using System;
using System.Collections.Generic;
using System.IO;
using Newtonsoft.Json;
using NLog;
using Shadowsocks.Controller;

namespace Shadowsocks.Model
{
    [Serializable]
    public class Configuration
    {
        [JsonIgnore]
        private static Logger logger = LogManager.GetCurrentClassLogger();

        public string version;

        public List<Server> configs;

        // when strategy is set, index is ignored
        public string strategy;
        public int index;
        public bool global;
        public bool enabled;
        public bool shareOverLan;
        public bool isDefault;
        public bool isIPv6Enabled = false;
        public int localPort;
        public bool portableMode = true;
        public bool showPluginOutput;
        public string pacUrl;
        public string gfwListUrl;
        public bool useOnlinePac;
        public bool secureLocalPac = true;
        public bool availabilityStatistics;
        public bool autoCheckUpdate;
        public bool checkPreRelease;
        public bool isVerboseLogging;
        //public NLogConfig.LogLevel logLevel;
        public LogViewerConfig logViewer;
        public ProxyConfig proxy;
        public HotkeyConfig hotkey;

        [JsonIgnore]
        NLogConfig nLogConfig;

        private static readonly string CONFIG_FILE = "gui-config.json";
        private static readonly NLogConfig.LogLevel verboseLogLevel =
#if DEBUG
        NLogConfig.LogLevel.Trace;
#else
        NLogConfig.LogLevel.Debug;
#endif


        [JsonIgnore]
        public bool updated = false;

        [JsonIgnore]
        public string localHost => GetLocalHost();
        private string GetLocalHost()
        {
            return isIPv6Enabled ? "[::1]" : "127.0.0.1";
        }
        public Server GetCurrentServer()
        {
            if (index >= 0 && index < configs.Count)
                return configs[index];
            else
                return GetDefaultServer();
        }

        public static void CheckServer(Server server)
        {
            CheckServer(server.server);
            CheckPort(server.server_port);
            CheckPassword(server.password);
            CheckTimeout(server.timeout, Server.MaxServerTimeoutSec);
        }

        public static bool ChecksServer(Server server)
        {
            try
            {
                CheckServer(server);
                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        public static Configuration Load()
        {
            try
            {
                string configContent = File.ReadAllText(CONFIG_FILE);
                Configuration config = JsonConvert.DeserializeObject<Configuration>(configContent);
                config.isDefault = false;
                if (UpdateChecker.Asset.CompareVersion(UpdateChecker.Version, config.version ?? "0") > 0)
                {
                    config.updated = true;
                }

                if (config.configs == null)
                    config.configs = new List<Server>();
                if (config.configs.Count == 0)
                    config.configs.Add(GetDefaultServer());
                if (config.localPort == 0)
                    config.localPort = 1080;
                if (config.index == -1 && config.strategy == null)
                    config.index = 0;
                if (config.logViewer == null)
                    config.logViewer = new LogViewerConfig();
                if (config.proxy == null)
                    config.proxy = new ProxyConfig();
                if (config.hotkey == null)
                    config.hotkey = new HotkeyConfig();
                if (!System.Net.Sockets.Socket.OSSupportsIPv6)
                {
                    config.isIPv6Enabled = false; // disable IPv6 if os not support
                }
                //TODO if remote host(server) do not support IPv6 (or DNS resolve AAAA TYPE record) disable IPv6?

