// Copyright 1998-2015 Epic Games, Inc. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.IO;
using System.Diagnostics;
using System.Linq;

namespace UnrealBuildTool
{
	public enum PluginLoadedFrom
	{
		// Plugin is built-in to the engine
		Engine,

		// Project-specific plugin, stored within a game project directory
		GameProject
	}

	[DebuggerDisplay("\\{{FileName}\\}")]
	public class PluginInfo
	{
		// Plugin name
		public readonly string Name;

		// Path to the plugin
		public readonly string FileName;

		// Path to the plugin's root directory
		public readonly string Directory;

		// The plugin descriptor
		public PluginDescriptor Descriptor;

		// Where does this plugin live?
		public PluginLoadedFrom LoadedFrom;

		/// <summary>
		/// Constructs a PluginInfo object
		/// </summary>
		/// <param name="InFileName"></param>
		/// <param name="InLoadedFrom">Where this pl</param>
		public PluginInfo(string InFileName, PluginLoadedFrom InLoadedFrom)
		{
			Name = Path.GetFileNameWithoutExtension(InFileName);
			FileName = Path.GetFullPath(InFileName);
			Directory = Path.GetDirectoryName(FileName);
			Descriptor = PluginDescriptor.FromFile(FileName);
			LoadedFrom = InLoadedFrom;
		}
	}

	public class Plugins
	{
		/// <summary>
		/// Read all the plugins available to a given project
		/// </summary>
		/// <param name="ProjectFileName">Path to the project file (or null)</param>
		/// <returns>Sequence of PluginInfo objects, one for each discovered plugin</returns>
		public static List<PluginInfo> ReadAvailablePlugins(string ProjectFileName)
		{
			List<PluginInfo> Plugins = new List<PluginInfo>();

			// Read all the engine plugins
			string EnginePluginsDir = Path.Combine(BuildConfiguration.RelativeEnginePath, "Plugins");
			foreach(string PluginFileName in EnumeratePlugins(EnginePluginsDir))
			{
				PluginInfo Plugin = new PluginInfo(PluginFileName, PluginLoadedFrom.Engine);
				Plugins.Add(Plugin);
			}

			// Read all the project plugins
			if(!String.IsNullOrEmpty(ProjectFileName))
			{
				string ProjectPluginsDir = Path.Combine(Path.GetDirectoryName(ProjectFileName), "Plugins");
				foreach(string PluginFileName in EnumeratePlugins(ProjectPluginsDir))
				{
					PluginInfo Plugin = new PluginInfo(PluginFileName, PluginLoadedFrom.GameProject);
					Plugins.Add(Plugin);
				}
			}

			return Plugins;
		}

		/// <summary>
		/// Find paths to all the plugins under a given parent directory (recursively)
		/// </summary>
		/// <param name="ParentDirectory">Parent directory to look in. Plugins will be found in any *subfolders* of this directory.</param>
		/// <param name="FileNames">List of filenames. Will have all the discovered .uplugin files appended to it.</param>
		public static IEnumerable<string> EnumeratePlugins(string ParentDirectory)
		{
			List<string> FileNames = new List<string>();
			if(Directory.Exists(ParentDirectory))
			{
				EnumeratePluginsInternal(new DirectoryInfo(ParentDirectory), FileNames);
			}
			return FileNames;
		}

		/// <summary>
		/// Find paths to all the plugins under a given parent directory (recursively)
		/// </summary>
		/// <param name="ParentDirectory">Parent directory to look in. Plugins will be found in any *subfolders* of this directory.</param>
		/// <param name="FileNames">List of filenames. Will have all the discovered .uplugin files appended to it.</param>
		static void EnumeratePluginsInternal(DirectoryInfo ParentDirectory, List<string> FileNames)
		{
			foreach(DirectoryInfo ChildDirectory in ParentDirectory.EnumerateDirectories())
			{
				int InitialFileNamesCount = FileNames.Count;
				foreach(FileInfo PluginFileInfo in ChildDirectory.EnumerateFiles("*.uplugin", SearchOption.TopDirectoryOnly))
				{
					FileNames.Add(PluginFileInfo.FullName);
				}
				if(FileNames.Count == InitialFileNamesCount)
				{
					EnumeratePluginsInternal(ChildDirectory, FileNames);
				}
			}
		}
	}
}