using System;
using System.Data;
using System.Data.SqlClient;

namespace NDB.DataAccess.SqlServer
{
    public abstract class BaseDataAccess
    {
        #region Fields
        private readonly string _connectionString;
        #endregion

        protected BaseDataAccess(string connectionString)
        {
            _connectionString = connectionString;
        }

        #region Properties
        public SqlConnection Connection { get; private set; } = null;
        public SqlTransaction Transaction { get; private set; } = null;
        public SqlCommand Command { get; private set; } = null;
        #endregion

        #region Methods
        #region OpenConnection
        public void OpenConnection(string connStr = null)
        {
            Connection = new SqlConnection(connStr ?? _connectionString);
            Connection.Open();
        }
        #endregion

        #region OpenConnection
        public void CloseConnection()
        {
            Connection.Close();
        }
        #endregion

        #region OpenTransaction
        public void OpenTransaction()
        {
            Transaction = Connection.BeginTransaction();
        }
        #endregion

        #region OpenConnectionWithTransaction
        public void OpenConnectionWithTransaction()
        {
            OpenConnection();
            OpenTransaction();
        }
        #endregion

        #region Rollback
        public void Rollback()
        {
            CheckTransaction();
            if (Transaction.Connection == null)
                return;

            Transaction.Rollback();
        }

        private void CheckTransaction()
        {
            if (Transaction == null)
                throw new Exception("No open transaction found!");
        }
        #endregion

        #region Commit
        public void Commit()
        {
            CheckTransaction();
            if (Transaction.Connection == null)
                return;

            Transaction.Commit();
        }
        #endregion

        #region CreateCommand
        public void CreateCommand()
        {
            Command = new SqlCommand
            {
                Connection = Connection
            };

            if (Transaction != null)
                Command.Transaction = Transaction;
        }

        public void CreateCommand(CommandType commandType)
        {
            CreateCommand();
            Command.CommandType = commandType;
        }

        public void CreateCommand(CommandType commandType, string commandText)
        {
            CreateCommand(commandType);
            Command.CommandText = commandText;
        }
        #endregion

        #region GetDbValue
        protected T GetDbValue<T>(object obj)
        {
            if (obj != DBNull.Value && obj != null)
                return (T)obj;
            return default(T);
        }

        protected T GetDbValue<T>(IDataReader dr, string columnName)
        {
            if (dr[columnName] != DBNull.Value && dr[columnName] != null)
                return (T)dr[columnName];

            return default(T);
        }
        #endregion

        #region GetParamValue
        protected T GetParamValue<T>(string parameterName)
        {
            object obj = (Command.Parameters[parameterName]).Value;
            if (obj != DBNull.Value && obj != null)
                return (T)obj;

            return default(T);
        }
        #endregion

        #region AddParameterToCommand
        protected void AddParameterToCommand(string parameterName, ParameterDirection direction, DbType dbType, object value, int size = int.MinValue)
        {
            var param = Command.CreateParameter();
            param.ParameterName = parameterName;
            param.Direction = direction;
            param.DbType = dbType;

            if (value == null || value == DBNull.Value)
                param.Value = DBNull.Value;
            else
                param.Value = value;

            if (size != int.MinValue)
                param.Size = size;

            Command.Parameters.Add(param);
        }

        protected void AddParameterToCommand(string parameterName, ParameterDirection direction, DbType dbType)
        {
            var param = Command.CreateParameter();
            param.ParameterName = parameterName;
            param.Direction = direction;
            param.DbType = dbType;

            Command.Parameters.Add(param);
        }
        #endregion
        #endregion
    }
}