// Copyright (c) 2004-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as published by
// the Free Software Foundation
//
// There are special exceptions to the terms and conditions of the GPL 
// as it is applied to this software. View the full text of the 
// exception in file EXCEPTIONS in the directory of this software 
// distribution.
//
// 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 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

using System;
using System.Data;
using System.Text;
using MySql.Data.Common;
using System.Globalization;
using System.Diagnostics;
using System.Data.SqlTypes;
using MySql.Data.Types;
using System.Collections;
using MySql.Data.MySqlClient.Properties;

namespace MySql.Data.MySqlClient
{
    internal class ISSchemaProvider : SchemaProvider
    {
        public ISSchemaProvider(MySqlConnection connection) : base(connection)
        {
        }

        protected override DataTable GetCollections()
        {
           DataTable dt = base.GetCollections();

           object[][] collections = new object[][] 
            {
                new object[] {"Views", 2, 3},
                new object[] {"ViewColumns", 3, 4},
                new object[] {"Procedure Parameters", 5, 1},
                new object[] {"Procedures", 4, 3},
                new object[] {"Triggers", 2, 4}
            };

            FillTable(dt, collections);
            return dt;
        }

        protected override DataTable GetRestrictions()
        {
            DataTable dt = base.GetRestrictions();

            object[][] restrictions = new object[][] 
            {
                new object[] {"Procedure Parameters", "Database", "", 0},
                new object[] {"Procedure Parameters", "Schema", "", 1},
                new object[] {"Procedure Parameters", "Name", "", 2},
                new object[] {"Procedure Parameters", "Type", "", 3},
                new object[] {"Procedure Parameters", "Parameter", "", 4},
                new object[] {"Procedures", "Database", "", 0},
                new object[] {"Procedures", "Schema", "", 1},
                new object[] {"Procedures", "Name", "", 2},
                new object[] {"Procedures", "Type", "", 3},
                new object[] {"Views", "Database", "", 0},
                new object[] {"Views", "Schema", "", 1},
                new object[] {"Views", "Table", "", 2},
                new object[] {"ViewColumns", "Database", "", 0},
                new object[] {"ViewColumns", "Schema", "", 1},
                new object[] {"ViewColumns", "Table", "", 2},
                new object[] {"ViewColumns", "Column", "", 3},
                new object[] {"Triggers", "Database", "", 0},
                new object[] {"Triggers", "Schema", "", 1},
                new object[] {"Triggers", "Name", "", 2},
                new object[] {"Triggers", "EventObjectTable", "", 3},
            };
            FillTable(dt, restrictions);
            return dt;
        }

        public override DataTable GetDatabases(string[] restrictions)
        {
            string[] keys = new string[1];
            keys[0] = "SCHEMA_NAME";
            DataTable dt = Query("SCHEMATA", "", keys, restrictions);
            dt.Columns[1].ColumnName = "database_name";
            dt.TableName = "Databases";
            return dt;
        }

        public override DataTable GetTables(string[] restrictions)
        {
            string[] keys = new string[4];
            keys[0] = "TABLE_CATALOG";
            keys[1] = "TABLE_SCHEMA";
            keys[2] = "TABLE_NAME";
            keys[3] = "TABLE_TYPE";
            DataTable dt = Query("TABLES", "TABLE_TYPE != 'VIEW'", keys, restrictions);
            dt.TableName = "Tables";
            return dt;
        }

        public override DataTable GetColumns(string[] restrictions)
        {
            string[] keys = new string[4];
            keys[0] = "TABLE_CATALOG";
            keys[1] = "TABLE_SCHEMA";
            keys[2] = "TABLE_NAME";
            keys[3] = "COLUMN_NAME";
            DataTable dt = Query("COLUMNS", null, keys, restrictions);
            dt.Columns.Remove("CHARACTER_OCTET_LENGTH");
            dt.TableName = "Columns";
            return dt;
        }

        private DataTable GetViews(string[] restrictions)
        {
            string[] keys = new string[3];
            keys[0] = "TABLE_CATALOG";
            keys[1] = "TABLE_SCHEMA";
            keys[2] = "TABLE_NAME";
            DataTable dt = Query("VIEWS", null, keys, restrictions);
            dt.TableName = "Views";
            return dt;
        }

