package guru.mikelue.jdut.operation;
   
   import java.sql.Connection;
   import java.sql.SQLException;
   import java.util.List;
   import java.util.function.UnaryOperator;
   
   import guru.mikelue.jdut.datagrain.DataGrain;
   import guru.mikelue.jdut.datagrain.DataRow;
  
  /**
   * Operator to execute code by fed {@link List} of {@link DataRow}.
   */
  @FunctionalInterface
  public interface DataRowsOperator {
  	/**
  	 * The operator for surrounding of {@link DataRowsOperator}.
  	 */
  	public interface SurroundOperator {
  		/**
  		 * Converts this operator ot {@link UnaryOperator}.
  		 *
  		 * @return The unary operator
  		 */
  		default UnaryOperator<DataRowsOperator> asUnaryOperator()
  		{
  			return operator -> surround(operator);
  		}
  
  		/**
  		 * Surrounds operator.
  		 *
  		 * @param surroundedOperator The oprator to be surrounded
  		 *
  		 * @return The final function
  		 */
  		public DataRowsOperator../guru/mikelue/jdut/operation/DataRowsOperator.html#DataRowsOperator">DataRowsOperator surround(DataRowsOperator surroundedOperator);
  	}
  
  	/**
  	 * Does nothing.
  	 *
  	 * @param conn The connection object
  	 * @param dataRows The data of rows
  	 *
  	 * @return The same data rows
  	 */
  	static List<DataRow> none(Connection conn, List<DataRow> dataRows) { return dataRows; }
  
  	/**
  	 * Converts this instance to {@link DataGrainOperator}.
  	 *
  	 * @return The operator for {@link DataGrain}
  	 */
  	default DataGrainOperator toDataGrainOperator()
  	{
  		return (connection, dataGrain) -> new DataGrain(operate(connection, dataGrain.getRows()));
  	}
  
  	/**
  	 * Surrounds this instance by {@link SurroundOperator}.
  	 *
  	 * @param surroundOperator The operator to surrounding staff
  	 *
  	 * @return new operator of data rows
  	 */
  	default DataRowsOperator surroundedBy(SurroundOperator surroundOperator)
  	{
  		return surroundOperator.surround(this);
  	}
  
  	/**
  	 * Operates {@link List} of {@link DataRow} by {@link Connection}.
  	 *
  	 * @param connection The connection of database
  	 * @param dataRows The data grain to be operated
  	 *
  	 * @return The processed data rows
  	 *
  	 * @throws SQLException The SQL exception defined by JDBC
  	 */
  	public List<DataRow> operate(Connection connection, List<DataRow> dataRows) throws SQLException;
  }