Introduce IUpgradable and purchasable unit upgrades.

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -83,6 +83,12 @@ namespace OpenRA.Traits
 	public interface INotifyHarvest { void Harvested(Actor self, ResourceType resource); }
 	public interface INotifyInfiltrated { void Infiltrated(Actor self, Actor infiltrator); }
 
+	public interface IUpgradable
+	{
+		bool AcceptsUpgrade(string type);
+		void UpgradeAvailable(Actor self, string type, bool available);
+	}
+
 	public interface ISeedableResource { void Seed(Actor self); }
 
 	public interface IDemolishableInfo { bool IsValidTarget(ActorInfo actorInfo, Actor saboteur); }

OpenRA.Mods.RA/GlobalUpgradable.cs

@@ -0,0 +1,62 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using OpenRA.Mods.RA;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	public class GlobalUpgradableInfo : ITraitInfo
+	{
+		public readonly string[] Upgrades = { };
+		public readonly string[] Prerequisites = { };
+
+		public object Create(ActorInitializer init) { return new GlobalUpgradable(init.self, this); }
+	}
+
+	public class GlobalUpgradable : INotifyAddedToWorld
+	{
+		readonly GlobalUpgradableInfo info;
+		readonly GlobalUpgradeManager manager;
+
+		public GlobalUpgradable(Actor actor, GlobalUpgradableInfo info)
+		{
+			this.info = info;
+			manager = actor.Owner.PlayerActor.Trait<GlobalUpgradeManager>();
+		}
+
+		public void AddedToWorld(Actor self)
+		{
+			if (info.Prerequisites.Any())
+				manager.Register(self, this, info.Prerequisites);
+		}
+
+		public void RemovedFromWorld(Actor self)
+		{
+			if (info.Prerequisites.Any())
+				manager.Unregister(self, this, info.Prerequisites);
+		}
+
+		public void PrerequisitesUpdated(Actor self, bool available)
+		{
+			var upgrades = self.TraitsImplementing<IUpgradable>();
+			foreach (var u in upgrades)
+			{
+				foreach (var t in info.Upgrades)
+					if (u.AcceptsUpgrade(t))
+						u.UpgradeAvailable(self, t, available);
+			}
+		}
+	}
+}

OpenRA.Mods.RA/OpenRA.Mods.RA.csproj

@@ -550,6 +550,8 @@
     <Compile Include="Graphics\ActorPreview.cs" />
     <Compile Include="Graphics\SpriteActorPreview.cs" />
     <Compile Include="Graphics\VoxelActorPreview.cs" />
+    <Compile Include="GlobalUpgradable.cs" />
+    <Compile Include="Player\GlobalUpgradeManager.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenRA.Game\OpenRA.Game.csproj">

OpenRA.Mods.RA/Player/GlobalUpgradeManager.cs

@@ -0,0 +1,94 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation. For more information,
+ * see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using OpenRA.Graphics;
+using OpenRA.Primitives;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	[Desc("Attach this to the player actor.")]
+	public class GlobalUpgradeManagerInfo : ITraitInfo, Requires<TechTreeInfo>
+	{
+		public object Create(ActorInitializer init) { return new GlobalUpgradeManager(init); }
+	}
+
+	public class GlobalUpgradeManager : ITechTreeElement
+	{
+		readonly Actor self;
+		readonly Dictionary<string, List<Pair<Actor, GlobalUpgradable>>> upgradables = new Dictionary<string, List<Pair<Actor, GlobalUpgradable>>>();
+		readonly TechTree techTree;
+
+		public GlobalUpgradeManager(ActorInitializer init)
+		{
+			self = init.self;
+			techTree = self.Trait<TechTree>();
+		}
+
+		static string MakeKey(string[] prerequisites)
+		{
+			return "upgrade_" + string.Join("_", prerequisites.OrderBy(a => a));
+		}
+
+		public void Register(Actor actor, GlobalUpgradable u, string[] prerequisites)
+		{
+			var key = MakeKey(prerequisites);
+			if (!upgradables.ContainsKey(key))
+			{
+				upgradables.Add(key, new List<Pair<Actor, GlobalUpgradable>>());
+				techTree.Add(key, prerequisites, 0, this);
+			}
+
+			upgradables[key].Add(Pair.New(actor, u));
+
+			// Notify the current state
+			u.PrerequisitesUpdated(actor, techTree.HasPrerequisites(prerequisites));
+		}
+
+		public void Unregister(Actor actor, GlobalUpgradable u, string[] prerequisites)
+		{
+			var key = MakeKey(prerequisites);
+			var list = upgradables[key];
+
+			list.RemoveAll(x => x.First == actor && x.Second == u);
+			if (!list.Any())
+			{
+				upgradables.Remove(key);
+				techTree.Remove(key);
+			}
+		}
+
+		public void PrerequisitesAvailable(string key)
+		{
+			List<Pair<Actor, GlobalUpgradable>> list;
+			if (!upgradables.TryGetValue(key, out list))
+				return;
+
+			foreach (var u in list)
+				u.Second.PrerequisitesUpdated(u.First, true);
+		}
+
+		public void PrerequisitesUnavailable(string key)
+		{
+			List<Pair<Actor, GlobalUpgradable>> list;
+			if (!upgradables.TryGetValue(key, out list))
+				return;
+
+			foreach (var u in list)
+				u.Second.PrerequisitesUpdated(u.First, false);
+		}
+
+		public void PrerequisitesItemHidden(string key) { }
+		public void PrerequisitesItemVisible(string key) { }
+	}
+}