using System;
using System.Collections.Generic;
using System.Xml.Serialization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;


using Renci.SshNet;
using StackExchange.Redis;
using StackExchange.Redis.Extensions.Core;
using StackExchange.Redis.Extensions.Core.Abstractions;
using StackExchange.Redis.Extensions.Core.Configuration;
using StackExchange.Redis.Extensions.Core.Implementations;



namespace ServerCore;


// HANDOVER: AWS S3 SDK Wrapper 클래스 이다.
//           S3 저장소에 관리할 Bucket 정보를 관리해준다.


public abstract class RedisConnectorBase
{
    private readonly string m_connection_string = string.Empty;
    private readonly RedisConfiguration m_redis_config;

    private ConnectionMultiplexer? m_connector;

    private SshClient? m_ssh_tuneling;
    private ForwardedPortLocal? m_forwarded_port_local;

    public RedisConnectorBase(string connectionString)
    {
        m_redis_config = new RedisConfiguration()
        {
            ConnectionString = connectionString,
        };

        m_connection_string = connectionString;
    }

    public async Task<bool> tryConnectAsync()
    {
        if (false == isConfigureConnectionInfo())
        {
            return false;
        }

        try
        {
            if (false == isConnected())
            {
                ConnectionMultiplexer.SetFeatureFlag("preventthreadtheft", true);
                var config_options = ConfigurationOptions.Parse(m_connection_string);

                var connection = await ConnectionMultiplexer.ConnectAsync(config_options);
                if (null == connection)
                {
                    var err_msg = $"Failed to connectAsync RedisServer !!! : ConnectString:{m_connection_string}";
                    throw new Exception(err_msg);
                }

                m_connector = connection;

                connection.ConnectionFailed += onConnectfailed;
                connection.ErrorMessage += onError;
                connection.InternalError += onInternalError;
                connection.ConnectionRestored += onConnectionRestored;
                connection.ConfigurationChanged += onConfigurationChanged;
                connection.ConfigurationChangedBroadcast += onMasterSlaveChanged;
            }
        }
        catch(Exception e) 
        {
            var err_msg = $"Exception !!!, Failed to perform in tryConnectAsync() !!! : exception:{e}, connectionString:{m_connection_string} - {toBasicString()}";
            Log.getLogger().error(err_msg);

            return false;
        }

        return true;
    }

    protected void setConnectionMultiplexer(ConnectionMultiplexer connector) => m_connector = connector;
    
    public bool tryConnect()
    {
        if (false == isConfigureConnectionInfo())
        {
            return false;
        }

        try
        {
            if (false == isConnected())
            {
                var config_options = ConfigurationOptions.Parse(m_connection_string);

                var connection = ConnectionMultiplexer.Connect(config_options);
                if (null == connection)
                {
                    var err_msg = $"Failed to connect RedisServer !!! : ConnectString:{m_connection_string}";
                    throw new Exception(err_msg);
                }

                m_connector = connection;

                connection.ConnectionFailed += onConnectfailed;
                connection.ErrorMessage += onError;
                connection.InternalError += onInternalError;
                connection.ConnectionRestored += onConnectionRestored;
                connection.ConfigurationChanged += onConfigurationChanged;
                connection.ConfigurationChangedBroadcast += onMasterSlaveChanged;
            }
        }
        catch (Exception e)
        {
            var err_msg = $"Exception !!!, try connectAsync failed !!! : Exception:{e} - {toBasicString()}";
            Log.getLogger().error(err_msg);

