import 'package:flutter/widgets.dart';

/// Spacing tokens (dp) on a 4dp grid.
abstract final class AppSpacing {
  static const double xxs = 2;
  static const double xs = 4;
  static const double sm = 8;
  static const double md = 12;
  static const double lg = 16;
  static const double xl = 24;
  static const double xxl = 32;
  static const double xxxl = 48;

  /// Minimum size of interactive targets (WCAG 2.5.5 / Material: 48dp).
  static const double minTouchTarget = 48;

  /// Page padding per width class.
  static EdgeInsets pagePadding(double width) => EdgeInsets.symmetric(
    horizontal: width >= AppBreakpoints.expanded
        ? xxl
        : width >= AppBreakpoints.medium
        ? xl
        : lg,
    vertical: lg,
  );
}

/// Corner radius tokens (dp).
abstract final class AppRadius {
  static const double sm = 8;
  static const double md = 12;
  static const double lg = 16;
  static const double xl = 28;

  static BorderRadius get smAll => BorderRadius.circular(sm);
  static BorderRadius get mdAll => BorderRadius.circular(md);
  static BorderRadius get lgAll => BorderRadius.circular(lg);
}

/// Width breakpoints: compact < 600, medium 600-1023, expanded >= 1024.
abstract final class AppBreakpoints {
  static const double medium = 600;
  static const double expanded = 1024;

  /// Max content width for forms/text on wide screens.
  static const double maxContentWidth = 560;

  /// Max width of the centered auth card (Spec #1 § 6) from the medium class on.
  static const double authCardMaxWidth = 480;
}

enum AppWidthClass {
  compact,
  medium,
  expanded;

  static AppWidthClass of(double width) => width >= AppBreakpoints.expanded
      ? expanded
      : width >= AppBreakpoints.medium
      ? medium
      : compact;
}