#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);

			var key = ExternalMod.MakeKey(mod);
			mods.Remove(key);

			foreach (var source in sources.Distinct())
			{
				var path = Path.Combine(source, "ModMetadata", key + ".yaml");
				try
				{
					if (File.Exists(path))
						File.Delete(path);
				}
				catch (Exception e)
				{
					Log.Write("debug", "Failed to remove mod metadata file '{0}'", path);
					Log.Write("debug", e.ToString());
				}
			}
		}

		public ExternalMod this[string key] { get { return mods[key]; } }
		public int Count { get { return mods.Count; } }
		public ICollection<string> Keys { get { return mods.Keys; } }
		public ICollection<ExternalMod> Values { get { return mods.Values; } }
		public bool ContainsKey(string key) { return mods.ContainsKey(key); }
		public IEnumerator<KeyValuePair<string, ExternalMod>> GetEnumerator() { return mods.GetEnumerator(); }
		public bool TryGetValue(string key, out ExternalMod value) { return mods.TryGetValue(key, out value); }
		IEnumerator IEnumerable.GetEnumerator() { return mods.GetEnumerator(); }
	}
}