        private DataTable GetViewColumns(string[] restrictions)
        {
            StringBuilder where = new StringBuilder();
            StringBuilder sql = new StringBuilder(
                "SELECT C.* FROM information_schema.columns C");
            sql.Append(" JOIN information_schema.views V ");
            sql.Append("ON C.table_schema=V.table_schema AND C.table_name=V.table_name ");
            if (restrictions != null && restrictions.Length >= 2 &&
                restrictions[1] != null)
                where.AppendFormat(CultureInfo.InvariantCulture, "C.table_schema='{0}' ", restrictions[1]);
            if (restrictions != null && restrictions.Length >= 3 &&
                restrictions[2] != null)
            {
                if (where.Length > 0)
                    where.Append("AND ");
                where.AppendFormat(CultureInfo.InvariantCulture, "C.table_name='{0}' ", restrictions[2]);
            }
            if (restrictions != null && restrictions.Length == 4 &&
                restrictions[3] != null)
            {
                if (where.Length > 0)
                    where.Append("AND ");
                where.AppendFormat(CultureInfo.InvariantCulture, "C.column_name='{0}' ", restrictions[3]);
            }
            if (where.Length > 0)
                sql.AppendFormat(CultureInfo.InvariantCulture, " WHERE {0}", where);
            DataTable dt = GetTable(sql.ToString());
            dt.TableName = "ViewColumns";
            dt.Columns[0].ColumnName = "VIEW_CATALOG";
            dt.Columns[1].ColumnName = "VIEW_SCHEMA";
            dt.Columns[2].ColumnName  = "VIEW_NAME";
            return dt;
        }

        private DataTable GetTriggers(string[] restrictions)
        {
            string[] keys = new string[4];
            keys[0] = "TRIGGER_CATALOG";
            keys[1] = "TRIGGER_SCHEMA";
            keys[2] = "EVENT_OBJECT_TABLE";
            keys[3] = "TRIGGER_NAME";
            DataTable dt = Query("TRIGGERS", null, keys, restrictions);
            dt.TableName = "Triggers";
            return dt;
        }

        /// <summary>
        /// Return schema information about procedures and functions
        /// Restrictions supported are:
        /// schema, name, type
        /// </summary>
        /// <param name="restrictions"></param>
        /// <returns></returns>
        public override DataTable GetProcedures(string[] restrictions)
        {
            // if the user has said that we have access to mysql.proc then
            // we use that as it is a lot faster
//            if (connection.HasProcAccess)
  //              return base.GetProcedures(restrictions);

            string[] keys = new string[4];
            keys[0] = "ROUTINE_CATALOG";
            keys[1] = "ROUTINE_SCHEMA";
            keys[2] = "ROUTINE_NAME";
            keys[3] = "ROUTINE_TYPE";

            DataTable dt = Query("ROUTINES", null, keys, restrictions);
            dt.TableName = "Procedures";
            return dt;
        }

        private DataTable GetProceduresWithParameters(string[] restrictions)
        {
            DataTable dt = GetProcedures(restrictions);
            dt.Columns.Add("ParameterList", typeof(string));

            foreach (DataRow row in dt.Rows)
            {
                row["ParameterList"] = GetProcedureParameterLine(row);
            }
            return dt;
        }

        private string GetProcedureParameterLine(DataRow isRow)
        {
            string sql = "SHOW CREATE {0} `{1}`.`{2}`";
            sql = String.Format(sql, isRow["ROUTINE_TYPE"], isRow["ROUTINE_SCHEMA"],
                isRow["ROUTINE_NAME"]);
            MySqlCommand cmd = new MySqlCommand(sql, connection);
            using (MySqlDataReader reader = cmd.ExecuteReader())
            {
                reader.Read();

                // if we are not the owner of this proc or have permissions
                // then we will get null for the body
                if (reader.IsDBNull(2)) return null;

                string sql_mode = reader.GetString(1);

                string body = reader.GetString(2);
                MySqlTokenizer tokenizer = new MySqlTokenizer(body);
                tokenizer.AnsiQuotes = sql_mode.IndexOf("ANSI_QUOTES") != -1;
                tokenizer.BackslashEscapes = sql_mode.IndexOf("NO_BACKSLASH_ESCAPES") == -1;

                string token = tokenizer.NextToken();
                while (token != "(")
                    token = tokenizer.NextToken();
                int start = tokenizer.StartIndex + 1;
                token = tokenizer.NextToken();
                while (token != ")" || tokenizer.Quoted)
                {
                    token = tokenizer.NextToken();
                    // if we see another ( and we are not quoted then we
                    // are in a size element and we need to look for the closing paren
                    if (token == "(" && !tokenizer.Quoted)
                    {
                        while (token != ")" || tokenizer.Quoted)
                            token = tokenizer.NextToken();
                        token = tokenizer.NextToken();
                    }
                }
                return body.Substring(start, tokenizer.StartIndex - start);
            }
        }

