PostgreSQL function to generate sonata media path

sonata_media_path.sql

-- Function: public.sonata_media_path(bigint, text, text, text)

-- DROP FUNCTION public.sonata_media_path(bigint, text, text, text);

CREATE OR REPLACE FUNCTION public.sonata_media_path(
    id bigint,
    context text,
    size text,
    reference text)
  RETURNS text AS
$BODY$
DECLARE
	firstLevel 		bigint;
	secondLevel		bigint;
	repFirstLevel	text;
	repSecondLevel	text;
	filepath		text;
	filename		text;
BEGIN
	-- initial calculations and 0 padding
	firstLevel := (id / 100000);
	secondLevel := ((id - (firstLevel * 100000)) / 1000);
	-- 0 padding
	repFirstLevel := lpad((firstLevel + 1)::text, 4, '0');
	repSecondLevel := lpad((secondLevel + 1)::text, 2, '0');
	-- make the filepath
	filepath := '/uploads/media/' || context || '/' || repFirstLevel || '/' || repSecondLevel || '/';
	-- make the filename
	filename := 'thumb_' || id::text || '_' || context || '_' || size || '.' || split_part(reference, '.', 2);

	RETURN filepath || filename;
END;
$BODY$
  LANGUAGE plpgsql STABLE SECURITY DEFINER
  COST 100;