frontend/src/utils/crypto.ts

export const base64UrlEncode = (arrayBuffer: ArrayBuffer): string => {
  const bytes = new Uint8Array(arrayBuffer);
  let binary = "";
  for (let i = 0; i < bytes.byteLength; i++)
    binary += String.fromCharCode(bytes[i]);
  return btoa(binary)
    .replace(/\+/g, "-")
    .replace(/\//g, "_")
    .replace(/=+$/, "");
};

export const sha256 = async (input: string): Promise<string> => {
  const encoder = new TextEncoder();
  const data = encoder.encode(input);
  const digest = await crypto.subtle.digest("SHA-256", data);
  return base64UrlEncode(digest);
};

export const randomString = (size = 64): string => {
  const charset =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~";
  const values = crypto.getRandomValues(new Uint8Array(size));
  return Array.from(values, (v) => charset[v % charset.length]).join("");
};