        private void GetParametersForRoutineFromIS(DataTable dt, string[] restrictions)
        {
            Debug.Assert(dt != null);

            string[] keys = new string[5];
            keys[0] = "SPECIFIC_CATALOG";
            keys[1] = "SPECIFIC_SCHEMA";
            keys[2] = "SPECIFIC_NAME";
            keys[3] = "ROUTINE_TYPE";
            keys[4] = "PARAMETER_NAME";

            StringBuilder sql = new StringBuilder(@"SELECT * FROM INFORMATION_SCHEMA.PARAMETERS");
            // now get our where clause and append it if there is one
            string where = GetWhereClause(null, keys, restrictions);
            if (!String.IsNullOrEmpty(where))
                sql.AppendFormat(CultureInfo.InvariantCulture, " WHERE {0}", where);

            MySqlDataAdapter da = new MySqlDataAdapter(sql.ToString(), connection);
            da.Fill(dt);
        }

        private DataTable GetParametersFromIS(string[] restrictions, DataTable routines)
        {
            DataTable parms = new DataTable();

            if (routines == null || routines.Rows.Count == 0)
            {
                if (restrictions == null)
                {
                    // first fill our table with the proper structure
                    MySqlDataAdapter da = new MySqlDataAdapter("SELECT * FROM INFORMATION_SCHEMA.PARAMETERS WHERE 1=2", connection);
                    da.Fill(parms);
                }
                else
                    GetParametersForRoutineFromIS(parms, restrictions);
            }
            else foreach (DataRow routine in routines.Rows)
            {
                if (restrictions != null && restrictions.Length >= 3)
                    restrictions[2] = routine["ROUTINE_NAME"].ToString();

                GetParametersForRoutineFromIS(parms, restrictions);
            }
            parms.TableName = "Procedure Parameters";
            return parms;
        }

        internal DataTable CreateParametersTable()
        {
            DataTable dt = new DataTable("Procedure Parameters");
            dt.Columns.Add("SPECIFIC_CATALOG", typeof(string));
            dt.Columns.Add("SPECIFIC_SCHEMA", typeof(string));
            dt.Columns.Add("SPECIFIC_NAME", typeof(string));
            dt.Columns.Add("ORDINAL_POSITION", typeof(Int32));
            dt.Columns.Add("PARAMETER_MODE", typeof(string));
            dt.Columns.Add("PARAMETER_NAME", typeof(string));
            dt.Columns.Add("DATA_TYPE", typeof(string));
            dt.Columns.Add("CHARACTER_MAXIMUM_LENGTH", typeof(Int32));
            dt.Columns.Add("CHARACTER_OCTET_LENGTH", typeof(Int32));
            dt.Columns.Add("NUMERIC_PRECISION", typeof(byte));
            dt.Columns.Add("NUMERIC_SCALE", typeof(Int32));
            dt.Columns.Add("CHARACTER_SET_NAME", typeof(string));
            dt.Columns.Add("COLLATION_NAME", typeof(string));
            dt.Columns.Add("DTD_IDENTIFIER", typeof(string));
            dt.Columns.Add("ROUTINE_TYPE", typeof(string));
            return dt;
        }

        /// <summary>
        /// Return schema information about parameters for procedures and functions
        /// Restrictions supported are:
        /// schema, name, type, parameter name
        /// </summary>
        public virtual DataTable GetProcedureParameters(string[] restrictions,
            DataTable routines)
        {
            if (connection.driver.Version.isAtLeast(6, 0, 6))
                return GetParametersFromIS(restrictions, routines);
            try
            {
                DataTable dt = CreateParametersTable();
                GetParametersFromShowCreate(dt, restrictions, routines);
                return dt;
            }
            catch (InvalidOperationException ioe)
            {
                throw new InvalidOperationException(Resources.UnableToRetrieveParameters, ioe);
            }
        }

        protected override DataTable GetSchemaInternal(string collection, string[] restrictions)
        {
            DataTable dt = base.GetSchemaInternal(collection, restrictions);
            if (dt != null)
                return dt;

