import { DatabaseConnection } from '../shared/db/index';
import { QueryBuilder } from '../shared/utils/QueryBuilder';

/**
 * The tracked-ticker universe (FREE-DATA-STACK §4.1):
 * watchlist ∪ holdings ∪ tickers screened in the last 30 days.
 *
 * This is the news pipeline's first and biggest filter — stories about
 * tickers outside the universe are never stored. Cached for 10 minutes;
 * the universe changes slowly.
 */
export class UniverseProvider {
  private static readonly CACHE_TTL_MS = 10 * 60 * 1000;
  private static readonly SNAPSHOT_LOOKBACK_DAYS = 30;

  private cache: { universe: Set<string>; expiresAt: number } = {
    universe: new Set(),
    expiresAt: 0,
  };

  constructor(private readonly db: DatabaseConnection) {}

  getUniverse(): Set<string> {
    if (Date.now() < this.cache.expiresAt) return this.cache.universe;

    const sinceDay = new Date(
      Date.now() - UniverseProvider.SNAPSHOT_LOOKBACK_DAYS * 24 * 60 * 60 * 1000,
    )
      .toISOString()
      .slice(0, 10);

    const tickers = new Set<string>();
    const add = (rows: { ticker: string }[]) =>
      rows.forEach((r) => tickers.add(r.ticker.toUpperCase()));

    add(this.db.all(new QueryBuilder('UNIVERSE_QUERIES.DISTINCT_WATCHLIST_TICKERS')));
    add(this.db.all(new QueryBuilder('UNIVERSE_QUERIES.DISTINCT_HOLDING_TICKERS')));
    add(
      this.db.all(new QueryBuilder('UNIVERSE_QUERIES.DISTINCT_SNAPSHOT_TICKERS_SINCE', [sinceDay])),
    );

    this.cache = { universe: tickers, expiresAt: Date.now() + UniverseProvider.CACHE_TTL_MS };
    return tickers;
  }

  /** Force next getUniverse() to re-read (e.g. after a watchlist change). */
  invalidate(): void {
    this.cache.expiresAt = 0;
  }
}