// Copyright (c) CypherCore <http://github.com/CypherCore> All rights reserved.
// Licensed under the GNU GENERAL PUBLIC LICENSE. See LICENSE file in the project root for full license information.


using Framework.Configuration;
using Framework.Constants;
using Framework.Cryptography;
using Framework.Database;
using Framework.Networking;
using Game.Chat;
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

namespace Game.Networking
{
    public class RASocket : ISocket
    {
        Socket _socket;
        IPAddress _remoteAddress;
        byte[] _receiveBuffer;

        public RASocket(Socket socket)
        {
            _socket = socket;
            _remoteAddress = ((IPEndPoint)_socket.RemoteEndPoint).Address;
            _receiveBuffer = new byte[1024];
        }

        public void Accept()
        {
            // wait 1 second for active connections to send negotiation request
            for (int counter = 0; counter < 10 && _socket.Available == 0; counter++)
                Thread.Sleep(100);

            if (_socket.Available > 0)
            {
                // Handle subnegotiation
                _socket.Receive(_receiveBuffer);

                // Send the end-of-negotiation packet
                byte[] reply = { 0xFF, 0xF0 };
                _socket.Send(reply);
            }

            Send("Authentication Required\r\n");
            Send("Email: ");
            string userName = ReadString();
            if (userName.IsEmpty())
            {
                CloseSocket();
                return;
            }

            Log.outInfo(LogFilter.CommandsRA, $"Accepting RA connection from user {userName} (IP: {_remoteAddress})");

            Send("Password: ");
            string password = ReadString();
            if (password.IsEmpty())
            {
                CloseSocket();
                return;
            }

            if (!CheckAccessLevelAndPassword(userName, password))
            {
                Send("Authentication failed\r\n");
                CloseSocket();
                return;
            }

            Log.outInfo(LogFilter.CommandsRA, $"User {userName} (IP: {_remoteAddress}) authenticated correctly to RA");

            // Authentication successful, send the motd
            foreach (string line in Global.WorldMgr.GetMotd())
                Send(line);

            Send("\r\n");

            // Read commands
            for (; ; )
            {
                Send("\r\nCypher>");
                string command = ReadString();

                if (!ProcessCommand(command))
                    break;
            }

            CloseSocket();
        }

        public bool Update()
        {
            return IsOpen();
        }

        void Send(string str)
        {
            if (!IsOpen())
                return;

            _socket.Send(Encoding.UTF8.GetBytes(str));
        }

        string ReadString()
        {
            try
            {
                string str = "";
                do
                {
                    int bytes = _socket.Receive(_receiveBuffer);
                    if (bytes == 0)
                        return "";

                    str = string.Concat(str, Encoding.UTF8.GetString(_receiveBuffer, 0, bytes));
                }
                while (!str.Contains("\n"));

                return str.TrimEnd('\r', '\n');
            }
            catch (Exception ex)
            {
                Log.outException(ex);
                return "";
            }
        }

        bool CheckAccessLevelAndPassword(string email, string password)
        {
            //"SELECT a.id, a.username FROM account a LEFT JOIN battlenet_accounts ba ON a.battlenet_account = ba.id WHERE ba.email = ?"
            PreparedStatement stmt = LoginDatabase.GetPreparedStatement(LoginStatements.SEL_BNET_GAME_ACCOUNT_LIST);
            stmt.AddValue(0, email);
            SQLResult result = DB.Login.Query(stmt);
            if (result.IsEmpty())
            {
                Log.outInfo(LogFilter.CommandsRA, $"User {email} does not exist in database");
                return false;
            }

            uint accountId = result.Read<uint>(0);
            string username = result.Read<string>(1);

            stmt = LoginDatabase.GetPreparedStatement(LoginStatements.SEL_ACCOUNT_ACCESS_BY_ID);
            stmt.AddValue(0, accountId);
            result = DB.Login.Query(stmt);
            if (result.IsEmpty())
            {
                Log.outInfo(LogFilter.CommandsRA, $"User {email} has no privilege to login");
                return false;
            }

            //"SELECT SecurityLevel, RealmID FROM account_access WHERE AccountID = ? and (RealmID = ? OR RealmID = -1) ORDER BY SecurityLevel desc");
            if (result.Read<byte>(0) < ConfigMgr.GetDefaultValue("Ra.MinLevel", (byte)AccountTypes.Administrator))
            {
                Log.outInfo(LogFilter.CommandsRA, $"User {email} has no privilege to login");
                return false;
            }
            else if (result.Read<int>(1) != -1)
            {
                Log.outInfo(LogFilter.CommandsRA, $"User {email} has to be assigned on all realms (with RealmID = '-1')");
                return false;
            }

            stmt = LoginDatabase.GetPreparedStatement(LoginStatements.SEL_CHECK_PASSWORD);
            stmt.AddValue(0, accountId);
            result = DB.Login.Query(stmt);
            if (!result.IsEmpty())
            {
                var salt = result.Read<byte[]>(0);
                var verifier = result.Read<byte[]>(1);

                if (SRP6.CheckLogin(username, password, salt, verifier))
                    return true;
            }

            Log.outInfo(LogFilter.CommandsRA, $"Wrong password for user: {email}");
            return false;
        }

        bool ProcessCommand(string command)
        {
            if (command.Length == 0)
                return false;

            Log.outInfo(LogFilter.CommandsRA, $"Received command: {command}");

            // handle quit, exit and logout commands to terminate connection
            if (command == "quit" || command == "exit" || command == "logout")
            {
                Send("Closing\r\n");
                return false;
            }

            RemoteAccessHandler cmd = new(CommandPrint);
            cmd.ParseCommands(command);

            return true;
        }

        public bool IsOpen() { return _socket.Connected; }

        public void CloseSocket()
        {
            if (_socket == null)
                return;

            try
            {
                _socket.Shutdown(SocketShutdown.Both);
                _socket.Close();
            }
            catch (Exception ex)
            {
                Log.outDebug(LogFilter.Network, "WorldSocket.CloseSocket: {0} errored when shutting down socket: {1}", _remoteAddress.ToString(), ex.Message);
            }
        }

        void CommandPrint(string text)
        {
            if (text.IsEmpty())
                return;

            Send(text);
        }
    }
}