            return false;
        }

        return true;
    }

    //=========================================================================================
    // sshHost : ec2-54-69-223-245.us-west-2.compute.amazonaws.com // SSH 서버 (Jump Host or Bastion)
    // sshPort : 2211 // SSH 포트
    // sshUsername : "ubuntu" // SSH 사용자 이름
    // privateKeyPath : @"D:\SVN\Caliverse\Metaverse\trunk\Caliverse\Server\Security\SSH-Keys\pem\USWest2-KeyPair.pem" // Private Key 보안 파일 참조 경로
    // localPort : 16379 // 로컬에서 사용할 포트
    // redisHost : "clustercfg.metaverse-qa-cluster.ocif0u.usw2.cache.amazonaws.com" // Redis 클러스터 호스트
    // redisPort : 6379 // Redis 사용 포트
    // redisPassword : "wiUaVvNwX4PhBj&8"
    //=========================================================================================
    public bool startTuneling( string sshHost, int sshPort, string sshUserName, string privateKeyPath
                             , int localPort, string redisHost, int redisPort, string redisPassword )
    {
        // SSH Private Key 설정
        PrivateKeyFile privateKey = new PrivateKeyFile(privateKeyPath);
        var keyFiles = new[] { privateKey };

        try
        {
            var ssh_client = new SshClient(sshHost, sshPort, sshUserName, keyFiles);

            // SSH 연결 시도
            ssh_client.Connect();

            // 포트 포워딩 설정 (로컬 포트 -> 원격 Redis 호스트)
            var portForward = new ForwardedPortLocal("127.0.0.1", (uint)localPort, redisHost, (uint)redisPort);
            ssh_client.AddForwardedPort(portForward);

            portForward.Start();

            m_forwarded_port_local = portForward;
            m_ssh_tuneling = ssh_client;
        }
        catch(Exception e)
        {
            var err_msg = $"Exception !!!, Failed to function in startTuneling() !!! : Exception:{e}";
            Log.getLogger().error(err_msg);

            return false;
        }

        return true;
    }

    public void stopTuneling()
    {
        if (null != m_forwarded_port_local)
        {
            m_forwarded_port_local.Stop();
            m_forwarded_port_local = null;
        }

        if(null != m_ssh_tuneling)
        {
            // SSH 연결 종료
            m_ssh_tuneling.Disconnect();
            m_ssh_tuneling = null;
        }
    }

    protected bool isConfigureConnectionInfo()
    {
        if ( 0 >= m_connection_string.Length )
        {
            var err_msg = $"Invalid Configure of RedisConnector, Empty m_connectionString !!! - {toBasicString()}";
            Log.getLogger().error(err_msg);
            return false;
        }

        return true;
    }

    public bool isConnected()
    {
        if(   null == m_connector
           || false == m_connector.IsConnected)
        {
            return false;
        }

        return true;
    }

    public IDatabase? getDatabase()
    {
        if(false == isConnected())
        {
            return null;
        }

        return m_connector?.GetDatabase();
    }

    public ConnectionMultiplexer? getConnectionMultiplexer() => m_connector;

    #region event
    protected virtual void onConnectionRestored(object? sender, ConnectionFailedEventArgs e)
    {
        Log.getLogger().warn($"Redis connection restored !!! : {e} - {toBasicString()}");
    }

    protected void onConnectfailed(object? sender, ConnectionFailedEventArgs e)
    {
        Log.getLogger().error($"Redis connect failed !!! : ConnectionFailed:{e.Exception} - {toBasicString()}");
    }

    protected void onError(object? sender, RedisErrorEventArgs e)
    {
        Log.getLogger().error($"Redis connection restored !!! : RedisError:{e} - {toBasicString()}");
    }

    protected void onInternalError(object? sender, InternalErrorEventArgs e)
    {
        Log.getLogger().error($"Redis internal error !!! : InternalError:{e} - {toBasicString()}");
    }

    protected void onConfigurationChanged(object? sender, EndPointEventArgs e)
    {
        Log.getLogger().warn($"Redis configuration changed !!! : EndPoint:{e} - {toBasicString()}");
    }

    protected void onMasterSlaveChanged(object? sender, EndPointEventArgs e)
    {
        Log.getLogger().warn($"Redis changed master-slave !!! : EndPoint:{e.EndPoint} - {toBasicString()}");
    }
    #endregion event


    public string toBasicString()
    {
        return $"RedisConnector - Class:{this.getTypeName()}, ConnectString:{m_connection_string}";
    }
}