import { Env } from "../types";
import { FeedEvent } from "../domain/events";
import { FeedId } from "../domain/value-objects/feed-id";
import { BackgroundScheduler } from "../infrastructure/worker";
import { bumpCounters } from "./stats";
import { notifySubscribers } from "../infrastructure/websub";
import { cacheFaviconForDomain } from "../infrastructure/favicon-fetcher";

/**
 * Apply the side effects of a feed's domain events — the single place that maps
 * "what happened" (FeedCreated, EmailIngested) to its consequences. Counter
 * writes are awaited (they must land); WebSub pings and favicon fetches are
 * handed to the caller's background scheduler (`ctx.waitUntil` at the edge, a
 * no-op when none is available).
 */
export async function applyFeedEvents(
  feedId: FeedId,
  events: FeedEvent[],
  env: Env,
  schedule: BackgroundScheduler,
): Promise<void> {
  for (const event of events) {
    switch (event.type) {
      case "FeedCreated":
        await bumpCounters(env.EMAIL_STORAGE, {
          feeds_created: 1,
          last_feed_created_at: new Date().toISOString(),
        });
        break;
      case "EmailIngested":
        await bumpCounters(env.EMAIL_STORAGE, {
          emails_received: 1,
          last_email_at: new Date().toISOString(),
        });
        schedule(notifySubscribers(feedId.value, env));
        if (event.iconDomain) {
          schedule(cacheFaviconForDomain(event.iconDomain, env));
        }
        break;
    }
  }
}