import { eq, inArray, and } from "drizzle-orm";
import { db } from "@/lib/db/client";
import { pushSubscriptions, users } from "@/lib/db/schema";
import type { TicketDTO, MessageDTO } from "@/lib/tickets/types";
import { webpush, ensureVapidConfigured } from "./vapid";

export interface PushSubscriptionKeys {
  endpoint: string;
  keys: { p256dh: string; auth: string };
}

/** Re-subscribing from the same browser (e.g. after clearing site data and re-granting) overwrites the old row via the endpoint's unique constraint, rather than accumulating stale duplicates. */
export async function savePushSubscription(
  userId: string,
  sub: PushSubscriptionKeys,
  userAgent?: string,
): Promise<void> {
  await db
    .insert(pushSubscriptions)
    .values({ userId, endpoint: sub.endpoint, p256dh: sub.keys.p256dh, auth: sub.keys.auth, userAgent })
    .onConflictDoUpdate({
      target: pushSubscriptions.endpoint,
      set: { userId, p256dh: sub.keys.p256dh, auth: sub.keys.auth, userAgent },
    });
}

export async function deletePushSubscriptionByEndpoint(endpoint: string): Promise<void> {
  await db.delete(pushSubscriptions).where(eq(pushSubscriptions.endpoint, endpoint));
}

/** A user's own subscribed devices/browsers, for the "manage notifications" settings list — never exposes the endpoint/keys, only what's useful to tell rows apart. */
export async function listPushSubscriptionsForUser(userId: string) {
  const rows = await db.query.pushSubscriptions.findMany({
    where: eq(pushSubscriptions.userId, userId),
    orderBy: (t, { desc }) => desc(t.createdAt),
  });
  return rows.map((r) => ({ id: r.id, userAgent: r.userAgent, createdAt: r.createdAt }));
}

/** Deletes one of the current user's own subscriptions by id — scoped so a user can only ever remove their own. */
export async function deleteOwnPushSubscription(userId: string, id: string): Promise<void> {
  await db
    .delete(pushSubscriptions)
    .where(and(eq(pushSubscriptions.id, id), eq(pushSubscriptions.userId, userId)));
}

async function sendPushToUsers(userIds: string[], payload: { title: string; body: string; url: string }): Promise<void> {
  if (userIds.length === 0 || !ensureVapidConfigured()) return;

  const subs = await db.query.pushSubscriptions.findMany({ where: inArray(pushSubscriptions.userId, userIds) });

  await Promise.all(
    subs.map(async (sub) => {
      try {
        await webpush.sendNotification(
          { endpoint: sub.endpoint, keys: { p256dh: sub.p256dh, auth: sub.auth } },
          JSON.stringify(payload),
        );
      } catch (err) {
        // A 404/410 means the push service no longer recognizes this
        // subscription (browser unsubscribed, site data cleared, endpoint
        // expired) — prune it so future sends stop failing on it. Any other
        // error (a transient network blip, ...) is left alone to retry on
        // the next event rather than deleting a possibly-still-good row.
        const statusCode = (err as { statusCode?: number }).statusCode;
        if (statusCode === 404 || statusCode === 410) {
          await db.delete(pushSubscriptions).where(eq(pushSubscriptions.endpoint, sub.endpoint));
        } else {
          console.error("[push] send failed for", sub.endpoint, err);
        }
      }
    }),
  );
}

/**
 * Pushes to every admin plus the ticket's assignee (if any) — the same
 * "who should know about this" set the in-page toast uses (see
 * lib/tickets/visibility.ts), so a subscribed device is notified even while
 * its browser tab is frozen in the background. Callers only invoke this for
 * customer-authored messages; an agent's own reply or internal note is the
 * agent's own action, not a signal anyone needs pushed to them.
 */
export async function notifyPushForCustomerMessage(
  ticket: TicketDTO,
  message: MessageDTO,
  ticketIsNew: boolean,
): Promise<void> {
  const admins = await db.query.users.findMany({ where: eq(users.role, "admin") });
  const userIds = new Set(admins.map((u) => u.id));
  if (ticket.assigneeId) userIds.add(ticket.assigneeId);

  await sendPushToUsers([...userIds], {
    title: ticketIsNew ? "Новая заявка" : `Сообщение от ${message.authorName}`,
    body: ticketIsNew ? ticket.subject : message.body.slice(0, 120),
    url: `/tickets/${ticket.id}`,
  });
}