// The verification of releases (lib/src/release.dart) against the Go
// reference: the verify section of test/vectors/release_vectors.json,
// written by tool/release_go_vectors.go with provider.Verify, and every
// release of the mutation corpus that fails at step 10. A port of
// release.test.ts of datekeys-ts.
@TestOn('vm')
library;

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

import 'package:datekeys/datekeys.dart' show fromHex;
import 'package:datekeys/src/bls12381_curve.dart';
import 'package:datekeys/src/bls12381_hash.dart';
import 'package:datekeys/src/bls12381_pairing.dart';
import 'package:datekeys/src/errors.dart';
import 'package:datekeys/src/ibe.dart';
import 'package:datekeys/src/release.dart';
import 'package:test/test.dart';

import 'tlock_support.dart';

typedef Json = Map<String, Object?>;

Json readJson(String path) => jsonDecode(File(path).readAsStringSync()) as Json;

final Json g = readJson('test/vectors/release_vectors.json');

List<Json> section(Json file, String name) =>
    (file[name]! as List).cast<Json>();

String s(Json v, String key) => v[key]! as String;

TestProfile profileOf(String name) {
  final c = section(g, 'profiles').firstWhere((p) => p['name'] == name);
  return quicknet().copyWith(
    scheme: s(c, 'scheme'),
    publicKey: fromHex(s(c, 'public_key')),
  );
}

DateKeysException dateKeysError(void Function() body, String label) {
  try {
    body();
  } on DateKeysException catch (e) {
    return e;
  }
  fail('$label: no DateKeysException');
}

const invalid =
    'provider: the signature is not a canonical point encoding, or does not '
    'verify as the BLS signature of round 1000 under datekeys:quicknet:v1: '
    'ERR_RELEASE_INVALID';

String onlyQuicknet(String scheme) =>
    'provider: profile datekeys:quicknet:v1 uses scheme $scheme; only '
    'bls-unchained-g1-rfc9380 releases are verified here: ERR_UNKNOWN_PROFILE';

void main() {
  test('the profile of the tests is the pinned Quicknet of testdata/', () {
    final q = readJson('testdata/vectors/profile_quicknet.json');
    expect(
      [
        q['profile_id'],
        q['scheme'],
        q['public_key'],
        q['chain_hash'],
        q['genesis_time'],
        q['period_seconds'],
      ],
      [
        quicknetId,
        quicknetScheme,
        quicknetPublicKey,
        quicknetChainHash,
        quicknetGenesisTime,
        quicknetPeriod,
      ],
    );
    // The last round, as the round resolution of spec §15 gives it.
    final last = section(
      readJson('testdata/vectors/quicknet_rounds.json'),
      'vectors',
    ).firstWhere((v) => v['name'] == 'last representable round time');
    expect(quicknet().maxRound, last['round']);
    expect(quicknet().maxRound, g['max_round']);
    // The published signatures of the tests are those of the fixtures.
    expect(
      (readJson('testdata/fixtures/time_only.json')['release']!
          as Json)['signature'],
      signature1000,
    );
    expect(
      (readJson('testdata/fixtures/empty_payload.json')['release']!
          as Json)['signature'],
      signature1001,
    );
  });

  test(
    'verifies as provider.Verify, in its order and with its codes and texts',
    () {
      // Where this library departs from Go, on purpose. Only the scheme of
      // Quicknet is verified, as in datekeys-ts: Go verifies the other
      // schemes of drand, and names an unknown one in its own text. And the
      // point at infinity is never a valid signature (spec §63 step 10):
      // Go accepts it when the key is the point at infinity too, as kilic
      // drops both pairs of its check, a key that no pinned profile has
      // (spec §12.1).
      final departs = {
        'another scheme of drand': onlyQuicknet('pedersen-bls-unchained'),
        'another scheme of drand on G1': onlyQuicknet('bls-unchained-on-g1'),
        'a scheme that is not of drand': onlyQuicknet('datekeys-test'),
        'the key and the signature are the point at infinity': invalid,
      };
      var accepted = 0;
      for (final c in section(g, 'verify')) {
        final name = s(c, 'name');
        final p = profileOf(s(c, 'profile'));
        final round = c['round']! as int;
        final r = Release(
          c['release_round']! as int,
          fromHex(s(c, 'signature')),
        );
        final want = departs[name];
        if (want != null) {
          expect(
            dateKeysError(() => verifyRelease(p, round, r), name).message,
            want,
            reason: name,
          );
          continue;
        }
        if (c['go'] == 'ok') {
          verifyRelease(p, round, r);
          accepted++;
          continue;
        }
        final e = dateKeysError(() => verifyRelease(p, round, r), name);
        expect([e.code.code, e.message], [c['code'], c['text']], reason: name);
      }
      expect(accepted, 4);
      expect(
        departs.keys,
        everyElement(isIn(section(g, 'verify').map((c) => c['name']))),
      );
    },
  );

