import { createWriteStream } from "node:fs";

const fileName = "./passwords.json";

export async function getPasswordFor(level: number): Promise<string | null> {
  try {
    const file = Bun.file(fileName);
    const data = await file.json();
    return data[`natas${level}`];
  } catch (e) {
    return null;
  }
}

export async function savePassword(
  level: number,
  password: string
): Promise<void> {
  let data = {};

  try {
    const file = Bun.file(fileName);
    data = await file.json();
  } catch (e) {}

  data[`natas${level}`] = password;
  createWriteStream(fileName).end();
  await Bun.write(fileName, JSON.stringify(data, null, 2));
}

export function hex2bin(hex: string): number[] {
  const buf = [];
  for (let i = 0; i < hex.length; i += 2) {
    const byte = hex.slice(i, i + 2);
    buf.push(parseInt(byte, 16));
  }
  return buf;
}

export function bytes2str(bytes: number[]): string {
  return bytes.map((c) => String.fromCharCode(c)).join("");
}

export function xor(str: string, key: string | number[]): number[] {
  const result = [];
  str.split("").forEach((c, idx) => {
    const pIdx = idx % key.length;
    let c2;
    if (typeof key === "string") c2 = key.charCodeAt(pIdx);
    else c2 = key[pIdx];
    result.push(c.charCodeAt(0) ^ c2);
  });
  return result;
}

export function determinePeriod(
  arr: number[],
  threshold: number = 1,
  limit: number = 50
): number {
  let period = 1;
  let lowest = null;
  while (period < limit) {
    let sum = 0;
    for (let i = period; i < arr.length; i++) {
      sum += arr[i] ^ arr[i - period];
    }
    console.log(period, sum);

    if (sum === 0) return period;
    if (lowest === null || sum < lowest[0]) lowest = [sum, period];
    period += 1;
  }

  if (lowest <= threshold) return lowest[1];
}