using Crestron.SimplSharp;
using Org.BouncyCastle.Asn1.X509;
using Serilog;
using Serilog.Configuration;
using Serilog.Core;
using Serilog.Events;
using Serilog.Formatting;
using Serilog.Formatting.Json;
using System;
using System.IO;
using System.Security.Authentication;
using WebSocketSharp;
using WebSocketSharp.Server;
using X509Certificate2 = System.Security.Cryptography.X509Certificates.X509Certificate2;

namespace PepperDash.Core;

/// <summary>
/// Provides a WebSocket-based logging sink for debugging purposes, allowing log events to be broadcast to connected
/// WebSocket clients.
/// </summary>
/// <remarks>This class implements the <see cref="ILogEventSink"/> interface and is designed to send
/// formatted log events to WebSocket clients connected to a secure WebSocket server. The server is hosted locally
/// and uses a self-signed certificate for SSL/TLS encryption.</remarks>
public class DebugWebsocketSink : ILogEventSink, IKeyed
{
    private HttpServer _httpsServer;
    
    private readonly string _path = "/debug/join/";
    private const string _certificateName = "selfCres";
    private const string _certificatePassword = "cres12345";

    /// <summary>
    /// Gets the port number on which the HTTPS server is currently running.
    /// </summary>
    public int Port 
    { get 
        { 
            
            if(_httpsServer == null) return 0;
            return _httpsServer.Port;
        } 
    }

    /// <summary>
    /// Gets the WebSocket URL for the current server instance.
    /// </summary>
    /// <remarks>The URL is dynamically constructed based on the server's current IP address, port,
    /// and WebSocket path.</remarks>
    public string Url
    {
        get
        {
            if (_httpsServer == null) return "";
            return $"wss://{CrestronEthernetHelper.GetEthernetParameter(CrestronEthernetHelper.ETHERNET_PARAMETER_TO_GET.GET_CURRENT_IP_ADDRESS, 0)}:{_httpsServer.Port}{_httpsServer.WebSocketServices[_path].Path}";
        }
    }

    /// <summary>
    /// Gets a value indicating whether the HTTPS server is currently listening for incoming connections.
    /// </summary>
    public bool IsRunning { get => _httpsServer?.IsListening ?? false; }        

    /// <inheritdoc/>
    public string Key => "DebugWebsocketSink";

    private readonly ITextFormatter _textFormatter;

    /// <summary>
    /// Initializes a new instance of the <see cref="DebugWebsocketSink"/> class with the specified text formatter.
    /// </summary>
    /// <remarks>This constructor initializes the WebSocket sink and ensures that a certificate is
    /// available for secure communication. If the required certificate does not exist, it will be created
    /// automatically. Additionally, the sink is configured to stop the server when the program is
    /// stopping.</remarks>
    /// <param name="formatProvider">The text formatter used to format log messages. If null, a default JSON formatter is used.</param>
    public DebugWebsocketSink(ITextFormatter formatProvider)
    {

        _textFormatter = formatProvider ?? new JsonFormatter();

        if (!File.Exists($"\\user\\{_certificateName}.pfx"))
            CreateCert();

        CrestronEnvironment.ProgramStatusEventHandler += type =>
        {
            if (type == eProgramStatusEventType.Stopping)
            {
                StopServer();
            }
        };
    }

    private static void CreateCert()
    {
        try
        {               
            var utility = new BouncyCertificate();
            
            var ipAddress = CrestronEthernetHelper.GetEthernetParameter(CrestronEthernetHelper.ETHERNET_PARAMETER_TO_GET.GET_CURRENT_IP_ADDRESS, 0);
            var hostName = CrestronEthernetHelper.GetEthernetParameter(CrestronEthernetHelper.ETHERNET_PARAMETER_TO_GET.GET_HOSTNAME, 0);
            var domainName = CrestronEthernetHelper.GetEthernetParameter(CrestronEthernetHelper.ETHERNET_PARAMETER_TO_GET.GET_DOMAIN_NAME, 0);

