Full Text Search "sort of" with prefix, infix, fuzzy, and similarity on the Almighty Postgres

fts.sql

SELECT
        pos,
        sim,
        p.*        
FROM
        produtos AS p,
        NULLIF(POSITION('seme' IN LOWER(COALESCE(p.gtin, '') || ' ' || COALESCE(p.descricao, ''))), 0) AS pos,
        NULLIF(SIMILARITY(LOWER(COALESCE(p.gtin, '') || ' ' || COALESCE(p.descricao, '')), 'seme'), 0) AS sim
WHERE
        (LOWER(COALESCE(p.gtin, '') || ' ' || COALESCE(p.descricao, ''))) LIKE 'seme%'
OR      (LOWER(COALESCE(p.gtin, '') || ' ' || COALESCE(p.descricao, ''))) LIKE '%seme%'
OR      'seme' % ANY(STRING_TO_ARRAY(LOWER(COALESCE(p.gtin, '') || ' ' || COALESCE(p.descricao, '')), ' '))
AND     (pos > 0 OR sim > 0)
ORDER BY
        pos ASC NULLS LAST, sim DESC NULLS LAST
LIMIT 10;