using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MVVMDatabaseSample.Util
{
    internal sealed class SqlDBManager
    {
        public static SqlDBManager Instance { get; private set; } = new SqlDBManager();

        public string ConnectionString { get; set; }

        public SqlConnection Connection { get; private set; }

        private SqlCommand _sqlCommand;

        public bool GetConnection()
        {
            try
            {
                _sqlCommand = new SqlCommand();
                _sqlCommand.Connection = this.Connection;

                this.Connection = new SqlConnection(ConnectionString);
                this.Connection.Open();

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        public DataSet ExecuteQuery(DataSet ds, string query)
        {
            ds.Reset();
            lock (this)
            {
                SqlDataAdapter adapter = new SqlDataAdapter();
                adapter.SelectCommand = _sqlCommand;
                adapter.SelectCommand.Connection = this.Connection;
                adapter.SelectCommand.CommandText = query;
                adapter.Fill(ds);
            }

            return ds;
        }
    }
}