import { readFile, writeFile, mkdir } from "node:fs/promises";
import { DATA } from "./paths.js";

// What happened to the catalog and the university, newest first, for the dashboard: the same
// events the Telegram messages report, plus republished documents without new problems.
// The last hundred are kept on disk, so a restart does not empty the feed.

const FILE = "events.json";
const MAX = 100;
let events;

async function load() {
  if (events) return events;
  try {
    events = JSON.parse(await readFile(DATA + FILE, "utf8"));
    if (!Array.isArray(events)) events = [];
  } catch {
    events = [];
  }
  return events;
}

/**
 * Adds events: `{kind, title, text?, doc?}`. Kinds: new, republished, failed, year, year_late,
 * source_down, source_up.
 */
export async function recordEvents(list) {
  if (!list.length) return;
  await load();
  const t = new Date().toISOString();
  events.unshift(...list.map((e) => ({ t, ...e })));
  events.length = Math.min(events.length, MAX);
  await mkdir(DATA, { recursive: true });
  await writeFile(DATA + FILE, JSON.stringify(events));
}

export async function listEvents(limit = 50) {
  return (await load()).slice(0, limit);
}