// 月度概览页面 — 心情色彩月历 + 月度统计 + 精选日记
// 对齐 Open Design 原型稿 screens/monthly.html

import 'package:flutter/material.dart';
import 'package:nuanji_app/core/theme/app_colors.dart';
import 'package:nuanji_app/core/theme/app_radius.dart';
import 'package:nuanji_app/core/theme/app_shadows.dart';
import 'package:nuanji_app/core/theme/app_typography.dart';

/// 月度概览页面
class MonthlyPage extends StatefulWidget {
  const MonthlyPage({super.key});

  @override
  State<MonthlyPage> createState() => _MonthlyPageState();
}

class _MonthlyPageState extends State<MonthlyPage> {
  late DateTime _focusedMonth;

  @override
  void initState() {
    super.initState();
    _focusedMonth = DateTime.now();
  }

  void _goToPreviousMonth() {
    setState(() {
      _focusedMonth = DateTime(_focusedMonth.year, _focusedMonth.month - 1);
    });
  }

  void _goToNextMonth() {
    setState(() {
      _focusedMonth = DateTime(_focusedMonth.year, _focusedMonth.month + 1);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Column(
          children: [
            // 月头部导航
            _MonthHeader(
              month: _focusedMonth,
              onPrevious: _goToPreviousMonth,
              onNext: _goToNextMonth,
            ),
            // 可滚动内容区
            Expanded(
              child: ListView(
                padding: const EdgeInsets.symmetric(horizontal: 20),
                children: [
                  const SizedBox(height: 16),
                  // 心情色彩月历
                  _MoodCalendar(month: _focusedMonth),
                  const SizedBox(height: 20),
                  // 月度统计 2x2
                  const _MonthSummary(),
                  const SizedBox(height: 20),
                  // 精选日记
                  const _Highlights(),
                  const SizedBox(height: 32),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

// ===== 月头部导航 =====

class _MonthHeader extends StatelessWidget {
  const _MonthHeader({
    required this.month,
    required this.onPrevious,
    required this.onNext,
  });

  final DateTime month;
  final VoidCallback onPrevious;
  final VoidCallback onNext;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colorScheme = theme.colorScheme;
    final title = '${month.year}年${month.month}月';

    return Padding(
      padding: const EdgeInsets.fromLTRB(20, 8, 12, 0),
      child: Row(
        children: [
          Expanded(
            child: Text(
              title,
              style: theme.textTheme.headlineSmall?.copyWith(
                fontFamily: AppTypography.displayFont,
                fontWeight: FontWeight.w700,
              ),
            ),
          ),
          _NavButton(
            icon: Icons.chevron_left_rounded,
            onTap: onPrevious,
            borderColor: colorScheme.outline,
            foregroundColor: colorScheme.onSurface,
          ),
          const SizedBox(width: 8),
          _NavButton(
            icon: Icons.chevron_right_rounded,
            onTap: onNext,
            borderColor: colorScheme.outline,
            foregroundColor: colorScheme.onSurface,
          ),
        ],
      ),
    );
  }
}

/// 圆形导航按钮 (44px 触摸目标)
class _NavButton extends StatelessWidget {
  const _NavButton({
    required this.icon,
    required this.onTap,
    required this.borderColor,
    required this.foregroundColor,
  });

  final IconData icon;
  final VoidCallback onTap;
  final Color borderColor;
  final Color foregroundColor;

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: 44,
      height: 44,
      child: OutlinedButton(
        onPressed: onTap,
        style: OutlinedButton.styleFrom(
          padding: EdgeInsets.zero,
          shape: const CircleBorder(),
          side: BorderSide(color: borderColor, width: 1.5),
          foregroundColor: foregroundColor,
          backgroundColor: Theme.of(context).colorScheme.surface,
        ),
        child: Icon(icon, size: 18),
      ),
    );
  }
}

// ===== 心情色彩月历 =====

class _MoodCalendar extends StatelessWidget {
  const _MoodCalendar({required this.month});

  final DateTime month;

  // 心情类型
  static const _moodTypes = [
    'happy', 'calm', 'sad', 'tired', 'love',
  ];

  // 心情 → emoji
  static const _moodEmojis = <String, String>{
    'happy': '😊',
    'calm': '😐',
    'sad': '😢',
    'tired': '😐',
    'love': '😡',
  };

  // 心情 → 背景色
  static const _moodBgColors = <String, Color>{
    'happy': AppColors.secondarySoftLight,
    'love': AppColors.roseSoftLight,
    'calm': AppColors.tertiarySoftLight,
    'sad': Color(0xFFD4DDE8),
    'tired': Color(0xFFE8E4E0),
  };

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colorScheme = theme.colorScheme;
    final now = DateTime.now();

