// Copyright � 2004, 2011, Oracle and/or its affiliates. All rights reserved.
//
// MySQL Connector/NET is licensed under the terms of the GPLv2
// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most 
// MySQL Connectors. There are special exceptions to the terms and 
// conditions of the GPLv2 as it is applied to this software, see the 
// FLOSS License Exception
// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
//
// This program is free software; you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published 
// by the Free Software Foundation; version 2 of the License.
//
// 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., 
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System;
using System.Collections;
using System.Text;
using System.Collections.Generic;
using MySql.Data.MySqlClient.Properties;
using System.Data;

namespace MySql.Data.MySqlClient
{
  /// <summary>
  /// Summary description for PreparedStatement.
  /// </summary>
  internal class PreparableStatement : Statement
  {
    private int executionCount;
    private int statementId;
    BitArray nullMap;
    List<MySqlParameter> parametersToSend = new List<MySqlParameter>();
    MySqlPacket packet;
    int dataPosition;
    int nullMapPosition;

    public PreparableStatement(MySqlCommand command, string text)
      : base(command, text)
    {
    }

    #region Properties

    public int ExecutionCount
    {
      get { return executionCount; }
      set { executionCount = value; }
    }

    public bool IsPrepared
    {
      get { return statementId > 0; }
    }

    public int StatementId
    {
      get { return statementId; }
    }

    #endregion

    public virtual void Prepare()
    {
      // strip out names from parameter markers
      string text;
      List<string> parameter_names = PrepareCommandText(out text);

      // ask our connection to send the prepare command
      MySqlField[] paramList = null;
      statementId = Driver.PrepareStatement(text, ref paramList);

      // now we need to assign our field names since we stripped them out
      // for the prepare
      for (int i = 0; i < parameter_names.Count; i++)
      {
        //paramList[i].ColumnName = (string) parameter_names[i];
        string parameterName = (string)parameter_names[i];
        MySqlParameter p = Parameters.GetParameterFlexible(parameterName, false);
        if (p == null)
          throw new InvalidOperationException(
              String.Format(Resources.ParameterNotFoundDuringPrepare, parameterName));
        p.Encoding = paramList[i].Encoding;
        parametersToSend.Add(p);
      }

      // now prepare our null map
      int numNullBytes = 0;
      if (paramList != null && paramList.Length > 0)
      {
        nullMap = new BitArray(paramList.Length);
        numNullBytes = (nullMap.Count + 7) / 8;
      }

      packet = new MySqlPacket(Driver.Encoding);

      // write out some values that do not change run to run
      packet.WriteByte(0);
      packet.WriteInteger(statementId, 4);
      packet.WriteByte((byte)0); // flags; always 0 for 4.1
      packet.WriteInteger(1, 4); // interation count; 1 for 4.1
      nullMapPosition = packet.Position;
      packet.Position += numNullBytes;  // leave room for our null map
      packet.WriteByte(1); // rebound flag
      // write out the parameter types
      foreach (MySqlParameter p in parametersToSend)
        packet.WriteInteger(p.GetPSType(), 2);
      dataPosition = packet.Position;
    }

    public override void Execute()
    {
      // if we are not prepared, then call down to our base
      if (!IsPrepared)
      {
        base.Execute();
        return;
      }

      //TODO: support long data here
      // create our null bitmap

      // we check this because Mono doesn't ignore the case where nullMapBytes
      // is zero length.
      //            if (nullMapBytes.Length > 0)
      //          {
      //            byte[] bits = packet.Buffer;
      //          nullMap.CopyTo(bits, 
      //        nullMap.CopyTo(nullMapBytes, 0);

      // start constructing our packet
      //            if (Parameters.Count > 0)
      //              nullMap.CopyTo(packet.Buffer, nullMapPosition);
      //if (parameters != null && parameters.Count > 0)
      //else
      //	packet.WriteByte( 0 );
      //TODO:  only send rebound if parms change

      // now write out all non-null values
      packet.Position = dataPosition;
      for (int i = 0; i < parametersToSend.Count; i++)
      {
        MySqlParameter p = parametersToSend[i];
        nullMap[i] = (p.Value == DBNull.Value || p.Value == null) ||
            p.Direction == ParameterDirection.Output;
        if (nullMap[i]) continue;
        packet.Encoding = p.Encoding;
        p.Serialize(packet, true, Connection.Settings);
      }
      if (nullMap != null)
        nullMap.CopyTo(packet.Buffer, nullMapPosition);

      executionCount++;

      Driver.ExecuteStatement(packet);
    }

    public override bool ExecuteNext()
    {
      if (!IsPrepared)
        return base.ExecuteNext();
      return false;
    }

    /// <summary>
    /// Prepares CommandText for use with the Prepare method
    /// </summary>
    /// <returns>Command text stripped of all paramter names</returns>
    /// <remarks>
    /// Takes the output of TokenizeSql and creates a single string of SQL
    /// that only contains '?' markers for each parameter.  It also creates
    /// the parameterMap array list that includes all the paramter names in the
    /// order they appeared in the SQL
    /// </remarks>
    private List<string> PrepareCommandText(out string stripped_sql)
    {
      StringBuilder newSQL = new StringBuilder();
      List<string> parameterMap = new List<string>();

      int startPos = 0;
      string sql = ResolvedCommandText;
      MySqlTokenizer tokenizer = new MySqlTokenizer(sql);
      string parameter = tokenizer.NextParameter();
      while (parameter != null)
      {
        if (parameter.IndexOf(StoredProcedure.ParameterPrefix) == -1)
        {
          newSQL.Append(sql.Substring(startPos, tokenizer.StartIndex - startPos));
          newSQL.Append("?");
          parameterMap.Add(parameter);
          startPos = tokenizer.StopIndex;
        }
        parameter = tokenizer.NextParameter();
      }
      newSQL.Append(sql.Substring(startPos));
      stripped_sql = newSQL.ToString();
      return parameterMap;
    }

    public virtual void CloseStatement()
    {
      if (!IsPrepared) return;

      Driver.CloseStatement(statementId);
      statementId = 0;
    }
  }
}

