using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using Common.Logging;
using WebDAVSharp.Server.Adapters;
using WebDAVSharp.Server.Exceptions;
using WebDAVSharp.Server.MethodHandlers;
using WebDAVSharp.Server.Stores;
using System.Web;
using System.Diagnostics;

namespace WebDAVSharp.Server {
	/// <summary>
	/// This class implements the core WebDAV server.
	/// </summary>
	public class WebDavServer : WebDavDisposableBase {
		/// <summary>
		/// The HTTP user
		/// </summary>
		public const string HttpUser = "HTTP.User";

		private readonly IHttpListener _listener;
		private readonly bool _ownsListener;
		private readonly IWebDavStore _store;
		private readonly Dictionary<string, IWebDavMethodHandler> _methodHandlers;
		private readonly ILog _log;
		private readonly object _threadLock = new object();

		private ManualResetEvent _stopEvent;
		private Thread _thread;

		/// <summary>
		/// Initializes a new instance of the <see cref="WebDavServer" /> class.
		/// </summary>
		/// <param name="store">The
		/// <see cref="IWebDavStore" /> store object that will provide
		/// collections and documents for this
		/// <see cref="WebDavServer" />.</param>
		/// <param name="listener">The
		/// <see cref="IHttpListener" /> object that will handle the web server portion of
		/// the WebDAV server; or
		/// <c>null</c> to use a fresh one.</param>
		/// <param name="methodHandlers">A collection of HTTP method handlers to use by this
		/// <see cref="WebDavServer" />;
		/// or
		/// <c>null</c> to use the built-in method handlers.</param>
		/// <exception cref="System.ArgumentNullException"><para>
		///   <paramref name="listener" /> is <c>null</c>.</para>
		/// <para>- or -</para>
		/// <para>
		///   <paramref name="store" /> is <c>null</c>.</para></exception>
		/// <exception cref="System.ArgumentException"><para>
		///   <paramref name="methodHandlers" /> is empty.</para>
		/// <para>- or -</para>
		/// <para>
		///   <paramref name="methodHandlers" /> contains a <c>null</c>-reference.</para></exception>
		public WebDavServer(IWebDavStore store, IHttpListener listener = null, IEnumerable<IWebDavMethodHandler> methodHandlers = null) {
			if (store == null)
				throw new ArgumentNullException("store");
			if (listener == null) {
				listener = new HttpListenerAdapter();
				_ownsListener = true;
			}
			methodHandlers = methodHandlers ?? WebDavMethodHandlers.BuiltIn;

			IWebDavMethodHandler[] webDavMethodHandlers = methodHandlers as IWebDavMethodHandler[] ?? methodHandlers.ToArray();

			if (!webDavMethodHandlers.Any())
				throw new ArgumentException("The methodHandlers collection is empty", "methodHandlers");
			if (webDavMethodHandlers.Any(methodHandler => methodHandler == null))
				throw new ArgumentException("The methodHandlers collection contains a null-reference", "methodHandlers");

			_listener = listener;
			_store = store;
			var handlersWithNames =
					from methodHandler in webDavMethodHandlers
					from name in methodHandler.Names
					select new {
						name,
						methodHandler
					};
			_methodHandlers = handlersWithNames.ToDictionary(v => v.name, v => v.methodHandler);
			_log = LogManager.GetLogger<WebDavServer>();
		}

		/// <summary>
		/// Gets the
		/// <see cref="IHttpListener" /> that this
		/// <see cref="WebDavServer" /> uses for
		/// the web server portion.
		/// </summary>
		/// <value>
		/// The listener.
		/// </value>
		internal IHttpListener Listener {
			get {
				return _listener;
			}
		}

		/// <summary>
		/// Gets the <see cref="IWebDavStore" /> this <see cref="WebDavServer" /> is hosting.
		/// </summary>
		/// <value>
		/// The store.
		/// </value>
		public IWebDavStore Store {
			get {
				return _store;
			}
		}

		public string ServiceUrl { get; set; }

		/// <summary>
		/// Releases unmanaged and - optionally - managed resources
		/// </summary>
		/// <param name="disposing"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
		protected override void Dispose(bool disposing) {
			lock (_threadLock) {
				if (_thread != null)
					Stop();
			}

			if (_ownsListener)
				_listener.Dispose();
		}

		///// <summary>
		///// Starts this
		///// <see cref="WebDavServer" /> and returns once it has
		///// been started successfully.
		///// </summary>
		///// <exception cref="System.InvalidOperationException">This WebDAVServer instance is already running, call to Start is invalid at this point</exception>
		///// <exception cref="ObjectDisposedException">This <see cref="WebDavServer" /> instance has been disposed of.</exception>
		///// <exception cref="InvalidOperationException">The server is already running.</exception>
		//public void Start(String Url)
		//    {
		//    Listener.Prefixes.Add(Url);
		//    EnsureNotDisposed();
		//    lock (_threadLock)
		//        {
		//        if (_thread != null)
		//            {
		//            throw new InvalidOperationException(
		//                "This WebDAVServer instance is already running, call to Start is invalid at this point");
		//            }

		//        _stopEvent = new ManualResetEvent(false);

		//        _thread = new Thread(BackgroundThreadMethod)
		//        {
		//            Name = "WebDAVServer.Thread",
		//            Priority = ThreadPriority.Highest
		//        };
		//        _thread.Start();
		//    }
		//}

