// Copyright 2011 Leo Przybylski. All rights reserved.
   //
   // Redistribution and use in source and binary forms, with or without modification, are
   // permitted provided that the following conditions are met:
   //
   //    1. Redistributions of source code must retain the above copyright notice, this list of
   //       conditions and the following disclaimer.
   //
   //    2. Redistributions in binary form must reproduce the above copyright notice, this list
  //       of conditions and the following disclaimer in the documentation and/or other materials
  //       provided with the distribution.
  //
  // THIS SOFTWARE IS PROVIDED BY <COPYRIGHT HOLDER> ''AS IS'' AND ANY EXPRESS OR IMPLIED
  // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  // FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> OR
  // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  // ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  // ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  // The views and conclusions contained in the software and documentation are those of the
  // authors and should not be interpreted as representing official policies, either expressed
  // or implied, of Leo Przybylski.
  package liquibase.sqlgenerator.ext;
  
  import liquibase.database.Database;
  import liquibase.database.core.OracleDatabase;
  import liquibase.exception.ValidationErrors;
  import liquibase.sql.Sql;
  import liquibase.sql.UnparsedSql;
  import liquibase.sqlgenerator.SqlGenerator;
  import liquibase.sqlgenerator.SqlGeneratorChain;
  import liquibase.sqlgenerator.core.AbstractSqlGenerator;
  import liquibase.statement.ext.DescribeSequenceStatement;
  
  import java.util.List;
  import java.util.ArrayList;
  import java.util.Arrays;
  
  import static liquibase.ext.Constants.EXTENSION_PRIORITY;
  
  /**
   * Getting the current sequence value
   *
   * @author Leo Przybylski (leo [at] rsmart.com)
   */
  public class DescribeSequenceGeneratorOracle extends AbstractSqlGenerator<DescribeSequenceStatement> {
      private static final String CREATE_SEQUENCE_STATEMENT = "CREATE TABLE IF NOT EXISTS %s (id bigint(19) NOT NULL auto_increment, PRIMARY KEY(id) )";
      private static final String SET_START_VALUE_STATEMENT = "INSERT INTO %s VALUES (%s)";
  
      @Override
      public int getPriority() {
          return EXTENSION_PRIORITY;
      }
      
      @Override
      public boolean supports(final DescribeSequenceStatement statement, final Database database) {
          return database instanceof OracleDatabase;
      }
  
      @Override
      public ValidationErrors validate(DescribeSequenceStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
          return new ValidationErrors();
      }
  
      @Override
      public Sql[] generateSql(DescribeSequenceStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {
          List<Sql> list = new ArrayList<Sql>();
          list.add(new UnparsedSql(String.format("select %s.nextval from dual", statement.getSequenceName())));
          list.addAll(Arrays.asList(sqlGeneratorChain.generateSql(statement, database)));
  
          return list.toArray(new Sql[list.size()]);
  
      }
  }