            switch (collection)
            {
                case "VIEWS":
                    return GetViews(restrictions);
                case "PROCEDURES":
                    return GetProcedures(restrictions);
                case "PROCEDURES WITH PARAMETERS":
                    return GetProceduresWithParameters(restrictions);
                case "PROCEDURE PARAMETERS":
                    return GetProcedureParameters(restrictions, null);
                case "TRIGGERS":
                    return GetTriggers(restrictions);
                case "VIEWCOLUMNS":
                    return GetViewColumns(restrictions);
            }
            return null;
        }

        private static string GetWhereClause(string initial_where, string[] keys, string[] values)
        {
            StringBuilder where = new StringBuilder(initial_where);
            if (values != null)
            {
                for (int i = 0; i < keys.Length; i++)
                {
                    if (i >= values.Length) break;
                    if (values[i] == null || values[i] == String.Empty) continue;
                    if (where.Length > 0)
                        where.Append(" AND ");
                    where.AppendFormat(CultureInfo.InvariantCulture, 
                        "{0} LIKE '{1}'", keys[i], values[i]);
                }
            }
            return where.ToString();
        }

        private DataTable Query(string table_name, string initial_where,
            string[] keys, string[] values)
        {
            StringBuilder query = new StringBuilder("SELECT * FROM INFORMATION_SCHEMA.");
            query.Append(table_name);

            string where = GetWhereClause(initial_where, keys, values);

            if (where.Length > 0)
                query.AppendFormat(CultureInfo.InvariantCulture, " WHERE {0}", where);

            return GetTable(query.ToString());
        }

        private DataTable GetTable(string sql)
        {
            DataTable table = new DataTable();
            MySqlDataAdapter da = new MySqlDataAdapter(sql, connection);
            da.Fill(table);
            return table;
        }

        public override DataTable GetForeignKeys(string[] restrictions)
        {
            if (!connection.driver.Version.isAtLeast(5, 1, 16))
                return base.GetForeignKeys(restrictions);

            string sql = @"SELECT rc.constraint_catalog, rc.constraint_schema,
                rc.constraint_name, kcu.table_catalog, kcu.table_schema, rc.table_name,
                rc.match_option, rc.update_rule, rc.delete_rule, 
                NULL as referenced_table_catalog,
                kcu.referenced_table_schema, rc.referenced_table_name 
                FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc
                LEFT JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu ON 
                kcu.constraint_catalog <=> rc.constraint_catalog AND
                kcu.constraint_schema <=> rc.constraint_schema AND 
                kcu.constraint_name <=> rc.constraint_name AND
                kcu.ORDINAL_POSITION=1 WHERE 1=1";

            StringBuilder where =new StringBuilder();
            if (restrictions.Length >= 2 && !String.IsNullOrEmpty(restrictions[1]))
                where.AppendFormat(CultureInfo.InvariantCulture, 
                    " AND rc.constraint_schema LIKE '{0}'", restrictions[1]);
            if (restrictions.Length >= 3 && !String.IsNullOrEmpty(restrictions[2]))
                where.AppendFormat(CultureInfo.InvariantCulture, 
                    " AND rc.table_name LIKE '{0}'", restrictions[2]);
            if (restrictions.Length >= 4 && !String.IsNullOrEmpty(restrictions[3]))
                where.AppendFormat(CultureInfo.InvariantCulture, 
                    " AND rc.constraint_name LIKE '{0}'", restrictions[2]);

            sql += where.ToString();

            return GetTable(sql);
        }

        public override DataTable GetForeignKeyColumns(string[] restrictions)
        {
            if (!connection.driver.Version.isAtLeast(5, 0, 6))
                return base.GetForeignKeyColumns(restrictions);

            string sql = @"SELECT kcu.* FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu
                WHERE kcu.referenced_table_name IS NOT NULL";

            StringBuilder where = new StringBuilder();
            if (restrictions.Length >= 2 && !String.IsNullOrEmpty(restrictions[1]))
                where.AppendFormat(CultureInfo.InvariantCulture, 
                    " AND kcu.constraint_schema LIKE '{0}'", restrictions[1]);
            if (restrictions.Length >= 3 && !String.IsNullOrEmpty(restrictions[2]))
                where.AppendFormat(CultureInfo.InvariantCulture, 
                    " AND kcu.table_name LIKE '{0}'", restrictions[2]);
            if (restrictions.Length >= 4 && !String.IsNullOrEmpty(restrictions[3]))
                where.AppendFormat(CultureInfo.InvariantCulture, 
                    " AND kcu.constraint_name LIKE '{0}'", restrictions[3]);

            sql += where.ToString();

            return GetTable(sql);
        }

        #region Procedures Support Rouines

        internal void GetParametersFromShowCreate(DataTable parametersTable,
            string[] restrictions, DataTable routines)
        {
            // this allows us to pass in a pre-populated routines table
            // and avoid the querying for them again.
            // we use this when calling a procedure or function
            if (routines == null)
                routines = GetSchema("procedures", restrictions);

