import { isNode } from '../utils/utils.js';

/**
 * Convert a base64 string to a Uint8Array for Node.js and browser environments.
 * @returns A Uint8Array
 */
export function base64ToBytes(base64String: string): Uint8Array {
  if (isNode()) {
    return new Uint8Array(Buffer.from(base64String, 'base64'));
  }
  /* eslint-env browser */
  const binString = atob(base64String);
  return Uint8Array.from(binString, (m) => m.codePointAt(0)!);
}

/**
 * Convert a Uint8Array to a base64 string for Node.js and browser environments.
 * @returns A base64 string
 */
export function bytesToBase64(byteArray: Uint8Array): string {
  if (isNode()) {
    return Buffer.from(byteArray).toString('base64');
  }
  /* eslint-env browser */
  const binString = Array.from(byteArray, (x) => String.fromCodePoint(x)).join(
    ''
  );
  return btoa(binString);
}

/**
 * Convert a byte array to a UTF-8 string. Warning: not all byte arrays are valid UTF-8.
 * @returns A decoded string
 */
export function bytesToString(byteArray: Uint8Array): string {
  return new TextDecoder().decode(byteArray);
}

/**
 * Returns a Uint8Array given an input string or Uint8Array.
 * @returns A base64 string
 */
export function coerceToBytes(input: Uint8Array | string): Uint8Array {
  if (typeof input === 'string') {
    return new TextEncoder().encode(input);
  }
  return input;
}

/**
 * Convert a Uint8Array to a hex string for Node.js and browser environments.
 * @returns A hex string
 */
export function bytesToHex(byteArray: Uint8Array): string {
  if (isNode()) {
    return Buffer.from(byteArray).toString('hex');
  }
  return Array.from(byteArray)
    .map((i) => i.toString(16).padStart(2, '0'))
    .join('');
}

/**
 * Convert a hex string to Uint8Array for Node.js and browser environments.
 * @returns A Uint8Array
 */
export function hexToBytes(hexString: string): Uint8Array {
  if (isNode()) {
    return Buffer.from(hexString, 'hex');
  }
  let hex = hexString;
  if (hexString.length % 2 !== 0) {
    hex = hexString.padStart(1, '0');
  }
  const byteArray = new Uint8Array(hex.length / 2);
  for (let i = 0; i < hex.length / 2; i++) {
    byteArray[i] = parseInt(hex.slice(2 * i, 2 * i + 2), 16);
  }
  return byteArray;
}