market_screener/server/domains/shared/services/CatalystCache.ts

import type { CatalystResult, Logger } from '../types/index';
import { CatalystAnalyst } from './CatalystAnalyst';

export class CatalystCache {
  private static readonly TTL_MS = 15 * 60 * 1000; // 15 minutes
  private cached: CatalystResult | null = null;
  private cachedAt: number | null = null;
  private isRefreshing = false;
  private analyst: CatalystAnalyst;
  private logger: Pick<Logger, 'write'>;

  constructor({ logger }: { logger?: Pick<Logger, 'write'> } = {}) {
    this.analyst = new CatalystAnalyst({ logger });
    this.logger = logger ?? { write: (msg: string) => process.stdout.write(msg) };
  }

  async get(): Promise<CatalystResult> {
    const now = Date.now();
    const isStale = !this.cachedAt || now - this.cachedAt > CatalystCache.TTL_MS;

    if (!isStale && this.cached) {
      return this.cached;
    }

    if (this.isRefreshing) {
      // Return stale cache while refresh in progress
      if (this.cached) {
        return this.cached;
      }
      // If no cache exists yet, wait for refresh to complete
      return new Promise((resolve) => {
        const checkInterval = setInterval(() => {
          if (!this.isRefreshing && this.cached) {
            clearInterval(checkInterval);
            resolve(this.cached!);
          }
        }, 100);
        // Timeout after 30s
        setTimeout(() => clearInterval(checkInterval), 30000);
      });
    }

    // Trigger refresh
    this.isRefreshing = true;
    try {
      this.logger.write('📡 Refreshing catalyst cache...\n');
      this.cached = await this.analyst.run();
      this.cachedAt = now;
    } catch (error) {
      this.logger.write(`⚠️  Catalyst refresh failed: ${error}\n`);
      // Return stale cache on error
      if (!this.cached) {
        this.cached = { tickers: [], tickerFrequency: {}, stories: [] };
      }
    } finally {
      this.isRefreshing = false;
    }

    return this.cached;
  }

  isExpired(): boolean {
    if (!this.cachedAt) return true;
    return Date.now() - this.cachedAt > CatalystCache.TTL_MS;
  }

  clear(): void {
    this.cached = null;
    this.cachedAt = null;
  }
}