// Display helpers for the keys and ids the native library hands back as
// base32 and hex — formatting only, no protocol meaning.

import "dart:typed_data";

/// Lowercase hex, as the message ids cross the ABI.
String hex(List<int> bytes) =>
    bytes.map((b) => b.toRadixString(16).padLeft(2, "0")).join();

/// The compact human check for a key: the first 20 base32 characters in
/// groups of four, the same shape every smol client shows.
String fingerprint(String keyB32) {
  final s = keyB32.substring(0, 20);
  return RegExp(".{4}").allMatches(s).map((m) => m[0]).join(" ");
}

/// The inverse of [hex]; throws on anything that is not even-length hex.
Uint8List unhex(String text) {
  if (text.length % 2 != 0) {
    throw FormatException("odd-length hex string");
  }
  return Uint8List.fromList(
      [for (var i = 0; i < text.length; i += 2) int.parse(text.substring(i, i + 2), radix: 16)]);
}