#if !UNITY_WEBGL || UNITY_EDITOR
using System;
using System.Collections.Generic;
using System.IO;

#if !NETFX_CORE || UNITY_EDITOR
using System.Net.Security;
#endif

#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
using BestHTTP.SecureProtocol.Org.BouncyCastle.Tls;
using BestHTTP.Connections.TLS;
using System.Threading;
#endif

#if NETFX_CORE
    using System.Threading.Tasks;
    using Windows.Networking.Sockets;

    using TcpClient = BestHTTP.PlatformSupport.TcpClient.WinRT.TcpClient;

    //Disable CD4014: Because this call is not awaited, execution of the current method continues before the call is completed. Consider applying the 'await' operator to the result of the call.
    #pragma warning disable 4014
#else
    using TcpClient = BestHTTP.PlatformSupport.TcpClient.General.TcpClient;
    using System.Security.Cryptography.X509Certificates;
#endif

using BestHTTP.Timings;

namespace BestHTTP.Connections
{
    public sealed class TCPConnector : IDisposable
    {
        public bool IsConnected { get { return this.Client != null && this.Client.Connected; } }

        public string NegotiatedProtocol { get; private set; }

        public TcpClient Client { get; private set; }

        public Stream TopmostStream { get; private set; }

        public Stream Stream { get; private set; }

        public bool LeaveOpen { get; set; }

        public void Connect(HTTPRequest request)
        {
            string negotiatedProtocol = HTTPProtocolFactory.W3C_HTTP1;

            Uri uri =
#if !BESTHTTP_DISABLE_PROXY
                request.HasProxy ? request.Proxy.Address :
#endif
                request.CurrentUri;

            #region TCP Connection

            if (Client == null)
                Client = new TcpClient();

            if (!Client.Connected)
            {
                Client.ConnectTimeout = request.ConnectTimeout;

#if NETFX_CORE
                Client.UseHTTPSProtocol =
#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
                    !Request.UseAlternateSSL &&
#endif
                    HTTPProtocolFactory.IsSecureProtocol(uri);
#endif

                if (HTTPManager.Logger.Level == Logger.Loglevels.All)
                    HTTPManager.Logger.Verbose("TCPConnector", string.Format("'{0}' - Connecting to {1}:{2}", request.CurrentUri.ToString(), uri.Host, uri.Port.ToString()), request.Context);

#if !NETFX_CORE && (!UNITY_WEBGL || UNITY_EDITOR)
                bool changed = false;
                int? sendBufferSize = null, receiveBufferSize = null;

                if (HTTPManager.SendBufferSize.HasValue)
                {
                    sendBufferSize = Client.SendBufferSize;
                    Client.SendBufferSize = HTTPManager.SendBufferSize.Value;
                    changed = true;
                }

                if (HTTPManager.ReceiveBufferSize.HasValue)
                {
                    receiveBufferSize = Client.ReceiveBufferSize;
                    Client.ReceiveBufferSize = HTTPManager.ReceiveBufferSize.Value;
                    changed = true;
                }

                if (HTTPManager.Logger.Level == Logger.Loglevels.All)
                {
                    if (changed)
                        HTTPManager.Logger.Verbose("TCPConnector", string.Format("'{0}' - Buffer sizes changed - Send from: {1} to: {2}, Receive from: {3} to: {4}, Blocking: {5}",
                                request.CurrentUri.ToString(),
                                sendBufferSize,
                                Client.SendBufferSize,
                                receiveBufferSize,
                                Client.ReceiveBufferSize,
                                Client.Client.Blocking),
                            request.Context);
                    else
                        HTTPManager.Logger.Verbose("TCPConnector", string.Format("'{0}' - Buffer sizes - Send: {1} Receive: {2} Blocking: {3}", request.CurrentUri.ToString(), Client.SendBufferSize, Client.ReceiveBufferSize, Client.Client.Blocking), request.Context);
                }
#endif

