import 'dart:convert';

import 'package:halkyon_base_server/src/totp/base32.dart';
import 'package:halkyon_base_server/src/totp/totp.dart';
import 'package:test/test.dart';

void main() {
  group("RFC 6238's test vectors (Appendix B), 8 digits", () {
    // The seeds of RFC 6238's reference code (Appendix A): ASCII
    // "1234567890" repeated to the hash's length.
    final seeds = {
      TotpHash.sha1: ascii.encode('12345678901234567890'),
      TotpHash.sha256: ascii.encode('12345678901234567890123456789012'),
      TotpHash.sha512: ascii.encode(
        '1234567890123456789012345678901234567890123456789012345678901234',
      ),
    };
    const vectors = [
      (59, '94287082', '46119246', '90693936'),
      (1111111109, '07081804', '68084774', '25091201'),
      (1111111111, '14050471', '67062674', '99943326'),
      (1234567890, '89005924', '91819424', '93441116'),
      (2000000000, '69279037', '90698825', '38618901'),
      (20000000000, '65353130', '77737706', '47863826'),
    ];
    for (final (seconds, withSha1, withSha256, withSha512) in vectors) {
      test('at $seconds s', () {
        final step = totpStepAt(
          DateTime.fromMillisecondsSinceEpoch(seconds * 1000, isUtc: true),
        );
        for (final (hash, expected) in [
          (TotpHash.sha1, withSha1),
          (TotpHash.sha256, withSha256),
          (TotpHash.sha512, withSha512),
        ]) {
          expect(
            totpCode(seeds[hash]!, step: step, digits: 8, hash: hash),
            expected,
            reason: hash.name,
          );
        }
      });
    }
  });

  group('checking a code', () {
    final secret = newTotpSecret();
    final now = DateTime.utc(2026, 10, 20, 12, 0, 15);
    final step = totpStepAt(now);
    String codeAt(int at) => totpCode(secret, step: at);

    test("the current step's code is accepted, and names its step to keep", () {
      expect(
        checkTotp(
          secret: secret,
          code: codeAt(step),
          now: now,
          lastAcceptedStep: null,
        ),
        isA<TotpAccepted>().having((accepted) => accepted.step, 'step', step),
      );
    });

    test('one step either side is accepted, two are not', () {
      for (final at in [step - 1, step + 1]) {
        expect(
          checkTotp(
            secret: secret,
            code: codeAt(at),
            now: now,
            lastAcceptedStep: null,
          ),
          isA<TotpAccepted>().having((accepted) => accepted.step, 'step', at),
        );
      }
      for (final at in [step - 2, step + 2]) {
        expect(
          checkTotp(
            secret: secret,
            code: codeAt(at),
            now: now,
            lastAcceptedStep: null,
          ),
          isA<TotpRefused>(),
        );
      }
    });

    test('a code accepted once is refused again, and so is an earlier one', () {
      expect(
        checkTotp(
          secret: secret,
          code: codeAt(step),
          now: now,
          lastAcceptedStep: step,
        ),
        isA<TotpRefused>().having(
          (refused) => refused.reason,
          'reason',
          TotpRefusal.reused,
        ),
      );
      expect(
        checkTotp(
          secret: secret,
          code: codeAt(step - 1),
          now: now,
          lastAcceptedStep: step,
        ),
        isA<TotpRefused>().having(
          (refused) => refused.reason,
          'reason',
          TotpRefusal.reused,
        ),
      );
      // The next step's code still counts after the current one was used.
      expect(
        checkTotp(
          secret: secret,
          code: codeAt(step + 1),
          now: now,
          lastAcceptedStep: step,
        ),
        isA<TotpAccepted>().having(
          (accepted) => accepted.step,
          'step',
          step + 1,
        ),
      );
    });

    test('a wrong code, and one that is no six digits', () {
      final right = codeAt(step);
      final wrong = '${(int.parse(right[0]) + 1) % 10}${right.substring(1)}';
      expect(
        checkTotp(
          secret: secret,
          code: wrong,
          now: now,
          lastAcceptedStep: null,
        ),
        isA<TotpRefused>().having(
          (refused) => refused.reason,
          'reason',
          TotpRefusal.wrong,
        ),
      );
      for (final malformed in ['', '12345', '1234567', '12345a', '١٢٣٤٥٦']) {
        expect(
          checkTotp(
            secret: secret,
            code: malformed,
            now: now,
            lastAcceptedStep: null,
          ),
          isA<TotpRefused>().having(
            (refused) => refused.reason,
            'reason',
            TotpRefusal.malformed,
          ),
          reason: malformed,
        );
      }
    });

