plezy/lib/theme/mono_tokens.dart

import 'dart:ui';
import 'package:flutter/material.dart';

MonoTokens tokens(BuildContext context) => Theme.of(context).extension<MonoTokens>()!;

/// M3E connected-group geometry for item [index] of a [count]-item group:
/// large radii on the group's outer corners, small radii between adjacent
/// items. Pair with `MonoTokens.groupGap` spacing for the hairline gaps.
BorderRadius groupItemRadii(BuildContext context, int index, int count) {
  final t = tokens(context);
  return BorderRadius.vertical(
    top: Radius.circular(index == 0 ? t.radiusLg : t.radiusXs),
    bottom: Radius.circular(index == count - 1 ? t.radiusLg : t.radiusXs),
  );
}

@immutable
class MonoTokens extends ThemeExtension<MonoTokens> {
  /// Effectively-stadium radius for pill shapes; the renderer proportionally
  /// clamps oversized RRect radii (same trick as FocusableButton).
  static const double radiusFull = 100;

  final double radiusSm;
  final double radiusMd;

  /// Outer corners of M3E grouped-list cards and connected button groups.
  final double radiusLg;

  /// Inner corners between adjacent items of an M3E group.
  final double radiusXs;

  /// Gap between adjacent items of an M3E group.
  final double groupGap;

  final double space;
  final Duration fast;
  final Duration normal;
  final Duration slow;

  /// M3E shape-morph duration (segment square→pill and friends).
  final Duration expressive;
  final Color bg;
  final Color surface;
  final Color outline;
  final Color text;
  final Color textMuted;

  const MonoTokens({
    required this.radiusSm,
    required this.radiusMd,
    required this.radiusLg,
    required this.radiusXs,
    required this.groupGap,
    required this.space,
    required this.fast,
    required this.normal,
    required this.slow,
    required this.expressive,
    required this.bg,
    required this.surface,
    required this.outline,
    required this.text,
    required this.textMuted,
  });

  @override
  MonoTokens copyWith({
    double? radiusSm,
    double? radiusMd,
    double? radiusLg,
    double? radiusXs,
    double? groupGap,
    double? space,
    Duration? fast,
    Duration? normal,
    Duration? slow,
    Duration? expressive,
    Color? bg,
    Color? surface,
    Color? outline,
    Color? text,
    Color? textMuted,
  }) => MonoTokens(
    radiusSm: radiusSm ?? this.radiusSm,
    radiusMd: radiusMd ?? this.radiusMd,
    radiusLg: radiusLg ?? this.radiusLg,
    radiusXs: radiusXs ?? this.radiusXs,
    groupGap: groupGap ?? this.groupGap,
    space: space ?? this.space,
    fast: fast ?? this.fast,
    normal: normal ?? this.normal,
    slow: slow ?? this.slow,
    expressive: expressive ?? this.expressive,
    bg: bg ?? this.bg,
    surface: surface ?? this.surface,
    outline: outline ?? this.outline,
    text: text ?? this.text,
    textMuted: textMuted ?? this.textMuted,
  );

  @override
  ThemeExtension<MonoTokens> lerp(covariant MonoTokens? other, double t) {
    if (other == null) return this;
    Color lerpC(Color a, Color b) => Color.lerp(a, b, t)!;
    Duration lerpD(Duration a, Duration b) =>
        Duration(milliseconds: lerpDouble(a.inMilliseconds.toDouble(), b.inMilliseconds.toDouble(), t)!.round());
    return MonoTokens(
      radiusSm: lerpDouble(radiusSm, other.radiusSm, t)!,
      radiusMd: lerpDouble(radiusMd, other.radiusMd, t)!,
      radiusLg: lerpDouble(radiusLg, other.radiusLg, t)!,
      radiusXs: lerpDouble(radiusXs, other.radiusXs, t)!,
      groupGap: lerpDouble(groupGap, other.groupGap, t)!,
      space: lerpDouble(space, other.space, t)!,
      fast: lerpD(fast, other.fast),
      normal: lerpD(normal, other.normal),
      slow: lerpD(slow, other.slow),
      expressive: lerpD(expressive, other.expressive),
      bg: lerpC(bg, other.bg),
      surface: lerpC(surface, other.surface),
      outline: lerpC(outline, other.outline),
      text: lerpC(text, other.text),
      textMuted: lerpC(textMuted, other.textMuted),
    );
  }
}