dateKeys-dart/test/locator_support.dart

// Helpers of the tests of the locator (stage 7a): the vectors of
// tool/locator_go_vectors.go, their edits and their compact addresses, and
// what a reader reads of a locator, as the generator writes it. They read no
// file, so that the tests that run on Node.js can use them.
library;

import 'dart:convert';
import 'dart:typed_data';

import 'package:datekeys/src/bytes.dart';
import 'package:datekeys/src/locator.dart';
import 'package:datekeys/src/profile.dart';
import 'package:datekeys/src/release.dart';
import 'package:datekeys/src/sha256.dart';

typedef Json = Map<String, Object?>;

/// The list [key] of [v], each item a list.
List<List<Object?>> rows(Json v, String key) => [
  for (final r in v[key]! as List<Object?>) r! as List<Object?>,
];

/// The text [i] of the table of [v]: `''` for no error.
String textOf(Json v, Object? i) =>
    (v['texts']! as List<Object?>)[i! as int]! as String;

/// An address as the generator writes it: the string, or [before, byte,
/// count, after] for one with a run of count copies of a byte.
String uriOf(Object? x) {
  if (x is String) return x;
  final l = x! as List<Object?>;
  return '${l[0]}${(l[1]! as String) * (l[2]! as int)}${l[3]}';
}

/// The edits [edits] of [base] applied in one pass: each [at, delete,
/// insert] replaces delete bytes at the offset at of the base with the bytes
/// of the hexadecimal insert, and [at, delete, byte, count] with count
/// copies of the byte. The offsets are those of the base, in order.
Uint8List applyLocatorEdits(List<int> base, Object? edits) {
  final out = BytesBuilder(copy: false);
  var pos = 0;
  for (final e in (edits! as List<Object?>).cast<List<Object?>>()) {
    final at = e[0]! as int;
    final delete = e[1]! as int;
    if (at < pos || at + delete > base.length) {
      throw StateError('edit at $at out of order or beyond the base');
    }
    out.add(base.sublist(pos, at));
    final insert = fromHex(e[2]! as String);
    final repeat = e.length > 3 ? e[3]! as int : 1;
    for (var i = 0; i < repeat; i++) {
      out.add(insert);
    }
    pos = at + delete;
  }
  out.add(base.sublist(pos));
  return out.takeBytes();
}

/// The lower-case hexadecimal SHA-256 of [b].
String sha256Hex(List<int> b) => toHex(sha256(b));

/// What a reader reads of [l], as the generator writes it: [[uri, offset,
/// host, usable]...], the key, the SHA-256 of the header, the digest of the
/// rest, its size and capsule_digest, with each address in full.
List<Object?> summaryOf(Locator l) => [
  [
    for (final a in l.addresses)
      [a.uri, a.offset, a.host, l.usable.contains(a)],
  ],
  toHex(l.envelopeKey),
  sha256Hex(l.envelopeHeader),
  toHex(l.restDigest),
  l.restSize,
  toHex(l.capsuleDigest),
];

/// The summary [s] of the generator, with each address in full.
List<Object?> expandSummary(Object? s) {
  final l = s! as List<Object?>;
  return [
    [
      for (final a in (l[0]! as List<Object?>).cast<List<Object?>>())
        [uriOf(a[0]), a[1], uriOf(a[2]), a[3]],
    ],
    ...l.sublist(1),
  ];
}

/// The release of [round] of the vectors [v], public data of drand.
Release releaseOf(Json v, int round) {
  final r = (v['releases']! as Json)['$round']! as String;
  return Release(round, fromHex(r));
}

/// The pinned Quicknet profile, edited as the generator names the edit.
Profile profileOf(String edit) {
  final p = quicknet();
  switch (edit) {
    case '':
      return p;
    case 'key not on the curve':
      final k = Uint8List.fromList(p.publicKey);
      k[k.length - 1] ^= 1;
      return p.copyWith(publicKey: k);
    case 'key at infinity':
      return p.copyWith(publicKey: [0xc0, ...List.filled(95, 0)]);
    case 'key of another network':
      // The generator of G2, compressed.
      return p.copyWith(
        publicKey: fromHex(
          '93e02b6052719f607dacd3a088274f65596bd0d09920b61ab5da61bbdc7f5049'
          '334cf11213945d57e5ac7d055d042b7e024aa2b2f08f0a91260805272dc51051'
          'c6e47ad4fa403b02b4510b647ae3d1770bac0326a805bbefd48056c8c121bdb8',
        ),
      );
    case 'chain hash of another network':
      final h = Uint8List.fromList(p.chainHash);
      h[0] ^= 1;
      return p.copyWith(chainHash: h);
  }
  throw ArgumentError(edit);
}

/// The release that an open case names: a round, or an edit of the release
/// of the case.
Release openRelease(Json v, int round, Object? release) {
  if (release is int) return releaseOf(v, release);
  final r = releaseOf(v, round);
  switch (release) {
    case 'flipped':
      final s = Uint8List.fromList(r.signature);
      s[s.length - 1] ^= 1;
      return Release(round, s);
    case 'short':
      return Release(round, r.signature.sublist(0, 47));
    case 'other round':
      return Release(round, releaseOf(v, 1001).signature);
  }
  throw ArgumentError('$release');
}

/// The text of the error that [body] throws, `''` when it returns: a
/// [LocatorException] or a DateKeysException by its message.
String errorText(void Function() body) {
  try {
    body();
    return '';
  } on LocatorException catch (e) {
    return e.message;
  } on ArgumentError catch (e) {
    // An error of the caller without a normative code, as checkWrite
    // reports an extension out of its place.
    return '${e.message}';
  } on Exception catch (e) {
    return '$e';
  }
}

/// The JSON of a constant of test/vectors.
Json decodeJson(String s) => jsonDecode(s) as Json;