import 'dart:async';

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/api/config_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_icons.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';
import 'package:miaoji_zhang/shared/services/shanghai_time.dart';
import 'package:miaoji_zhang/shared/services/session_store.dart';

enum _ReportKind { weekly, monthly, yearly }

class ReportPage extends StatefulWidget {
  final String? initialPeriod;
  final DateTime? initialAnchor;

  const ReportPage({super.key, this.initialPeriod, this.initialAnchor});

  @override
  State<ReportPage> createState() => _ReportPageState();
}

class _ReportPageState extends State<ReportPage> {
  PeriodReport? _report;
  bool _loading = true;
  String? _error;
  DateTime _anchor = ShanghaiTime.now;
  _ReportKind _kind = _ReportKind.monthly;
  int _loadRevision = 0;

  @override
  void initState() {
    super.initState();
    _anchor = widget.initialAnchor ?? ShanghaiTime.now;
    _kind = switch (widget.initialPeriod) {
      'week' => _ReportKind.weekly,
      'year' => _ReportKind.yearly,
      _ => _ReportKind.monthly,
    };
    PublicConfigApi.companionNotifier.addListener(_refreshCompanion);
    CurrentLedgerStore.instance.addListener(_load);
    unawaited(_load());
  }

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

  void _refreshCompanion() {
    if (mounted) setState(() {});
  }

  Future<void> _load() async {
    final revision = ++_loadRevision;
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final period = switch (_kind) {
        _ReportKind.weekly => 'week',
        _ReportKind.monthly => 'month',
        _ReportKind.yearly => 'year',
      };
      final local = ReportApi.local(period, _anchor);
      if (mounted && revision == _loadRevision) {
        setState(() => _report = local);
      }
      final remote = await ReportApi.remote(period, _anchor);
      if (mounted && revision == _loadRevision) {
        setState(() => _report = remote);
      }
    } catch (error) {
      if (mounted && revision == _loadRevision && _report == null) {
        setState(() => _error = apiErrorMessage(error));
      }
    } finally {
      if (mounted && revision == _loadRevision) {
        setState(() => _loading = false);
      }
    }
  }

  void _selectKind(_ReportKind kind) {
    if (_kind == kind) return;
    setState(() {
      _kind = kind;
      _anchor = ShanghaiTime.now;
      _report = null;
    });
    _load();
  }

  void _move(int direction) {
    final next = switch (_kind) {
      _ReportKind.weekly => _anchor.add(Duration(days: 7 * direction)),
      _ReportKind.monthly => DateTime(_anchor.year, _anchor.month + direction),
      _ReportKind.yearly => DateTime(_anchor.year + direction),
    };
    if (direction > 0 && _isFuture(next)) return;
    setState(() {
      _anchor = next;
      _report = null;
    });
    _load();
  }

  bool _isFuture(DateTime value) {
    final now = ShanghaiTime.now;
    return switch (_kind) {
      _ReportKind.weekly => value.isAfter(now),
      _ReportKind.monthly =>
        value.year > now.year ||
            (value.year == now.year && value.month > now.month),
      _ReportKind.yearly => value.year > now.year,
    };
  }

  @override
  Widget build(BuildContext context) {
    final report = _report;
    return Scaffold(
      appBar: AppBar(
        title: Text(SessionStore.instance.aiEnabled ? 'AI 报告' : '报告'),
        actions: [BackendStatusIcon(onRetry: _load)],
      ),
      body: Column(
        children: [
          _periodTabs(),
          _periodNavigator(),
          Expanded(
            child: !_loading && report == null && _error != null
                ? AsyncErrorView(message: _error!, onRetry: _load)
                : _loading && report == null
                ? Center(
                    child: CircularProgressIndicator(
                      color: AppTheme.primary,
                      strokeWidth: 2,
                    ),
                  )
                : report == null
                ? Center(
                    child: Text(
                      '暂无数据',
                      style: TextStyle(color: context.jz.text3),
                    ),
                  )
                : _reportBody(report),
          ),
        ],
      ),
    );
  }

  Widget _periodTabs() {
    const labels = {
      _ReportKind.weekly: '周报',
      _ReportKind.monthly: '月报',
      _ReportKind.yearly: '年报',
    };
    return Container(
      margin: const EdgeInsets.fromLTRB(16, 4, 16, 8),
      padding: const EdgeInsets.all(3),
      decoration: BoxDecoration(
        color: context.jz.line,
        borderRadius: BorderRadius.circular(11),
      ),
      child: Row(
        children: labels.entries.map((entry) {
          final selected = entry.key == _kind;
          return Expanded(
            child: InkWell(
              onTap: () => _selectKind(entry.key),
              borderRadius: BorderRadius.circular(9),
              child: AnimatedContainer(
                duration: const Duration(milliseconds: 180),
                padding: const EdgeInsets.symmetric(vertical: 8),
                decoration: BoxDecoration(
                  color: selected ? context.jz.card : Colors.transparent,
                  borderRadius: BorderRadius.circular(9),
                ),
                child: Text(
                  entry.value,
                  textAlign: TextAlign.center,
                  style: TextStyle(
                    fontSize: 12.5,
                    fontWeight: selected ? FontWeight.w800 : FontWeight.w500,
                    color: selected ? AppTheme.ai : context.jz.text2,
                  ),
                ),
              ),
            ),
          );
        }).toList(),
      ),
    );
  }

