using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient; 
using System.Data.Common;
using System.Windows.Forms;

namespace HelperDB
{
    public class DbHelperSQL 
    {
        private static string _ConnectionString = new XmlUse(Application.StartupPath + "\\AIMS.xml").GetNode("ConnectionString")[0].ToString();
        private static SqlConnection mConnection;
        public static SqlConnection Connection
        {
            get
            {
                if (DbHelperSQL.mConnection == null)
                {
                    DbHelperSQL.mConnection = new SqlConnection(DbHelperSQL._ConnectionString);
                }
                if (DbHelperSQL.mConnection.State == ConnectionState.Broken)
                {
                    DbHelperSQL.mConnection.Close();
                    DbHelperSQL.mConnection.Open();
                }
                if (DbHelperSQL.mConnection.State == ConnectionState.Closed)
                {
                    DbHelperSQL.mConnection.Open();
                }
                return DbHelperSQL.mConnection;
            }
        }
        private static bool bTransaction;
        private static SqlTransaction trans;
        public static void BeginTrans()
        {
            if (!bTransaction)
            {
                trans = Connection.BeginTransaction();
                bTransaction = true;
                return;
            }
            throw new DbAccessException("The transaction not Commit or Rollback.");
        }
       
        public static void CommitTrans()
        {
            if (bTransaction)
            {
                trans.Commit();
                trans = null;
                bTransaction = false;
                return;
            }
            throw new DbAccessException("not in a transaction.");
        }
        
        public static void RollbackTrans()
        {
            if (bTransaction)
            {
                trans.Rollback();
                trans = null;
                bTransaction = false;
                return;
            }
            throw new DbAccessException("not in a transaction.");
        }

        public static object GetSingle(string SQLString)
        {
            using (SqlConnection connection = new SqlConnection(_ConnectionString))
            {
                using (SqlCommand cmd = new SqlCommand(SQLString, connection))
                {
                    try
                    {
                        connection.Open();
                        object obj = cmd.ExecuteScalar();
                        if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                        {
                            return null;
                        }
                        else
                        {
                            return obj;
                        }
                    }
                    catch (System.Data.SqlClient.SqlException e)
                    {
                        connection.Close();
                        throw e;
                    }
                }
            }
        }


        public static bool Exists(string strSql)
        {
            object obj = DbHelperSQL.GetSingle(strSql);
            int cmdresult;
            if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
            {
                cmdresult = 0;
            }
            else
            {
                cmdresult = int.Parse(obj.ToString());
            }
            if (cmdresult == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        public static int ExecNonQuery(string sql)
        { 
            using (SqlConnection conn = new SqlConnection(_ConnectionString))
            {
                if (conn.State != ConnectionState.Open)
                    conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.Parameters.Clear();
                    cmd.CommandText = sql; 
                    return cmd.ExecuteNonQuery();
                }
            }
        }

        public static SqlDataReader GetDataReader(string sql)
        {
            SqlCommand sqlCommand = new SqlCommand(sql, DbHelperSQL.Connection, trans);
            return sqlCommand.ExecuteReader(CommandBehavior.CloseConnection);
        }

        public static SqlDataReader GetDataReader(string sql, params SqlParameter[] values)
        {
            SqlCommand sqlCommand = new SqlCommand(sql, DbHelperSQL.Connection, trans);
            sqlCommand.Parameters.AddRange(values);
            return sqlCommand.ExecuteReader(CommandBehavior.CloseConnection);
        }


        public static DataTable GetDataTable(string sql)
        {
            using (SqlConnection conn = new SqlConnection(_ConnectionString))
            {
                if (conn.State != ConnectionState.Open)
                    conn.Open();
                DataSet ds = new DataSet();
                SqlCommand cmd = new SqlCommand(sql, conn);
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(ds);
                return ds.Tables[0];
            }
        }
         
        public static DataSet GetDataSet(string sql)
        {
            using (SqlConnection conn = new SqlConnection(_ConnectionString))
            {
                if (conn.State != ConnectionState.Open)
                    conn.Open();
                DataSet ds = new DataSet();
                SqlCommand cmd = new SqlCommand(sql, conn);
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                try
                {
                    da.Fill(ds);
                }
                catch (Exception)
                {

                }
                return ds;
            }
        }

        public static bool ExecuteTrasaction(string sqlStr)
        {
            bool result = true;
            SqlTransaction sqlTransaction = null;
            try
            {
                sqlTransaction = DbHelperSQL.Connection.BeginTransaction("Tran");
                SqlCommand sqlCommand = new SqlCommand(sqlStr, DbHelperSQL.Connection, sqlTransaction);
                sqlCommand.ExecuteNonQuery();
                sqlTransaction.Commit();
                result = true;
            }
            catch
            {
                sqlTransaction.Rollback();
                result = false;
            }
            return result;
        }
         
        public static System.DateTime SystemDate()
        {
            string sql = "select getdate() as SysDate";
            DataTable dataTable = DbHelperSQL.GetDataTable(sql);
            return System.DateTime.Parse(System.DateTime.Parse(dataTable.Rows[0]["SysDate"].ToString()).ToString("yyyy-MM-dd HH:mm:ss"));
        }
    }
}