context: #region Copyright & License Information
  /*
   * Copyright 2007-2019 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, either version 3 of
   * the License, or (at your option) any later version. For more
   * information, see COPYING.
   */
  #endregion
  
  using System;
  using System.Collections;
  using System.Collections.Generic;
  using System.IO;
  using System.Linq;
  using OpenRA.FileFormats;
  using OpenRA.Graphics;
  
  namespace OpenRA
  {
  	[Flags]
  	enum ModRegistration { User = 1, System = 2 }
  
  	public class ExternalMod
  	{
  		public readonly string Id;
  		public readonly string Version;
  		public readonly string Title;
  		public readonly string LaunchPath;
  		public readonly string[] LaunchArgs;
  		public Sprite Icon { get; internal set; }
  
  		public static string MakeKey(Manifest mod) { return MakeKey(mod.Id, mod.Metadata.Version); }
  		public static string MakeKey(ExternalMod mod) { return MakeKey(mod.Id, mod.Version); }
  		public static string MakeKey(string modId, string modVersion) { return modId + "-" + modVersion; }
  	}
  
  	public class ExternalMods : IReadOnlyDictionary<string, ExternalMod>
  	{
  		readonly Dictionary<string, ExternalMod> mods = new Dictionary<string, ExternalMod>();
  		readonly SheetBuilder sheetBuilder;
  
  		public ExternalMods()
  		{
  			sheetBuilder = new SheetBuilder(SheetType.BGRA, 256);
  
  			// If the player has defined a local support directory (in the game directory)
  			// then this will override both the regular and system support dirs
  			var sources = new[] { Platform.SystemSupportDir, Platform.SupportDir };
  			foreach (var source in sources.Distinct())
  			{
  				var metadataPath = Path.Combine(source, "ModMetadata");
  				if (!Directory.Exists(metadataPath))
  					continue;
  
  				foreach (var path in Directory.GetFiles(metadataPath, "*.yaml"))
  				{
  					try
  					{
  						var yaml = MiniYaml.FromStream(File.OpenRead(path), path).First().Value;
  						LoadMod(yaml, path);
  					}
  					catch (Exception e)
  					{
  						Log.Write("debug", "Failed to parse mod metadata file '{0}'", path);
  						Log.Write("debug", e.ToString());
  					}
  				}
  			}
  		}
  
  		void LoadMod(MiniYaml yaml, string path = null, bool forceRegistration = false)
  		{
  			var mod = FieldLoader.Load<ExternalMod>(yaml);
  			var iconNode = yaml.Nodes.FirstOrDefault(n => n.Key == "Icon");
  			if (iconNode != null && !string.IsNullOrEmpty(iconNode.Value.Value))
  			{
  				using (var stream = new MemoryStream(Convert.FromBase64String(iconNode.Value.Value)))
  					mod.Icon = sheetBuilder.Add(new Png(stream));
  			}
  
  			// Avoid possibly overwriting a valid mod with an obviously bogus one
  			var key = ExternalMod.MakeKey(mod);
  			if ((forceRegistration || File.Exists(mod.LaunchPath)) && (path == null || Path.GetFileNameWithoutExtension(path) == key))
  				mods[key] = mod;
  		}
  
  		internal void Register(Manifest mod, string launchPath, ModRegistration registration)
  		{
  			if (mod.Metadata.Hidden)
  				return;
  
  			var iconData = "";
  			using (var stream = mod.Package.GetStream("icon.png"))
  				if (stream != null)
  					iconData = Convert.ToBase64String(stream.ReadAllBytes());
  
  			var key = ExternalMod.MakeKey(mod);
  			var yaml = new List<MiniYamlNode>()
  			{
  				new MiniYamlNode("Registration", new MiniYaml("", new List<MiniYamlNode>()
  				{
  					new MiniYamlNode("Id", mod.Id),
  					new MiniYamlNode("Version", mod.Metadata.Version),
  					new MiniYamlNode("Title", mod.Metadata.Title),
  					new MiniYamlNode("Icon", iconData),
  					new MiniYamlNode("LaunchPath", launchPath),
  					new MiniYamlNode("LaunchArgs", "Game.Mod=" + mod.Id)
  				}))
  			};
  
  			var sources = new List<string>();
  			if (registration.HasFlag(ModRegistration.System))
  				sources.Add(Platform.SystemSupportDir);
  
  			if (registration.HasFlag(ModRegistration.User))
  				sources.Add(Platform.SupportDir);
  
