// Nav-manifest guard. The sidebar truth lives in three places in
// this repo: the `_pages` list (ids + order = Cmd numbers), the
// `labelOf` switch (id → l10n key), and the two .arb files (key →
// DE/EN label). The operator guide documenting that nav lives in
// the PLATFORM repo (fai_chain/docs/studio/operator-guide.md),
// which this repo's CI cannot see — so the truth is exported as a
// committed manifest, `docs/nav.generated.json`, and the platform
// repo's docs_consistency test checks the guide against it.
//
// This test derives the manifest from the sources. When it differs
// from the committed file it REWRITES the file and fails once with
// instructions — commit the regenerated manifest and mirror it to
// fai_chain/docs/studio/nav.generated.json so the cross-repo guard
// stays truthful. Add/rename/reorder a page and forget the guide:
// the platform gate goes loudly red instead of the docs quietly
// rotting.

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

import 'package:flutter_test/flutter_test.dart';

const _manifestPath = 'docs/nav.generated.json';
const _mirrorHint =
    'fai_chain/docs/studio/nav.generated.json (same content)';

/// Extract the ordered page ids from the `_pages` list in main.dart.
List<String> _pageIds(String mainDart) {
  final block = RegExp(
    r'static const _pages = <_NavPage>\[(.*?)\n  \];',
    dotAll: true,
  ).firstMatch(mainDart);
  if (block == null) {
    fail('could not locate the _pages block in lib/main.dart');
  }
  return RegExp(r"id: '([a-z-]+)'")
      .allMatches(block.group(1)!)
      .map((m) => m.group(1)!)
      .toList();
}

/// Extract the id → l10n-key mapping from the `labelOf` switch.
Map<String, String> _labelKeys(String mainDart) {
  final keys = <String, String>{};
  for (final m in RegExp(
    r"case '([a-z-]+)':\s*\n\s*return l\.(nav\w+);",
  ).allMatches(mainDart)) {
    keys[m.group(1)!] = m.group(2)!;
  }
  if (keys.isEmpty) {
    fail('could not parse the labelOf switch in lib/main.dart');
  }
  return keys;
}

Map<String, dynamic> _arb(String path) =>
    jsonDecode(File(path).readAsStringSync()) as Map<String, dynamic>;

void main() {
  test('docs/nav.generated.json matches the sidebar truth', () {
    final mainDart = File('lib/main.dart').readAsStringSync();
    final ids = _pageIds(mainDart);
    final labelKeys = _labelKeys(mainDart);
    final de = _arb('lib/l10n/app_de.arb');
    final en = _arb('lib/l10n/app_en.arb');

    final pages = <Map<String, dynamic>>[];
    for (var i = 0; i < ids.length; i++) {
      final key = labelKeys[ids[i]];
      expect(
        key,
        isNotNull,
        reason:
            "page '${ids[i]}' has no labelOf case — add it so the "
            'sidebar can localize the label',
      );
      final labelDe = de[key] as String?;
      final labelEn = en[key] as String?;
      expect(
        labelDe,
        isNotNull,
        reason: "l10n key '$key' missing from app_de.arb",
      );
      expect(
        labelEn,
        isNotNull,
        reason: "l10n key '$key' missing from app_en.arb",
      );
      pages.add({
        'id': ids[i],
        'cmd': i + 1,
        'label_de': labelDe,
        'label_en': labelEn,
      });
    }

    const encoder = JsonEncoder.withIndent('  ');
    final manifest =
        '${encoder.convert({
          '_generated': 'by test/nav_manifest_test.dart — do not edit. '
              'Mirror to $_mirrorHint.',
          'pages': pages,
        })}\n';

    final file = File(_manifestPath);
    final current = file.existsSync() ? file.readAsStringSync() : null;
    if (current != manifest) {
      file.parent.createSync(recursive: true);
      file.writeAsStringSync(manifest);
      fail(
        'the sidebar nav changed: $_manifestPath was regenerated. '
        'Commit it, mirror it to $_mirrorHint, and update the '
        'operator guide — the platform repo\'s docs_consistency '
        'test checks the guide against this manifest.',
      );
    }
  });
}