// 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.Threading;
using MySqlConnector;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using System.Transactions;

namespace Framework.Database
{
    public class MySqlConnectionInfo
    {
        public MySqlConnection GetConnection()
        {
            return new MySqlConnection($"Server={Host};Port={PortOrSocket};User Id={Username};Password={Password};Database={Database};Allow User Variables=True;Pooling=true;ConnectionIdleTimeout=1800;Command Timeout=0");
        }

        public string Host;
        public string PortOrSocket;
        public bool UseSSL;
        public string Username;
        public string Password;
        public string Database;
        public int Poolsize;
    }

    public struct DBVersion
    {
        public int Major { get; }
        public int Minor { get; }
        public int Build { get; }
        public bool IsMariaDB { get; }

        public DBVersion(int major, int minor, int build, bool isMariaDB)
        {
            Major = major;
            Minor = minor;
            Build = build;
            IsMariaDB = isMariaDB;
        }

        public static DBVersion Parse(string versionString)
        {
            int start = 0;
            int index = versionString.IndexOf('.', start);

            string val = versionString.Substring(start, index - start).Trim();
            int major = Convert.ToInt32(val, System.Globalization.NumberFormatInfo.InvariantInfo);

            start = index + 1;
            index = versionString.IndexOf('.', start);

            val = versionString.Substring(start, index - start).Trim();
            int minor = Convert.ToInt32(val, System.Globalization.NumberFormatInfo.InvariantInfo);

            start = index + 1;
            int i = start;
            while (i < versionString.Length && Char.IsDigit(versionString, i))
                i++;
            val = versionString.Substring(start, i - start).Trim();
            int build = Convert.ToInt32(val, System.Globalization.NumberFormatInfo.InvariantInfo);

            return new DBVersion(major, minor, build, versionString.Contains("Maria"));
        }

        public bool IsAtLeast(int majorNum, int minorNum, int buildNum)
        {
            if (Major > majorNum) return true;
            if (Major == majorNum && Minor > minorNum) return true;
            if (Major == majorNum && Minor == minorNum && Build >= buildNum) return true;
            return false;
        }
    }

    public abstract class MySqlBase<T>
    {
        static Dictionary<T, string> _preparedQueries = new();

        ProducerConsumerQueue<ISqlOperation> _queue = new();
        MySqlConnectionInfo _connectionInfo;
        DatabaseUpdater<T> _updater;
        DatabaseWorker<T> _worker;
        DBVersion version;

        public MySqlErrorCode Initialize(MySqlConnectionInfo connectionInfo)
        {
            _connectionInfo = connectionInfo;
            _updater = new DatabaseUpdater<T>(this);
            _worker = new DatabaseWorker<T>(_queue, this);

            try
            {
                using (var connection = _connectionInfo.GetConnection())
                {
                    connection.Open();

                    version = DBVersion.Parse(connection.ServerVersion);
                    Log.outInfo(LogFilter.SqlDriver, $"Connected to DB: {_connectionInfo.Database} Server: {(version.IsMariaDB ? "MariaDB" : "MySQL")} Ver: {connection.ServerVersion}");
                    return MySqlErrorCode.None;
                }
            }
            catch (MySqlException ex)
            {
                return HandleMySQLException(ex);
            }
        }

        public bool DirectExecute(string sql, params object[] args)
        {
            return DirectExecute(new PreparedStatement(string.Format(sql, args)));
        }

        public bool DirectExecute(PreparedStatement stmt)
        {
            try
            {
                using (var Connection = _connectionInfo.GetConnection())
                {
                    Connection.Open();
                    using (MySqlCommand cmd = Connection.CreateCommand())
                    {
                        cmd.CommandText = stmt.CommandText;
                        foreach (var parameter in stmt.Parameters)
                            cmd.Parameters.AddWithValue("@" + parameter.Key, parameter.Value);

                        cmd.ExecuteNonQuery();
                        return true;
                    }
                }
            }
            catch (MySqlException ex)
            {
                HandleMySQLException(ex, stmt.CommandText, stmt.Parameters);
                return false;
            }
        }

        public void Execute(string sql, params object[] args)
        {
            Execute(new PreparedStatement(string.Format(sql, args)));
        }

        public void Execute(PreparedStatement stmt)
        {
            PreparedStatementTask task = new(stmt);
            _queue.Push(task);
        }

        public void ExecuteOrAppend(SQLTransaction trans, PreparedStatement stmt)
        {
            if (trans == null)
                Execute(stmt);
            else
                trans.Append(stmt);
        }

        public SQLResult Query(string sql, params object[] args)
        {
            return Query(new PreparedStatement(string.Format(sql, args)));
        }

        public SQLResult Query(PreparedStatement stmt)
        {
            try
            {
                MySqlConnection Connection = _connectionInfo.GetConnection();
                Connection.Open();

