import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../../models/sys_config.dart';
import '../../../services/api_client.dart';
import '../../../services/sys_service.dart';

/// 参数配置页。
class ConfigPage extends ConsumerStatefulWidget {
  const ConfigPage({super.key});

  @override
  ConsumerState<ConfigPage> createState() => _ConfigPageState();
}

class _ConfigPageState extends ConsumerState<ConfigPage> {
  final SystemService _service = SystemService();

  final List<SysConfig> _items = [];
  bool _loading = false;
  int _page = 1;
  bool _hasMore = true;
  String? _error;

  final TextEditingController _searchController = TextEditingController();
  String _searchKeyword = '';

  final ScrollController _scrollController = ScrollController();
  final int _limit = 20;

  @override
  void initState() {
    super.initState();
    _scrollController.addListener(_onScroll);
    _loadData();
  }

  @override
  void dispose() {
    _searchController.dispose();
    _scrollController.removeListener(_onScroll);
    _scrollController.dispose();
    super.dispose();
  }

  void _onScroll() {
    if (_scrollController.position.pixels >=
        _scrollController.position.maxScrollExtent - 200) {
      _loadMore();
    }
  }

  Future<void> _loadData({bool reset = false}) async {
    if (_loading) return;
    if (reset) {
      _page = 1;
      _hasMore = true;
      _items.clear();
    }
    setState(() {
      _loading = true;
      _error = null;
    });
    try {
      final list = await _service.getConfigList(page: _page, limit: _limit);
      _items.addAll(list);
      _hasMore = list.length >= _limit;
    } on ApiException catch (e) {
      _error = e.message;
    } catch (e) {
      _error = e.toString();
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _loadMore() async {
    if (_loading || !_hasMore) return;
    _page++;
    await _loadData();
  }

  Future<void> _refresh() async {
    await _loadData(reset: true);
  }

  void _onSearchChanged(String value) {
    _searchKeyword = value;
    // 本地过滤，因为 getConfigList 不支持搜索参数
    setState(() {});
  }

  List<SysConfig> get _filteredItems {
    if (_searchKeyword.isEmpty) return _items;
    return _items
        .where((c) => c.paramKey.toLowerCase().contains(
              _searchKeyword.toLowerCase(),
            ))
        .toList();
  }

  Future<void> _showForm({SysConfig? config}) async {
    final result = await showModalBottomSheet<Map<String, dynamic>>(
      context: context,
      isScrollControlled: true,
      builder: (context) => _ConfigForm(config: config),
    );

    if (result == null) return;

    try {
      await _service.saveConfig(result);
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('保存成功')),
        );
        _refresh();
      }
    } on ApiException catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(e.message)),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('保存失败：$e')),
        );
      }
    }
  }

  Future<void> _deleteConfig(SysConfig config) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('确认删除'),
        content: Text('确定要删除参数「${config.paramKey}」吗？'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false),
            child: const Text('取消'),
          ),
          FilledButton(
            onPressed: () => Navigator.pop(context, true),
            child: const Text('删除'),
          ),
        ],
      ),
    );

    if (confirmed != true) return;

    try {
      await _service.deleteConfig([int.tryParse(config.id) ?? 0]);
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('删除成功')),
        );
        _refresh();
      }
    } on ApiException catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(e.message)),
        );
      }
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('删除失败：$e')),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final filtered = _filteredItems;
    return Scaffold(
      appBar: AppBar(automaticallyImplyLeading: false, title: const Text('参数配置')),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 8),
            child: TextField(
              controller: _searchController,
              decoration: InputDecoration(
                hintText: '搜索参数键名',
                prefixIcon: const Icon(Icons.search),
                suffixIcon: _searchKeyword.isEmpty
                    ? null
                    : IconButton(
                        icon: const Icon(Icons.clear),
                        onPressed: () {
                          _searchController.clear();
                          _onSearchChanged('');
                        },
                      ),
                border: const OutlineInputBorder(),
              ),
              onChanged: _onSearchChanged,
            ),
          ),
          Expanded(child: _buildBody(filtered)),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _showForm(),
        child: const Icon(Icons.add),
      ),
    );
  }

