// Helpers of the tests of the opening: the cases of
// test/vectors/open_cases.json and of the mutation corpus replayed as
// capsule.Open of the Go reference was run on them, and the outcome of an
// opening in the form of those vectors. They read no file, so that the
// tests that run on Node.js can use them.
library;

import 'dart:async';
import 'dart:typed_data';

import 'package:datekeys/datekeys.dart';
import 'package:datekeys/src/age.dart' show X25519Identity;
import 'package:datekeys/src/security.dart' show evaluateSecurityInput;
import 'package:datekeys/src/sha256.dart' show sha256;

import 'open_vectors_support.dart';
import 'security_support.dart';
import 'source_support.dart';

export 'open_vectors_support.dart';
export 'security_support.dart';
export 'source_support.dart';

/// A source that answers every request with the release of a case, or
/// fails as its source_error says, and counts the requests.
final class CaseSource implements ReleaseSource {
  CaseSource(this.release, this.error);

  final Release? release;
  final Object? error;
  int calls = 0;

  @override
  Future<Release> fetch(PinnedProfile p, int round) async {
    calls++;
    final e = error;
    if (e != null) throw e;
    final r = release;
    if (r == null) {
      throw DateKeysException(
        ErrorCode.releaseUnavailable,
        'testkit: no release',
      );
    }
    return r;
  }
}

/// The failure of a source of a case: a DateKeysException of its code, or
/// its text alone, thrown as a String, whose text the opening keeps.
Object? sourceError(Json c) {
  final e = c['source_error'] as Json?;
  if (e == null) return null;
  final code = e['code'] as String?;
  if (code == null) return str(e, 'text');
  return DateKeysException(
    ErrorCode.values.firstWhere((x) => x.code == code),
    str(e, 'text'),
  );
}

/// An output that records what it receives, and fails at add when [fail].
final class RecordingOutput implements ByteSink {
  RecordingOutput({this.fail = false});

  final bool fail;
  final BytesBuilder received = BytesBuilder();
  bool closed = false;
  Object? aborted;
  final List<String> log = [];

  @override
  void add(Uint8List bytes) {
    log.add('add ${bytes.length}');
    if (closed || aborted != null) throw StateError('add after the end');
    if (fail) throw 'disk full';
    received.add(bytes);
  }

  @override
  void close() {
    log.add('close');
    if (aborted != null) throw StateError('close after abort');
    closed = true;
  }

  @override
  void abort(Object reason) {
    log.add('abort');
    aborted = reason;
  }
}

/// A file sink that keeps the files and fails at the call named, as the
/// recording sink of tool/open_go_vectors.go: begin, create i, write i,
/// close i or commit, with the text `no` and the call.
final class RecordingSink implements FileSink {
  RecordingSink([this.fail = '']);

  final String fail;
  List<BytesBuilder> files = [];
  Head? head;
  bool begun = false;
  bool committed = false;
  Object? aborted;
  final List<String> log = [];

  @override
  void begin(Head head) {
    log.add('begin');
    if (fail == 'begin') throw 'no begin';
    begun = true;
    this.head = head;
    files = [for (final _ in head.files) BytesBuilder()];
  }

  @override
  ByteSink create(int i) {
    log.add('create $i');
    if (fail == 'create $i') throw 'no create $i';
    return _RecordingFile(this, i);
  }

  @override
  void commit() {
    log.add('commit');
    if (fail == 'commit') throw 'no commit';
    committed = true;
  }

  @override
  void abort(Object reason) {
    log.add('abort');
    aborted = reason;
  }

  /// The state, as the vectors record it.
  String get state => committed
      ? 'committed'
      : aborted != null
      ? 'aborted'
      : begun
      ? 'begun'
      : 'untouched';
}

final class _RecordingFile implements ByteSink {
  _RecordingFile(this.s, this.i);
  final RecordingSink s;
  final int i;

  @override
  void add(Uint8List bytes) {
    s.log.add('write $i ${bytes.length}');
    if (s.fail == 'write $i') throw 'no write $i';
    s.files[i].add(bytes);
  }

  @override
  void close() {
    s.log.add('close $i');
    if (s.fail == 'close $i') throw 'no close $i';
  }

  @override
  void abort(Object reason) {
    s.log.add('abort $i');
  }
}

/// The outcome of an opening in the form of the vectors.
final class Outcome {
  Outcome(this.opened, this.output, this.sink, this.calls, this.securities);

  final Opened opened;
  final RecordingOutput output;
  final RecordingSink sink;
  final int calls;

  /// SECURITY_CBOR of each evaluation, a copy.
  final List<Uint8List> securities;

  String get result =>
      opened.error?.code.code ?? (opened.refusal != null ? 'refused' : 'ok');

  String get text =>
      opened.error?.message ??
      (opened.refusal != null ? '${opened.refusal}' : 'ok');

  List<List<Object?>> get checks => [
    for (final c in opened.checks)
      [c.step, c.name, c.ok, c.detail, c.error ?? ''],
  ];
}

/// The author keys that a case saves, with their labels.
Map<String, String> authorKeysOf(Json c) =>
    (c['author_keys'] as Map?)?.cast<String, String>() ?? const {};