  			// Make sure the mod is available for this session, even if saving it fails
  			LoadMod(yaml.First().Value, forceRegistration: true);
  
  			foreach (var source in sources.Distinct())
  			{
  				var metadataPath = Path.Combine(source, "ModMetadata");
  
  				try
  				{
  					Directory.CreateDirectory(metadataPath);
  					File.WriteAllLines(Path.Combine(metadataPath, key + ".yaml"), yaml.ToLines().ToArray());
  				}
  				catch (Exception e)
  				{
  					Log.Write("debug", "Failed to register current mod metadata");
  					Log.Write("debug", e.ToString());
  				}
  			}
  		}
  
  		/// <summary>
  		/// Removes invalid mod registrations:
  		/// * LaunchPath no longer exists
  		/// * LaunchPath and mod id matches the active mod, but the version is different
  		/// * Filename doesn't match internal key
  		/// * Fails to parse as a mod registration
  		/// </summary>
  		internal void ClearInvalidRegistrations(ExternalMod activeMod, ModRegistration registration)
  		{
  			var sources = new List<string>();
  			if (registration.HasFlag(ModRegistration.System))
  				sources.Add(Platform.SystemSupportDir);
  
  			if (registration.HasFlag(ModRegistration.User))
  				sources.Add(Platform.SupportDir);
  
  			var activeModKey = ExternalMod.MakeKey(activeMod);
  			foreach (var source in sources.Distinct())
  			{
  				var metadataPath = Path.Combine(source, "ModMetadata");
  				if (!Directory.Exists(metadataPath))
  					continue;
  
  				foreach (var path in Directory.GetFiles(metadataPath, "*.yaml"))
  				{
  					string modKey = null;
  					try
  					{
  						var yaml = MiniYaml.FromStream(File.OpenRead(path), path).First().Value;
  						var m = FieldLoader.Load<ExternalMod>(yaml);
  						modKey = ExternalMod.MakeKey(m);
  
  						// Continue to the next entry if it is the active mod (even if the LaunchPath is bogus)
  						if (modKey == activeModKey)
  							continue;
  
  						// Continue to the next entry if this one is valid
  						if (File.Exists(m.LaunchPath) && Path.GetFileNameWithoutExtension(path) == modKey &&
  							!(activeMod != null && m.LaunchPath == activeMod.LaunchPath && m.Id == activeMod.Id && m.Version != activeMod.Version))
  							continue;
  					}
  					catch (Exception e)
  					{
  						Log.Write("debug", "Failed to parse mod metadata file '{0}'", path);
  						Log.Write("debug", e.ToString());
  					}
  
  					// Remove from the ingame mod switcher
  					if (Path.GetFileNameWithoutExtension(path) == modKey)
  						mods.Remove(modKey);
  
  					// Remove stale or corrupted metadata
  					try
  					{
  						File.Delete(path);
  						Log.Write("debug", "Removed invalid mod metadata file '{0}'", path);
  					}
  					catch (Exception e)
  					{
  						Log.Write("debug", "Failed to remove mod metadata file '{0}'", path);
  						Log.Write("debug", e.ToString());
  					}
  				}
  			}
  		}
  
  		internal void Unregister(Manifest mod, ModRegistration registration)
  		{
  			var sources = new List<string>();
  			if (registration.HasFlag(ModRegistration.System))
  				sources.Add(Platform.SystemSupportDir);
  
  			if (registration.HasFlag(ModRegistration.User))
  				sources.Add(Platform.SupportDir);
  
  
gt: 			var key = ExternalMod.MakeKey(mod);