BadNote/test/stroke_simplify_test.dart

// Tests for RDP stroke simplification (R1/R10 perf).

import 'package:flutter_test/flutter_test.dart';

import 'package:badnote/editor/engine/stroke_model.dart';
import 'package:badnote/editor/engine/stroke_simplify.dart';

EditorStroke _stroke(List<List<double>> pts, {List<double?>? pressures}) =>
    EditorStroke.create(
      id: 's',
      points: [
        for (var i = 0; i < pts.length; i++)
          EditorPoint(
            x: pts[i][0],
            y: pts[i][1],
            pressure: pressures?[i],
          ),
      ],
    );

void main() {
  test('collinear points collapse to the two endpoints', () {
    final s = _stroke([
      [0.0, 0.0],
      [0.1, 0.1],
      [0.2, 0.2],
      [0.3, 0.3],
    ]);
    final out = simplifyStroke(s, tolerance: 0.0008);
    expect(out.points.length, 2);
    expect(out.points.first.x, 0.0);
    expect(out.points.last.x, 0.3);
  });

  test('a perceptually significant peak is kept', () {
    final s = _stroke([
      [0.0, 0.0],
      [0.5, 0.5], // far off the (0,0)-(1,0) line → kept
      [1.0, 0.0],
    ]);
    final out = simplifyStroke(s, tolerance: 0.0008);
    expect(out.points.length, 3);
  });

  test('a deviation within tolerance is dropped', () {
    final s = _stroke([
      [0.0, 0.0],
      [0.5, 0.0001], // perp dist 0.0001 < 0.0008 → dropped
      [1.0, 0.0],
    ]);
    final out = simplifyStroke(s, tolerance: 0.0008);
    expect(out.points.length, 2);
  });

  test('<= 2 points are returned unchanged (same instance)', () {
    final s = _stroke([
      [0.1, 0.1],
      [0.2, 0.2],
    ]);
    expect(identical(simplifyStroke(s), s), isTrue);
  });

  test('non-positive tolerance is a no-op', () {
    final s = _stroke([
      [0.0, 0.0],
      [0.1, 0.11],
      [0.2, 0.2],
    ]);
    expect(identical(simplifyStroke(s, tolerance: 0), s), isTrue);
  });

  test('pressure rides along on retained points', () {
    final s = _stroke([
      [0.0, 0.0],
      [0.5, 0.5],
      [1.0, 0.0],
    ], pressures: [
      0.2,
      0.9,
      0.3,
    ]);
    final out = simplifyStroke(s, tolerance: 0.0008);
    expect(out.points.map((p) => p.pressure), [0.2, 0.9, 0.3]);
  });

  test('metadata (color/width/tool/id) is preserved', () {
    final s = EditorStroke.create(
      id: 'keep-me',
      color: 0xFF112233,
      width: 0.02,
      tool: EditorTool.highlighter,
      points: [
        const EditorPoint(x: 0, y: 0),
        const EditorPoint(x: 0.1, y: 0.1),
        const EditorPoint(x: 0.2, y: 0.2),
      ],
    );
    final out = simplifyStroke(s, tolerance: 0.0008);
    expect(out.id, 'keep-me');
    expect(out.color, 0xFF112233);
    expect(out.width, 0.02);
    expect(out.tool, EditorTool.highlighter);
  });
}