feat: study home with daily plan card and quick actions

lib/models/study_plan.dart

@@ -0,0 +1,78 @@
+/// 「学习」首页需要的一份排程摘要。
+///
+/// 目前由 [StudyPlan.sample] 提供示例数据；接上新内核后，这里应改为由排程
+/// 返回的真实数据（到期条目数、新识记额度、历史平均速度等），UI 不需要改。
+class StudyPlan {
+  const StudyPlan({
+    required this.deckName,
+    required this.algorithm,
+    required this.totalItems,
+    required this.activatedItems,
+    required this.dueItems,
+    required this.newItems,
+    required this.secondsPerItem,
+  });
+
+  /// 当前单元集名称。
+  final String deckName;
+
+  /// 该单元集使用的调度算法标识，如 `NSP-0`、`SM-2`。
+  final String algorithm;
+
+  /// 单元集条目总数。
+  final int totalItems;
+
+  /// 已激活（学过至少一次）的条目数。
+  final int activatedItems;
+
+  /// 今天到期、需要复习的条目数。
+  final int dueItems;
+
+  /// 今天还可以引入的新识记条目数。
+  final int newItems;
+
+  /// 单个条目完成一轮多谜题测验的平均耗时（秒）。
+  ///
+  /// 用于把「今天要学多少」翻译成用户能感知的时间承诺。实测速度应当来自
+  /// 内核，这里先用经验值。
+  final int secondsPerItem;
+
+  /// 今天总共要处理的条目数。
+  int get itemCount => dueItems + newItems;
+
+  /// 今天是否无事可做。
+  bool get isEmpty => itemCount == 0;
+
+  /// 单元集整体完成度，0..1。
+  double get progress => totalItems == 0 ? 0 : activatedItems / totalItems;
+
+  /// 完成度百分比，保留一位小数。
+  String get progressPercent => '${(progress * 100).toStringAsFixed(1)}%';
+
+  /// 预计用时（分钟，向上取整）。条目数为 0 时返回 0。
+  int get estimatedMinutes => _minutes(itemCount, secondsPerItem);
+
+  /// 预计用时的展示文案。
+  String get estimatedLabel => isEmpty
+      ? '今天没有到期的内容'
+      : '预计用时 $estimatedMinutes 分钟';
+
+  /// 示例数据：高考必背古诗文，NSP-0 调度。
+  static const StudyPlan sample = StudyPlan(
+    deckName: '高考必背古诗文',
+    algorithm: 'NSP-0',
+    totalItems: 950,
+    activatedItems: 295,
+    dueItems: 18,
+    newItems: 35,
+    secondsPerItem: 13,
+  );
+
+  static int _minutes(int itemCount, int secondsPerItem) {
+    if (itemCount <= 0 || secondsPerItem <= 0) {
+      return 0;
+    }
+    final int totalSeconds = itemCount * secondsPerItem;
+    return (totalSeconds + 59) ~/ 60;
+  }
+}

lib/pages/study_page.dart

@@ -1,8 +1,12 @@
 import 'package:flutter/material.dart';
 
-import '../widgets/empty_state.dart';
+import '../models/study_plan.dart';
 
-/// 学习：今天到期的卡片与复习会话入口。
+/// 学习首页。
+///
+/// 信息层级刻意保持简单，和百词斩首页同构：
+///   当前材料 → 今日任务（要做什么 + 要多久）→ 唯一主行动 → 快捷入口。
+/// 但去掉它的商业化部分：没有广告位、没有课程倒计时、没有电商入口。
 class StudyPage extends StatelessWidget {
   const StudyPage({super.key});
 