                MySqlCommand cmd = Connection.CreateCommand();
                cmd.CommandText = stmt.CommandText;
                foreach (var parameter in stmt.Parameters)
                    cmd.Parameters.AddWithValue("@" + parameter.Key, parameter.Value);

                return new SQLResult(cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection));
            }
            catch (MySqlException ex)
            {
                HandleMySQLException(ex, stmt.CommandText, stmt.Parameters);
                return new SQLResult();
            }
        }

        public QueryCallback AsyncQuery(PreparedStatement stmt)
        {
            PreparedStatementTask task = new(stmt, true);
            // Store future result before enqueueing - task might get already processed and deleted before returning from this method
            Task<SQLResult> result = task.GetFuture();
            _queue.Push(task);
            return new QueryCallback(result);
        }

        public SQLQueryHolderCallback<R> DelayQueryHolder<R>(SQLQueryHolder<R> holder)
        {
            SQLQueryHolderTask<R> task = new(holder);
            // Store future result before enqueueing - task might get already processed and deleted before returning from this method
            Task<SQLQueryHolder<R>> result = task.GetFuture();
            _queue.Push(task);
            return new(result);
        }

        public void LoadPreparedStatements()
        {
            PreparedStatements();
        }

        public void PrepareStatement(T statement, string sql)
        {
            StringBuilder sb = new();
            int index = 0;
            for (var i = 0; i < sql.Length; i++)
            {
                if (sql[i].Equals('?'))
                    sb.Append("@" + index++);
                else
                    sb.Append(sql[i]);
            }

            _preparedQueries[statement] = sb.ToString();
        }

        public static PreparedStatement GetPreparedStatement(T statement)
        {
            return new PreparedStatement(_preparedQueries[statement]);
        }

        public void ApplyFile(string path, bool useDatabase = true)
        {
            // CLI Client connection info
            string args = $"-h{_connectionInfo.Host} ";
            args += $"-u{_connectionInfo.Username} ";

            if (!_connectionInfo.Password.IsEmpty())
                args += $"-p{_connectionInfo.Password} ";

            // Check if we want to connect through ip or socket (Unix only)
            if (OperatingSystem.IsWindows())
            {
                if (_connectionInfo.Host == ".")
                    args += "--protocol=PIPE ";
                else
                    args += $"-P{_connectionInfo.PortOrSocket} ";
            }
            else
            {
                if (!char.IsDigit(_connectionInfo.PortOrSocket[0]))
                {
                    // We can't check if host == "." here, because it is named localhost if socket option is enabled
                    args += "-P0 ";
                    args += "--protocol=SOCKET ";
                    args += $"-S{_connectionInfo.PortOrSocket} ";
                }
                else
                    // generic case
                    args += $"-P{_connectionInfo.PortOrSocket} ";
            }

            // Set the default charset to utf8
            args += "--default-character-set=utf8mb4 ";

            // Set max allowed packet to 1 GB
            args += "--max-allowed-packet=1GB ";

            if (!version.IsMariaDB && version.IsAtLeast(8, 0, 0))
            {
                if (_connectionInfo.UseSSL)
                    args += "--ssl-mode=REQUIRED ";
            }
            else
            {
                if (_connectionInfo.UseSSL)
                    args += "--ssl ";
            }

            // Since MySQL 9.4 command line client commands are disabled by default
            // We need to enable them to use `SOURCE` command
            if (version.Major >= 9 && version.Minor >= 4)
                args += "--commands=ON ";

            // Execute sql file
            args += "-e ";
            args += "\"BEGIN; SOURCE \"" + path + "\"; COMMIT;\" ";

            // Database
            if (useDatabase && !_connectionInfo.Database.IsEmpty())
                args += _connectionInfo.Database;

            // Invokes a mysql process which doesn't leak credentials to logs
            Process process = new();
            process.StartInfo = new(DBExecutableUtil.GetMySQLExecutable());
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.RedirectStandardOutput = true;
            process.StartInfo.RedirectStandardError = true;
            process.StartInfo.CreateNoWindow = true;
            process.StartInfo.Arguments = args;

            process.Start();

            process.WaitForExit();

