CREATE OR REPLACE FUNCTION public.c77_dbh_update_vacuum_stats()
    RETURNS void AS $$
DECLARE
    v_has_pgstattuple boolean;
BEGIN
    -- Check if pgstattuple is installed
    SELECT EXISTS (
        SELECT 1 FROM pg_extension WHERE extname = 'pgstattuple'
    ) INTO v_has_pgstattuple;

    -- Insert or update vacuum stats for all user tables
    INSERT INTO public.c77_dbh_vacuum_stats (
        table_name, last_vacuum, last_autovacuum, vacuum_count,
        dead_tuples, live_tuples, table_size, last_updated
    )
    SELECT
        (n.nspname || '.' || c.relname) AS table_name,
        s.last_vacuum,
        s.last_autovacuum,
        COALESCE(s.vacuum_count, 0) + COALESCE(s.autovacuum_count, 0) AS vacuum_count,
        s.n_dead_tup AS dead_tuples,
        s.n_live_tup AS live_tuples,
        pg_relation_size(c.oid) AS table_size,
        now() AS last_updated
    FROM pg_stat_all_tables s
             JOIN pg_class c ON c.oid = s.relid
             JOIN pg_namespace n ON n.oid = c.relnamespace
    WHERE n.nspname NOT IN ('pg_catalog', 'information_schema')
    ON CONFLICT (table_name) DO UPDATE
        SET
            last_vacuum = EXCLUDED.last_vacuum,
            last_autovacuum = EXCLUDED.last_autovacuum,
            vacuum_count = EXCLUDED.vacuum_count,
            dead_tuples = EXCLUDED.dead_tuples,
            live_tuples = EXCLUDED.live_tuples,
            table_size = EXCLUDED.table_size,
            last_updated = EXCLUDED.last_updated;

    -- Update bloat estimate
    IF v_has_pgstattuple THEN
        -- Use pgstattuple for precise bloat if available
        UPDATE public.c77_dbh_vacuum_stats v
        SET bloat_estimate = ROUND(CAST(COALESCE(t.free_percent + t.dead_tuple_percent, 0) AS numeric), 2)
        FROM (
                 SELECT (pgstattuple(c.oid)).*
                 FROM pg_class c
                          JOIN pg_namespace n ON n.oid = c.relnamespace
                 WHERE (n.nspname || '.' || c.relname) = v.table_name
             ) t
        WHERE v.last_updated = now();
    ELSE
        -- Fallback to heuristic bloat estimate
        UPDATE public.c77_dbh_vacuum_stats
        SET bloat_estimate = CASE
                                 WHEN live_tuples + dead_tuples = 0 THEN 0
                                 ELSE ROUND((dead_tuples::numeric / (live_tuples + dead_tuples)) * 100, 2)
            END
        WHERE last_updated = now();
    END IF;
END;
$$ LANGUAGE plpgsql;