@@ -10,11 +14,302 @@ class StudyPage extends StatelessWidget {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(title: const Text('学习')),
-      body: const EmptyState(
-        icon: Icons.school_outlined,
-        title: '开始今天的复习',
-        message: '待学习的卡片和到期需要复习的卡片会出现在这里。',
+      body: ListView(
+        padding: const EdgeInsets.fromLTRB(16, 8, 16, 32),
+        children: const <Widget>[
+          _DeckCard(plan: StudyPlan.sample),
+          SizedBox(height: 14),
+          _TodayPlanCard(plan: StudyPlan.sample),
+          SizedBox(height: 18),
+          _QuickActions(),
+        ],
       ),
     );
   }
 }
+
+/// 当前单元集：名称、算法、完成度。
+class _DeckCard extends StatelessWidget {
+  const _DeckCard({required this.plan});
+
+  final StudyPlan plan;
+
+  @override
+  Widget build(BuildContext context) {
+    final ThemeData theme = Theme.of(context);
+    final ColorScheme colors = theme.colorScheme;
+    final TextTheme text = theme.textTheme;
+
+    return _SurfaceCard(
+      onTap: () => _pending(context, '单元集切换'),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: <Widget>[
+          Row(
+            children: <Widget>[
+              Container(
+                width: 48,
+                height: 48,
+                decoration: BoxDecoration(
+                  color: colors.primaryContainer,
+                  borderRadius: BorderRadius.circular(12),
+                ),
+                child: Icon(
+                  Icons.menu_book_rounded,
+                  color: colors.onPrimaryContainer,
+                ),
+              ),
+              const SizedBox(width: 12),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: <Widget>[
+                    Text(
+                      plan.deckName,
+                      style: text.titleMedium,
+                      maxLines: 1,
+                      overflow: TextOverflow.ellipsis,
+                    ),
+                    const SizedBox(height: 2),
+                    Text(
+                      '调度算法 ${plan.algorithm}',
+                      style: text.bodySmall?.copyWith(
+                        color: colors.onSurfaceVariant,
+                      ),
+                    ),
+                  ],
+                ),
+              ),
+              Icon(
+                Icons.unfold_more_rounded,
+                size: 20,
+                color: colors.onSurfaceVariant,
+              ),
+            ],
+          ),
+          const SizedBox(height: 16),
+          ClipRRect(
+            borderRadius: BorderRadius.circular(6),
+            child: LinearProgressIndicator(
+              value: plan.progress,
+              minHeight: 8,
+              backgroundColor: colors.surfaceContainerHighest,
+            ),
+          ),
+          const SizedBox(height: 8),
+          Row(
+            children: <Widget>[
+              Text(
+                '${plan.activatedItems} / ${plan.totalItems}',
+                style: text.bodySmall?.copyWith(color: colors.onSurfaceVariant),
+              ),
+              const Spacer(),
+              Text(
+                plan.progressPercent,
+                style: text.bodySmall?.copyWith(
+                  color: colors.onSurfaceVariant,
+                  fontWeight: FontWeight.w600,
+                ),
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+/// 今日任务：两个数字 + 时长承诺 + 唯一主行动。
+class _TodayPlanCard extends StatelessWidget {
+  const _TodayPlanCard({required this.plan});
+
+  final StudyPlan plan;
+
+  @override
+  Widget build(BuildContext context) {
+    final ThemeData theme = Theme.of(context);
+    final ColorScheme colors = theme.colorScheme;
+    final TextTheme text = theme.textTheme;
+
+    return _SurfaceCard(
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: <Widget>[
+          Text('今日计划', style: text.titleMedium),
+          const SizedBox(height: 18),
+          Row(
+            children: <Widget>[
+              Expanded(child: _BigStat(label: '待复习', value: plan.dueItems)),
+              Expanded(child: _BigStat(label: '待新识', value: plan.newItems)),
+            ],
+          ),
+          const SizedBox(height: 16),
+          Center(
+            child: Row(
+              mainAxisSize: MainAxisSize.min,
+              children: <Widget>[
+                Icon(
+                  Icons.schedule_rounded,
+                  size: 16,
+                  color: colors.onSurfaceVariant,
+                ),
+                const SizedBox(width: 6),
+                Text(
+                  plan.estimatedLabel,
+                  style: text.bodyMedium?.copyWith(
+                    color: colors.onSurfaceVariant,
+                  ),
+                ),
+              ],
+            ),
+          ),
+          const SizedBox(height: 16),
+          FilledButton(
+            onPressed: plan.isEmpty ? null : () => _pending(context, '学习会话'),
+            style: FilledButton.styleFrom(
+              minimumSize: const Size.fromHeight(52),
+              textStyle: text.titleMedium,
+            ),
+            child: Text(plan.isEmpty ? '今天已完成' : '开始学习'),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _BigStat extends StatelessWidget {
+  const _BigStat({required this.label, required this.value});
+
+  final String label;
+  final int value;
+
+  @override
+  Widget build(BuildContext context) {
+    final ThemeData theme = Theme.of(context);
+    final ColorScheme colors = theme.colorScheme;
+
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: <Widget>[
+        Text(
+          label,
+          style: theme.textTheme.bodyMedium?.copyWith(
+            color: colors.onSurfaceVariant,
+          ),
+        ),
+        const SizedBox(height: 2),
+        Row(
+          crossAxisAlignment: CrossAxisAlignment.baseline,
+          textBaseline: TextBaseline.alphabetic,
+          children: <Widget>[
+            Text(
+              '$value',
+              style: theme.textTheme.displaySmall?.copyWith(
+                fontWeight: FontWeight.w700,
+                height: 1.1,
+              ),
+            ),
+            const SizedBox(width: 6),
+            Text(
+              '条',
+              style: theme.textTheme.bodySmall?.copyWith(
+                color: colors.onSurfaceVariant,
+              ),
+            ),
+          ],
+        ),
+      ],
+    );
+  }
+}
+
+/// 快捷入口。都是「学习域」内的次级入口，维护类操作不放这里。
+class _QuickActions extends StatelessWidget {
+  const _QuickActions();
+
+  static const List<(IconData, String)> _items = <(IconData, String)>[
+    (Icons.star_border_rounded, '收藏夹'),
+    (Icons.volume_up_outlined, '语音缓存'),
+    (Icons.history_rounded, '最近学习'),
+    (Icons.replay_rounded, '难点重练'),
+  ];
+
+  @override
+  Widget build(BuildContext context) {
+    final ThemeData theme = Theme.of(context);
+    final ColorScheme colors = theme.colorScheme;
+
+    return Row(
+      children: <Widget>[
+        for (final (int index, (IconData icon, String label)) in _items.indexed)
+          Expanded(
+            child: Padding(
+              padding: EdgeInsets.only(left: index == 0 ? 0 : 8),
+              child: Material(
+                color: colors.surfaceContainerLow,
+                borderRadius: BorderRadius.circular(16),
+                child: InkWell(
+                  borderRadius: BorderRadius.circular(16),
+                  onTap: () => _pending(context, label),
+                  child: Padding(
+                    padding: const EdgeInsets.symmetric(vertical: 14),
+                    child: Column(
+                      children: <Widget>[
+                        Icon(icon, size: 22, color: colors.primary),
+                        const SizedBox(height: 8),
+                        Text(
+                          label,
+                          style: theme.textTheme.labelSmall?.copyWith(
+                            color: colors.onSurfaceVariant,
+                          ),
+                          maxLines: 1,
+                          overflow: TextOverflow.ellipsis,
+                        ),
+                      ],
+                    ),
+                  ),
+                ),
+              ),
+            ),
+          ),
+      ],
+    );
+  }
+}
+
+/// 统一的卡片外观，避免每处重复写圆角和底色。
+class _SurfaceCard extends StatelessWidget {
+  const _SurfaceCard({required this.child, this.onTap});
+
+  final Widget child;
+
+  /// 可点击时给出水波纹反馈；为 null 时是纯展示卡片。
+  final VoidCallback? onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    final BorderRadius radius = BorderRadius.circular(20);
+    return Material(
+      color: Theme.of(context).colorScheme.surfaceContainerLow,
+      borderRadius: radius,
+      clipBehavior: Clip.antiAlias,
+      child: InkWell(
+        onTap: onTap,
+        borderRadius: radius,
+        child: Padding(padding: const EdgeInsets.all(18), child: child),
+      ),
+    );
+  }
+}
+
+/// 尚未接入内核的入口，点击给出明确反馈而不是静默无响应。
+void _pending(BuildContext context, String feature) {
+  ScaffoldMessenger.of(context).showSnackBar(
+    SnackBar(
+      content: Text('$feature 尚未接入内核'),
+      behavior: SnackBarBehavior.floating,
+      margin: const EdgeInsets.fromLTRB(16, 0, 16, 88),
+    ),
+  );
+}