#if NETFX_CORE && !UNITY_EDITOR && !ENABLE_IL2CPP
                try
                {
                    Client.Connect(uri.Host, uri.Port);
                }
                finally
                {
                    request.Timing.Add(TimingEventNames.TCP_Connection);
                }
#else
                System.Net.IPAddress[] addresses = null;
                try
                {
                    if (Client.ConnectTimeout > TimeSpan.Zero)
                    {
                        // https://forum.unity3d.com/threads/best-http-released.200006/page-37#post-3150972
                        using (System.Threading.ManualResetEvent mre = new System.Threading.ManualResetEvent(false))
                        {
                            IAsyncResult result = System.Net.Dns.BeginGetHostAddresses(uri.Host, (res) => { try { mre.Set(); } catch { } }, null);
                            bool success = mre.WaitOne(Client.ConnectTimeout);
                            if (success)
                            {
                                addresses = System.Net.Dns.EndGetHostAddresses(result);
                            }
                            else
                            {
                                throw new TimeoutException("DNS resolve timed out!");
                            }
                        }
                    }
                    else
                    {
                        addresses = System.Net.Dns.GetHostAddresses(uri.Host);
                    }
                }
                finally
                {
                    request.Timing.Add(TimingEventNames.DNS_Lookup);
                }

                if (HTTPManager.Logger.Level == Logger.Loglevels.All)
                    HTTPManager.Logger.Verbose("TCPConnector", string.Format("'{0}' - DNS Query returned with addresses: {1}", request.CurrentUri.ToString(), addresses != null ? addresses.Length : -1), request.Context);

                if (request.IsCancellationRequested)
                    throw new Exception("IsCancellationRequested");

                try
                {
                    Client.Connect(addresses, uri.Port, request);
                }
                finally
                {
                    request.Timing.Add(TimingEventNames.TCP_Connection);
                }

                if (request.IsCancellationRequested)
                    throw new Exception("IsCancellationRequested");
#endif

                if (HTTPManager.Logger.Level <= Logger.Loglevels.Information)
                    HTTPManager.Logger.Information("TCPConnector", "Connected to " + uri.Host + ":" + uri.Port.ToString(), request.Context);
            }
            else if (HTTPManager.Logger.Level <= Logger.Loglevels.Information)
                HTTPManager.Logger.Information("TCPConnector", "Already connected to " + uri.Host + ":" + uri.Port.ToString(), request.Context);

#endregion

            if (Stream == null)
            {
                bool isSecure = HTTPProtocolFactory.IsSecureProtocol(request.CurrentUri);

                // set the stream to Client.GetStream() so the proxy, if there's any can use it directly.
                this.Stream = this.TopmostStream = Client.GetStream();

                /*if (Stream.CanTimeout)
                    Stream.ReadTimeout = Stream.WriteTimeout = (int)Request.Timeout.TotalMilliseconds;*/

#if !BESTHTTP_DISABLE_PROXY
                if (request.HasProxy)
                {
                    try
                    {
                        request.Proxy.Connect(this.Stream, request);
                    }
                    finally
                    {
                        request.Timing.Add(TimingEventNames.Proxy_Negotiation);
                    }
                }

                if (request.IsCancellationRequested)
                    throw new Exception("IsCancellationRequested");
#endif

                // proxy connect is done, we can set the stream to a buffered one. HTTPProxy requires the raw NetworkStream for HTTPResponse's ReadUnknownSize!
                this.Stream = this.TopmostStream = new BufferedReadNetworkStream(Client.GetStream(), Math.Max(8 * 1024, HTTPManager.ReceiveBufferSize ?? Client.ReceiveBufferSize));

                // We have to use Request.CurrentUri here, because uri can be a proxy uri with a different protocol
                if (isSecure)
                {
                    DateTime tlsNegotiationStartedAt = DateTime.Now;
#region SSL Upgrade

#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
                    if (HTTPManager.UseAlternateSSLDefaultValue)
                    {
                        var handler = new TlsClientProtocol(this.Stream);

                        List<ProtocolName> protocols = new List<ProtocolName>();
#if !BESTHTTP_DISABLE_HTTP2
                        SupportedProtocols protocol = HTTPProtocolFactory.GetProtocolFromUri(request.CurrentUri);
                        if (protocol == SupportedProtocols.HTTP && request.IsKeepAlive)
                        {
                            // http/2 over tls (https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids)
                            protocols.Add(ProtocolName.AsUtf8Encoding(HTTPProtocolFactory.W3C_HTTP2));
                        }
#endif

                        protocols.Add(ProtocolName.AsUtf8Encoding(HTTPProtocolFactory.W3C_HTTP1));

                        AbstractTls13Client tlsClient = null;
                        if (HTTPManager.TlsClientFactory == null)
                        {
                            tlsClient = HTTPManager.DefaultTlsClientFactory(request, protocols);
                        }
                        else
                        {
                            try
                            {
                                tlsClient = HTTPManager.TlsClientFactory(request, protocols);
                            }
                            catch (Exception ex)
                            {
                                HTTPManager.Logger.Exception(nameof(TCPConnector), nameof(HTTPManager.TlsClientFactory), ex, request.Context);
                            }
                        