  test('gives the code of every release of the mutation corpus that fails at '
      'step 10', () {
    final corpus = section(
      readJson('testdata/vectors/mutations.json'),
      'cases',
    ).where((c) => c['step'] == 10).toList();
    const names = [
      'DateKey A + release of round B',
      'release of another round',
      'release signature is the point at infinity',
      'release signature negated',
      'release signature re-encoded with x + p',
      'release signature with the infinity flag and a payload',
      'negated release signature and U re-encoded with c0 + p',
    ];
    expect(
      [for (final c in corpus) s(c, 'name')]..sort(),
      [
        ...names,
        for (final n in names) 'format 2: $n',
        for (final n in names) 'format 3: $n',
      ]..sort(),
    );
    for (final c in corpus) {
      final name = s(c, 'name');
      final dkc = c['dkc']! as Json;
      final base = dkc['base'] as String?;
      final bytes = applyEdits(
        base == null
            ? Uint8List(0)
            : File('testdata/fixtures/$base').readAsBytesSync(),
        dkc['edits']! as List<Object?>,
      );
      final rel = c['release']! as Json;
      final e = dateKeysError(
        () => verifyRelease(
          quicknet(),
          dateKeyRound(bytes),
          Release(rel['round']! as int, fromHex(s(rel, 'signature'))),
        ),
        name,
      );
      expect(e.code.code, c['error'], reason: name);
    }
  });

  test(
    'hashes the round with the DST of RFC 9380 for G1, not the one of G2 that '
    'bls-unchained-on-g1 uses',
    () {
      final key = G2Point.decode(fromHex(quicknetPublicKey))!;
      final sig = G1Point.decode(fromHex(signature1000))!;
      bool verifies(String dst) => pairingCheck([
        (hashToG1(roundIdentity(1000), dst), key),
        (-sig, G2Point.generator),
      ]);
      expect(quicknetDst, 'BLS_SIG_BLS12381G1_XMD:SHA-256_SSWU_RO_NUL_');
      expect(verifies(quicknetDst), isTrue);
      expect(verifies('BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_NUL_'), isFalse);
    },
  );

  test('the supplied release is handed over for any round, unverified, and '
      'there is none without one', () async {
    final r = Release(1001, fromHex(signature1001));
    expect(await suppliedRelease(r).fetch(quicknet(), 1000), same(r));
    await expectLater(
      suppliedRelease().fetch(quicknet(), 1000),
      throwsA(
        isA<DateKeysException>().having(
          (e) => e.message,
          'message',
          'release: no release supplied for round 1000: '
              'ERR_RELEASE_UNAVAILABLE',
        ),
      ),
    );
  });

  test('whatever a source throws is ERR_RELEASE_UNAVAILABLE at step 9, keeping '
      'only its text', () async {
    final p = quicknet();
    final r = Release(1000, fromHex(signature1000));
    expect(await fetchRelease(suppliedRelease(r), p, 1000), same(r));
    Future<DateKeysException> failure(Object thrown) async {
      try {
        await fetchRelease(_Throwing(thrown), p, 1000);
      } on DateKeysException catch (e) {
        return e;
      }
      fail('no failure');
    }

    // A release that is not available keeps its text.
    final none = await failure(
      DateKeysException(ErrorCode.releaseUnavailable, 'relay: not yet'),
    );
    expect(none.message, 'relay: not yet: ERR_RELEASE_UNAVAILABLE');
    // Another code is kept as text only.
    final other = await failure(
      DateKeysException(ErrorCode.releaseInvalid, 'relay: bad signature'),
    );
    expect(
      [other.code, other.message],
      [
        ErrorCode.releaseUnavailable,
        'capsule: release source: relay: bad signature: ERR_RELEASE_INVALID: '
            'ERR_RELEASE_UNAVAILABLE',
      ],
    );
    // And any other failure too.
    final io = await failure(const FormatException('no JSON'));
    expect(
      [io.code, io.message],
      [
        ErrorCode.releaseUnavailable,
        'capsule: release source: FormatException: no JSON: '
            'ERR_RELEASE_UNAVAILABLE',
      ],
    );
    // The verification of step 10 comes after, on what the source gave.
    expect(
      dateKeysError(
        () => verifyRelease(p, 1000, Release(1001, fromHex(signature1001))),
        'another round',
      ).code,
      ErrorCode.roundMismatch,
    );
  });
}

final class _Throwing implements ReleaseSource {
  _Throwing(this.error);

  final Object error;

  @override
  Future<Release> fetch(PinnedProfile p, int round) async => throw error;
}