using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using Netch.Models;
using Netch.Utils;

namespace Netch.Controllers
{
    public class TUNTAPController : Guard, IModeController
    {
        public bool TestNatRequired { get; } = true;

        // ByPassLan IP
        private readonly List<string> _bypassLanIPs = new List<string>
            {"10.0.0.0/8", "172.16.0.0/16", "192.168.0.0/16"};

        private Mode _savedMode = new Mode();
        private Server _savedServer = new Server();

        /// <summary>
        ///     服务器 IP 地址
        /// </summary>
        private IPAddress[] _serverAddresses = new IPAddress[0];

        /// <summary>
        ///     本地 DNS 服务控制器
        /// </summary>
        public DNSController pDNSController = new DNSController();

        public TUNTAPController()
        {
            StartedKeywords.Add("Running");
            StoppedKeywords.AddRange(new[] {"failed", "invalid vconfig file"});
        }

        public override string Name { get; protected set; } = "tun2socks";
        public override string MainFile { get; protected set; } = "tun2socks.exe";

        /// <summary>
        ///     配置 TUNTAP 适配器
        /// </summary>
        private bool Configure()
        {
            // 查询服务器 IP 地址
            var destination = Dns.GetHostAddressesAsync(_savedServer.Hostname);
            if (destination.Wait(1000))
            {
                if (destination.Result.Length == 0) return false;

                _serverAddresses = destination.Result;
            }

            // 搜索出口
            return SearchTapAdapter();
        }

        private readonly List<IPNetwork> _directIPs = new List<IPNetwork>();
        private readonly List<IPNetwork> _proxyIPs = new List<IPNetwork>();


        /// <summary>
        ///     设置绕行规则
        /// </summary>
        /// <returns>是否设置成功</returns>
        private bool SetupRouteTable()
        {
            Logging.Info("收集路由表规则");
            Global.MainForm.StatusText(i18N.Translate("SetupBypass"));

            Logging.Info("绕行 → 全局绕过 IP");
            _directIPs.AddRange(Global.Settings.BypassIPs.Select(IPNetwork.Parse));

            Logging.Info("绕行 → 服务器 IP");
            _directIPs.AddRange(_serverAddresses.Where(address => !IPAddress.IsLoopback(address))
                .Select(address => IPNetwork.Parse(address.ToString(), 32)));

            Logging.Info("绕行 → 局域网 IP");
            _directIPs.AddRange(_bypassLanIPs.Select(IPNetwork.Parse));

            switch (_savedMode.Type)
            {
                case 1:
                    // 代理规则
                    Logging.Info("代理 → 规则 IP");
                    _proxyIPs.AddRange(_savedMode.Rule.Select(IPNetwork.Parse));

                    //处理 NAT 类型检测，由于协议的原因，无法仅通过域名确定需要代理的 IP，自己记录解析了返回的 IP，仅支持默认检测服务器
                    if (Global.Settings.STUN_Server == "stun.stunprotocol.org")
                        try
                        {
                            Logging.Info("代理 → STUN 服务器 IP");
                            _proxyIPs.AddRange(new[]
                            {
                                Dns.GetHostAddresses(Global.Settings.STUN_Server)[0],
                                Dns.GetHostAddresses("stunresponse.coldthunder11.com")[0]
                            }.Select(ip => IPNetwork.Parse(ip.ToString(), 32)));
                        }
                        catch
                        {
                            Logging.Info("NAT 类型测试域名解析失败，将不会被添加到代理列表");
                        }

                    if (Global.Settings.TUNTAP.ProxyDNS)
                    {
                        Logging.Info("代理 → 自定义 DNS");
                        if (Global.Settings.TUNTAP.UseCustomDNS)
                        {
                            var dns = string.Empty;
                            foreach (var value in Global.Settings.TUNTAP.DNS)
                            {
                                dns += value;
                                dns += ',';
                            }

