import 'dart:typed_data';
import 'dart:ui' as ui;

import 'package:fintracker_app/core/theme/app_theme.dart';
import 'package:fintracker_app/core/widgets/service_mark.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter_test/flutter_test.dart';

Future<ByteData> _render(WidgetTester tester, double size) async {
  final key = GlobalKey();
  tester.view.physicalSize = Size(size, size);
  tester.view.devicePixelRatio = 1;
  addTearDown(tester.view.reset);
  await tester.pumpWidget(
    Directionality(
      textDirection: TextDirection.ltr,
      child: Center(
        child: RepaintBoundary(
          key: key,
          child: ServiceMark(size: size),
        ),
      ),
    ),
  );
  final boundary =
      key.currentContext!.findRenderObject()! as RenderRepaintBoundary;
  return (await tester.runAsync(() async {
    final image = await boundary.toImage();
    return image.toByteData(format: ui.ImageByteFormat.rawRgba);
  }))!;
}

Color _at(ByteData data, int size, int x, int y) {
  final i = (y * size + x) * 4;
  return Color.fromARGB(
    data.getUint8(i + 3),
    data.getUint8(i),
    data.getUint8(i + 1),
    data.getUint8(i + 2),
  );
}

void main() {
  testWidgets(
    'a gradient disc with three white bars, and nothing outside the disc',
    (tester) async {
      const size = 256;
      final data = await _render(tester, size.toDouble());

      // scale of the 512 design grid
      int px(num v) => (v * size / 512).round();

      expect(
        _at(data, size, 2, 2).a,
        0,
        reason: 'the corner is outside the disc',
      );
      // the tallest bar (x 316..380, y 131..381): white in its middle
      expect(_at(data, size, px(348), px(256)), const Color(0xFFFFFFFF));
      // between two bars the disc shows through, and it is coloured, not white
      final gap = _at(data, size, px(210), px(300));
      expect(gap.a, 1);
      expect(gap.b, greaterThan(gap.r), reason: 'blue-violet, not grey');
      // the gradient runs from the accent (top left) toward violet (bottom right)
      final start = _at(data, size, px(90), px(90));
      final end = _at(data, size, px(430), px(430));
      expect(end.r, greaterThan(start.r));
      expect(start.b * 255, greaterThan(200));
      expect(
        (start.g - end.g) * 255,
        greaterThan(40),
        reason: 'the green channel falls off toward violet',
      );
    },
  );

  test('the near end of the gradient is the app accent', () {
    expect(AppTheme.seed, const Color(0xFF14AFFF));
    expect(ServiceMark.violet, isNot(AppTheme.seed));
  });
}