		/// <summary>
		/// Starts this
		/// <see cref="WebDavServer" /> and returns once it has
		/// been stopped successfully.
		/// </summary>
		/// <exception cref="System.InvalidOperationException">This WebDAVServer instance is not running, call to Stop is invalid at this point</exception>
		/// <exception cref="ObjectDisposedException">This <see cref="WebDavServer" /> instance has been disposed of.</exception>
		/// <exception cref="InvalidOperationException">The server is not running.</exception>
		public void Stop() {
			EnsureNotDisposed();
			lock (_threadLock) {
				if (_thread == null) {
					throw new InvalidOperationException(
							"This WebDAVServer instance is not running, call to Stop is invalid at this point");
				}

				_stopEvent.Set();
				_thread.Join();

				_stopEvent.Close();
				_stopEvent = null;
				_thread = null;
			}
		}

		///// <summary>
		///// The background thread method.
		///// </summary>
		//private void BackgroundThreadMethod()
		//{
		//    _log.Info("WebDAVServer background thread has started");
		//    try
		//    {
		//        _listener.Start();
		//        while (true)
		//        {
		//            if (_stopEvent.WaitOne(0))
		//                return;

		//            IHttpListenerContext context = Listener.GetContext(_stopEvent);
		//            if (context == null)
		//            {
		//                _log.Debug("Exiting thread");
		//                return;
		//            }

		//            ThreadPool.QueueUserWorkItem(ProcessRequest, context);
		//        }
		//    }
		//    finally
		//    {
		//        _listener.Stop();
		//        _log.Info("WebDAVServer background thread has terminated");
		//    }
		//}

		/// <summary>
		/// Processes the request.
		/// </summary>
		/// <param name="context">The context.</param>
		/// <exception cref="WebDAVSharp.Server.Exceptions.WebDavMethodNotAllowedException">If the method to process is not allowed</exception>
		/// <exception cref="WebDAVSharp.Server.Exceptions.WebDavUnauthorizedException">If the user is unauthorized or has no access</exception>
		/// <exception cref="WebDAVSharp.Server.Exceptions.WebDavNotFoundException">If the item was not found</exception>
		/// <exception cref="WebDAVSharp.Server.Exceptions.WebDavNotImplementedException">If a method is not yet implemented</exception>
		/// <exception cref="WebDAVSharp.Server.Exceptions.WebDavInternalServerException">If the server had an internal problem</exception>
		public void ProcessRequest(HttpContext context, String fileName) {

			//IHttpListenerContext context = (IHttpListenerContext)state;

			//TODO: (Charly): enable authentication
			// For authentication
			Thread.SetData(Thread.GetNamedDataSlot(HttpUser), context.User?.Identity);

			_log.Info(context.Request.HttpMethod + " " + fileName);
			_log.Debug($"WebDAV - {context.Request.HttpMethod} - {fileName} - {context.User?.Identity?.AuthenticationType}: {context.User?.Identity?.Name}");
			try {
				try {
					string method = context.Request.HttpMethod;
					IWebDavMethodHandler methodHandler;
					if (!_methodHandlers.TryGetValue(method, out methodHandler))
						throw new WebDavMethodNotAllowedException(string.Format(CultureInfo.InvariantCulture, "%s ({0})", context.Request.HttpMethod));

					context.Response.AppendHeader("DAV", "1,2,1#extend");

					methodHandler.ProcessRequest(this, context, Store, String.IsNullOrWhiteSpace(fileName) ? "/" : fileName);

				}
				catch (WebDavException) {
					throw;
				}
				catch (UnauthorizedAccessException) {
					throw new WebDavUnauthorizedException();
				}
				catch (FileNotFoundException ex) {
					_log.Warn(ex.Message);
					throw new WebDavNotFoundException(innerException: ex);
				}
				catch (DirectoryNotFoundException ex) {
					_log.Warn(ex.Message);
					throw new WebDavNotFoundException(innerException: ex);
				}
				catch (NotImplementedException ex) {
					_log.Warn(ex.Message);
					throw new WebDavNotImplementedException(innerException: ex);
				}
				catch (Exception ex) {
					_log.Warn(ex.Message);
					throw new WebDavInternalServerException(innerException: ex);
				}
			}
			catch (WebDavException ex) {
				_log.Warn(ex.StatusCode + " " + ex.Message);
				Trace.WriteLine($"WebDAV - {ex.StatusCode} - {ex.StatusDescription} : {ex.Message}", "Warning");	//
				context.Response.StatusCode = ex.StatusCode;
				context.Response.StatusDescription = ex.StatusDescription;
				if (ex.Message != context.Response.StatusDescription) {
					byte[] buffer = Encoding.UTF8.GetBytes(ex.Message);
					context.Response.ContentEncoding = Encoding.UTF8;
					//context.Response.ContentLength64 = buffer.Length;
					context.Response.OutputStream.Write(buffer, 0, buffer.Length);
				}
				//context.Response.Close();
			}
			finally {
				_log.Info(context.Response.StatusCode + " " + context.Response.StatusDescription + ": " + context.Request.HttpMethod + " " + fileName);
				string headers = "";
				try {
					foreach (var key in context.Response.Headers.AllKeys) {
						headers += $"\t{key}: {context.Response.Headers[key]}\n";
					}
				}
				catch (Exception ex) {
					Trace.TraceError(ex.ToString());
				}
				Trace.WriteLine($"WebDAV - {context.Response.StatusCode} {context.Response.StatusDescription}: {context.Request.HttpMethod} {fileName}\n{headers}", "Info");
			}
		}
	}
}