using System.Data;
using System.Text.RegularExpressions;
using BotSharp.Plugin.SqlDriver.Settings;
using MySql.Data.MySqlClient;
using Newtonsoft.Json;
using NPOI.SS.UserModel;

namespace BotSharp.Plugin.ExcelHandler.Services;

public class MySqlService : IDbService
{
    private readonly IServiceProvider _services;
    private readonly ILogger<MySqlService> _logger;

    private string _mysqlConnection = "";
    private double _excelRowSize = 0;
    private double _excelColumnSize = 0;
    private string _tableName = "tempTable";
    private string _database = "";
    private string _currentFileName = string.Empty;
    private List<string> _headerColumns = new List<string>();
    private List<string> _columnTypes = new List<string>();

    public MySqlService(
        IServiceProvider services,
        ILogger<MySqlService> logger)
    {
        _services = services;
        _logger = logger;
    }

    public string Provider => "mysql";

    public IEnumerable<SqlContextOut> WriteExcelDataToDB(IWorkbook workbook)
    {
        var numTables = workbook.NumberOfSheets;
        var results = new List<SqlContextOut>();
        var state = _services.GetRequiredService<IConversationStateService>();

        for (int sheetIdx = 0; sheetIdx < numTables; sheetIdx++)
        {
            ISheet sheet = workbook.GetSheetAt(sheetIdx);

            var (isCreateSuccess, message) = SqlCreateTableFn(sheet);

            if (!isCreateSuccess)
            {
                results.Add(new SqlContextOut
                {
                    isSuccessful = isCreateSuccess,
                    Message = message,
                    FileName = _currentFileName
                });
                continue;
            }

            string table = $"{_database}.{_tableName}";
            state.SetState("tmp_table", table);

            var (isInsertSuccess, insertMessage) = SqlInsertDataFn(sheet);
            string exampleData = GetInsertExample(table);

            results.Add(new SqlContextOut
            {
                isSuccessful = isInsertSuccess,
                Message = $"{insertMessage}\r\nExample Data: {exampleData}. \r\n The remaining data contains different values. ",
                FileName = _currentFileName
            });
        }
        return results;
    }

    #region Private methods
    private string ProcessInsertSqlQuery(string dataSql)
    {
        var wrapUpCols = _headerColumns.Select(x => $"`{x}`").ToList();
        var transferedCols = '(' + string.Join(',', wrapUpCols) + ')';
        string insertSqlQuery = $"Insert into {_tableName} {transferedCols} Values {dataSql}";
        return insertSqlQuery;
    }

    private (bool, string) SqlInsertDataFn(ISheet sheet)
    {
        try
        {
            string dataSql = ParseSheetData(sheet);
            string insertDataSql = ProcessInsertSqlQuery(dataSql);
            ExecuteSqlQueryForInsertion(insertDataSql);

            return (true, $"{_currentFileName}: \r\n {_excelRowSize} records have been successfully inserted into `{_database}`.`{_tableName}` table");
        }
        catch (Exception ex)
        {
            return (false, $"{_currentFileName}: Failed to parse excel data into `{_database}`.`{_tableName}` table. ####Error: {ex.Message}");
        }
    }

    private string ParseSheetData(ISheet singleSheet)
    {
        var stringBuilder = new StringBuilder();

        for (int rowIdx = 1; rowIdx < _excelRowSize + 1; rowIdx++)
        {
            IRow row = singleSheet.GetRow(rowIdx);
            stringBuilder.Append('(');
            for (int colIdx = 0; colIdx < _excelColumnSize; colIdx++)
            {
                var cell = row.GetCell(colIdx, MissingCellPolicy.CREATE_NULL_AS_BLANK);

                switch (cell.CellType)
                {
                    case CellType.String:
                        //if (cell.DateCellValue == null || cell.DateCellValue == DateTime.MinValue)
                        //{
                        //    sb.Append($"{cell.DateCellValue}");
                        //    break;
                        //}
                        stringBuilder.Append($"'{cell.StringCellValue.Replace("'", "''")}'");
                        break;
                    case CellType.Numeric:
                        stringBuilder.Append($"{cell.NumericCellValue}");
                        break;
                    case CellType.Blank:
                        stringBuilder.Append($"null");
                        break;
                    default:
                        stringBuilder.Append($"''");
                        break;
                }

                if (colIdx != (_excelColumnSize - 1))
                {
                    stringBuilder.Append(", ");
                }
            }
            stringBuilder.Append(')');
            stringBuilder.Append(rowIdx == _excelRowSize ? ';' : ", \r\n");
        }
        return stringBuilder.ToString();
    }

