CREATE OR REPLACE FUNCTION generateMatches(tournament INT, basegroups INT) RETURNS VOID AS $$
DECLARE
    counter INTEGER := 0;
    level INTEGER := 0;
    identifier INTEGER := 1;
    groupid INTEGER := 0;
    teamrow RECORD;
    grouperow RECORD;
    groups_on_level INTEGER;
BEGIN
    groups_on_level := basegroups;
    LOOP
        LOOP
            EXIT WHEN counter = groups_on_level;
            INSERT INTO "Groups" (id_tournament, name, level)
                VALUES (tournament, identifier, level);
            counter := counter + 1;
            identifier := identifier + 1;
        END LOOP;
        EXIT WHEN groups_on_level = 1;
        groups_on_level := groups_on_level / 2;
        counter := 0;
        level := level + 1;
    END LOOP;

    counter := 1;
    FOR teamrow IN
        SELECT * FROM "Teams" WHERE id_tournament = tournament
    LOOP
        IF (counter > basegroups) THEN
            counter := 1;
        END IF;
        groupid := (SELECT id FROM "Groups" WHERE name = counter AND id_tournament = tournament);
        INSERT INTO "GroupElements" (id_team, id_group, position)
            VALUES (teamrow.id, groupid, 0);
        counter := counter + 1;
    END LOOP;
    FOR grouperow IN
        SELECT x.id_team AS id_team1, y.id_team AS id_team2, g.id AS id_group
            FROM "GroupElements" x CROSS JOIN "GroupElements" y INNER JOIN "Groups" g ON x.id_group = g.id
            WHERE x.id_group = y.id_group AND x.id_team < y.id_team AND g.id_tournament = tournament
    LOOP
        INSERT INTO "Matches" (id_team1, id_team2, score1, score2, id_group)
            VALUES (grouperow.id_team1, grouperow.id_team2, 0, 0, grouperow.id_group);
    END LOOP;
    FOR grouperow IN
        SELECT * FROM "Groups" g WHERE g.id_tournament = tournament AND g.level != 0
    LOOP
        INSERT INTO "Matches" (score1, score2, id_group) VALUES (0, 0, grouperow.id);
    END LOOP;
END;
$$ LANGUAGE plpgsql;