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

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

/// 角色管理页。
class RolePage extends ConsumerStatefulWidget {
  const RolePage({super.key});

  @override
  ConsumerState<RolePage> createState() => _RolePageState();
}

class _RolePageState extends ConsumerState<RolePage> {
  final SystemService _service = SystemService();

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

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

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

  @override
  void 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.getRoleList(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);
  }

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

    if (result == null) return;

    try {
      await _service.saveRole(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> _deleteRole(SysRole role) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('确认删除'),
        content: Text('确定要删除角色「${role.roleName}」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.deleteRole([int.tryParse(role.roleId) ?? 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) {
    return Scaffold(
      appBar: AppBar(automaticallyImplyLeading: false, title: const Text('角色管理')),
      body: _buildBody(),
      floatingActionButton: FloatingActionButton(
        onPressed: () => _showForm(),
        child: const Icon(Icons.add),
      ),
    );
  }

  Widget _buildBody() {
    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) {
              return const Padding(
                padding: EdgeInsets.all(16),
                child: Center(child: Text('没有更多数据')),
              );
            }
            return const SizedBox.shrink();
          }
          final role = _items[index];
          return Card(
            margin: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
            child: ListTile(
              title: Text(role.roleName),
              subtitle: Text(role.remark.isEmpty ? '无备注' : role.remark),
              trailing: PopupMenuButton<String>(
                onSelected: (value) {
                  if (value == 'edit') {
                    _showForm(role: role);
                  } else if (value == 'delete') {
                    _deleteRole(role);
                  }
                },
                itemBuilder: (context) => [
                  const PopupMenuItem(value: 'edit', child: Text('编辑')),
                  const PopupMenuItem(value: 'delete', child: Text('删除')),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}

/// 角色表单。
class _RoleForm extends StatefulWidget {
  const _RoleForm({this.role});

  final SysRole? role;

  @override
  State<_RoleForm> createState() => _RoleFormState();
}

class _RoleFormState extends State<_RoleForm> {
  final _formKey = GlobalKey<FormState>();
  late TextEditingController _roleNameCtrl;
  late TextEditingController _remarkCtrl;

  @override
  void initState() {
    super.initState();
    _roleNameCtrl = TextEditingController(text: widget.role?.roleName ?? '');
    _remarkCtrl = TextEditingController(text: widget.role?.remark ?? '');
  }

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

  void _submit() {
    if (!_formKey.currentState!.validate()) return;
    final data = <String, dynamic>{
      'roleName': _roleNameCtrl.text.trim(),
      'remark': _remarkCtrl.text.trim(),
    };
    if (widget.role != null) {
      data['roleId'] = widget.role!.roleId;
    }
    Navigator.pop(context, data);
  }

  @override
  Widget build(BuildContext context) {
    final isEdit = widget.role != 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 ? '编辑角色' : '新增角色',
                style: Theme.of(context).textTheme.titleLarge,
              ),
              const SizedBox(height: 16),
              TextFormField(
                controller: _roleNameCtrl,
                decoration: const InputDecoration(
                  labelText: '角色名称',
                  border: OutlineInputBorder(),
                ),
                validator: (v) =>
                    (v == null || v.trim().isEmpty) ? '请输入角色名称' : null,
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _remarkCtrl,
                maxLines: 3,
                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'),
                  ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }
}