ThemeExtension colours for light and dark

import 'package:flutter/material.dart';

@immutable
class AppColors extends ThemeExtension<AppColors> {
  const AppColors({required this.success, required this.warning, required this.priceTag});
  final Color success, warning, priceTag;

  static const light = AppColors(
    success: Color(0xFF1B7F4B),
    warning: Color(0xFFB26A00),
    priceTag: Color(0xFFE8F1FF),
  );
  static const dark = AppColors(
    success: Color(0xFF6FD6A0),
    warning: Color(0xFFFFB84D),
    priceTag: Color(0xFF1F2A3D),
  );

  @override
  AppColors copyWith({Color? success, Color? warning, Color? priceTag}) => AppColors(
        success: success ?? this.success,
        warning: warning ?? this.warning,
        priceTag: priceTag ?? this.priceTag,
      );

  @override
  AppColors lerp(ThemeExtension<AppColors>? other, double t) {
    if (other is! AppColors) return this;
    // Lets theme changes cross-fade smoothly during AnimatedTheme.
    return AppColors(
      success: Color.lerp(success, other.success, t)!,
      warning: Color.lerp(warning, other.warning, t)!,
      priceTag: Color.lerp(priceTag, other.priceTag, t)!,
    );
  }
}

class AppTheme {
  static ThemeData build(Brightness b) {
    final scheme = ColorScheme.fromSeed(seedColor: const Color(0xFF3057E0), brightness: b);
    return ThemeData(
      useMaterial3: true,
      colorScheme: scheme,
      extensions: [b == Brightness.dark ? AppColors.dark : AppColors.light],
    );
  }
}

extension AppColorsX on BuildContext {
  AppColors get appColors => Theme.of(this).extension<AppColors>()!;
}

// MaterialApp(
//   theme: AppTheme.build(Brightness.light),
//   darkTheme: AppTheme.build(Brightness.dark),
//   themeMode: ThemeMode.system,
// )