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