// Copyright © 2004, 2018, Oracle and/or its affiliates. All rights reserved.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0, as
// published by the Free Software Foundation.
//
// This program is also distributed with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation.  The authors of MySQL hereby grant you an
// additional permission to link the program and your derivative works
// with the separately licensed software that they have included with
// MySQL.
//
// Without limiting anything contained in the foregoing, this file,
// which is part of MySQL Connector/NET, is also subject to the
// Universal FOSS Exception, version 1.0, a copy of which can be found at
// http://oss.oracle.com/licenses/universal-foss-exception.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License, version 2.0, for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System;
using System.Collections;
using System.Data.Common;
using MySql.Data.Types;
using System.Data;

namespace MySql.Data.MySqlClient
{
    public sealed partial class MySqlDataReader : DbDataReader, IDataReader, IDataRecord
    {
        /// <summary>
        /// Returns a DataTable that describes the column metadata of the MySqlDataReader.
        /// </summary>
        /// <returns></returns>
        public override DataTable GetSchemaTable()
        {
            // Only Results from SQL SELECT Queries 
            // get a DataTable for schema of the result
            // otherwise, DataTable is null reference
            if (this.FieldCount == 0)
            {
                return null;
            }

            DataTable dataTableSchema = new DataTable("SchemaTable");

            dataTableSchema.Columns.Add("ColumnName", typeof(string));
            dataTableSchema.Columns.Add("ColumnOrdinal", typeof(int));
            dataTableSchema.Columns.Add("ColumnSize", typeof(int));
            dataTableSchema.Columns.Add("NumericPrecision", typeof(int));
            dataTableSchema.Columns.Add("NumericScale", typeof(int));
            dataTableSchema.Columns.Add("IsUnique", typeof(bool));
            dataTableSchema.Columns.Add("IsKey", typeof(bool));
            DataColumn dc = dataTableSchema.Columns["IsKey"];
            dc.AllowDBNull = true; // IsKey can have a DBNull
            dataTableSchema.Columns.Add("BaseCatalogName", typeof(string));
            dataTableSchema.Columns.Add("BaseColumnName", typeof(string));
            dataTableSchema.Columns.Add("BaseSchemaName", typeof(string));
            dataTableSchema.Columns.Add("BaseTableName", typeof(string));
            dataTableSchema.Columns.Add("DataType", typeof(Type));
            dataTableSchema.Columns.Add("AllowDBNull", typeof(bool));
            dataTableSchema.Columns.Add("ProviderType", typeof(int));
            dataTableSchema.Columns.Add("IsAliased", typeof(bool));
            dataTableSchema.Columns.Add("IsExpression", typeof(bool));
            dataTableSchema.Columns.Add("IsIdentity", typeof(bool));
            dataTableSchema.Columns.Add("IsAutoIncrement", typeof(bool));
            dataTableSchema.Columns.Add("IsRowVersion", typeof(bool));
            dataTableSchema.Columns.Add("IsHidden", typeof(bool));
            dataTableSchema.Columns.Add("IsLong", typeof(bool));
            dataTableSchema.Columns.Add("IsReadOnly", typeof(bool));

            int ord = 1;
            for (int i = 0; i < this.FieldCount; i++)
            {
                MySqlField f = this.ResultSet.Fields[i];
                DataRow r = dataTableSchema.NewRow();
                r["ColumnName"] = f.ColumnName;
                r["ColumnOrdinal"] = ord++;
                r["ColumnSize"] = f.IsTextField ? f.ColumnLength / f.MaxLength : f.ColumnLength;
                int prec = f.Precision;
                int pscale = f.Scale;
                if (prec != -1)
                {
                    r["NumericPrecision"] = (short)prec;
                }

                if (pscale != -1)
                {
                    r["NumericScale"] = (short)pscale;
                }

                r["DataType"] = this.GetFieldType(i);
                r["ProviderType"] = (int)f.Type;
                r["IsLong"] = f.IsBlob && (f.ColumnLength > 255 || f.ColumnLength == -1);
                r["AllowDBNull"] = f.AllowsNull;
                r["IsReadOnly"] = false;
                r["IsRowVersion"] = false;
                r["IsUnique"] = false;
                r["IsKey"] = f.IsPrimaryKey;
                r["IsAutoIncrement"] = f.IsAutoIncrement;
                r["BaseSchemaName"] = f.DatabaseName;
                r["BaseCatalogName"] = null;
                r["BaseTableName"] = f.RealTableName;
                r["BaseColumnName"] = f.OriginalColumnName;

                dataTableSchema.Rows.Add(r);
            }

            return dataTableSchema;
        }

    }
}