import 'dart:math' as math;
import 'dart:async';
import 'package:miaoji_zhang/shared/services/shanghai_time.dart';

import 'package:flutter/material.dart';
import 'package:miaoji_zhang/shared/api/api_client.dart';
import 'package:miaoji_zhang/shared/api/business_api.dart';
import 'package:miaoji_zhang/shared/services/current_ledger_store.dart';
import 'package:miaoji_zhang/shared/theme/app_theme.dart';
import 'package:miaoji_zhang/shared/widgets/app_controls.dart';
import 'package:miaoji_zhang/shared/widgets/async_error_view.dart';
import 'package:miaoji_zhang/shared/widgets/backend_status_icon.dart';
import 'package:miaoji_zhang/shared/widgets/category_icon.dart';

class StatsPage extends StatefulWidget {
  const StatsPage({super.key});

  @override
  State<StatsPage> createState() => _StatsPageState();
}

class _StatsPageState extends State<StatsPage> {
  String _period = 'month';
  DateTime _anchor = ShanghaiTime.now;
  PeriodStats? _stats;
  String? _error;
  bool _loading = true;
  int _loadRevision = 0;

  @override
  void initState() {
    super.initState();
    CurrentLedgerStore.instance.addListener(_load);
    unawaited(_load());
  }

  @override
  void dispose() {
    CurrentLedgerStore.instance.removeListener(_load);
    super.dispose();
  }

  Future<void> _load() async {
    final revision = ++_loadRevision;
    if (mounted) {
      setState(() {
        _loading = true;
        _error = null;
      });
    }
    try {
      final local = TxApi.periodStatsLocal(_period, _anchor);
      if (mounted && revision == _loadRevision) {
        setState(() => _stats = local);
      }
    } catch (error) {
      if (mounted && revision == _loadRevision) {
        setState(() => _error = apiErrorMessage(error));
      }
    }
    try {
      final remote = await TxApi.periodStatsRemote(_period, _anchor);
      if (mounted && revision == _loadRevision) {
        setState(() => _stats = remote);
      }
    } catch (_) {
    } finally {
      if (mounted && revision == _loadRevision) {
        setState(() => _loading = false);
      }
    }
  }

  void _selectPeriod(String value) {
    if (_period == value) return;
    setState(() {
      _period = value;
      _anchor = ShanghaiTime.now;
      _stats = null;
    });
    _load();
  }

  void _shift(int direction) {
    final next = switch (_period) {
      'week' => _anchor.add(Duration(days: 7 * direction)),
      'year' => DateTime(_anchor.year + direction, 1, 1),
      _ => DateTime(_anchor.year, _anchor.month + direction, 1),
    };
    if (direction > 0 && _isAfterCurrentPeriod(next)) return;
    setState(() {
      _anchor = next;
      _stats = null;
    });
    _load();
  }

  bool _isAfterCurrentPeriod(DateTime value) {
    final now = ShanghaiTime.now;
    return switch (_period) {
      'week' => value.isAfter(now),
      'year' => value.year > now.year,
      _ =>
        value.year > now.year ||
            (value.year == now.year && value.month > now.month),
    };
  }

