import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:rippr/src/ui/theme.dart';

/// V3-16's acceptance criterion is "contrast ratios meet WCAG AA for body text" --
/// asserted directly here rather than trusted from a palette chosen by eye. AA is 4.5:1
/// for normal text, 3:1 for large text (18pt, or 14pt bold and up -- the headline
/// figures in `BigStat`).
void main() {
  group('contrastRatio', () {
    test('black on white is the maximum possible ratio, 21:1', () {
      expect(
        contrastRatio(const Color(0xFF000000), const Color(0xFFFFFFFF)),
        closeTo(21.0, 0.01),
      );
    });

    test('a colour against itself is 1:1', () {
      const c = Color(0xFFFF5722);
      expect(contrastRatio(c, c), closeTo(1.0, 0.01));
    });

    test('is symmetric regardless of argument order', () {
      const a = Color(0xFF101418);
      const b = Color(0xFFF2F5F8);
      expect(contrastRatio(a, b), contrastRatio(b, a));
    });
  });

  group('pocketed theme (WCAG AA)', () {
    final colors = ripprTheme().colorScheme;

    test('body text on the ground meets AA normal text (4.5:1)', () {
      expect(contrastRatio(colors.onSurface, ripprBackground), greaterThanOrEqualTo(4.5));
    });

    test('body text on a surface card meets AA normal text (4.5:1)', () {
      expect(contrastRatio(colors.onSurface, colors.surface), greaterThanOrEqualTo(4.5));
    });

    test('the primary accent on the ground meets AA large text (3:1)', () {
      // The accent is used for headline figures and buttons, not small body copy --
      // held to the large-text threshold, matching how it's actually used on screen.
      expect(contrastRatio(colors.primary, ripprBackground), greaterThanOrEqualTo(3.0));
    });

    test('the instrument-blue tertiary on the ground meets AA large text (3:1)', () {
      expect(contrastRatio(colors.tertiary, ripprBackground), greaterThanOrEqualTo(3.0));
    });

    test('the instrument-blue tertiary on a surface card meets AA large text (3:1)', () {
      expect(contrastRatio(colors.tertiary, colors.surface), greaterThanOrEqualTo(3.0));
    });
  });

  group('mounted theme (WCAG AA)', () {
    final colors = ripprMountedTheme().colorScheme;

    test('body text on the ground meets AA normal text (4.5:1)', () {
      expect(
        contrastRatio(colors.onSurface, ripprMountedBackground),
        greaterThanOrEqualTo(4.5),
      );
    });

    test('the primary accent on the ground meets AA large text (3:1) -- this is the '
        'theme sunlight legibility actually depends on', () {
      expect(
        contrastRatio(colors.primary, ripprMountedBackground),
        greaterThanOrEqualTo(3.0),
      );
    });

    test('the instrument-blue tertiary meets AA normal text on the ground '
        '(darkened further than the pocketed theme specifically for this)', () {
      expect(
        contrastRatio(colors.tertiary, ripprMountedBackground),
        greaterThanOrEqualTo(4.5),
      );
    });
  });
}