// import { mkdirSync, readFileSync, writeFileSync } from "fs";
// import { writeFile } from "fs/promises";

export class DHSecretClient {
  private token!: Promise<string>; //Set by init

  private headerName = "x-hoard-auth-token";

  private cache: Record<string, { value: string; expires?: number }> = {};
  private cacheLocation: string;

  /**
   * @param dhBaseUri uri for hosted Dragon's Hoard instance
   * @param cacheDir path to cache dir
   */
  constructor(
    private dhBaseUri: string,
    private cacheDir: string,
  ) {
    this.cacheLocation = this.cacheDir.trim().replace(/\/^/, "") + "/.dh_cache";
    // mkdirSync(this.cacheDir, { recursive: true });
    // writeFileSync(this.cacheLocation, "{}", { encoding: "utf-8", flag: "wx" });
    // this.readDiskCache();
    this.token = this.fetchToken();
  }

  private async fetchToken() {
    const cacheKey = "token";
    if (this.cache[cacheKey]) {
      return this.cache[cacheKey].value;
    }

    const req = await fetch(this.dhBaseUri + "/api/access/token");

    if (req.status !== 200) throw Error(await req.text());

    const token = await req.text();

    if (!token) throw Error("Token not included in response body");

    this.writeCache(cacheKey, token);

    return token;
  }

  // private readDiskCache() {
  //   const cache = readFileSync(this.cacheLocation, "utf-8");

  //   this.cache = JSON.parse(cache || "{}");
  // }
  // private async writeDiskCache() {
  //   await writeFile(this.cacheLocation, JSON.stringify(this.cache), "utf-8");
  // }

  private writeCache(key: string, value: string, expires?: number) {
    this.cache[key] = { value, expires };

    // this.writeDiskCache();
  }

  private readCache(key: string) {
    const item = this.cache[key];

    if (!item) return null;

    if (item && item.expires && item.expires < Date.now()) {
      delete this.cache[key];
      // this.writeDiskCache();
      return null;
    }

    return item.value;
  }

  async fetchSecret(secret_name: string, environment?: string) {
    const uri = this.dhBaseUri + "/api/keys/" + secret_name +
      (environment ? "?env=" + environment : "");

    const cached = this.readCache(secret_name);

    if (cached !== null) return cached;

    const req = await fetch(uri, {
      headers: {
        [this.headerName]: await this.token,
      },
    });

    if (req.status !== 200) throw Error(await req.text());

    const secret = await req.text();

    if (!secret) throw Error("Secret not included in response body");

    this.writeCache(secret_name, secret);

    return secret;
  }
}