import { getCryptoBackend } from './backend.js';

export interface X25519KeyPair {
  publicKey: Uint8Array; // 32 bytes
  privateKey: Uint8Array; // 32 bytes
}

export async function generateX25519KeyPair(): Promise<X25519KeyPair> {
  const backend = getCryptoBackend();
  const kp = backend.generateKeyPair();
  return { publicKey: kp.publicKey, privateKey: kp.privateKey };
}

// ---- base64 helpers (used to persist private keys client-side) ----------
// Use browser-native btoa/atob. Both are available in Tauri webview and RN
// (Expo polyfills atob/btoa). No external dep needed.

export async function toBase64(bytes: Uint8Array): Promise<string> {
  let binary = '';
  for (let i = 0; i < bytes.length; i++) {
    binary += String.fromCharCode(bytes[i]!);
  }
  return btoa(binary);
}

export async function fromBase64(input: string): Promise<Uint8Array> {
  const binary = atob(input);
  const out = new Uint8Array(binary.length);
  for (let i = 0; i < binary.length; i++) {
    out[i] = binary.charCodeAt(i);
  }
  return out;
}

// Wipe a key best-effort. JS can't truly guarantee zeroization but
// overwriting the buffer removes the value from live references.
export function wipe(bytes: Uint8Array): void {
  for (let i = 0; i < bytes.length; i++) bytes[i] = 0;
}