// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under MIT X11 license (for details please see \doc\license.txt)

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

using ICSharpCode.NRefactory.TypeSystem;

namespace ICSharpCode.NRefactory.Documentation
{
	/// <summary>
	/// Provides documentation from an .xml file (as generated by the Microsoft C# compiler).
	/// </summary>
	public class XmlDocumentationProvider : IDocumentationProvider
	{
		readonly IDictionary<string, string> xmlDocumentation;
		
		#region Load From File
		public XmlDocumentationProvider(string fileName)
		{
			if (fileName == null)
				throw new ArgumentNullException("fileName");
			this.xmlDocumentation = new Dictionary<string, string>();
			using (XmlTextReader xmlReader = new XmlTextReader(fileName)) {
				xmlReader.MoveToContent();
				if (string.IsNullOrEmpty(xmlReader.GetAttribute("redirect"))) {
					ReadXmlDoc(xmlReader);
				} else {
					string redirectionTarget = GetRedirectionTarget(xmlReader.GetAttribute("redirect"));
					if (redirectionTarget != null) {
						Debug.WriteLine("XmlDoc " + fileName + " is redirecting to " + redirectionTarget);
						using (XmlTextReader redirectedXmlReader = new XmlTextReader(redirectionTarget)) {
							ReadXmlDoc(redirectedXmlReader);
						}
					} else {
						Debug.WriteLine("XmlDoc " + fileName + " is redirecting to " + xmlReader.GetAttribute("redirect") + ", but that file was not found.");
					}
				}
			}
		}
		
		static string GetRedirectionTarget(string target)
		{
			string programFilesDir = Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles);
			programFilesDir = AppendDirectorySeparator(programFilesDir);
			
			string corSysDir = System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory();
			corSysDir = AppendDirectorySeparator(corSysDir);
			
			return LookupLocalizedXmlDoc(target.Replace("%PROGRAMFILESDIR%", programFilesDir)
			                             .Replace("%CORSYSDIR%", corSysDir));
		}
		
		static string AppendDirectorySeparator(string dir)
		{
			if (dir.EndsWith("\\", StringComparison.Ordinal) || dir.EndsWith("/", StringComparison.Ordinal))
				return dir;
			else
				return dir + Path.DirectorySeparatorChar;
		}
		
		internal static string LookupLocalizedXmlDoc(string fileName)
		{
			string xmlFileName = Path.ChangeExtension(fileName, ".xml");
			string currentCulture = System.Threading.Thread.CurrentThread.CurrentUICulture.TwoLetterISOLanguageName;
			string localizedXmlDocFile = GetLocalizedName(xmlFileName, currentCulture);
			
			Debug.WriteLine("Try find XMLDoc @" + localizedXmlDocFile);
			if (File.Exists(localizedXmlDocFile)) {
				return localizedXmlDocFile;
			}
			Debug.WriteLine("Try find XMLDoc @" + xmlFileName);
			if (File.Exists(xmlFileName)) {
				return xmlFileName;
			}
			if (currentCulture != "en") {
				string englishXmlDocFile = GetLocalizedName(xmlFileName, "en");
				Debug.WriteLine("Try find XMLDoc @" + englishXmlDocFile);
				if (File.Exists(englishXmlDocFile)) {
					return englishXmlDocFile;
				}
			}
			return null;
		}
		
		static string GetLocalizedName(string fileName, string language)
		{
			string localizedXmlDocFile = Path.GetDirectoryName(fileName);
			localizedXmlDocFile = Path.Combine(localizedXmlDocFile, language);
			localizedXmlDocFile = Path.Combine(localizedXmlDocFile, Path.GetFileName(fileName));
			return localizedXmlDocFile;
		}
		#endregion
		
		#region Load from XmlReader
		public XmlDocumentationProvider(XmlReader reader)
		{
			if (reader == null)
				throw new ArgumentNullException("reader");
			this.xmlDocumentation = new Dictionary<string, string>();
			ReadXmlDoc(reader);
		}
		
		public XmlDocumentationProvider(IDictionary<string, string> dictionary)
		{
			if (dictionary == null)
				throw new ArgumentNullException("dictionary");
			this.xmlDocumentation = dictionary;
		}
		
		void ReadXmlDoc(XmlReader reader)
		{
			while (reader.Read()) {
				if (reader.IsStartElement()) {
					switch (reader.LocalName) {
						case "members":
							ReadMembersSection(reader);
							break;
					}
				}
			}
		}
		
		void ReadMembersSection(XmlReader reader)
		{
			while (reader.Read()) {
				switch (reader.NodeType) {
					case XmlNodeType.EndElement:
						if (reader.LocalName == "members") {
							return;
						}
						break;
					case XmlNodeType.Element:
						if (reader.LocalName == "member") {
							string memberAttr = reader.GetAttribute(0);
							string innerXml   = reader.ReadInnerXml();
							xmlDocumentation[memberAttr] = innerXml;
						}
						break;
				}
			}
		}
		#endregion
		
		/// <summary>
		/// Gets all entries in the documentation file.
		/// </summary>
		public IDictionary<string, string> XmlDocumentation {
			get { return xmlDocumentation; }
		}
		
		public string GetDocumentation(string key)
		{
			if (key == null)
				throw new ArgumentNullException("key");
			
			string result;
			if (xmlDocumentation.TryGetValue(key, out result))
				return result;
			else
				return null;
		}
		
		public string GetDocumentation(IEntity entity)
		{
			return GetDocumentation(GetDocumentationKey(entity));
		}
		
		public static string GetDocumentationKey(IEntity entity)
		{
			if (entity == null)
				throw new ArgumentNullException("entity");
			throw new NotImplementedException();
		}
	}
}