  Widget _periodNavigator() {
    final label =
        _report?.periodLabel ??
        switch (_kind) {
          _ReportKind.weekly => '本周',
          _ReportKind.monthly =>
            _anchor.year.toString() + '年' + _anchor.month.toString() + '月',
          _ReportKind.yearly => _anchor.year.toString() + '年',
        };
    return Padding(
      padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          IconButton(
            tooltip: '上一个周期',
            onPressed: () => _move(-1),
            icon: Icon(Icons.chevron_left_rounded),
          ),
          Container(
            constraints: const BoxConstraints(minWidth: 150),
            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
            decoration: BoxDecoration(
              color: context.jz.card,
              borderRadius: BorderRadius.circular(18),
              border: Border.all(color: context.jz.line),
            ),
            child: Text(
              label,
              textAlign: TextAlign.center,
              style: TextStyle(fontSize: 13, fontWeight: FontWeight.w700),
            ),
          ),
          IconButton(
            tooltip: '下一个周期',
            onPressed: _isFuture(_nextAnchor()) ? null : () => _move(1),
            icon: Icon(Icons.chevron_right_rounded),
          ),
        ],
      ),
    );
  }

  DateTime _nextAnchor() => switch (_kind) {
    _ReportKind.weekly => _anchor.add(const Duration(days: 7)),
    _ReportKind.monthly => DateTime(_anchor.year, _anchor.month + 1),
    _ReportKind.yearly => DateTime(_anchor.year + 1),
  };

  Widget _reportBody(PeriodReport report) {
    return RefreshIndicator(
      onRefresh: _load,
      child: ListView(
        padding: const EdgeInsets.fromLTRB(16, 4, 16, 24),
        children: [
          Container(
            padding: const EdgeInsets.all(20),
            decoration: BoxDecoration(
              color: AppTheme.ai,
              borderRadius: BorderRadius.circular(18),
            ),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  '✦ ' + PublicConfigApi.companionName + _kindLabel + '报告',
                  style: TextStyle(
                    fontSize: 11,
                    color: Colors.white.withValues(alpha: 0.85),
                  ),
                ),
                SizedBox(height: 8),
                Text(
                  report.periodLabel +
                      '，一共支出 ¥' +
                      report.expense.toStringAsFixed(0),
                  style: TextStyle(
                    fontSize: 20,
                    fontWeight: FontWeight.w800,
                    color: Colors.white,
                  ),
                ),
                SizedBox(height: 16),
                Row(
                  children: [
                    _num('收入', report.income),
                    _num('支出', report.expense),
                    _num('结余', report.balance),
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Text(
                            '笔数',
                            style: TextStyle(
                              fontSize: 10,
                              color: Colors.white.withValues(alpha: 0.8),
                            ),
                          ),
                          SizedBox(height: 3),
                          Text(
                            report.count.toString(),
                            style: TextStyle(
                              fontSize: 15,
                              fontWeight: FontWeight.w700,
                              color: Colors.white,
                            ),
                          ),
                        ],
                      ),
                    ),
                  ],
                ),
              ],
            ),
          ),
          SizedBox(height: 10),
          Card(
            child: Column(
              children: [
                if (report.peakLabel != null)
                  _highlight(
                    AppIcons.fire,
                    context.jz.expenseBackground,
                    AppTheme.red,
                    (_kind == _ReportKind.yearly ? '支出最高的月份：' : '最烧钱的一天：') +
                        report.peakLabel!,
                    '支出 ¥' +
                        report.peakAmount.toStringAsFixed(0) +
                        (report.peakNote != null
                            ? '，最大一笔是“' + report.peakNote! + '”'
                            : ''),
                  ),

