import 'dart:ui' as ui;

import 'package:flutter/services.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:halkyon_ui/halkyon_ui.dart';
import 'package:material_ui/material_ui.dart';

/// How many pixels [text] inks in [family] at [weight]: heavier strokes ink
/// more.
Future<int> ink(String text, String family, FontWeight weight) async {
  final painter = TextPainter(
    text: TextSpan(
      text: text,
      style: TextStyle(
        fontFamily: family,
        fontSize: 40,
        fontWeight: weight,
        color: const Color(0xFF000000),
      ),
    ),
    textDirection: TextDirection.ltr,
  )..layout();
  final recorder = ui.PictureRecorder();
  painter.paint(Canvas(recorder), Offset.zero);
  final image = await recorder.endRecording().toImage(
    painter.width.ceil(),
    painter.height.ceil(),
  );
  final pixels = (await image.toByteData())!;
  var inked = 0;
  for (var alpha = 3; alpha < pixels.lengthInBytes; alpha += 4) {
    if (pixels.getUint8(alpha) > 128) {
      inked++;
    }
  }
  return inked;
}

void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  test("the font is the package's own, as an app finds a package's font", () {
    expect(appFontFamily, 'packages/halkyon_ui/Noto Sans');
  });

  test("the theme sets text in Noto Sans, with the apps' CJK fonts for what "
      'it lacks, named as an app declares them', () {
    for (final brightness in Brightness.values) {
      final style = appTheme(brightness).textTheme.bodyLarge!;
      expect(style.fontFamily, appFontFamily);
      expect(style.fontFamilyFallback, [
        'Noto Sans JP',
        'Noto Sans SC',
        'Noto Sans TC',
        'Noto Sans KR',
      ]);
    }
  });

  test("a language's own CJK font comes first, so shared Han characters "
      'take its shapes', () {
    expect(appFontFallbackFor(null).first, 'Noto Sans JP');
    expect(appFontFallbackFor('en'), appFontFallback);
    expect(appFontFallbackFor('ja').first, 'Noto Sans JP');
    expect(appFontFallbackFor('zh-Hans').first, 'Noto Sans SC');
    expect(appFontFallbackFor('zh').first, 'Noto Sans SC');
    expect(appFontFallbackFor('zh-Hant').first, 'Noto Sans TC');
    expect(appFontFallbackFor('zh-TW').first, 'Noto Sans TC');
    expect(appFontFallbackFor('ko').first, 'Noto Sans KR');
    expect(hasOwnFont('ko'), isTrue);
    expect(hasOwnFont('de'), isFalse);
    // Every font stays, once.
    expect(appFontFallbackFor('ko').toSet(), appFontFallback.toSet());
    expect(appFontFallbackFor('ko'), hasLength(4));
  });

  test('Noto Sans draws every weight from its one file', () async {
    // In this package's own tests it is the root project, whose assets have
    // no `packages/` prefix; an app's test of the name is in example/.
    final loader = FontLoader(appFontFamily)
      ..addFont(rootBundle.load('assets/fonts/NotoSans-Variable.ttf'));
    await loader.load();

    const text = 'Ἀθῆναι Halkyon';
    final regular = await ink(text, appFontFamily, FontWeight.w400);
    final bold = await ink(text, appFontFamily, FontWeight.w700);
    expect(bold, greaterThan(regular * 1.2));
  });
}