// DateKeys, instants and rounds (lib/src/datekey.dart), as datekey.test.ts
// of datekeys-ts: properties that hold for every value, on random values of
// a fixed seed: dk1_ strings that read back, instants that format and parse
// back to the nanosecond, and rounds whose time is the first at or after
// the instant. The values and the texts of Go are in the differential
// (formats_datekey.json and formats_time.json). It reads no file: it runs on
// the VM and compiled to JavaScript.
library;

import 'dart:math';

import 'package:datekeys/src/datekey.dart';
import 'package:datekeys/src/errors.dart';
import 'package:datekeys/src/profile.dart';
import 'package:test/test.dart';

String codeOf(void Function() body) {
  try {
    body();
    return 'ok';
  } on DateKeysException catch (e) {
    return e.code.code;
  }
}

// A random int in 0..n-1 for n up to 2^53, from two halves.
int below(Random r, int n) {
  final hi = r.nextInt(1 << 21);
  final lo = r.nextInt(4294967296);
  return (hi * 4294967296 + lo) % n;
}

void main() {
  final q = quicknet();

  test('dk1_ strings of valid DateKeys read back, and invalid ones have '
      'none', () {
    final r = Random(7);
    for (var i = 0; i < 300; i++) {
      final d = DateKey(
        ['datekeys:quicknet:v1', 'a', '0:._-', 'z' * 128][i % 4],
        1 + below(r, maxDateKeyRound),
      );
      final s = compactDateKey(d);
      expect(s, startsWith(dk1Prefix));
      expect(parseDateKey(s), d);
      expect('$d', s);
      expect(
        canonicalJson(d),
        '{"version":1,"network":"${d.profileId}","round":${d.round}}',
      );
    }
    for (final d in [
      const DateKey('A', 1),
      const DateKey('a', 0),
      const DateKey('a', maxDateKeyRound + 1),
      const DateKey('', 1),
    ]) {
      expect([canonicalJson(d), compactDateKey(d)], [null, '']);
    }
  });

  test('instants order by seconds, then nanoseconds', () {
    Instant t(int s, int ns) => Instant(s, ns);
    expect(compareInstants(t(1, 0), t(1, 0)), 0);
    expect(compareInstants(t(1, 0), t(1, 1)), -1);
    expect(compareInstants(t(1, 999999999), t(2, 0)), -1);
    expect(compareInstants(t(2, 0), t(1, 999999999)), 1);
    expect(compareInstants(t(-5, 3), t(-5, 2)), 1);
    expect(t(3, 4), t(3, 4));
    expect(t(3, 4).hashCode, t(3, 4).hashCode);
    expect([t(2, 0), t(1, 5), t(1, 4)]..sort(), [t(1, 4), t(1, 5), t(2, 0)]);
    expect(() => Instant(0, -1), throwsRangeError);
    expect(() => Instant(0, 1000000000), throwsRangeError);
  });

  test('instants format and parse back, to the nanosecond', () {
    final r = Random(11);
    // From 0000-01-01 to 9999-12-31, in UTC.
    const first = -62167219200;
    const span = 253402300799 - first + 1;
    for (var i = 0; i < 2000; i++) {
      final t = Instant(
        first + below(r, span),
        [0, 1, 999999999, r.nextInt(1000000000)][i % 4],
      );
      expect(parseRfc3339(formatRfc3339Nano(t)), t);
      final whole = parseRfc3339(formatRfc3339(t));
      expect([whole.seconds, whole.nanos], [t.seconds, 0]);
      expect('$t', formatRfc3339Nano(t));
    }
    expect(() => parseRfc3339('2023-08-23'), throwsFormatException);
  });

  test('instants convert to and from DateTime', () {
    final t = DateTime.utc(2030, 1, 2, 3, 4, 5, 678);
    expect(
      Instant.fromDateTime(t),
      Instant(t.millisecondsSinceEpoch ~/ 1000, 678000000),
    );
    expect(Instant.fromDateTime(t).toDateTime(), t);
    final before = DateTime.utc(1969, 12, 31, 23, 59, 59, 500);
    expect(Instant.fromDateTime(before), Instant(-1, 500000000));
    expect(Instant(-1, 500000000).toDateTime(), before);
  });

  test('a long horizon is more than 365 days ahead, to the nanosecond', () {
    final now = Instant(1790000000, 500);
    Instant at(int s, int ns) => Instant(now.seconds + s, ns);
    expect(longHorizonSeconds, 365 * 24 * 60 * 60);
    expect(isLongHorizon(at(longHorizonSeconds, 500), now), isFalse);
    expect(isLongHorizon(at(longHorizonSeconds, 501), now), isTrue);
    expect(isLongHorizon(at(1, 0), now), isFalse);
  });

  test('the round of an instant is the first whose time is at or after it, '
      'on profiles of other periods too', () {
    final r = Random(13);
    for (final p in [
      q,
      q.copyWith(period: 1),
      q.copyWith(period: 7, genesisTime: 1),
      q.copyWith(period: 86400, genesisTime: 253402300799 - 86400 * 10),
    ]) {
      final last = p.maxRound;
      final lastTime = roundTime(p, last).seconds;
      expect(lastTime <= maxUnixTime, isTrue);
      expect(lastTime + p.period > maxUnixTime, isTrue);
      expect(codeOf(() => roundTime(p, last + 1)), 'ERR_DATEKEY_INVALID');
      expect(codeOf(() => roundTime(p, 0)), 'ERR_DATEKEY_INVALID');
      for (var i = 0; i < 300; i++) {
        final at = Instant(
          p.genesisTime + below(r, lastTime - p.genesisTime + 1),
          [0, 0, 1, r.nextInt(1000000000)][i % 4],
        );
        final d = resolveDateKey(p, at);
        final t = roundTime(p, d.round);
        expect(compareInstants(t, at) >= 0, isTrue);
        if (d.round > 1) {
          expect(compareInstants(roundTime(p, d.round - 1), at) < 0, isTrue);
        }
        expect(unlockAt(d, p), t);
        validateDateKey(d, p);
      }
      // Before the genesis and after the last round.
      expect(
        codeOf(() => resolveDateKey(p, Instant(p.genesisTime - 1, 999999999))),
        'ERR_DATEKEY_INVALID',
      );
      expect(
        codeOf(() => resolveDateKey(p, Instant(lastTime, 1))),
        'ERR_DATEKEY_INVALID',
      );
    }
    expect(unlockAt(const DateKey('other', 2), q), isNull);
    expect(
      codeOf(() => validateDateKey(const DateKey('other', 2), q)),
      'ERR_PROFILE_MISMATCH',
    );
    expect(
      codeOf(() => resolveDateKey(q.copyWith(period: 0), Instant(0))),
      'ERR_UNKNOWN_PROFILE',
    );
  });
}