                if (SessionStore.instance.aiEnabled)
                  _highlight(
                    AppIcons.chat,
                    context.jz.aiBackground,
                    AppTheme.ai,
                    PublicConfigApi.companionName +
                        '记账占比 ' +
                        report.aiRatio.toStringAsFixed(0) +
                        '%',
                    report.aiRatio > 50 ? '大部分账单都通过 AI 完成' : '可以试试用一句话完成记账',
                  ),
              ],
            ),
          ),
          if (report.categoryRanking.isNotEmpty) ...[
            SizedBox(height: 10),
            _categoryRanking(report.categoryRanking),
          ],
          SizedBox(height: 10),
          if (SessionStore.instance.aiEnabled)
            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: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Row(
                    children: [
                      AppIcons.icon(
                        AppIcons.avatarAsset(
                          PublicConfigApi.companionAvatarKey,
                        ),
                        size: 15,
                        color: AppTheme.ai,
                      ),
                      SizedBox(width: 7),
                      Text(
                        PublicConfigApi.companionName + '点评',
                        style: TextStyle(
                          fontSize: 12,
                          fontWeight: FontWeight.w700,
                          color: AppTheme.ai,
                        ),
                      ),
                    ],
                  ),
                  SizedBox(height: 8),
                  Text(
                    '“' + report.commentary + '”',
                    style: TextStyle(
                      fontSize: 12.5,
                      height: 1.75,
                      color: context.jz.text2,
                    ),
                  ),
                ],
              ),
            ),
        ],
      ),
    );
  }

  Widget _categoryRanking(List<ReportCategoryRank> ranking) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.fromLTRB(14, 14, 14, 10),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              '支出分类排行',
              style: TextStyle(fontSize: 13.5, fontWeight: FontWeight.w800),
            ),
            SizedBox(height: 12),
            ...ranking.indexed.map((entry) {
              final index = entry.$1;
              final item = entry.$2;
              return Padding(
                padding: const EdgeInsets.only(bottom: 11),
                child: Row(
                  children: [
                    SizedBox(
                      width: 22,
                      child: Text(
                        (index + 1).toString().padLeft(2, '0'),
                        style: TextStyle(
                          fontSize: 11,
                          fontWeight: FontWeight.w800,
                          color: index == 0
                              ? AppTheme.primary
                              : context.jz.text3,
                        ),
                      ),
                    ),
                    CategoryIconBox(
                      iconKey: item.iconKey,
                      colorKey: item.colorKey,
                      size: 32,
                    ),
                    SizedBox(width: 10),
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Row(
                            children: [
                              Expanded(
                                child: Text(
                                  item.name,
                                  style: TextStyle(
                                    fontSize: 12.5,
                                    fontWeight: FontWeight.w700,
                                  ),
                                ),
                              ),
                              Text(
                                '¥' + item.amount.toStringAsFixed(0),
                                style: TextStyle(
                                  fontSize: 12,
                                  fontWeight: FontWeight.w700,
                                ),
                              ),
                              SizedBox(width: 7),
                              SizedBox(
                                width: 38,
                                child: Text(
                                  item.percent.toStringAsFixed(0) + '%',
                                  textAlign: TextAlign.right,
                                  style: TextStyle(
                                    fontSize: 10.5,
                                    color: context.jz.text3,
                                  ),
                                ),
                              ),
                            ],
                          ),
                          SizedBox(height: 6),
                          ClipRRect(
                            borderRadius: BorderRadius.circular(3),
                            child: LinearProgressIndicator(
                              minHeight: 5,
                              value: (item.percent / 100).clamp(0.0, 1.0),
                              backgroundColor: context.jz.line,
                              color: index == 0
                                  ? AppTheme.primary
                                  : AppTheme.primaryLight,
                            ),
                          ),
                        ],
                      ),
                    ),
                  ],
                ),
              );
            }),
          ],
        ),
      ),
    );
  }

  String get _kindLabel => switch (_kind) {
    _ReportKind.weekly => '周',
    _ReportKind.monthly => '月',
    _ReportKind.yearly => '年',
  };

  Widget _num(String label, double value) {
    return Expanded(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            label,
            style: TextStyle(
              fontSize: 10,
              color: Colors.white.withValues(alpha: 0.8),
            ),
          ),
          SizedBox(height: 3),
          Text(
            '¥' + value.toStringAsFixed(0),
            style: TextStyle(
              fontSize: 15,
              fontWeight: FontWeight.w700,
              color: Colors.white,
            ),
          ),
        ],
      ),
    );
  }

  Widget _highlight(
    String iconAsset,
    Color background,
    Color foreground,
    String title,
    String description,
  ) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Container(
            width: 30,
            height: 30,
            decoration: BoxDecoration(
              color: background,
              borderRadius: BorderRadius.circular(9),
            ),
            child: Center(
              child: AppIcons.icon(iconAsset, size: 16, color: foreground),
            ),
          ),
          SizedBox(width: 11),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  title,
                  style: TextStyle(fontSize: 12.5, fontWeight: FontWeight.w600),
                ),
                SizedBox(height: 3),
                Text(
                  description,
                  style: TextStyle(
                    fontSize: 11,
                    color: context.jz.text2,
                    height: 1.55,
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}