import "dotenv/config";

const AUTH_KEY = Bun.env.TBA_AUTH_KEY as string;
if (!AUTH_KEY) {
  process.exit(1);
}

const authHeaders = new Headers({
  "X-TBA-Auth-Key": AUTH_KEY,
});

const BASE_URL = "https://www.thebluealliance.com/api/v3";

interface CacheEntry {
  etag: string;
  data: string;
  staleTime: number;
}

const CACHE_PATH = Bun.env.CACHE_PATH as string;
if (!CACHE_PATH) {
  process.exit(1);
}

async function initializeCache() {
  let data = {};

  const cacheFile = Bun.file(".cache");
  if (cacheFile.size > 0) {
    data = JSON.parse(await cacheFile.text());
  }

  return data;
}

const tbaCache: { [name: string]: CacheEntry } = await initializeCache();

async function writeCache() {
  Bun.write(CACHE_PATH, JSON.stringify(tbaCache));
}

interface TBAResponse {
  data: string;
  status: number;
}

function updateCache(
  endpoint: string,
  etag: string | null,
  data: string,
  maxAge: number,
) {
  if (etag) {
    tbaCache[endpoint] = { etag, data, staleTime: Date.now() + maxAge * 1000 };
  }
}

function fetchCache(endpoint: string) {
  return tbaCache[endpoint];
}

async function getTBAEndpoint(endpoint: string): Promise<TBAResponse> {
  const time = Date.now();
  if (tbaCache[endpoint] && tbaCache[endpoint].staleTime > time) {
    console.log("Cache hit... " + endpoint);
    return { data: fetchCache(endpoint).data, status: 200 };
  }

  console.log("Fetching... " + endpoint);
  const headers = new Headers(authHeaders);
  if (tbaCache[endpoint]) {
    headers.append("If-None-Match", tbaCache[endpoint].etag);
  }
  const response = await fetch(BASE_URL + endpoint, { headers });

  let data;
  if (response.status === 200) {
    data = await response.text();
    const maxAge = parseInt(
      response.headers
        .get("cache-control")
        ?.split(",")
        .filter((d) => d.includes("max-age"))[0]
        .trim()
        .split("=")[1] as string,
    );
    updateCache(endpoint, response.headers.get("ETag"), data, maxAge);
  } else if (response.status === 304) {
    // Safety: a 304 response indicates out cache is valid based on ETag
    data = fetchCache(endpoint).data as string;

    console.log("Unchanged... " + endpoint);
  } else {
    data = await response.text();
  }

  return {
    data,
    status: response.status,
  };
}

const response = await getTBAEndpoint(
  "/team/frc4043/event/2024pncmp/matches/simple",
);

console.log(response.data);

writeCache();