                config.proxy.CheckConfig();

                try
                {
                    config.nLogConfig = NLogConfig.LoadXML();
                    switch (config.nLogConfig.GetLogLevel())
                    {
                        case NLogConfig.LogLevel.Fatal:
                        case NLogConfig.LogLevel.Error:
                        case NLogConfig.LogLevel.Warn:
                        case NLogConfig.LogLevel.Info:
                            config.isVerboseLogging = false;
                            break;
                        case NLogConfig.LogLevel.Debug:
                        case NLogConfig.LogLevel.Trace:
                            config.isVerboseLogging = true;
                            break;
                    }
                }
                catch (Exception e)
                {
                    // todo: route the error to UI since there is no log file in this scenario
                    logger.Error(e, "Cannot get the log level from NLog config file. Please check if the nlog config file exists with corresponding XML nodes.");
                }

                return config;
            }
            catch (Exception e)
            {
                if (!(e is FileNotFoundException))
                    logger.LogUsefulException(e);
                return new Configuration
                {
                    index = 0,
                    isDefault = true,
                    localPort = 1080,
                    autoCheckUpdate = true,
                    configs = new List<Server>()
                    {
                        GetDefaultServer()
                    },
                    logViewer = new LogViewerConfig(),
                    proxy = new ProxyConfig(),
                    hotkey = new HotkeyConfig(),
                };
            }
        }

        public static void Save(Configuration config)
        {
            config.version = UpdateChecker.Version;
            if (config.index >= config.configs.Count)
                config.index = config.configs.Count - 1;
            if (config.index < -1)
                config.index = -1;
            if (config.index == -1 && config.strategy == null)
                config.index = 0;
            config.isDefault = false;
            try
            {
                using (StreamWriter sw = new StreamWriter(File.Open(CONFIG_FILE, FileMode.Create)))
                {
                    string jsonString = JsonConvert.SerializeObject(config, Formatting.Indented);
                    sw.Write(jsonString);
                    sw.Flush();
                }
                try
                {             
                    // apply changs to NLog.config
                    config.nLogConfig.SetLogLevel(config.isVerboseLogging? verboseLogLevel : NLogConfig.LogLevel.Info);
                    NLogConfig.SaveXML(config.nLogConfig);
                }
                catch (Exception e)
                {
                    logger.Error(e, "Cannot set the log level to NLog config file. Please check if the nlog config file exists with corresponding XML nodes.");
                }
            }
            catch (IOException e)
            {
                logger.LogUsefulException(e);
            }
        }

        public static Server AddDefaultServerOrServer(Configuration config, Server server = null, int? index = null)
        {
            if (config != null && config.configs != null)
            {
                server = (server ?? GetDefaultServer());

                config.configs.Insert(index.GetValueOrDefault(config.configs.Count), server);

                //if (index.HasValue)
                //    config.configs.Insert(index.Value, server);
                //else
                //    config.configs.Add(server);
            }
            return server;
        }

        public static Server GetDefaultServer()
        {
            return new Server();
        }

        private static void Assert(bool condition)
        {
            if (!condition)
                throw new Exception(I18N.GetString("assertion failure"));
        }

        public static void CheckPort(int port)
        {
            if (port <= 0 || port > 65535)
                throw new ArgumentException(I18N.GetString("Port out of range"));
        }

        public static void CheckLocalPort(int port)
        {
            CheckPort(port);
            if (port == 8123)
                throw new ArgumentException(I18N.GetString("Port can't be 8123"));
        }

        private static void CheckPassword(string password)
        {
            if (password.IsNullOrEmpty())
                throw new ArgumentException(I18N.GetString("Password can not be blank"));
        }

        public static void CheckServer(string server)
        {
            if (server.IsNullOrEmpty())
                throw new ArgumentException(I18N.GetString("Server IP can not be blank"));
        }

        public static void CheckTimeout(int timeout, int maxTimeout)
        {
            if (timeout <= 0 || timeout > maxTimeout)
                throw new ArgumentException(
                    I18N.GetString("Timeout is invalid, it should not exceed {0}", maxTimeout));
        }

        public static void CheckProxyAuthUser(string user)
        {
            if (user.IsNullOrEmpty())
                throw new ArgumentException(I18N.GetString("Auth user can not be blank"));
        }

        public static void CheckProxyAuthPwd(string pwd)
        {
            if (pwd.IsNullOrEmpty())
                throw new ArgumentException(I18N.GetString("Auth pwd can not be blank"));
        }
    }
}