// Copyright (c) 2023, Sudipto Chandra
// All rights reserved. Check LICENSE file for details.

import 'dart:typed_data';

import 'codecs/base16.dart';

Base16Codec _codecFromParameters({
  bool upper = false,
}) {
  if (upper) {
    return Base16Codec.upper;
  } else {
    return Base16Codec.lower;
  }
}

/// Converts 8-bit integer sequence to 4-bit Base-16 character sequence.
///
/// Parameters:
/// - [input] is a sequence of 8-bit integers.
/// - If [upper] is true, the uppercase standard alphabet is used.
/// - [codec] is the [Base16Codec] to use. It is derived from the other
///   parameters if not provided.
String toHex(
  List<int> input, {
  Base16Codec? codec,
  bool upper = false,
}) {
  codec ??= _codecFromParameters(upper: upper);
  var out = codec.encoder.convert(input);
  return String.fromCharCodes(out);
}

/// Converts 4-bit Base-16 character sequence to 8-bit integer sequence.
///
/// Parameters:
/// - [input] should be a valid Base-16 (hexadecimal) string.
/// - [codec] is the [Base16Codec] to use. It is derived from the other
///   parameters if not provided.
///
/// Throws:
/// - [FormatException] if the [input] contains invalid characters.
///
/// This implementation can handle both uppercase and lowercase alphabets. If a
/// partial string is detected, the following bits are assumed to be zeros.
Uint8List fromHex(
  String input, {
  Base16Codec? codec,
}) {
  codec ??= _codecFromParameters();
  return codec.decoder.convert(input.codeUnits);
}