            CrestronConsole.PrintLine(string.Format("DomainName: {0} | HostName: {1} | {1}.{0}@{2}", domainName, hostName, ipAddress));

            var certificate = utility.CreateSelfSignedCertificate(string.Format("CN={0}.{1}", hostName, domainName), [string.Format("{0}.{1}", hostName, domainName), ipAddress], [KeyPurposeID.id_kp_serverAuth, KeyPurposeID.id_kp_clientAuth]);

            //Crestron fails to let us do this...perhaps it should be done through their Dll's but haven't tested               

            var separator = Path.DirectorySeparatorChar;
                            
            utility.CertificatePassword = _certificatePassword;
            utility.WriteCertificate(certificate, @$"{separator}user{separator}", _certificateName);               
        }
        catch (Exception ex)
        {
            //Debug.Console(0, "WSS CreateCert Failed\r\n{0}\r\n{1}", ex.Message, ex.StackTrace);
            CrestronConsole.PrintLine("WSS CreateCert Failed\r\n{0}\r\n{1}", ex.Message, ex.StackTrace);
        }
    }

    /// <summary>
    /// Sends a log event to all connected WebSocket clients.
    /// </summary>
    /// <remarks>The log event is formatted using the configured text formatter and then broadcasted  
    /// to all clients connected to the WebSocket server. If the WebSocket server is not          initialized or not
    /// listening, the method exits without performing any action.</remarks>
    /// <param name="logEvent">The log event to be formatted and broadcasted. Cannot be null.</param>
    public void Emit(LogEvent logEvent)
    {
        if (_httpsServer == null || !_httpsServer.IsListening) return;

        var sw = new StringWriter();
        _textFormatter.Format(logEvent, sw);

        _httpsServer.WebSocketServices[_path].Sessions.Broadcast(sw.ToString());           
    }

    /// <summary>
    /// Starts the WebSocket server on the specified port and configures it with the appropriate certificate.
    /// </summary>
    /// <remarks>This method initializes the WebSocket server and binds it to the specified port.  It
    /// also applies the server's certificate for secure communication. Ensure that the port is not already in use
    /// and that the certificate file is accessible.</remarks>
    /// <param name="port">The port number on which the WebSocket server will listen. Must be a valid, non-negative port number.</param>
    public void StartServerAndSetPort(int port)
    {
        Debug.Console(0, "Starting Websocket Server on port: {0}", port);


        Start(port, $"\\user\\{_certificateName}.pfx", _certificatePassword);
    }

    private void Start(int port, string certPath = "", string certPassword = "")
    {
        try
        {
            _httpsServer = new HttpServer(port, true);                

            if (!string.IsNullOrWhiteSpace(certPath))
            {
                Debug.Console(0, "Assigning SSL Configuration");

                _httpsServer.SslConfiguration.ServerCertificate = new X509Certificate2(certPath, certPassword);
                _httpsServer.SslConfiguration.ClientCertificateRequired = false;
                _httpsServer.SslConfiguration.CheckCertificateRevocation = false;
                _httpsServer.SslConfiguration.EnabledSslProtocols = SslProtocols.Tls12;
                //this is just to test, you might want to actually validate
                _httpsServer.SslConfiguration.ClientCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) =>
                    {
                        Debug.Console(0, "HTTPS ClientCerticateValidation Callback triggered");
                        return true;
                    };
            }
            Debug.Console(0, "Adding Debug Client Service");
            _httpsServer.AddWebSocketService<DebugClient>(_path);
            Debug.Console(0, "Assigning Log Info");
            _httpsServer.Log.Level = LogLevel.Trace;
            _httpsServer.Log.Output = (d, s) =>
            {
                uint level;

                switch(d.Level)
                {
                    case WebSocketSharp.LogLevel.Fatal:
                        level = 3;
                        break;
                    case WebSocketSharp.LogLevel.Error:
                        level = 2;
                        break;
                    case WebSocketSharp.LogLevel.Warn:
                        level = 1;
                        break;
                    case WebSocketSharp.LogLevel.Info:
                        level = 0;
                        break;
                    case WebSocketSharp.LogLevel.Debug:
                        level = 4;
                        break;
                    case WebSocketSharp.LogLevel.Trace:
                        level = 5;
                        break;
                    default:
                        level = 4;
                        break;
                }
                