  @override
  Widget build(BuildContext context) {
    final stats = _stats;
    return Scaffold(
      appBar: AppBar(
        title: Text('统计'),
        actions: [BackendStatusIcon(onRetry: _load)],
      ),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 4, 16, 8),
            child: JzSegmentedControl<String>(
              value: _period,
              options: const [
                JzOption(value: 'week', label: '周'),
                JzOption(value: 'month', label: '月'),
                JzOption(value: 'year', label: '年'),
              ],
              onChanged: _selectPeriod,
            ),
          ),
          Expanded(
            child: _loading && stats == null
                ? Center(
                    child: CircularProgressIndicator(
                      color: AppTheme.primary,
                      strokeWidth: 2,
                    ),
                  )
                : stats == null && _error != null
                ? AsyncErrorView(message: _error!, onRetry: _load)
                : RefreshIndicator(
                    onRefresh: _load,
                    child: ListView(
                      physics: const AlwaysScrollableScrollPhysics(),
                      padding: const EdgeInsets.fromLTRB(16, 0, 16, 24),
                      children: [
                        _periodNavigator(stats?.periodLabel ?? ''),
                        if (_loading)
                          LinearProgressIndicator(
                            minHeight: 2,
                            color: AppTheme.primary,
                            backgroundColor: context.jz.primaryBackground,
                          ),
                        if (_error != null) _refreshNotice(_error!),
                        if (stats != null) ...[
                          SizedBox(height: 10),
                          _summaryCard(stats),
                          SizedBox(height: 10),
                          if (stats.totalExpense == 0 && stats.totalIncome == 0)
                            _emptyCard()
                          else ...[
                            _categoryCard(stats),
                            SizedBox(height: 10),
                            if (stats.analysis case final analysis?)
                              _analysisCard(analysis),
                            SizedBox(height: 10),
                            _trendCard(stats),
                            if (stats.byCategory.isNotEmpty) ...[
                              SizedBox(height: 10),
                              _rankingCard(stats),
                            ],
                          ],
                        ],
                      ],
                    ),
                  ),
          ),
        ],
      ),
    );
  }

  Widget _periodNavigator(String label) {
    final nextAnchor = switch (_period) {
      'week' => _anchor.add(const Duration(days: 7)),
      'year' => DateTime(_anchor.year + 1, 1, 1),
      _ => DateTime(_anchor.year, _anchor.month + 1, 1),
    };
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        IconButton(
          tooltip: '上一个周期',
          onPressed: () => _shift(-1),
          icon: Icon(Icons.chevron_left_rounded),
        ),
        SizedBox(
          width: 170,
          child: Text(
            label,
            textAlign: TextAlign.center,
            style: TextStyle(fontSize: 15, fontWeight: FontWeight.w700),
          ),
        ),
        IconButton(
          tooltip: '下一个周期',
          onPressed: _isAfterCurrentPeriod(nextAnchor) ? null : () => _shift(1),
          icon: Icon(Icons.chevron_right_rounded),
        ),
      ],
    );
  }

  Widget _summaryCard(PeriodStats stats) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 17),
        child: Row(
          children: [
            _summaryValue('支出', stats.totalExpense, AppTheme.red),
            _divider(),
            _summaryValue('收入', stats.totalIncome, AppTheme.primaryDeep),
            _divider(),
            _summaryValue(
              '结余',
              stats.balance,
              stats.balance < 0 ? AppTheme.red : context.jz.text,
            ),
          ],
        ),
      ),
    );
  }

  Widget _summaryValue(String label, double amount, Color color) {
    return Expanded(
      child: Column(
        children: [
          Text(
            label,
            style: TextStyle(fontSize: 10.5, color: context.jz.text3),
          ),
          SizedBox(height: 5),
          FittedBox(
            fit: BoxFit.scaleDown,
            child: Text(
              '¥${amount.toStringAsFixed(2)}',
              style: TextStyle(
                fontSize: 14,
                fontWeight: FontWeight.w800,
                color: color,
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _divider() => Container(width: 1, height: 34, color: context.jz.line);

  Widget _emptyCard() {
    return Card(
      child: Padding(
        padding: EdgeInsets.symmetric(vertical: 48),
        child: Center(
          child: Text(
            '这个周期还没有账单记录',
            style: TextStyle(fontSize: 13, color: context.jz.text3),
          ),
        ),
      ),
    );
  }