    private (bool, string) SqlCreateTableFn(ISheet sheet)
    {
        try
        {
            var conv = _services.GetRequiredService<IConversationService>();
            _tableName = $"excel_{conv.ConversationId.Split('-').Last()}_{sheet.SheetName}";
            _headerColumns = ParseSheetColumn(sheet);
            string createTableSql = CreateDBTableSqlString(_tableName, _headerColumns, null ,true);
            ExecuteSqlQueryForInsertion(createTableSql);
            createTableSql = createTableSql.Replace(_tableName, $"{_database}.{_tableName}");
            return (true, createTableSql);
        }
        catch (Exception ex)
        {
            return (false, ex.Message);
        }
    }

    private List<string> ParseSheetColumn(ISheet sheet)
    {
        if (sheet.PhysicalNumberOfRows < 2)
            throw new Exception("No data found in the excel file");

        _excelRowSize = sheet.PhysicalNumberOfRows - 1;
        var headerRow = sheet.GetRow(0);
        var headerColumn = headerRow.Cells.Select(x => x.StringCellValue.Replace(" ", "_")).ToList();
        _excelColumnSize = headerColumn.Count;
        return headerColumn;
    }

    private string CreateDBTableSqlString(string tableName, List<string> headerColumns, List<string>? columnTypes = null, bool isMemory = false)
    {
        _columnTypes = columnTypes.IsNullOrEmpty() ? headerColumns.Select(x => "VARCHAR(128)").ToList() : columnTypes;

        /*if (!headerColumns.Any(x => x.Equals("id", StringComparison.OrdinalIgnoreCase)))
        {
            headerColumns.Insert(0, "Id");
            _columnTypes?.Insert(0, "INT UNSIGNED AUTO_INCREMENT");
        }*/

        var createTableSql = $"DROP TABLE IF EXISTS {tableName}; CREATE TABLE if not exists {tableName} ( \n";
        createTableSql += string.Join(", \n", headerColumns.Select((x, i) => $"`{x}` {_columnTypes[i]}"));
        var indexSql = string.Join(", \n", headerColumns.Select(x => $"KEY `idx_{tableName}_{x}` (`{x}`)"));
        createTableSql += $", \n{indexSql}\n);";

        return createTableSql;
    }

    private void ExecuteSqlQueryForInsertion(string sqlQuery)
    {
        using var connection = GetDbConnection();
        _database = connection.Database;
        using (MySqlCommand cmd = new MySqlCommand(sqlQuery, connection))
        {
            cmd.ExecuteNonQuery();
        }
    }

    private string GetInsertExample(string tableName)
    {
        using var connection = GetDbConnection();
        _database = connection.Database;
        var sqlQuery = $"SELECT * FROM {tableName} LIMIT 2;";
        using var cmd = new MySqlCommand(sqlQuery, connection);
        using var reader = cmd.ExecuteReader();

        var dataExample = new DataTable();
        dataExample.Load(reader);

        return JsonConvert.SerializeObject(dataExample);
    }

    private List<string> GetAllTableSchema(MySqlConnection mySqlDbConnection)
    {
        string schemaQuery = $@"
            SELECT TABLE_NAME, COLUMN_NAME, DATA_TYPE, IS_NULLABLE, COLUMN_KEY, EXTRA
            FROM INFORMATION_SCHEMA.COLUMNS
            WHERE TABLE_SCHEMA = '{mySqlDbConnection.Database}';";

        var tables = new List<string>();

        using MySqlCommand cmd = new MySqlCommand(schemaQuery, mySqlDbConnection);
        using (var reader = cmd.ExecuteReader())
        {
            if (reader.HasRows)
            {
                while (reader.Read())
                {
                    string tableName = reader.GetString("TABLE_NAME");
                    tables.Add(tableName);
                }
            }
            return tables.Distinct().ToList();
        }
    }
    #endregion

    #region Db connection
    private MySqlConnection GetDbConnection()
    {
        if (string.IsNullOrEmpty(_mysqlConnection))
        {
            InitializeDatabase();
        }
        var dbConnection = new MySqlConnection(_mysqlConnection);
        dbConnection.Open();
        return dbConnection;
    }

    private void InitializeDatabase()
    {
        var sqlSettings = _services.GetRequiredService<SqlDriverSetting>();
        _mysqlConnection = sqlSettings.MySqlTempConnectionString;
        var databaseName = GetDatabaseName(_mysqlConnection);
        _logger.LogInformation($"Connected to MySQL database {databaseName}");
    }

    private string GetDatabaseName(string connectionString)
    {
        string pattern = @"database=([^;]+)";
        Regex regex = new Regex(pattern, RegexOptions.IgnoreCase);
        Match match = regex.Match(connectionString);
        return match.Success ? match.Groups[1].Value : string.Empty;
    }
    #endregion
}