                            dns = dns.Trim();
                            dns = dns.Substring(0, dns.Length - 1);
                            RouteAction(Action.Create, dns, 32, RouteType.TUNTAP);
                        }
                        else
                        {
                            _proxyIPs.AddRange(
                                new[] {"1.1.1.1", "8.8.8.8", "9.9.9.9", "185.222.222.222"}.Select(ip =>
                                    IPNetwork.Parse(ip, 32)));
                        }
                    }

                    break;
                case 2:
                    // 绕过规则

                    // 将 TUN/TAP 网卡权重放到最高
                    Process.Start(new ProcessStartInfo
                        {
                            FileName = "netsh",
                            Arguments = $"interface ip set interface {Global.TUNTAP.Index} metric=0",
                            WindowStyle = ProcessWindowStyle.Hidden,
                            UseShellExecute = true,
                            CreateNoWindow = true
                        }
                    );

                    if (_savedMode.BypassChina)
                    {
                        Logging.Info("绕行 → 中国 IP");

                        foreach (var str in File.ReadAllLines("bin\\china_ip_list", Encoding.UTF8))
                        {
                            if (IPNetwork.TryParse(str, out var entry))
                            {
                                _directIPs.Add(entry);
                            }
                        }
                    }

                    Logging.Info("绕行 → 规则 IP");
                    _directIPs.AddRange(_savedMode.Rule.Select(IPNetwork.Parse));

                    Logging.Info("代理 → 全局");
                    if (!RouteAction(Action.Create, IPNetwork.Parse("0.0.0.0", 0), RouteType.TUNTAP))
                    {
                        State = State.Stopped;
                        return false;
                    }

                    break;
            }

            Logging.Info("设置路由规则");
            RouteAction(Action.Create, _directIPs, RouteType.Gateway);
            RouteAction(Action.Create, _proxyIPs, RouteType.TUNTAP);

            return true;
        }


        /// <summary>
        ///     清除绕行规则
        /// </summary>
        private bool ClearRouteTable()
        {
            switch (_savedMode.Type)
            {
                case 1:
                    break;
                case 2:
                    RouteAction(Action.Delete, "0.0.0.0", 0, RouteType.TUNTAP, 10);
                    break;
            }

            RouteAction(Action.Delete, _directIPs, RouteType.Gateway);
            RouteAction(Action.Delete, _proxyIPs, RouteType.TUNTAP);
            _directIPs.Clear();
            _proxyIPs.Clear();
            return true;
        }


        public bool Start(Server s, Mode mode)
        {
            _savedMode = mode;
            _savedServer = s;

            if (!Configure()) return false;

            SetupRouteTable();

            var adapterName = TUNTAP.GetName(Global.TUNTAP.ComponentID);

            string dns;
            if (Global.Settings.TUNTAP.UseCustomDNS)
            {
                if (Global.Settings.TUNTAP.DNS.Any())
                {
                    dns = Global.Settings.TUNTAP.DNS.Aggregate((current, ip) => $"{current},{ip}");
                }
                else
                {
                    Global.Settings.TUNTAP.DNS.Add("1.1.1.1");
                    dns = "1.1.1.1";
                }
            }
            else
            {
                var _ = pDNSController.Start();
                dns = "127.0.0.1";
            }

            var argument = new StringBuilder();
            if (s.IsSocks5())
                argument.Append($"-proxyServer {s.Hostname}:{s.Port} ");
            else
                argument.Append($"-proxyServer 127.0.0.1:{Global.Settings.Socks5LocalPort} ");

            argument.Append(
                $"-tunAddr {Global.Settings.TUNTAP.Address} -tunMask {Global.Settings.TUNTAP.Netmask} -tunGw {Global.Settings.TUNTAP.Gateway} -tunDns {dns} -tunName \"{adapterName}\" ");

            if (Global.Settings.TUNTAP.UseFakeDNS && Global.Flags.SupportFakeDns)
                argument.Append("-fakeDns ");

            return StartInstanceAuto(argument.ToString(), ProcessPriorityClass.RealTime);
        }

        /// <summary>
        ///     TUN/TAP停止
        /// </summary>
        public override void Stop()
        {
            var tasks = new[]
            {
                Task.Factory.StartNew(StopInstance),
                Task.Factory.StartNew(ClearRouteTable),
                Task.Factory.StartNew(pDNSController.Stop)
            };
            Task.WaitAll(tasks);
        }

        public bool TestFakeDNS()
        {
            var exited = false;
            var helpStr = new StringBuilder();
            try
            {
                void OnOutputDataReceived(object sender, DataReceivedEventArgs e)
                {
                    if (e.Data == null)
                    {
                        exited = true;
                        return;
                    }

                    helpStr.Append(e.Data);
                }

                InitInstance("-h");
                // Instance.OutputDataReceived += OnOutputDataReceived;
                Instance.ErrorDataReceived += OnOutputDataReceived;
                Instance.Start();
                Instance.BeginOutputReadLine();
                Instance.BeginErrorReadLine();
                while (!exited)
                {
                    Thread.Sleep(200);
                }

                return helpStr.ToString().Contains("-fakeDns");
            }
            catch
            {
                return false;
            }
        }