    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: colorScheme.surface,
        borderRadius: AppRadius.mdBorder,
        boxShadow: AppShadows.soft(context),
        border: Border.all(color: colorScheme.outlineVariant),
      ),
      child: Column(
        children: [
          // 星期标题行
          _WeekdayRow(colorScheme: colorScheme),
          const SizedBox(height: 8),
          // 7列网格
          _buildGrid(context, now),
        ],
      ),
    );
  }

  Widget _buildGrid(BuildContext context, DateTime now) {
    final firstDay = DateTime(month.year, month.month, 1);
    // 周日=0 → 偏移量; weekday 返回 1(周一)..7(周日)
    final startOffset = firstDay.weekday % 7; // 周日开头
    final daysInMonth = DateTime(month.year, month.month + 1, 0).day;

    final cells = <Widget>[];

    // 空白填充
    for (var i = 0; i < startOffset; i++) {
      cells.add(const SizedBox.shrink());
    }

    // 模拟心情数据（确定性伪随机，同一天固定同心情）
    final rng = _SeededRandom(month.year * 100 + month.month);

    for (var d = 1; d <= daysInMonth; d++) {
      final isToday = now.year == month.year &&
          now.month == month.month &&
          now.day == d;

      // 每天随机一个心情
      final moodIndex = rng.nextInt(5);
      final mood = _moodTypes[moodIndex];
      final bgColor = _moodBgColors[mood] ?? Colors.transparent;
      final emoji = _moodEmojis[mood] ?? '';

      cells.add(
        _MoodCell(
          day: d,
          emoji: emoji,
          bgColor: bgColor,
          isToday: isToday,
        ),
      );
    }

    return GridView.count(
      crossAxisCount: 7,
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      mainAxisSpacing: 3,
      crossAxisSpacing: 3,
      childAspectRatio: 1,
      children: cells,
    );
  }
}

/// 简单确定性伪随机数生成器（仅用于模拟数据）
class _SeededRandom {
  _SeededRandom(int seed) : _state = seed;
  int _state;

  int nextInt(int max) {
    _state = (_state * 1103515245 + 12345) & 0x7FFFFFFF;
    return _state % max;
  }
}

/// 星期标题行
class _WeekdayRow extends StatelessWidget {
  const _WeekdayRow({required this.colorScheme});

  final ColorScheme colorScheme;

  @override
  Widget build(BuildContext context) {
    const weekdays = ['日', '一', '二', '三', '四', '五', '六'];
    return Row(
      children: weekdays.map((day) {
        return Expanded(
          child: Center(
            child: Text(
              day,
              style: TextStyle(
                fontSize: 11,
                fontWeight: FontWeight.w500,
                color: colorScheme.onSurfaceVariant,
              ),
            ),
          ),
        );
      }).toList(),
    );
  }
}

/// 单个心情格子
class _MoodCell extends StatelessWidget {
  const _MoodCell({
    required this.day,
    required this.emoji,
    required this.bgColor,
    required this.isToday,
  });

  final int day;
  final String emoji;
  final Color bgColor;
  final bool isToday;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;

    return GestureDetector(
      onTap: () {
        // TODO: 选择日期，跳转详情
      },
      child: Container(
        decoration: BoxDecoration(
          color: bgColor,
          borderRadius: BorderRadius.circular(6),
          border: isToday
              ? Border.all(color: AppColors.accent, width: 2)
              : null,
        ),
        alignment: Alignment.center,
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(
              '$day',
              style: TextStyle(
                fontSize: 12,
                color: colorScheme.onSurface,
                fontWeight: isToday ? FontWeight.w700 : FontWeight.w400,
              ),
            ),
            const SizedBox(height: 1),
            Text(
              emoji,
              style: const TextStyle(fontSize: 10),
            ),
          ],
        ),
      ),
    );
  }
}

// ===== 月度统计 2x2 =====

class _MonthSummary extends StatelessWidget {
  const _MonthSummary();

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          '本月总结',
          style: theme.textTheme.headlineSmall?.copyWith(
            fontFamily: AppTypography.displayFont,
            fontWeight: FontWeight.w700,
          ),
        ),
        const SizedBox(height: 16),
        GridView.count(
          crossAxisCount: 2,
          shrinkWrap: true,
          physics: const NeverScrollableScrollPhysics(),
          mainAxisSpacing: 12,
          crossAxisSpacing: 12,
          childAspectRatio: 1.2,
          children: [
            _StatCard(
              icon: '📝',
              value: '28',
              label: '日记篇数',
              bgColor: AppColors.tertiarySoftLight,
              valueColor: const Color(0xFFB8860B),
            ),
            _StatCard(
              icon: '🔥',
              value: '12',
              label: '最长连续',
              bgColor: AppColors.secondarySoftLight,
              valueColor: const Color(0xFF2D7D46),
            ),
            _StatCard(
              icon: '😊',
              value: '72%',
              label: '好心情占比',
              bgColor: AppColors.roseSoftLight,
              valueColor: const Color(0xFF9B4D4D),
            ),
            _StatCard(
              icon: '📸',
              value: '18',
              label: '照片数量',
              bgColor: const Color(0xFFD4DDE8),
              valueColor: const Color(0xFF4A6B8A),
            ),
          ],
        ),
      ],
    );
  }
}

