const textEncoder = new TextEncoder();
const textDecoder = new TextDecoder();
const base32Alphabet = "abcdefghijklmnopqrstuvwxyz234567";

export function utf8Bytes(value: string): Uint8Array {
  return textEncoder.encode(value);
}

export function utf8String(bytes: Uint8Array): string {
  return textDecoder.decode(bytes);
}

export function randomBytes(length: number): Uint8Array {
  const bytes = new Uint8Array(length);
  crypto.getRandomValues(bytes);
  return bytes;
}

export function hexFromBytes(bytes: Uint8Array): string {
  return [...bytes].map((byte) => byte.toString(16).padStart(2, "0")).join("");
}

export function randomHex(byteLength: number): string {
  return hexFromBytes(randomBytes(byteLength));
}

export function base32FromBytes(bytes: Uint8Array): string {
  let output = "";
  let buffer = 0;
  let bits = 0;

  for (const byte of bytes) {
    buffer = (buffer << 8) | byte;
    bits += 8;

    while (bits >= 5) {
      output += base32Alphabet[(buffer >>> (bits - 5)) & 31];
      bits -= 5;
    }
  }

  if (bits > 0) output += base32Alphabet[(buffer << (5 - bits)) & 31];
  return output;
}

export function base64UrlEncode(bytes: Uint8Array): string {
  let binary = "";
  for (const byte of bytes) binary += String.fromCharCode(byte);
  return btoa(binary).replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/g, "");
}

export function base64UrlDecode(value: string): Uint8Array {
  const normalized = value.replace(/-/g, "+").replace(/_/g, "/");
  const padded = normalized.padEnd(Math.ceil(normalized.length / 4) * 4, "=");
  const binary = atob(padded);
  const bytes = new Uint8Array(binary.length);
  for (let i = 0; i < binary.length; i += 1) bytes[i] = binary.charCodeAt(i);
  return bytes;
}

export function constantTimeEqual(a: string, b: string): boolean {
  const maxLength = Math.max(a.length, b.length);
  let diff = a.length ^ b.length;

  for (let i = 0; i < maxLength; i += 1) {
    diff |= (a.charCodeAt(i) || 0) ^ (b.charCodeAt(i) || 0);
  }

  return diff === 0;
}