        /// <summary>
        ///     搜索出口和TUNTAP适配器
        /// </summary>
        public static bool SearchTapAdapter()
        {
            // 搜索 TUN/TAP 适配器的索引
            if (string.IsNullOrEmpty(Global.TUNTAP.ComponentID = TUNTAP.GetComponentID()))
            {
                Logging.Info("找不到 TAP 适配器");
                if (MessageBoxX.Show(i18N.Translate("TUN/TAP driver is not detected. Is it installed now?"),
                    confirm: true) == DialogResult.OK)
                {
                    TUNTAP.addtap();
                    // 给点时间，不然立马安装完毕就查找适配器可能会导致找不到适配器ID
                    Thread.Sleep(1000);
                    if (string.IsNullOrEmpty(Global.TUNTAP.ComponentID = TUNTAP.GetComponentID()))
                    {
                        Logging.Error("找不到 TAP 适配器，驱动可能安装失败");
                        return false;
                    }
                }
                else
                {
                    Logging.Info("取消安装 TAP 驱动 ");
                    return false;
                }
            }

            // 根据 ComponentID 寻找 Tap适配器
            try
            {
                var adapter = NetworkInterface.GetAllNetworkInterfaces().First(_ => _.Id == Global.TUNTAP.ComponentID);
                Global.TUNTAP.Adapter = adapter;
                Global.TUNTAP.Index = adapter.GetIPProperties().GetIPv4Properties().Index;
                Logging.Info(
                    $"TAP 适配器：{adapter.Name} {adapter.Id} {adapter.Description}, index: {Global.TUNTAP.Index}");
            }
            catch (Exception e)
            {
                var msg = e switch
                {
                    InvalidOperationException _ => $"找不到标识符为 {Global.TUNTAP.ComponentID} 的 TAP 适配器: {e.Message}",
                    NetworkInformationException _ => $"获取 Tap 适配器信息错误: {e.Message}",
                    _ => $"Tap 适配器其他异常: {e}"
                };
                Logging.Error(msg);
                return false;
            }

            return true;
        }


        private enum RouteType
        {
            Gateway,
            TUNTAP
        }

        private enum Action
        {
            Create,
            Delete
        }

        private static void RouteAction(Action action, IEnumerable<IPNetwork> ipNetworks, RouteType routeType,
            int metric = 0)
        {
            foreach (var address in ipNetworks)
            {
                RouteAction(action, address, routeType, metric);
            }
        }

        private static bool RouteAction(Action action, string address, byte cidr, RouteType routeType, int metric = 0)
        {
            return RouteAction(action, IPNetwork.Parse(address, cidr), routeType, metric);
        }

        private static bool RouteAction(Action action, IPNetwork ipNetwork, RouteType routeType, int metric = 0)
        {
            string gateway;
            int index;
            switch (routeType)
            {
                case RouteType.Gateway:
                    gateway = Global.Outbound.Gateway.ToString();
                    index = Global.Outbound.Index;
                    break;
                case RouteType.TUNTAP:
                    gateway = Global.Settings.TUNTAP.Gateway;
                    index = Global.TUNTAP.Index;
                    break;
                default:
                    throw new ArgumentOutOfRangeException(nameof(routeType), routeType, null);
            }

            var result = action switch
            {
                Action.Create => NativeMethods.CreateRoute(ipNetwork.Network.ToString(), ipNetwork.Cidr, gateway, index,
                    metric),
                Action.Delete => NativeMethods.DeleteRoute(ipNetwork.Network.ToString(), ipNetwork.Cidr, gateway, index,
                    metric),
                _ => throw new ArgumentOutOfRangeException(nameof(action), action, null)
            };

            if (!result)
            {
                Logging.Warning($"{action} Route on {routeType} Adapter failed: {ipNetwork} metric {metric}");
            }

            return result;
        }
    }
}