package PWC325;

/**
 * PL/Java implementation for PWC 325
 * Task 2
 * See <https://perlweeklychallenge.org/blog/perl-weekly-challenge-325>
 *
 *
 * To compile on the local machine:

 $ export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64/  # if not already set
 $ mvn clean build
 $ scp target/PWC325-1.jar  luca@rachel:/tmp


 * To install into PostgreSQL execute:

 select sqlj.install_jar( 'file:///tmp/PWC325-1.jar', 'PWC325', true );
 select sqlj.set_classpath( 'public', 'PWC325' );

 select pwc325.task2_pljava();

 and then to redeploy:

 select sqlj.replace_jar( 'file:///tmp/PWC325-1.jar', 'PWC325', true );

*/

import org.postgresql.pljava.*;
import org.postgresql.pljava.annotation.Function;
import static org.postgresql.pljava.annotation.Function.Effects.IMMUTABLE;
import static org.postgresql.pljava.annotation.Function.OnNullInput.RETURNS_NULL;

import java.util.*;
import java.util.stream.*;
import java.sql.SQLException;
import java.util.logging.*;
import java.sql.ResultSet;
import java.sql.Date;

public class Task2 {

    private final static Logger logger = Logger.getAnonymousLogger();

    @Function( schema = "pwc325",
	       onNullInput = RETURNS_NULL,
	       effects = IMMUTABLE )
    public static final int[] task2_pljava( int[] prices ) throws SQLException {
	logger.log( Level.INFO, "Entering pwc325.task2_pljava" );

	List<Integer> new_prices = new LinkedList<Integer>();

	for ( int i = 0; i < prices.length; i++ ) {
	    int current = prices[ i ];

	    for ( int j = i + 1; j < prices.length; j++ )
		if ( prices[ j ] < prices[ i ] ) {
		    current -= prices[ j ];
		    break;
		}

	    new_prices.add( current );
	}

	int result[] = new int[ new_prices.size() ];
	for ( int i = 0; i < new_prices.size(); i++ )
	    result[ i ] = new_prices.get( i );

	return result;
    }
}