/// 单张统计小卡片
class _StatCard extends StatelessWidget {
  const _StatCard({
    required this.icon,
    required this.value,
    required this.label,
    required this.bgColor,
    required this.valueColor,
  });

  final String icon;
  final String value;
  final String label;
  final Color bgColor;
  final Color valueColor;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: bgColor,
        borderRadius: AppRadius.mdBorder,
      ),
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text(icon, style: const TextStyle(fontSize: 24)),
          const SizedBox(height: 8),
          Text(
            value,
            style: TextStyle(
              fontFamily: AppTypography.displayFont,
              fontSize: 24,
              fontWeight: FontWeight.w700,
              color: valueColor,
            ),
          ),
          const SizedBox(height: 2),
          Text(
            label,
            style: theme.textTheme.labelSmall?.copyWith(
              color: theme.colorScheme.onSurfaceVariant,
            ),
          ),
        ],
      ),
    );
  }
}

// ===== 精选日记 =====

class _Highlights extends StatelessWidget {
  const _Highlights();

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    // 模拟精选日记数据
    const highlights = [
      (
        emoji: '😊',
        emojiBg: AppColors.roseSoftLight,
        date: '5月14日',
        title: '和朋友聚餐的欢乐时光',
        badge: '最佳心情',
        badgeBg: AppColors.roseSoftLight,
        badgeFg: Color(0xFF9B4D4D),
      ),
      (
        emoji: '⭐',
        emojiBg: AppColors.tertiarySoftLight,
        date: '5月21日',
        title: '完成了第一个小目标',
        badge: '里程碑',
        badgeBg: AppColors.tertiarySoftLight,
        badgeFg: Color(0xFFB8860B),
      ),
      (
        emoji: '📚',
        emojiBg: AppColors.secondarySoftLight,
        date: '5月28日',
        title: '期末考试结束',
        badge: '最详尽记录',
        badgeBg: AppColors.secondarySoftLight,
        badgeFg: Color(0xFF2D7D46),
      ),
    ];

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          '本月精选',
          style: theme.textTheme.headlineSmall?.copyWith(
            fontFamily: AppTypography.displayFont,
            fontWeight: FontWeight.w700,
          ),
        ),
        const SizedBox(height: 16),
        ...highlights.map((item) {
          return _HighlightCard(
            emoji: item.emoji,
            emojiBg: item.emojiBg,
            date: item.date,
            title: item.title,
            badge: item.badge,
            badgeBg: item.badgeBg,
            badgeFg: item.badgeFg,
          );
        }),
      ],
    );
  }
}

/// 单张精选日记卡片
class _HighlightCard extends StatelessWidget {
  const _HighlightCard({
    required this.emoji,
    required this.emojiBg,
    required this.date,
    required this.title,
    required this.badge,
    required this.badgeBg,
    required this.badgeFg,
  });

  final String emoji;
  final Color emojiBg;
  final String date;
  final String title;
  final String badge;
  final Color badgeBg;
  final Color badgeFg;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colorScheme = theme.colorScheme;

    return Container(
      margin: const EdgeInsets.only(bottom: 12),
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: colorScheme.surface,
        borderRadius: AppRadius.mdBorder,
        boxShadow: AppShadows.soft(context),
        border: Border.all(color: colorScheme.outlineVariant),
      ),
      child: Row(
        children: [
          // 48x48 emoji 圆圈
          Container(
            width: 48,
            height: 48,
            decoration: BoxDecoration(
              color: emojiBg,
              shape: BoxShape.circle,
            ),
            alignment: Alignment.center,
            child: Text(emoji, style: const TextStyle(fontSize: 24)),
          ),
          const SizedBox(width: 12),
          // 标题 + 日期
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  date,
                  style: theme.textTheme.labelSmall?.copyWith(
                    color: colorScheme.onSurfaceVariant,
                  ),
                ),
                const SizedBox(height: 2),
                Text(
                  title,
                  style: theme.textTheme.titleMedium?.copyWith(
                    fontFamily: AppTypography.displayFont,
                    fontWeight: FontWeight.w600,
                  ),
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                ),
              ],
            ),
          ),
          // badge pill
          Container(
            padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
            decoration: BoxDecoration(
              color: badgeBg,
              borderRadius: AppRadius.pillBorder,
            ),
            child: Text(
              badge,
              style: TextStyle(
                fontSize: 11,
                fontWeight: FontWeight.w600,
                color: badgeFg,
              ),
            ),
          ),
        ],
      ),
    );
  }
}