    test('a code typed with spaces, as apps show it, counts', () {
      final right = codeAt(step);
      expect(
        checkTotp(
          secret: secret,
          code: '${right.substring(0, 3)} ${right.substring(3)}',
          now: now,
          lastAcceptedStep: null,
        ),
        isA<TotpAccepted>(),
      );
    });

    test('another secret makes other codes', () {
      expect(
        checkTotp(
          secret: newTotpSecret(),
          code: codeAt(step),
          now: now,
          lastAcceptedStep: null,
        ),
        isA<TotpRefused>(),
      );
    });
  });

  test('a new secret has 160 random bits, never the same twice', () {
    final secret = newTotpSecret();
    expect(secret, hasLength(20));
    expect(newTotpSecret(), isNot(secret));
  });

  test('steps are 30 s of Unix time, in UTC', () {
    expect(totpStepAt(DateTime.utc(1970, 1, 1, 0, 0, 29)), 0);
    expect(totpStepAt(DateTime.utc(1970, 1, 1, 0, 0, 30)), 1);
    expect(
      totpStepAt(DateTime.utc(2026, 10, 20, 12)),
      totpStepAt(DateTime.utc(2026, 10, 20, 12).toLocal()),
    );
  });

  test('the otpauth URI names the issuer and account, escaped, and how codes '
      'are made', () {
    final uri = otpauthUri(
      issuer: 'learn.halkyon.eu',
      account: 'Ünal & Co: alice',
      secret: ascii.encode('12345678901234567890'),
    );
    expect(uri.scheme, 'otpauth');
    expect(uri.host, 'totp');
    expect(
      uri.toString(),
      'otpauth://totp/learn.halkyon.eu:%C3%9Cnal%20%26%20Co%3A%20alice'
      '?secret=GEZDGNBVGY3TQOJQGEZDGNBVGY3TQOJQ&issuer=learn.halkyon.eu'
      '&algorithm=SHA1&digits=6&period=30',
    );
    expect(uri.queryParameters['issuer'], 'learn.halkyon.eu');
    expect(
      base32Decode(uri.queryParameters['secret']!),
      ascii.encode('12345678901234567890'),
    );
  });

  test("an issuer's spaces are escaped as %20 in the label and the query "
      "alike, as authenticators read them, never as '+'", () {
    final uri = otpauthUri(
      issuer: 'Halkyon Learn & Co',
      account: 'alice',
      secret: ascii.encode('12345678901234567890'),
    );
    expect(
      uri.toString(),
      'otpauth://totp/Halkyon%20Learn%20%26%20Co:alice'
      '?secret=GEZDGNBVGY3TQOJQGEZDGNBVGY3TQOJQ'
      '&issuer=Halkyon%20Learn%20%26%20Co'
      '&algorithm=SHA1&digits=6&period=30',
    );
    expect(uri.queryParameters['issuer'], 'Halkyon Learn & Co');
  });

  group("RFC 4648's base 32 (section 10)", () {
    const vectors = {
      '': '',
      'f': 'MY======',
      'fo': 'MZXQ====',
      'foo': 'MZXW6===',
      'foob': 'MZXW6YQ=',
      'fooba': 'MZXW6YTB',
      'foobar': 'MZXW6YTBOI======',
    };
    for (final MapEntry(key: plain, value: encoded) in vectors.entries) {
      test('"$plain"', () {
        expect(base32Encode(ascii.encode(plain)), encoded);
        expect(base32Decode(encoded), ascii.encode(plain));
        expect(
          base32Decode(encoded.replaceAll('=', '')),
          ascii.encode(plain),
          reason: 'without its padding',
        );
        expect(
          base32Encode(ascii.encode(plain), padding: false),
          encoded.replaceAll('=', ''),
        );
      });
    }

    test('refuses what is no base 32', () {
      for (final text in [
        'MY=Y',
        'M',
        'MZX',
        'MZXW6Y',
        'mzxw6ytb',
        'MZXW1YTB',
        'MZ',
      ]) {
        expect(() => base32Decode(text), throwsFormatException, reason: text);
      }
    });
  });
}