import chokidar from "chokidar";
import { LRUCache } from "lru-cache";
import path from "path";

let maxKeys = 10_000;
let cache = makeCache(maxKeys);

function makeCache(maxEntries) {
  return new LRUCache({
    maxSize: maxEntries,
    ttl: 60_000,
    allowStale: false,
    updateAgeOnGet: false,
    updateAgeOnHas: false
  });
}

function scaleCache() {
  const { heapUsed, heapTotal } = process.memoryUsage();
  const freeHeapRatio = (heapTotal - heapUsed) / heapTotal;
  const newMax = freeHeapRatio > 0.5 ? 20_000 : freeHeapRatio < 0.2 ? 5_000 : 10_000;
  if (newMax !== maxKeys) {
    maxKeys = newMax;
    cache = makeCache(maxKeys);
    console.log(`[SCALER] freeHeap ${((heapTotal - heapUsed) / 1e6).toFixed(1)}MB → maxKeys: ${maxKeys}`);
  }
}

setInterval(scaleCache, 60_000);
scaleCache();

const watchPath = path.join(process.cwd(), "public");
chokidar.watch(watchPath, { ignoreInitial: true }).on("all", () => {
  cache.clear();
});

export { cache };