  Widget _buildBody(List<SysConfig> items) {
    if (_error != null && _items.isEmpty) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(_error!),
            const SizedBox(height: 8),
            FilledButton.tonal(
              onPressed: _refresh,
              child: const Text('重试'),
            ),
          ],
        ),
      );
    }

    if (items.isEmpty && !_loading) {
      return const Center(child: Text('暂无数据'));
    }

    return RefreshIndicator(
      onRefresh: _refresh,
      child: ListView.builder(
        controller: _scrollController,
        physics: const AlwaysScrollableScrollPhysics(),
        itemCount: items.length + 1,
        itemBuilder: (context, index) {
          if (index == items.length) {
            if (_loading) {
              return const Padding(
                padding: EdgeInsets.all(16),
                child: Center(child: CircularProgressIndicator()),
              );
            }
            if (!_hasMore && _searchKeyword.isEmpty) {
              return const Padding(
                padding: EdgeInsets.all(16),
                child: Center(child: Text('没有更多数据')),
              );
            }
            return const SizedBox.shrink();
          }
          final config = items[index];
          return Card(
            margin: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
            child: ListTile(
              title: Text(config.paramKey),
              subtitle: Text(
                '值：${config.paramValue.isEmpty ? "（空）" : config.paramValue}'
                '${config.remark.isNotEmpty ? "\n备注：${config.remark}" : ""}',
              ),
              trailing: PopupMenuButton<String>(
                onSelected: (value) {
                  if (value == 'edit') {
                    _showForm(config: config);
                  } else if (value == 'delete') {
                    _deleteConfig(config);
                  }
                },
                itemBuilder: (context) => [
                  const PopupMenuItem(value: 'edit', child: Text('编辑')),
                  const PopupMenuItem(value: 'delete', child: Text('删除')),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}

/// 参数配置表单。
class _ConfigForm extends StatefulWidget {
  const _ConfigForm({this.config});

  final SysConfig? config;

  @override
  State<_ConfigForm> createState() => _ConfigFormState();
}

class _ConfigFormState extends State<_ConfigForm> {
  final _formKey = GlobalKey<FormState>();
  late TextEditingController _paramKeyCtrl;
  late TextEditingController _paramValueCtrl;
  late TextEditingController _remarkCtrl;

  @override
  void initState() {
    super.initState();
    _paramKeyCtrl = TextEditingController(text: widget.config?.paramKey ?? '');
    _paramValueCtrl =
        TextEditingController(text: widget.config?.paramValue ?? '');
    _remarkCtrl = TextEditingController(text: widget.config?.remark ?? '');
  }

  @override
  void dispose() {
    _paramKeyCtrl.dispose();
    _paramValueCtrl.dispose();
    _remarkCtrl.dispose();
    super.dispose();
  }

  void _submit() {
    if (!_formKey.currentState!.validate()) return;
    final data = <String, dynamic>{
      'paramKey': _paramKeyCtrl.text.trim(),
      'paramValue': _paramValueCtrl.text.trim(),
      'remark': _remarkCtrl.text.trim(),
    };
    if (widget.config != null) {
      data['id'] = widget.config!.id;
    }
    Navigator.pop(context, data);
  }

  @override
  Widget build(BuildContext context) {
    final isEdit = widget.config != null;
    return Padding(
      padding: EdgeInsets.only(
        bottom: MediaQuery.of(context).viewInsets.bottom,
      ),
      child: SingleChildScrollView(
        padding: const EdgeInsets.all(16),
        child: Form(
          key: _formKey,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text(
                isEdit ? '编辑参数' : '新增参数',
                style: Theme.of(context).textTheme.titleLarge,
              ),
              const SizedBox(height: 16),
              TextFormField(
                controller: _paramKeyCtrl,
                decoration: const InputDecoration(
                  labelText: '参数键名',
                  border: OutlineInputBorder(),
                ),
                validator: (v) =>
                    (v == null || v.trim().isEmpty) ? '请输入参数键名' : null,
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _paramValueCtrl,
                maxLines: 3,
                decoration: const InputDecoration(
                  labelText: '参数值',
                  border: OutlineInputBorder(),
                ),
                validator: (v) =>
                    (v == null || v.trim().isEmpty) ? '请输入参数值' : null,
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _remarkCtrl,
                maxLines: 2,
                decoration: const InputDecoration(
                  labelText: '备注',
                  border: OutlineInputBorder(),
                ),
              ),
              const SizedBox(height: 24),
              Row(
                mainAxisAlignment: MainAxisAlignment.end,
                children: [
                  TextButton(
                    onPressed: () => Navigator.pop(context),
                    child: const Text('取消'),
                  ),
                  const SizedBox(width: 8),
                  FilledButton(
                    onPressed: _submit,
                    child: const Text('保存'),
                  ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }
}