                            if (tlsClient == null)
                                tlsClient = HTTPManager.DefaultTlsClientFactory(request, protocols);
                        }

                        //tlsClient.LoggingContext = request.Context;
                        handler.Connect(tlsClient);

                        var applicationProtocol = tlsClient.GetNegotiatedApplicationProtocol();
                        if (!string.IsNullOrEmpty(applicationProtocol))
                            negotiatedProtocol = applicationProtocol;

                        Stream = handler.Stream;
                    }
                    else
#endif
                    {
#if !NETFX_CORE
                        SslStream sslStream = null;

                        if (HTTPManager.ClientCertificationProvider == null)
                            sslStream = new SslStream(Client.GetStream(), false, (sender, cert, chain, errors) =>
                            {
                                if (HTTPManager.DefaultCertificationValidator != null)
                                    return HTTPManager.DefaultCertificationValidator(request, cert, chain, errors);
                                else
                                    return true;
                            });
                        else
                            sslStream = new SslStream(Client.GetStream(), false, (sender, cert, chain, errors) =>
                            {
                                if (HTTPManager.DefaultCertificationValidator != null)
                                    return HTTPManager.DefaultCertificationValidator(request, cert, chain, errors);
                                else
                                    return true;
                            },
                            (object sender, string targetHost, X509CertificateCollection localCertificates, X509Certificate remoteCertificate, string[] acceptableIssuers) =>
                            {
                                return HTTPManager.ClientCertificationProvider(request, targetHost, localCertificates, remoteCertificate, acceptableIssuers);
                            });

                        if (!sslStream.IsAuthenticated)
                        {
#if !BESTHTTP_DISABLE_HTTP2 && !BESTHTTP_DISABLE_ALTERNATE_SSL && false
                            List<SslApplicationProtocol> protocols = new List<SslApplicationProtocol>();
                            SupportedProtocols protocol = HTTPProtocolFactory.GetProtocolFromUri(request.CurrentUri);
                            if (protocol == SupportedProtocols.HTTP && request.IsKeepAlive)
                            {
                                // http/2 over tls (https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids)
                                protocols.Add(new SslApplicationProtocol(HTTPProtocolFactory.W3C_HTTP2));
                            }
                            protocols.Add(new SslApplicationProtocol(HTTPProtocolFactory.W3C_HTTP1));

                            SslClientAuthenticationOptions options = new SslClientAuthenticationOptions();
                            options.ApplicationProtocols = protocols;
                            options.TargetHost = request.CurrentUri.Host;
                            var task = sslStream.AuthenticateAsClientAsync(options, default(System.Threading.CancellationToken));
                            task.Wait();

                            try
                            {
                                negotiatedProtocol = System.Text.Encoding.UTF8.GetString(sslStream.NegotiatedApplicationProtocol.Protocol.Span);
                            }
                            catch (Exception ex)
                            {
                                HTTPManager.Logger.Exception(nameof(TCPConnector), "Accessing SslStream's NegotiatedApplicationProtocol throwed an exception, falling back using HTTP/1.1", ex, request.Context);
                                negotiatedProtocol = HTTPProtocolFactory.W3C_HTTP1;
                            }
#else
                            sslStream.AuthenticateAsClient(request.CurrentUri.Host);
#endif
                        }
                        Stream = sslStream;
#else
                        Stream = Client.GetStream();
#endif
                    }
#endregion

                    request.Timing.Add(TimingEventNames.TLS_Negotiation, DateTime.Now - tlsNegotiationStartedAt);
                }
            }

            this.NegotiatedProtocol = negotiatedProtocol;
        }

        public void Close()
        {
            if (Client != null && !this.LeaveOpen)
            {
                try
                {
                    if (Stream != null)
                        Stream.Close();
                }
                catch { }
                finally
                {
                    Stream = null;
                }

                try
                {
                    if (TopmostStream != null)
                        TopmostStream.Close();
                }
                catch { }
                finally
                {
                    TopmostStream = null;
                }

                try
                {
                    Client.Close();
                }
                catch { }
                finally
                {                  
                    Client = null;
                }
            }
        }

        public void Dispose()
        {
            Close();
        }
    }
}
#endif