package com.megatim.fdxcommons.tools.database.queries;

import java.util.List;
import java.util.stream.IntStream;

/**
 *
 * @author Gabuntu
 */
public class GroupByQuery {

    private final List<String> groupingColumns;

    public GroupByQuery(List<String> groupingColumns) {
        this.groupingColumns = groupingColumns;
    }

    public String query() {
        StringBuilder query = new StringBuilder("");
        if (!groupingColumns.isEmpty()) {
            query
                    .append(" GROUP BY ")
                    .append(buildQuery());
        }
        return query.toString();
    }

    private String buildQuery() {
        StringBuilder query = new StringBuilder();

        int size = groupingColumns.size();
        IntStream.range(0, size).forEach(index -> {
            String column = groupingColumns.get(index);
            query.append(column);
            if ((index + 1) < size) {
                query.append(",");
            }
        });

        return query.toString();
    }
}