  Widget _categoryCard(PeriodStats stats) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.fromLTRB(16, 18, 16, 16),
        child: Column(
          children: [
            SizedBox(
              height: 178,
              child: _CategoryDonut(
                categories: stats.byCategory,
                total: stats.totalExpense,
              ),
            ),
            SizedBox(height: 12),
            Wrap(
              spacing: 12,
              runSpacing: 8,
              children: stats.byCategory.take(8).map((category) {
                final color = categoryColorMeta(category.colorKey).foreground;
                return Row(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Container(
                      width: 9,
                      height: 9,
                      decoration: BoxDecoration(
                        color: color,
                        borderRadius: BorderRadius.circular(3),
                      ),
                    ),
                    SizedBox(width: 5),
                    Text(
                      '${category.name} ${category.percent.toStringAsFixed(0)}%',
                      style: TextStyle(fontSize: 10.5, color: context.jz.text2),
                    ),
                  ],
                );
              }).toList(),
            ),
          ],
        ),
      ),
    );
  }

  Widget _analysisCard(String text) {
    return Container(
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: context.jz.aiBackground,
        borderRadius: BorderRadius.circular(14),
        border: Border.all(color: AppTheme.ai.withValues(alpha: 0.12)),
      ),
      child: Row(
        children: [
          Container(
            width: 30,
            height: 30,
            decoration: BoxDecoration(
              color: context.jz.card,
              borderRadius: BorderRadius.circular(10),
            ),
            child: Icon(
              Icons.auto_awesome_rounded,
              size: 16,
              color: AppTheme.ai,
            ),
          ),
          SizedBox(width: 10),
          Expanded(
            child: Text(
              text,
              style: TextStyle(
                fontSize: 12,
                color: context.jz.text2,
                height: 1.5,
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _trendCard(PeriodStats stats) {
    final title = switch (_period) {
      'week' => '每日支出趋势',
      'year' => '每月支出趋势',
      _ => '每日支出趋势',
    };
    return Card(
      child: Padding(
        padding: const EdgeInsets.fromLTRB(16, 16, 16, 14),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              title,
              style: TextStyle(fontSize: 13, fontWeight: FontWeight.w700),
            ),
            SizedBox(height: 16),
            SizedBox(
              height: 116,
              child: _TrendBars(points: stats.trend, period: _period),
            ),
          ],
        ),
      ),
    );
  }

  Widget _rankingCard(PeriodStats stats) {
    final maxAmount = stats.byCategory.first.amount;
    return Card(
      child: Padding(
        padding: const EdgeInsets.fromLTRB(14, 8, 14, 8),
        child: Column(
          children: stats.byCategory.take(8).map((category) {
            final color = categoryColorMeta(category.colorKey).foreground;
            return Padding(
              padding: const EdgeInsets.symmetric(vertical: 8),
              child: Row(
                children: [
                  CategoryIconBox(
                    iconKey: category.iconKey,
                    colorKey: category.colorKey,
                    size: 34,
                  ),
                  SizedBox(width: 12),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Row(
                          children: [
                            Text(
                              category.name,
                              style: TextStyle(
                                fontSize: 12.5,
                                fontWeight: FontWeight.w600,
                              ),
                            ),
                            Spacer(),
                            Text(
                              '¥${category.amount.toStringAsFixed(2)}',
                              style: TextStyle(
                                fontSize: 12.5,
                                fontWeight: FontWeight.w700,
                              ),
                            ),
                          ],
                        ),
                        SizedBox(height: 6),
                        ClipRRect(
                          borderRadius: BorderRadius.circular(3),
                          child: LinearProgressIndicator(
                            value: maxAmount == 0
                                ? 0
                                : category.amount / maxAmount,
                            minHeight: 4,
                            backgroundColor: context.jz.background,
                            color: color,
                          ),
                        ),
                      ],
                    ),
                  ),
                ],
              ),
            );
          }).toList(),
        ),
      ),
    );
  }

  Widget _refreshNotice(String message) {
    return Container(
      margin: const EdgeInsets.only(top: 8),
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 9),
      decoration: BoxDecoration(
        color: context.jz.warningBackground,
        borderRadius: BorderRadius.circular(12),
      ),
      child: Row(
        children: [
          Icon(Icons.info_outline_rounded, size: 16, color: AppTheme.orange),
          SizedBox(width: 8),
          Expanded(
            child: Text(
              message,
              style: TextStyle(fontSize: 11, color: context.jz.text2),
            ),
          ),
          TextButton(onPressed: _load, child: Text('重试')),
        ],
      ),
    );
  }
}

class _CategoryDonut extends StatelessWidget {
  final List<CategoryStat> categories;
  final double total;

  const _CategoryDonut({required this.categories, required this.total});

