BadNote/test/pressure_curve_test.dart

// Tests for the configurable pen-pressure response (F5).

import 'dart:math' as math;

import 'package:flutter_test/flutter_test.dart';

import 'package:badnote/editor/input/pressure_curve.dart';

void main() {
  test('linear is the identity over [0,1]', () {
    const c = PressureCurve.linear;
    expect(c.apply(0.0), closeTo(0.0, 1e-9));
    expect(c.apply(0.5), closeTo(0.5, 1e-9));
    expect(c.apply(1.0), closeTo(1.0, 1e-9));
  });

  test('floor raises the minimum, endpoints stay anchored at floor and 1', () {
    const c = PressureCurve(floor: 0.4);
    expect(c.apply(0.0), closeTo(0.4, 1e-9)); // floor
    expect(c.apply(1.0), closeTo(1.0, 1e-9)); // full
    expect(c.apply(0.5), closeTo(0.4 + 0.6 * 0.5, 1e-9)); // 0.7
  });

  test('gamma < 1 boosts light pressure (more sensitive)', () {
    const c = PressureCurve(gamma: 0.5);
    // pow(0.25, 0.5) = 0.5 → output 0.5 > input 0.25
    expect(c.apply(0.25), closeTo(0.5, 1e-9));
    expect(c.apply(0.25), greaterThan(0.25));
  });

  test('gamma > 1 dampens light pressure (firmer)', () {
    const c = PressureCurve(gamma: 2.0);
    expect(c.apply(0.5), closeTo(0.25, 1e-9)); // 0.5^2
    expect(c.apply(0.5), lessThan(0.5));
  });

  test('output is clamped: out-of-range and NaN inputs are safe', () {
    const c = PressureCurve(floor: 0.2);
    expect(c.apply(-1.0), closeTo(0.2, 1e-9)); // clamped to 0 → floor
    expect(c.apply(2.0), closeTo(1.0, 1e-9)); // clamped to 1 → full
    expect(c.apply(double.nan), closeTo(0.2, 1e-9)); // NaN → 0 → floor
  });

  test('marker-style high floor compresses the range toward full width', () {
    const marker = PressureCurve(floor: 0.9);
    expect(marker.apply(0.0), closeTo(0.9, 1e-9));
    expect(marker.apply(1.0), closeTo(1.0, 1e-9));
    // Even a light touch stays near full width.
    expect(marker.apply(0.1), greaterThan(0.9));
  });

  group('PressureCurve.shaped', () {
    const floor = 0.1;

    test('every shape maps 0→floor and 1→1', () {
      for (final shape in PressureCurveShape.values) {
        final c = PressureCurve.shaped(shape, floor: floor);
        expect(c.apply(0.0), closeTo(floor, 1e-9), reason: '$shape at 0');
        expect(c.apply(1.0), closeTo(1.0, 1e-9), reason: '$shape at 1');
      }
    });

    test('midpoints differ across shapes', () {
      final mids = {
        for (final shape in PressureCurveShape.values)
          shape: PressureCurve.shaped(shape).apply(0.5),
      };
      expect(mids[PressureCurveShape.linear], closeTo(0.5, 1e-9));
      expect(mids[PressureCurveShape.soft], closeTo(math.pow(0.5, 0.6), 1e-9));
      expect(mids[PressureCurveShape.quadratic], closeTo(0.25, 1e-9));
      expect(mids[PressureCurveShape.cubic], closeTo(0.125, 1e-9));
      expect(mids[PressureCurveShape.sqrt], closeTo(math.sqrt(0.5), 1e-9));
      final logMid = math.log(1 + kLogarithmicPressureK * 0.5) /
          math.log(1 + kLogarithmicPressureK);
      expect(mids[PressureCurveShape.logarithmic], closeTo(logMid, 1e-9));

      // Soft (γ<1) > linear > quadratic > cubic at p=0.5; log is above linear.
      expect(mids[PressureCurveShape.soft]! > mids[PressureCurveShape.linear]!,
          isTrue);
      expect(
          mids[PressureCurveShape.linear]! >
              mids[PressureCurveShape.quadratic]!,
          isTrue);
      expect(
          mids[PressureCurveShape.quadratic]! >
              mids[PressureCurveShape.cubic]!,
          isTrue);
      expect(
          mids[PressureCurveShape.logarithmic]! >
              mids[PressureCurveShape.linear]!,
          isTrue);
      // Distinct midpoints (no two shapes collide at p=0.5).
      expect(mids.values.toSet().length, PressureCurveShape.values.length);
    });

    test('shaped presets set expected gamma (except log)', () {
      expect(PressureCurve.shaped(PressureCurveShape.linear).gamma, 1.0);
      expect(PressureCurve.shaped(PressureCurveShape.soft).gamma, 0.6);
      expect(PressureCurve.shaped(PressureCurveShape.quadratic).gamma, 2.0);
      expect(PressureCurve.shaped(PressureCurveShape.cubic).gamma, 3.0);
      expect(PressureCurve.shaped(PressureCurveShape.sqrt).gamma, 0.5);
      expect(PressureCurve.shaped(PressureCurveShape.logarithmic).shape,
          PressureCurveShape.logarithmic);
    });
  });
}