test/study_plan_test.dart

@@ -0,0 +1,57 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mobile/models/study_plan.dart';
+
+void main() {
+  test('预计用时按条目数与平均耗时向上取整', () {
+    // 18 + 35 = 53 条 × 13 秒 = 689 秒 → 12 分钟
+    expect(StudyPlan.sample.itemCount, 53);
+    expect(StudyPlan.sample.estimatedMinutes, 12);
+    expect(StudyPlan.sample.estimatedLabel, '预计用时 12 分钟');
+  });
+
+  test('没有任务时不给时长承诺，也不算空转', () {
+    const StudyPlan plan = StudyPlan(
+      deckName: '空单元集',
+      algorithm: 'SM-2',
+      totalItems: 10,
+      activatedItems: 0,
+      dueItems: 0,
+      newItems: 0,
+      secondsPerItem: 13,
+    );
+
+    expect(plan.isEmpty, isTrue);
+    expect(plan.estimatedMinutes, 0);
+    expect(plan.estimatedLabel, '今天没有到期的内容');
+  });
+
+  test('完成度保留一位小数', () {
+    const StudyPlan plan = StudyPlan(
+      deckName: '高考必背古诗文',
+      algorithm: 'NSP-0',
+      totalItems: 950,
+      activatedItems: 295,
+      dueItems: 0,
+      newItems: 0,
+      secondsPerItem: 0,
+    );
+
+    expect(plan.progress, closeTo(0.3105, 0.0001));
+    expect(plan.progressPercent, '31.1%');
+  });
+
+  test('条目总数为 0 时不除零', () {
+    const StudyPlan plan = StudyPlan(
+      deckName: '空集',
+      algorithm: 'SM-2',
+      totalItems: 0,
+      activatedItems: 0,
+      dueItems: 0,
+      newItems: 0,
+      secondsPerItem: 13,
+    );
+
+    expect(plan.progress, 0);
+    expect(plan.progressPercent, '0.0%');
+  });
+}

test/widget_test.dart

@@ -41,4 +41,20 @@ void main() {
     bar = tester.widget<NavigationBar>(find.byType(NavigationBar));
     expect(bar.selectedIndex, 3);
   });
+
+  testWidgets('学习首页展示今日任务与唯一主行动', (WidgetTester tester) async {
+    await tester.pumpWidget(const KiriMemoApp());
+
+    expect(find.text('今日计划'), findsOneWidget);
+    expect(find.text('待复习'), findsOneWidget);
+    expect(find.text('待新识'), findsOneWidget);
+    expect(find.text('开始学习'), findsOneWidget);
+
+    // 未接入内核的入口点击后要有反馈，不能静默无响应。
+    await tester.tap(find.text('开始学习'));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 300));
+
+    expect(find.text('学习会话 尚未接入内核'), findsOneWidget);
+  });
 }