                Debug.Console(level, "{1} {0}\rCaller:{2}\rMessage:{3}\rs:{4}", d.Level.ToString(), d.Date.ToString(), d.Caller.ToString(), d.Message, s);
            };
            Debug.Console(0, "Starting");

            _httpsServer.Start();
            Debug.Console(0, "Ready");
        }
        catch (Exception ex)
        {
            Debug.Console(0, "WebSocket Failed to start {0}", ex.Message);
        }
    }

    /// <summary>
    /// Stops the WebSocket server if it is currently running.
    /// </summary>
    /// <remarks>This method halts the WebSocket server and releases any associated resources.  After
    /// calling this method, the server will no longer accept or process incoming connections.</remarks>
    public void StopServer()
    {
        Debug.Console(0, "Stopping Websocket Server");
        _httpsServer?.Stop();

        _httpsServer = null;
    }
}

/// <summary>
/// Configures the logger to write log events to a debug WebSocket sink.
/// </summary>
/// <remarks>This extension method allows you to direct log events to a WebSocket sink for debugging
/// purposes.</remarks>
public static class DebugWebsocketSinkExtensions
{
    /// <summary>
    /// Configures a logger to write log events to a debug WebSocket sink.
    /// </summary>
    /// <remarks>This method adds a sink that writes log events to a WebSocket for debugging purposes.
    /// It is typically used during development to stream log events in real-time.</remarks>
    /// <param name="loggerConfiguration">The logger sink configuration to apply the WebSocket sink to.</param>
    /// <param name="formatProvider">An optional text formatter to format the log events. If not provided, a default formatter will be used.</param>
    /// <returns>A <see cref="LoggerConfiguration"/> object that can be used to further configure the logger.</returns>
    public static LoggerConfiguration DebugWebsocketSink(
                         this LoggerSinkConfiguration loggerConfiguration,
                                          ITextFormatter formatProvider = null)
    {
        return loggerConfiguration.Sink(new DebugWebsocketSink(formatProvider));
    }
}

/// <summary>
/// Represents a WebSocket client for debugging purposes, providing connection lifecycle management and message
/// handling functionality.
/// </summary>
/// <remarks>The <see cref="DebugClient"/> class extends <see cref="WebSocketBehavior"/> to handle
/// WebSocket connections, including events for opening, closing, receiving messages, and errors. It tracks the
/// duration of the connection and logs relevant events for debugging.</remarks>
public class DebugClient : WebSocketBehavior
{
    private DateTime _connectionTime;

    /// <summary>
    /// Gets the duration of time the WebSocket connection has been active.
    /// </summary>
    public TimeSpan ConnectedDuration
    {
        get
        {
            if (Context.WebSocket.IsAlive)
            {
                return DateTime.Now - _connectionTime;
            }
            else
            {
                return new TimeSpan(0);
            }
        }
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="DebugClient"/> class.
    /// </summary>
    /// <remarks>This constructor creates a new <see cref="DebugClient"/> instance and logs its
    /// creation using the <see cref="Debug.Console(int, string)"/> method with a debug level of 0.</remarks>
    public DebugClient()
    {
        Debug.Console(0, "DebugClient Created");
    }

    /// <inheritdoc/>
    protected override void OnOpen()
    {
        base.OnOpen();

        var url = Context.WebSocket.Url;
        Debug.Console(0, Debug.ErrorLogLevel.Notice, "New WebSocket Connection from: {0}", url);

        _connectionTime = DateTime.Now;
    }

    /// <inheritdoc/>
    protected override void OnMessage(MessageEventArgs e)
    {
        base.OnMessage(e);

        Debug.Console(0, "WebSocket UiClient Message: {0}", e.Data);
    }

    /// <inheritdoc/>
    protected override void OnClose(CloseEventArgs e)
    {
        base.OnClose(e);

        Debug.Console(0, Debug.ErrorLogLevel.Notice, "WebSocket UiClient Closing: {0} reason: {1}", e.Code, e.Reason);

    }

    /// <inheritdoc/>
    protected override void OnError(WebSocketSharp.ErrorEventArgs e)
    {
        base.OnError(e);

        Debug.Console(2, Debug.ErrorLogLevel.Notice, "WebSocket UiClient Error: {0} message: {1}", e.Exception, e.Message);
    }
}