package org.apache.torque.oid;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  import java.math.BigDecimal;
  import java.sql.Connection;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.apache.torque.adapter.DB;
  import org.apache.torque.util.SQLBuilder;
  
  import com.workingdogs.village.QueryDataSet;
  import com.workingdogs.village.Record;
  import com.workingdogs.village.Value;
  
  /***
   * This generator works with databases that have an sql syntax for
   * getting an id prior to inserting a row into the database.
   *
   * @author <a href="mailto:jmcnally@collab.net">John D. McNally</a>
   * @version $Id: SequenceIdGenerator.java 473821 2006-11-11 22:37:25Z tv $
   */
  public class SequenceIdGenerator implements IdGenerator
  {
      /*** The log. */
      private static Log log = LogFactory.getLog(SequenceIdGenerator.class);
  
      /*** the adapter that knows the correct sql syntax */
      private DB dbAdapter;
  
      /*** The internal name of the Database that this Generator is connected to */
      private String name = null;
  
      /***
       * Creates an IdGenerator which will work with the specified database.
       *
       * @param dbAdapter the adapter that knows the correct sql syntax.
       * @param name The name of the datasource to find the correct schema
       */
      public SequenceIdGenerator(final DB dbAdapter, final String name)
      {
          this.dbAdapter = dbAdapter;
          this.name = name;
      }
  
      /***
       * Retrieves an id as an int.
       *
       * @param connection A Connection.
       * @param keyInfo an Object that contains additional info.
       * @return An int with the value for the id.
       * @exception Exception Database error.
       */
      public int getIdAsInt(Connection connection, Object keyInfo)
          throws Exception
      {
          return getIdAsVillageValue(connection, keyInfo).asInt();
      }
  
      /***
       * Retrieves an id as an long.
       *
       * @param connection A Connection.
       * @param keyInfo an Object that contains additional info.
       * @return A long with the value for the id.
       * @exception Exception Database error.
       */
      public long getIdAsLong(Connection connection, Object keyInfo)
          throws Exception
      {
          return getIdAsVillageValue(connection, keyInfo).asLong();
      }
  
      /***
       * Retrieves an id as a BigDecimal.
       *
       * @param connection A Connection.
       * @param keyInfo an Object that contains additional info.
       * @return A BigDecimal id
       * @exception Exception Database error.
      */
     public BigDecimal getIdAsBigDecimal(Connection connection, Object keyInfo)
         throws Exception
     {
         return getIdAsVillageValue(connection, keyInfo).asBigDecimal();
     }
 
     /***
      * Retrieves an id as an String.
      *
      * @param connection A Connection.
      * @param keyInfo an Object that contains additional info.
      * @return A String id
      * @exception Exception Database error.
      */
     public String getIdAsString(Connection connection, Object keyInfo)
         throws Exception
     {
         return getIdAsVillageValue(connection, keyInfo).asString();
     }
 
     /***
      * A flag to determine the timing of the id generation
      *
      * @return a <code>boolean</code> value
      */
     public boolean isPriorToInsert()
     {
         return true;
     }
 
     /***
      * A flag to determine the timing of the id generation
      *
      * @return a <code>boolean</code> value
      */
     public boolean isPostInsert()
     {
         return false;
     }
 
     /***
      * A flag to determine whether a Connection is required to
      * generate an id.
      *
      * @return a <code>boolean</code> value
      */
     public boolean isConnectionRequired()
     {
         return true;
     }
 
     /***
      * Retrieves an id as a Village Value.
      *
      * @param connection A Connection.
      * @param keyInfo an Object that contains additional info.
      * @return A Village Value id.
      * @exception Exception Database error.
      */
     private Value getIdAsVillageValue(Connection connection, Object keyInfo)
         throws Exception
     {
         String sequenceName = SQLBuilder.getFullTableName(String.valueOf(keyInfo), name);
         String idSql = dbAdapter.getIDMethodSQL(sequenceName);
         if (log.isDebugEnabled())
         {
             log.debug(idSql);
         }
 
         // Execute the query.
         QueryDataSet qds = new QueryDataSet(connection, idSql);
         Record rec;
         try
         {
             qds.fetchRecords(1);
             rec = qds.getRecord(0);  // Records are 0 based.
         }
         finally
         {
             qds.close();
         }
         return rec.getValue(1); // Values are 1 based.
     }
 }