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: _DonutPainter(categories.take(8).toList(), context.jz.line),
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(
              '周期支出',
              style: TextStyle(fontSize: 10.5, color: context.jz.text3),
            ),
            SizedBox(height: 3),
            Text(
              '¥${total.toStringAsFixed(0)}',
              style: TextStyle(fontSize: 20, fontWeight: FontWeight.w800),
            ),
          ],
        ),
      ),
    );
  }
}

class _DonutPainter extends CustomPainter {
  final List<CategoryStat> categories;
  final Color lineColor;

  _DonutPainter(this.categories, this.lineColor);

  @override
  void paint(Canvas canvas, Size size) {
    final center = Offset(size.width / 2, size.height / 2);
    final radius = math.min(size.width, size.height) / 2 - 12;
    const strokeWidth = 22.0;
    final rect = Rect.fromCircle(center: center, radius: radius);
    canvas.drawCircle(
      center,
      radius,
      Paint()
        ..color = lineColor
        ..style = PaintingStyle.stroke
        ..strokeWidth = strokeWidth,
    );
    final total = categories.fold<double>(0, (sum, item) => sum + item.amount);
    if (total == 0) return;
    var start = -math.pi / 2;
    for (final category in categories) {
      final sweep = category.amount / total * math.pi * 2;
      final gap = math.min(0.025, sweep / 4);
      canvas.drawArc(
        rect,
        start + gap,
        math.max(0, sweep - gap * 2),
        false,
        Paint()
          ..color = categoryColorMeta(category.colorKey).foreground
          ..style = PaintingStyle.stroke
          ..strokeWidth = strokeWidth
          ..strokeCap = StrokeCap.round,
      );
      start += sweep;
    }
  }

  @override
  bool shouldRepaint(covariant _DonutPainter oldDelegate) => true;
}

class _TrendBars extends StatelessWidget {
  final List<PeriodTrendPoint> points;
  final String period;

  const _TrendBars({required this.points, required this.period});

  @override
  Widget build(BuildContext context) {
    final maxValue = points.fold<double>(
      0,
      (maximum, point) => math.max(maximum, point.expense),
    );
    return Row(
      crossAxisAlignment: CrossAxisAlignment.end,
      children: points.indexed.map((entry) {
        final index = entry.$1;
        final point = entry.$2;
        final height = maxValue == 0
            ? 2.0
            : math.max(2.0, point.expense / maxValue * 78).toDouble();
        final showLabel =
            period != 'month' ||
            index == 0 ||
            index == points.length - 1 ||
            (index + 1) % 5 == 0;
        return Expanded(
          child: Padding(
            padding: EdgeInsets.symmetric(
              horizontal: period == 'month' ? 1 : 3,
            ),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.end,
              children: [
                Tooltip(
                  message:
                      '${point.label} ¥${point.expense.toStringAsFixed(2)}',
                  child: Container(
                    height: height,
                    decoration: BoxDecoration(
                      color: point.expense == maxValue && maxValue > 0
                          ? AppTheme.primary
                          : context.jz.primaryBackground,
                      borderRadius: const BorderRadius.vertical(
                        top: Radius.circular(4),
                      ),
                    ),
                  ),
                ),
                SizedBox(height: 6),
                SizedBox(
                  height: 14,
                  child: showLabel
                      ? FittedBox(
                          fit: BoxFit.scaleDown,
                          child: Text(
                            point.label,
                            style: TextStyle(
                              fontSize: 9,
                              color: context.jz.text3,
                            ),
                          ),
                        )
                      : null,
                ),
              ],
            ),
          ),
        );
      }).toList(),
    );
  }
}