BEGIN;

-- Numbers target every direction in the city. Keep route_id for older clients.
ALTER TABLE alerts ADD COLUMN IF NOT EXISTS route_numbers TEXT[] NOT NULL DEFAULT '{}';
UPDATE alerts a SET route_numbers = ARRAY[upper(regexp_replace(r.route_number, '[[:space:]№]', '', 'g'))]
FROM routes r WHERE r.id=a.route_id AND cardinality(a.route_numbers)=0;
CREATE INDEX IF NOT EXISTS idx_alerts_route_numbers ON alerts USING gin(route_numbers);

-- Removing one direction must not remove a notification for the whole number.
ALTER TABLE alerts DROP CONSTRAINT IF EXISTS alerts_route_id_fkey;
ALTER TABLE alerts ADD CONSTRAINT alerts_route_id_fkey FOREIGN KEY(route_id) REFERENCES routes(id) ON DELETE SET NULL;

-- One source publication creates one alert. A NULL alert_id preserves deletion.
-- Legacy per-direction links stay intact until that publication is edited/reviewed.
CREATE TABLE IF NOT EXISTS telegram_message_alerts (
  message_id INTEGER PRIMARY KEY REFERENCES telegram_import_messages(id) ON DELETE CASCADE,
  alert_id INTEGER UNIQUE REFERENCES alerts(id) ON DELETE SET NULL
);

COMMIT;