            Log.outInfo(LogFilter.SqlUpdates, process.StandardOutput.ReadToEnd());
            Log.outError(LogFilter.SqlUpdates, process.StandardError.ReadToEnd());

            if (process.ExitCode != 0)
            {
                Log.outFatal(LogFilter.SqlUpdates, $"Applying of file \'{path}\' to database \'{GetDatabaseName()}\' failed!" +
                    " If you are a user, please pull the latest revision from the repository. " +
                    "Also make sure you have not applied any of the databases with your sql client. " +
                    "You cannot use auto-update system and import sql files from CypherCore repository with your sql client. " +
                    "If you are a developer, please fix your sql query.");

                throw new Exception("update failed");
            }
        }

        public static void EscapeString(ref string str)
        {
            str = MySqlHelper.EscapeString(str);
        }

        public void CommitTransaction(SQLTransaction transaction)
        {
            _queue.Push(new TransactionTask(transaction));
        }

        public TransactionCallback AsyncCommitTransaction(SQLTransaction transaction)
        {
            TransactionWithResultTask task = new(transaction);
            Task<bool> result = task.GetFuture();
            _queue.Push(task);
            return new TransactionCallback(result);
        }

        public MySqlErrorCode DirectCommitTransaction(SQLTransaction transaction)
        {
            using (var Connection = _connectionInfo.GetConnection())
            {
                string query = "";

                Connection.Open();
                using (MySqlTransaction trans = Connection.BeginTransaction())
                {
                    try
                    {
                        using (var scope = new TransactionScope())
                        {
                            foreach (var cmd in transaction.commands)
                            {
                                cmd.Transaction = trans;
                                cmd.Connection = Connection;
                                cmd.ExecuteNonQuery();
                                query = cmd.CommandText;
                            }

                            trans.Commit();
                            scope.Complete();
                        }
                        return  MySqlErrorCode.None;
                    }
                    catch (MySqlException ex) //error occurred
                    {
                        trans.Rollback();
                        return HandleMySQLException(ex, query);
                    }
                }
            }
        }

        MySqlErrorCode HandleMySQLException(MySqlException ex, string query = "", Dictionary<int, object> parameters = null)
        {
            MySqlErrorCode code = (MySqlErrorCode)ex.Number;
            if (ex.InnerException is MySqlException)
                code = (MySqlErrorCode)((MySqlException)ex.InnerException).Number;

            StringBuilder stringBuilder = new($"SqlException: MySqlErrorCode: {code} Message: {ex.Message} SqlQuery: {query} ");
            if (parameters != null)
            {
                stringBuilder.Append("Parameters: ");
                foreach (var pair in parameters)
                    stringBuilder.Append($"{pair.Key} : {pair.Value}");
            }

            Log.outError(LogFilter.Sql, stringBuilder.ToString());

            switch (code)
            {
                case MySqlErrorCode.BadFieldError:
                case MySqlErrorCode.NoSuchTable:
                    Log.outError(LogFilter.Sql, "Your database structure is not up to date. Please make sure you've executed all queries in the sql/updates folders.");
                    break;
                case MySqlErrorCode.ParseError:
                    Log.outError(LogFilter.Sql, "Error while parsing SQL. Core fix required.");
                    break;
            }

            return code;
        }

        public DatabaseUpdater<T> GetUpdater()
        {
            return _updater;
        }

        public bool IsAutoUpdateEnabled(DatabaseTypeFlags updateMask)
        {
            switch (GetType().Name)
            {
                case "LoginDatabase":
                    return updateMask.HasAnyFlag(DatabaseTypeFlags.Login);
                case "CharacterDatabase":
                    return updateMask.HasAnyFlag(DatabaseTypeFlags.Character);
                case "WorldDatabase":
                    return updateMask.HasAnyFlag(DatabaseTypeFlags.World);
                case "HotfixDatabase":
                    return updateMask.HasAnyFlag(DatabaseTypeFlags.Hotfix);
            }
            return false;
        }

        public string GetDatabaseName()
        {
            return _connectionInfo.Database;
        }

        public abstract void PreparedStatements();
    }

    public static class DBExecutableUtil
    {
        static string mysqlExecutablePath;

        public static string GetMySQLExecutable()
        {
            return mysqlExecutablePath;
        }

        public static bool CheckExecutable()
        {
            string mysqlExePath = ConfigMgr.GetDefaultValue("MySQLExecutable", "");
            if (mysqlExePath.IsEmpty() || !File.Exists(mysqlExePath))
            {
                Log.outFatal(LogFilter.SqlUpdates, $"Didn't find any executable MySQL binary at \'{mysqlExePath}\' or in path, correct the path in the *.conf (\"MySQLExecutable\").");
                return false;
            }

            // Correct the path to the cli
            mysqlExecutablePath = mysqlExePath;
            return true;
        }
    }
}