            MySqlCommand cmd = connection.CreateCommand();

            foreach (DataRow routine in routines.Rows)
            {
                string showCreateSql = String.Format("SHOW CREATE {0} `{1}`.`{2}`",
                    routine["ROUTINE_TYPE"], routine["ROUTINE_SCHEMA"],
                    routine["ROUTINE_NAME"]);
                cmd.CommandText = showCreateSql;
                try
                {
                    string nameToRestrict = null;
                    if (restrictions != null && restrictions.Length == 5 &&
                        restrictions[4] != null)
                        nameToRestrict = restrictions[4];
                    using (MySqlDataReader reader = cmd.ExecuteReader())
                    {
                        reader.Read();
                        string body = reader.GetString(2);
                        reader.Close();
                        ParseProcedureBody(parametersTable, body, routine, nameToRestrict);
                    }
                }
                catch (SqlNullValueException snex)
                {
                    throw new InvalidOperationException(
                        String.Format(Resources.UnableToRetrieveSProcData, routine["ROUTINE_NAME"]), snex);
                }
            }
        }

        private void ParseProcedureBody(DataTable parametersTable, string body,
            DataRow row, string nameToRestrict)
        {
            ArrayList modes = new ArrayList(new string[3] { "IN", "OUT", "INOUT" });

            string sqlMode = row["SQL_MODE"].ToString();

            int pos = 1;
            MySqlTokenizer tokenizer = new MySqlTokenizer(body);
            tokenizer.AnsiQuotes = sqlMode.IndexOf("ANSI_QUOTES") != -1;
            tokenizer.BackslashEscapes = sqlMode.IndexOf("NO_BACKSLASH_ESCAPES") == -1;
            tokenizer.ReturnComments = false;
            string token = tokenizer.NextToken();

            // this block will scan for the opening paren while also determining
            // if this routine is a function.  If so, then we need to add a
            // parameter row for the return parameter since it is ordinal position
            // 0 and should appear first.
            while (token != "(")
            {
                if (String.Compare(token, "FUNCTION", true) == 0 &&
                    nameToRestrict == null)
                {
                    parametersTable.Rows.Add(parametersTable.NewRow());
                    InitParameterRow(row, parametersTable.Rows[0]);
                }
                token = tokenizer.NextToken();
            }
            token = tokenizer.NextToken();  // now move to the next token past the (

            while (token != ")")
            {
                DataRow parmRow = parametersTable.NewRow();
                InitParameterRow(row, parmRow);
                parmRow["ORDINAL_POSITION"] = pos++;

                // handle mode and name for the parameter
                string mode = token.ToUpper(CultureInfo.InvariantCulture);
                if (!tokenizer.Quoted && modes.Contains(mode))
                {
                    parmRow["PARAMETER_MODE"] = mode;
                    token = tokenizer.NextToken();
                }
                if (tokenizer.Quoted)
                    token = token.Substring(1, token.Length - 2);
                parmRow["PARAMETER_NAME"] = token;

                // now parse data type
                token = ParseDataType(parmRow, tokenizer);
                if (token == ",")
                    token = tokenizer.NextToken();

                // now determine if we should include this row after all
                // we need to parse it before this check so we are correctly
                // positioned for the next parameter
                if (nameToRestrict == null ||
                    String.Compare(parmRow["PARAMETER_NAME"].ToString(), nameToRestrict, true) == 0)
                    parametersTable.Rows.Add(parmRow);
            }

            // now parse out the return parameter if there is one.
            token = tokenizer.NextToken().ToUpper(CultureInfo.InvariantCulture);
            if (String.Compare(token, "RETURNS", true) == 0)
            {
                DataRow parameterRow = parametersTable.Rows[0];
                parameterRow["PARAMETER_NAME"] = "RETURN_VALUE";
                ParseDataType(parameterRow, tokenizer);
            }
        }

