /// </summary>
+        public bool SetBalance(UplinkAccount account, int newBalance)
+        {
+            if (newBalance < 0)
+                return false;
+
+            var dif = newBalance - account.Balance;
+            account.Balance = newBalance;
+            RaiseLocalEvent(new UplinkAccountBalanceChanged(account, dif));
+            return true;
+
+        }
+
+        public bool TryPurchaseItem(UplinkAccount acc, string itemId, EntityCoordinates spawnCoords, [NotNullWhen(true)] out IEntity? purchasedItem)
+        {
+            purchasedItem = null;
+
+            if (!_listingSystem.TryGetListing(itemId, out var listing))
+            {
+                return false;
+            }
+
+            if (acc.Balance < listing.Price)
+            {
+                return false;
+            }
+
+            if (!RemoveFromBalance(acc, listing.Price))
+            {
+                return false;
+            }
+
+            purchasedItem = EntityManager.SpawnEntity(listing.ItemId, spawnCoords);
+            return true;
+        }
+    }
+}