\c dcntrlized;

-- 005_alarm_deliveries.sql — a durable per-device delivery ledger.
--
-- Why this exists: pg_notify and the WebSocket fan-out are not durable. A phone
-- that is offline at trigger time misses the frame forever, and the in-memory
-- catch-up cache only lives in the process that produced the event. This table is
-- the durable record of who still owes an alarm, so "no auto-stop" is safe: the
-- alarm stays live until the owner disarms it, and every subscribed device has a
-- row here until it has been told.
--
-- Shape: one row per (alert, subscription, event), written in the SAME
-- transaction as the alarm_events insert and therefore before the NOTIFY on
-- commit. If this insert fails the trigger fails — a fan-out that records no debt
-- would be exactly the silent failure this design prevents.
--
-- Cascades are in the schema, not in application code: deleting an alert or a
-- subscription removes its ledger rows. event_id deliberately has no foreign key:
-- the ledger is the record of what a device owes, and it must outlive nothing but
-- its alert/subscription (both of which cascade).
--
-- Idempotent (same guard pattern as 002/003/004): a re-apply of the whole
-- sequence is a clean no-op.

DO $$
BEGIN
    IF NOT EXISTS (SELECT 1 FROM pg_namespace WHERE nspname = 'alarm') THEN
        RETURN;
    END IF;

    CREATE TABLE IF NOT EXISTS alarm.alarm_deliveries (
        alert_id        UUID        NOT NULL REFERENCES alarm.alerts(id)          ON DELETE CASCADE,
        subscription_id UUID        NOT NULL REFERENCES alarm.subscriptions(id)   ON DELETE CASCADE,
        event_id        UUID        NOT NULL,
        created_at      TIMESTAMPTZ NOT NULL DEFAULT now(),
        acked_at        TIMESTAMPTZ,
        PRIMARY KEY (alert_id, subscription_id, event_id)
    );

    -- The check-in reads by alert + subscription; the pending index keeps
    -- "who still owes this alert" a small partial scan instead of a table scan.
    CREATE INDEX IF NOT EXISTS alarm_deliveries_alert_idx
        ON alarm.alarm_deliveries (alert_id);
    CREATE INDEX IF NOT EXISTS alarm_deliveries_pending_idx
        ON alarm.alarm_deliveries (alert_id, subscription_id)
        WHERE acked_at IS NULL;

    IF EXISTS (SELECT 1 FROM pg_roles WHERE rolname = 'alarm_user') THEN
        GRANT SELECT, INSERT, UPDATE, DELETE ON alarm.alarm_deliveries TO alarm_user;
    END IF;
END
$$;