        /// <summary>
        /// Initializes a new row for the procedure parameters table.
        /// </summary>
        private static void InitParameterRow(DataRow procedure, DataRow parameter)
        {
            parameter["SPECIFIC_CATALOG"] = null;
            parameter["SPECIFIC_SCHEMA"] = procedure["ROUTINE_SCHEMA"];
            parameter["SPECIFIC_NAME"] = procedure["ROUTINE_NAME"];
            parameter["PARAMETER_MODE"] = "IN";
            parameter["ORDINAL_POSITION"] = 0;
            parameter["ROUTINE_TYPE"] = procedure["ROUTINE_TYPE"];
        }

        /// <summary>
        ///  Parses out the elements of a procedure parameter data type.
        /// </summary>
        private string ParseDataType(DataRow row, MySqlTokenizer tokenizer)
        {
            StringBuilder dtd = new StringBuilder(
                tokenizer.NextToken().ToUpper(CultureInfo.InvariantCulture));
            row["DATA_TYPE"] = dtd.ToString();
            string type = row["DATA_TYPE"].ToString();

            string token = tokenizer.NextToken();
            if (token == "(")
            {
                token = tokenizer.ReadParenthesis();
                dtd.AppendFormat(CultureInfo.InvariantCulture, "{0}", token);
                if (type != "ENUM" && type != "SET")
                    ParseDataTypeSize(row, token);
                token = tokenizer.NextToken();
            }
            else
                dtd.Append(GetDataTypeDefaults(type, row));

            while (token != ")" && 
                   token != "," && 
                   String.Compare(token, "begin", true) != 0 &&
                   String.Compare(token, "return", true) != 0)
            {
                if (String.Compare(token, "CHARACTER", true) == 0 ||
                    String.Compare(token, "BINARY", true) == 0)
                { }  // we don't need to do anything with this
                else if (String.Compare(token, "SET", true) == 0 ||
                         String.Compare(token, "CHARSET", true) == 0)
                    row["CHARACTER_SET_NAME"] = tokenizer.NextToken();
                else if (String.Compare(token, "ASCII", true) == 0)
                    row["CHARACTER_SET_NAME"] = "latin1";
                else if (String.Compare(token, "UNICODE", true) == 0)
                    row["CHARACTER_SET_NAME"] = "ucs2";
                else if (String.Compare(token, "COLLATE", true) == 0)
                    row["COLLATION_NAME"] = tokenizer.NextToken();
                else
                    dtd.AppendFormat(CultureInfo.InvariantCulture, " {0}", token);
                token = tokenizer.NextToken();
            }

            if (dtd.Length > 0)
                row["DTD_IDENTIFIER"] = dtd.ToString();

            // now default the collation if one wasn't given
            if (row["COLLATION_NAME"].ToString().Length == 0 &&
                row["CHARACTER_SET_NAME"].ToString().Length > 0)
                row["COLLATION_NAME"] = CharSetMap.GetDefaultCollation(
                    row["CHARACTER_SET_NAME"].ToString(), connection);

            // now set the octet length
            if (row["CHARACTER_MAXIMUM_LENGTH"] != DBNull.Value)
                row["CHARACTER_OCTET_LENGTH"] =
                    CharSetMap.GetMaxLength(row["CHARACTER_SET_NAME"].ToString(), connection) *
                    (int)row["CHARACTER_MAXIMUM_LENGTH"];

            return token;
        }

        private static string GetDataTypeDefaults(string type, DataRow row)
        {
            string format = "({0},{1})";

            if (MetaData.IsNumericType(type) &&
                row["NUMERIC_PRECISION"].ToString().Length == 0)
            {
                row["NUMERIC_PRECISION"] = 10;
                row["NUMERIC_SCALE"] = 0;
                if (!MetaData.SupportScale(type))
                    format = "({0})";
                return String.Format(format, row["NUMERIC_PRECISION"],
                    row["NUMERIC_SCALE"]);
            }
            return String.Empty;
        }

        private static void ParseDataTypeSize(DataRow row, string size)
        {
            size = size.Trim('(', ')');
            string[] parts = size.Split(',');

            if (!MetaData.IsNumericType(row["DATA_TYPE"].ToString()))
            {
                row["CHARACTER_MAXIMUM_LENGTH"] = Int32.Parse(parts[0]);
                // will set octet length in a minute
            }
            else
            {
                row["NUMERIC_PRECISION"] = Int32.Parse(parts[0]);
                if (parts.Length == 2)
                    row["NUMERIC_SCALE"] = Int32.Parse(parts[1]);
            }
        }

        #endregion

    }
}