import 'package:flutter/material.dart';

import '../models/app_status.dart';
import '../models/study_plan.dart';
import '../widgets/stat_block.dart';

/// 学习首页。
///
/// 信息层级刻意保持简单，和百词斩首页同构：
///   顶部状态标识 → 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});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        bottom: false,
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            const Padding(
              padding: EdgeInsets.fromLTRB(16, 12, 16, 2),
              child: _StatusStrip(status: AppStatus.sample),
            ),
            Expanded(
              child: ListView(
                padding: const EdgeInsets.fromLTRB(16, 10, 16, 32),
                children: const <Widget>[
                  _DeckCard(plan: StudyPlan.sample),
                  SizedBox(height: 14),
                  _TodayPlanCard(plan: StudyPlan.sample),
                  SizedBox(height: 18),
                  _QuickActions(),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

/// 顶部状态标识：计划接力 / 今日记忆 / 云同步，右侧是搜索与日志入口。
///
/// 状态用图形和颜色表达，文字只留给「今日记忆」这个需要被读懂的标签；
/// 完整语义（"云同步: 成功" 等）放进 tooltip 与无障碍描述里。
/// 窄屏时胶囊横向滚动，右侧按钮始终可见。
class _StatusStrip extends StatelessWidget {
  const _StatusStrip({required this.status});

  final AppStatus status;

  static const Color _streak = Color(0xFFFFB300);
  static const Color _success = Color(0xFF4CAF50);

  @override
  Widget build(BuildContext context) {
    final ColorScheme colors = Theme.of(context).colorScheme;
    final (IconData syncIcon, Color syncColor) = switch (status.sync) {
      SyncState.success => (Icons.cloud_done_rounded, _success),
      SyncState.syncing => (Icons.cloud_sync_rounded, colors.tertiary),
      SyncState.failed => (Icons.cloud_off_rounded, colors.error),
      SyncState.unknown => (Icons.cloud_queue_rounded, colors.outline),
    };

    return Row(
      children: <Widget>[
        Expanded(
          child: SingleChildScrollView(
            scrollDirection: Axis.horizontal,
            child: Row(
              children: <Widget>[
                _Pill(
                  leading: Icon(
                    Icons.bolt_rounded,
                    size: 16,
                    color: _streak,
                  ),
                  value: '${status.streakDays}',
                  tooltip: status.streakLabel,
                ),
                const SizedBox(width: 8),
                _Pill(
                  label: '今日记忆',
                  value: '${status.todayItems}',
                  tooltip: status.todayLabel,
                ),
                const SizedBox(width: 8),
                _Pill(
                  leading: Icon(syncIcon, size: 16, color: syncColor),
                  tooltip: status.syncLabel,
                ),
              ],
            ),
          ),
        ),
        IconButton(
          icon: const Icon(Icons.search_rounded),
          tooltip: '搜索条目',
          visualDensity: VisualDensity.compact,
          onPressed: () => _pending(context, '搜索'),
        ),
        IconButton(
          icon: const Icon(Icons.receipt_long_outlined),
          tooltip: '学习日志',
          visualDensity: VisualDensity.compact,
          onPressed: () => _pending(context, '学习日志'),
        ),
      ],
    );
  }
}

class _Pill extends StatelessWidget {
  const _Pill({this.leading, this.label, this.value, this.tooltip});

  final Widget? leading;
  final String? label;
  final String? value;
  final String? tooltip;

  @override
  Widget build(BuildContext context) {
    final ThemeData theme = Theme.of(context);
    final ColorScheme colors = theme.colorScheme;
    final TextTheme text = theme.textTheme;
    final Widget? leading = this.leading;
    final String? label = this.label;
    final String? value = this.value;

    final Widget pill = Container(
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 7),
      decoration: ShapeDecoration(
        color: colors.surfaceContainerHigh,
        shape: const StadiumBorder(),
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          if (leading != null) ...<Widget>[
            leading,
            const SizedBox(width: 6),
          ],
          if (label != null)
            Text(
              label,
              style: text.labelMedium?.copyWith(color: colors.onSurfaceVariant),
            ),
          if (label != null && value != null) const SizedBox(width: 6),
          if (value != null)
            Text(
              value,
              style: text.labelLarge?.copyWith(
                fontWeight: FontWeight.w700,
                color: colors.onSurface,
              ),
            ),
        ],
      ),
    );

    final String? tooltip = this.tooltip;
    return tooltip == null ? pill : Tooltip(message: tooltip, child: pill);
  }
}

/// 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: StatBlock(
                  label: '待复习',
                  value: '${plan.dueItems}',
                  unit: '条',
                ),
              ),
              Expanded(
                child: StatBlock(
                  label: '待新识',
                  value: '${plan.newItems}',
                  unit: '条',
                ),
              ),
            ],
          ),
          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'),
          ),
        ],
      ),
    );
  }
}

/// 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.quiz_outlined, '自我测试'),
    (Icons.attach_file_rounded, '附带资料'),
    (Icons.tune_rounded, '计划设置'),
  ];

  @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),
    ),
  );
}