nj/app/lib/core/constants/design_tokens.dart

// 暖记设计常量 — 间距 / 动画 / 触摸目标

import 'package:flutter/animation.dart';

class DesignTokens {
  DesignTokens._();

  // ===== 间距（4px 基准，9 级）=====
  static const double spacing4 = 4;
  static const double spacing8 = 8;
  static const double spacing12 = 12;
  static const double spacing16 = 16;
  static const double spacing20 = 20;
  static const double spacing24 = 24;
  static const double spacing32 = 32;
  static const double spacing40 = 40;
  static const double spacing48 = 48;

  // ===== 安全区 & 布局常量（对齐 spec §1）=====
  static const double safeTop = 54;       // iPhone Dynamic Island
  static const double safeBottom = 34;    // Home Indicator
  static const double tabHeight = 56;     // 底部 Tab 栏
  static const double touchMin = 44;      // WCAG 最小触控目标
  static const double containerMax = 390; // 移动端容器宽度

  // ===== 动画时长 =====
  static const Duration animFast = Duration(milliseconds: 150);
  static const Duration animNormal = Duration(milliseconds: 300);
  static const Duration animSlow = Duration(milliseconds: 500);

  // ===== 弹性曲线 cubic-bezier(0.34, 1.56, 0.64, 1) =====
  static const Curve warmCurve = Curves.easeOutBack;

  // ===== 列表/网格 =====
  static const int journalGridCrossAxisCountMobile = 2;
  static const int journalGridCrossAxisCountTablet = 3;
  static const int journalGridCrossAxisCountDesktop = 4;

  // ===== 日记限制 =====
  static const int maxTagsPerJournal = 10;
  static const int maxTitleLength = 100;
  static const int maxStrokesPerElement = 5000;
  static const int maxUndoSteps = 50;

  // ===== 班级码 =====
  static const int classCodeLength = 6;
  static const int classCodeMaxAttempts = 5;
  static const int classCodeLockoutMinutes = 30;
}