-- ============================================================
-- Broadcast recipient correlation + aggregate counts
--
-- Problem this solves:
--   * broadcast_recipients had no column to correlate with Meta's
--     message id, so webhook status updates (sent/delivered/read)
--     could not be mirrored into the recipient row and the broadcast
--     aggregate counts never advanced.
--   * aggregate counts on `broadcasts` (sent/delivered/read/replied/
--     failed) were updated ad-hoc by the sender, which drifted quickly
--     once webhooks arrived out of band.
--
-- This migration:
--   1. Adds whatsapp_message_id (+ unique index) so webhooks can find
--      a recipient given Meta's message id.
--   2. Adds a composite index on (broadcast_id, status) so the
--      aggregate trigger's COUNT(*) FILTER scans are fast.
--   3. Installs an AFTER INSERT/UPDATE/DELETE trigger on
--      broadcast_recipients that re-aggregates the parent broadcasts
--      row. Keeps writer code trivial — the webhook + hook only touch
--      the recipient row; counts stay consistent automatically.
--
-- Idempotent — safe to run multiple times.
-- ============================================================

ALTER TABLE broadcast_recipients
  ADD COLUMN IF NOT EXISTS whatsapp_message_id TEXT;

-- UNIQUE so webhook retries can't create duplicate correlations.
CREATE UNIQUE INDEX IF NOT EXISTS idx_broadcast_recipients_wamid
  ON broadcast_recipients (whatsapp_message_id)
  WHERE whatsapp_message_id IS NOT NULL;

-- Fast path for the aggregate trigger's COUNT(*) FILTER subqueries.
CREATE INDEX IF NOT EXISTS idx_broadcast_recipients_broadcast_status
  ON broadcast_recipients (broadcast_id, status);

-- ============================================================
-- Aggregate trigger
-- ============================================================
CREATE OR REPLACE FUNCTION public.recompute_broadcast_counts(bid UUID)
RETURNS VOID AS $$
BEGIN
  UPDATE broadcasts b SET
    sent_count      = agg.sent_count,
    delivered_count = agg.delivered_count,
    read_count      = agg.read_count,
    replied_count   = agg.replied_count,
    failed_count    = agg.failed_count,
    updated_at      = NOW()
  FROM (
    SELECT
      COUNT(*) FILTER (WHERE status IN ('sent','delivered','read','replied')) AS sent_count,
      COUNT(*) FILTER (WHERE status IN ('delivered','read','replied'))        AS delivered_count,
      COUNT(*) FILTER (WHERE status IN ('read','replied'))                    AS read_count,
      COUNT(*) FILTER (WHERE status = 'replied')                              AS replied_count,
      COUNT(*) FILTER (WHERE status = 'failed')                               AS failed_count
    FROM broadcast_recipients
    WHERE broadcast_id = bid
  ) agg
  WHERE b.id = bid;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER SET search_path = public;

CREATE OR REPLACE FUNCTION public.broadcast_recipient_aggregate_trigger()
RETURNS TRIGGER AS $$
BEGIN
  IF TG_OP = 'DELETE' THEN
    PERFORM public.recompute_broadcast_counts(OLD.broadcast_id);
    RETURN OLD;
  END IF;

  -- INSERT or UPDATE — only recompute when status changed (or on fresh insert)
  IF TG_OP = 'INSERT' OR OLD.status IS DISTINCT FROM NEW.status THEN
    PERFORM public.recompute_broadcast_counts(NEW.broadcast_id);
  END IF;
  RETURN NEW;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER SET search_path = public;

DROP TRIGGER IF EXISTS broadcast_recipients_aggregate ON broadcast_recipients;
CREATE TRIGGER broadcast_recipients_aggregate
AFTER INSERT OR UPDATE OR DELETE ON broadcast_recipients
FOR EACH ROW EXECUTE FUNCTION public.broadcast_recipient_aggregate_trigger();