/// Opens the capsule of the case [c] with its options, in memory or from
/// a source, with [evaluator], the default of the opening when null.
Future<Outcome> openCase(
  Json c,
  Uint8List dkc, {
  bool fromSource = false,
  SecurityEvaluator? evaluator,
}) async {
  final rel = c['release'] as Json?;
  final source = CaseSource(
    rel == null
        ? null
        : Release(rel['round']! as int, fromHex(str(rel, 'signature'))),
    sourceError(c),
  );
  AccessKey? key;
  final dkk = c['dkk'] as String?;
  if (dkk != null) {
    key = decodeAccessKey(fromHex(dkk));
    final material = c['dkk_material'] as String?;
    if (material != null) {
      key = AccessKey(
        credentialId: key.credentialId,
        capsuleId: key.capsuleId,
        type: key.type,
        material: fromHex(material),
        verification: key.verification,
        critical: key.critical,
        noncritical: key.noncritical,
      );
    }
  }
  final file = c['dkk_file'] as String?;
  final output = RecordingOutput(fail: c['output_fail'] == true);
  final sink = RecordingSink(c['sink_fail'] as String? ?? '');
  final securities = <Uint8List>[];
  final evaluate = evaluator ?? evaluateSecurityInput;
  final options = OpenOptions(
    source: source,
    now: () => parseRfc3339(str(c, 'now')),
    registry: c['registry'] == 'empty' ? newRegistry([]) : null,
    extensions: caseExtensions(c),
    identities: [
      for (final s in (c['identities'] as List<Object?>? ?? const []))
        X25519Identity.parse(s! as String).secretKey,
    ],
    accessKey: key,
    accessKeyFile: file == null ? null : fromHex(file),
    output: output,
    sink: sink,
    authorKeys: authorKeysOf(c),
    evaluator: (input) {
      securities.add(Uint8List.fromList(input.security));
      return evaluate(input);
    },
    accept: c['accept'] == 'refuse' ? (_) => throw 'not trusted' : null,
  );
  final opened = fromSource
      ? await openCapsuleSource(ChunkySource(dkc), options)
      : await openCapsule(dkc, options);
  key?.wipe();
  return Outcome(opened, output, sink, source.calls, securities);
}

/// What the vectors record of the content of a capsule of format 1 or 2
/// that opens: its length and its SHA-256.
Json contentOf(Outcome o) {
  final b = o.output.received.toBytes();
  return {'length': b.length, 'sha256': toHex(sha256(b))};
}

/// What the vectors record of the files of a capsule of format 3 that
/// opens: [path, size, SHA-256 of what the sink received].
List<List<Object?>> filesOf(Outcome o) => [
  for (var i = 0; i < o.opened.head!.files.length; i++)
    [
      o.opened.head!.files[i].path,
      o.opened.head!.files[i].size,
      toHex(sha256(o.sink.files[i].toBytes())),
    ],
];

/// The unusable extensions of each object, as the vectors record them.
Json unusableOf(Opened o) {
  List<List<Object?>> u(List<Unusable> us) => [
    for (final x in us) [x.id, x.version, x.error.message],
  ];
  return {
    if (o.inspection.unusableExtensions.isNotEmpty)
      'header': u(o.inspection.unusableExtensions),
    if (o.unusableControlExtensions.isNotEmpty)
      'control': u(o.unusableControlExtensions),
    if (o.unusableAccessKeyExtensions.isNotEmpty)
      'dkk': u(o.unusableAccessKeyExtensions),
    if (o.unusableHeadExtensions.isNotEmpty)
      'head': u(o.unusableHeadExtensions),
  };
}

/// Checks the outcome [o] of the case [c] against what Go gave, field by
/// field; returns the differences, empty when there is none.
List<String> differences(Json c, Outcome o) {
  final out = <String>[];
  void same(String what, Object? got, Object? want) {
    final g = canonical(got);
    final w = canonical(want);
    if (g != w) out.add('$what: got $g, want $w');
  }

  same('result', o.result, c['result']);
  same('text', o.text, c['text']);
  same('checks', o.checks, c['checks']);
  same('release requests', o.calls, c['release_requests']);
  same('sink', o.sink.state, c['sink']);
  if (c['content'] != null) same('content', contentOf(o), c['content']);
  if (c['files'] != null) same('files', filesOf(o), c['files']);
  same('unusable', unusableOf(o.opened), c['unusable'] ?? <String, Object?>{});
  // The output: closed only for a capsule of format 1 or 2 that opens,
  // aborted after any failure, untouched by a capsule of format 3 that
  // opens (spec §56).
  final format3 = o.opened.format == CapsuleFormat.format3;
  final outputState = o.output.closed
      ? 'closed'
      : o.output.aborted != null
      ? 'aborted'
      : 'untouched';
  same(
    'output',
    outputState,
    o.result == 'ok' ? (format3 ? 'untouched' : 'closed') : 'aborted',
  );
  if (o.result != 'ok') {
    same('received before the failure was published', o.output.closed, false);
    same('head of a failure', o.opened.head == null, true);
    same('verdicts of a failure', o.opened.verdicts == null, true);
    same('payload length of a failure', o.opened.payloadLength, null);
  }
  // The verdicts of a capsule of format 3 that opens, evaluated once.
  final verdicts = c['verdicts'] as Json?;
  same('verdicts recorded', verdicts != null, o.result == 'ok' && format3);
  if (verdicts != null && o.opened.verdicts != null) {
    same('evaluations', o.securities.length, 1);
    if (o.securities.length == 1) {
      out.addAll(
        verdictDifferences(
          verdicts,
          o.opened.verdicts!,
          cmsParts(o.securities.single),
        ),
      );
    }
  }
  return out;
}