// Device-independent correctness guard: a drawn point must map to the right
// NORMALIZED page coordinate through a non-identity (zoomed) transform, so ink
// stays glued to the page under zoom/pan.

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

import 'package:badnote/editor/canvas/pen_canvas.dart';
import 'package:badnote/editor/canvas/pen_stroke.dart';

void main() {
  const pageSize = Size(400, 600);

  testWidgets('a stylus point maps to correct normalized coords at 2x zoom',
      (tester) async {
    final committed = <PenStroke>[];
    final controller = TransformationController()
      ..value = (Matrix4.identity()..scaleByDouble(2.0, 2.0, 2.0, 1));
    addTearDown(controller.dispose);

    await tester.pumpWidget(MaterialApp(
      home: Scaffold(
        body: Center(
          child: SizedBox(
            width: pageSize.width,
            height: pageSize.height,
            child: PenCanvas(
              pageWidget: Container(color: const Color(0xFFEEEEEE)),
              pageSize: pageSize,
              strokes: const <PenStroke>[],
              transformationController: controller,
              tool: CanvasTool.pen,
              color: const Color(0xFF000000),
              strokeWidth: 0.004,
              onStrokeComplete: committed.add,
              onEraseStroke: (_, __) {},
            ),
          ),
        ),
      ),
    ));

    // Down at the canvas-local point (200, 300). At 2x scale, scene = (100,150),
    // normalized = (100/400, 150/600) = (0.25, 0.25).
    final topLeft = tester.getTopLeft(find.byType(PenCanvas));
    final g = await tester.startGesture(topLeft + const Offset(200, 300),
        kind: PointerDeviceKind.stylus);
    await g.moveBy(const Offset(8, 8)); // make it a stroke, not a tap
    await g.up();
    await tester.pump();

    expect(committed, hasLength(1));
    final first = committed.single.points.first;
    expect(first.x, closeTo(0.25, 1e-3));
    expect(first.y, closeTo(0.25, 1e-3));
  });
}