using FastGithub.Configuration;
using FastGithub.HttpServer;
using Microsoft.AspNetCore.Connections;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Server.Kestrel.Core;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using System;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;

namespace FastGithub
{
    /// <summary>
    /// Kestrel扩展
    /// </summary>
    public static class KestrelServerOptionsExtensions
    {
        /// <summary>
        /// 无限制
        /// </summary>
        /// <param name="kestrel"></param>
        public static void NoLimit(this KestrelServerOptions kestrel)
        {
            kestrel.Limits.MaxRequestBodySize = null;
            kestrel.Limits.MinResponseDataRate = null;
            kestrel.Limits.MinRequestBodyDataRate = null;
        }

        /// <summary>
        /// 监听http代理
        /// </summary>
        /// <param name="kestrel"></param>
        public static void ListenHttpProxy(this KestrelServerOptions kestrel)
        {
            var options = kestrel.ApplicationServices.GetRequiredService<IOptions<FastGithubOptions>>().Value;
            var httpProxyPort = options.HttpProxyPort;

            if (CanListenTcp(httpProxyPort) == false)
            {
                throw new FastGithubException($"tcp端口{httpProxyPort}已经被其它进程占用，请在配置文件更换{nameof(FastGithubOptions.HttpProxyPort)}为其它端口");
            }

            var logger = kestrel.GetLogger();
            kestrel.Listen(IPAddress.Loopback, httpProxyPort);
            logger.LogInformation($"已监听http://{IPAddress.Loopback}:{httpProxyPort}，http代理服务启动完成");
        }

        /// <summary>
        /// 尝试监听ssh反向代理
        /// </summary>
        /// <param name="kestrel"></param>
        public static void ListenSshReverseProxy(this KestrelServerOptions kestrel)
        {
            var sshPort = ReverseProxyPort.Ssh;
            kestrel.Listen(IPAddress.Loopback, sshPort, listen => listen.UseConnectionHandler<SshReverseProxyHandler>());

            if (OperatingSystem.IsWindows())
            {
                kestrel.GetLogger().LogInformation($"已监听ssh://{IPAddress.Loopback}:{sshPort}，github的ssh反向代理服务启动完成");
            }
        }

        /// <summary>
        /// 尝试监听http反向代理
        /// </summary>
        /// <param name="kestrel"></param>
        public static void ListenHttpReverseProxy(this KestrelServerOptions kestrel)
        {
            var httpPort = ReverseProxyPort.Http;
            kestrel.Listen(IPAddress.Loopback, httpPort);

            if (OperatingSystem.IsWindows())
            {
                kestrel.GetLogger().LogInformation($"已监听http://{IPAddress.Loopback}:{httpPort}，http反向代理服务启动完成");
            }
        }

        /// <summary>
        /// 监听https反向代理
        /// </summary>
        /// <param name="kestrel"></param>
        /// <exception cref="FastGithubException"></exception>
        public static void ListenHttpsReverseProxy(this KestrelServerOptions kestrel)
        {
            var certService = kestrel.ApplicationServices.GetRequiredService<CertService>();
            certService.CreateCaCertIfNotExists();
            certService.InstallAndTrustCaCert();

            var httpsPort = ReverseProxyPort.Https;
            kestrel.Listen(IPAddress.Loopback, httpsPort, listen =>
            {
                listen.UseFlowAnalyze();
                listen.UseHttps(https =>
                {
                    https.ServerCertificateSelector = (ctx, domain) => certService.GetOrCreateServerCert(domain);
                });
            });

            if (OperatingSystem.IsWindows())
            {
                var logger = kestrel.GetLogger();
                logger.LogInformation($"已监听https://{IPAddress.Loopback}:{httpsPort}，https反向代理服务启动完成");
            }
        }

        /// <summary>
        /// 获取日志
        /// </summary>
        /// <param name="kestrel"></param>
        /// <returns></returns>
        private static ILogger GetLogger(this KestrelServerOptions kestrel)
        {
            var loggerFactory = kestrel.ApplicationServices.GetRequiredService<ILoggerFactory>();
            return loggerFactory.CreateLogger($"{nameof(FastGithub)}.{nameof(HttpServer)}");
        }

        /// <summary>
        /// 是否可以监听指定tcp端口
        /// </summary>
        /// <param name="port"></param>
        /// <param name="addressFamily"></param>
        /// <returns></returns>
        private static bool CanListenTcp(int port, AddressFamily addressFamily = AddressFamily.InterNetwork)
        {
            var tcpListeners = IPGlobalProperties.GetIPGlobalProperties().GetActiveTcpListeners();
            return tcpListeners.Any(item => item.AddressFamily == addressFamily && item.Port == port) == false;
        }
    }
}