// ChainSegments — the canonical single-select segment control
// (night-log decision "pill segment as canon"; usertest finding
// #14: the same choice pattern appeared as four different
// widgets). Guards both the widget behaviour and the canon
// itself: no page may reintroduce TabBar / SegmentedButton /
// ChoiceChip for single-select segments.

import 'dart:io';

import 'package:flutter/material.dart';
import 'dart:ui' show Tristate;
import 'package:flutter_test/flutter_test.dart';

import 'package:chain_studio/widgets/chain_segments.dart';

Widget _host(Widget child) =>
    MaterialApp(home: Scaffold(body: Center(child: child)));

void main() {
  testWidgets('tapping a segment reports the new value once', (tester) async {
    final changes = <String>[];
    await tester.pumpWidget(
      _host(
        ChainSegments<String>(
          items: const [
            ChainSegmentItem('all', 'Alle'),
            ChainSegmentItem('flow', 'Flow'),
            ChainSegmentItem('step', 'Schritt'),
          ],
          value: 'all',
          onChanged: changes.add,
        ),
      ),
    );
    await tester.tap(find.text('Flow'));
    await tester.pump();
    expect(changes, ['flow']);
    // Tapping the already-selected value must NOT re-fire — call
    // sites use the callback to trigger refetches.
    await tester.tap(find.text('Alle'));
    await tester.pump();
    expect(changes, ['flow']);
  });

  testWidgets('segments expose button + selected semantics', (tester) async {
    final handle = tester.ensureSemantics();
    await tester.pumpWidget(
      _host(
        ChainSegments<int>(
          items: const [
            ChainSegmentItem(0, 'Ausstehend'),
            ChainSegmentItem(1, 'Verlauf'),
          ],
          value: 0,
          onChanged: (_) {},
        ),
      ),
    );
    final pending = tester.getSemantics(find.text('Ausstehend'));
    expect(pending.flagsCollection.isSelected, Tristate.isTrue);
    final history = tester.getSemantics(find.text('Verlauf'));
    expect(history.flagsCollection.isSelected, Tristate.isFalse);
    handle.dispose();
  });

  test('canon guard: no page reintroduces TabBar/SegmentedButton/ChoiceChip',
      () {
    // The night-log decision made the pill segment the ONE way to
    // render a single-select segment. This sweep keeps the three
    // retired Material patterns out of lib/ for good (comments
    // don't count; the widget file itself is exempt).
    final offenders = <String>[];
    final banned = RegExp(
      r'\b(TabBar|TabBarView|TabController|SegmentedButton|ChoiceChip)\b',
    );
    final files = Directory('lib')
        .listSync(recursive: true)
        .whereType<File>()
        .where((f) => f.path.endsWith('.dart'))
        .where((f) => !f.path.contains('chain_segments.dart'));
    for (final f in files) {
      final lines = f.readAsLinesSync();
      for (var i = 0; i < lines.length; i++) {
        final line = lines[i];
        final code = line.contains('//')
            ? line.substring(0, line.indexOf('//'))
            : line;
        if (banned.hasMatch(code)) {
          offenders.add('${f.path}:${i + 1}: ${line.trim()}');
        }
      }
    }
    expect(
      offenders,
      isEmpty,
      reason:
          'Single-select segments use ChainSegments (canon). '
          'Found retired patterns:\n${offenders.join('\n')}',
    );
  });
}