import 'package:flutter/material.dart';

import '../models/org_node.dart';

/// 组织选择项：携带层级深度与是否可选，用于按组织树自上而下排序并缩进展示。
class OrgPickerOption {
  const OrgPickerOption({
    required this.node,
    this.depth = 0,
    this.selectable = true,
  });

  final OrgNode node;
  final int depth;
  final bool selectable;
}

/// 组织选择器：以底部弹窗形式展示层级组织列表，支持关键字实时搜索，
/// 选中后通过 Navigator.pop 返回对应的 [OrgPickerOption]。
class OrgPickerSheet extends StatefulWidget {
  const OrgPickerSheet({
    super.key,
    required this.title,
    required this.searchHint,
    required this.emptyHint,
    required this.options,
    this.selectedId,
  });

  final String title;
  final String searchHint;
  final String emptyHint;
  final List<OrgPickerOption> options;
  final String? selectedId;

  @override
  State<OrgPickerSheet> createState() => _OrgPickerSheetState();
}

class _OrgPickerSheetState extends State<OrgPickerSheet> {
  final _searchController = TextEditingController();
  String _keyword = '';
  String? _selectedId;

  @override
  void initState() {
    super.initState();
    _selectedId = widget.selectedId;
  }

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

  void _onSelect(OrgPickerOption option) {
    if (_selectedId == option.node.id) {
      Navigator.pop(context, option);
      return;
    }
    setState(() => _selectedId = option.node.id);
    Future.delayed(const Duration(milliseconds: 120), () {
      if (mounted) Navigator.pop(context, option);
    });
  }

  List<OrgPickerOption> get _filteredOptions {
    final keyword = _keyword.trim().toLowerCase();
    final list = widget.options.where((option) {
      if (!option.selectable) return false;
      if (keyword.isEmpty) return true;
      return option.node.name.toLowerCase().contains(keyword);
    }).toList();
    // 将当前已选中的组织置顶展示，方便快速找到并确认当前选择。
    if (_selectedId?.isNotEmpty == true) {
      final selectedIndex = list.indexWhere((o) => o.node.id == _selectedId);
      if (selectedIndex > 0) {
        final selected = list.removeAt(selectedIndex);
        list.insert(0, selected);
      }
    }
    return list;
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final filtered = _filteredOptions;
    return Padding(
      padding: EdgeInsets.only(bottom: MediaQuery.of(context).viewInsets.bottom),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          // 标题栏
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 16, 16, 8),
            child: Row(
              children: [
                Expanded(
                  child: Text(
                    widget.title,
                    style: theme.textTheme.titleMedium
                        ?.copyWith(fontWeight: FontWeight.bold),
                  ),
                ),
                IconButton(
                  icon: const Icon(Icons.close),
                  tooltip: MaterialLocalizations.of(context).closeButtonTooltip,
                  onPressed: () => Navigator.pop(context),
                ),
              ],
            ),
          ),
          const Divider(height: 1),
          // 搜索框
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
            child: TextField(
              controller: _searchController,
              autofocus: true,
              decoration: InputDecoration(
                hintText: widget.searchHint,
                border: const OutlineInputBorder(),
                prefixIcon: const Icon(Icons.search),
                suffixIcon: _keyword.isEmpty
                    ? null
                    : IconButton(
                        icon: const Icon(Icons.clear),
                        onPressed: () {
                          _searchController.clear();
                          setState(() => _keyword = '');
                        },
                      ),
                contentPadding: const EdgeInsets.symmetric(horizontal: 12),
              ),
              onChanged: (v) => setState(() => _keyword = v),
            ),
          ),
          // 结果列表
          ConstrainedBox(
            constraints: const BoxConstraints(maxHeight: 420),
            child: filtered.isEmpty
                ? SizedBox(
                    height: 120,
                    child: Center(
                      child: Text(
                        widget.emptyHint,
                        style: TextStyle(
                          color: theme.colorScheme.onSurfaceVariant,
                        ),
                      ),
                    ),
                  )
                : ListView.separated(
                    shrinkWrap: true,
                    padding: const EdgeInsets.symmetric(vertical: 8),
                    itemCount: filtered.length,
                    separatorBuilder: (_, __) => const Divider(
                      height: 1,
                      indent: 16,
                      endIndent: 16,
                    ),
                    itemBuilder: (context, index) {
                      final option = filtered[index];
                      final selected = _selectedId == option.node.id;
                      final baseStyle = theme.textTheme.bodyMedium;
                      return ListTile(
                        dense: true,
                        contentPadding: EdgeInsets.only(
                          left: 16 + option.depth * 16.0,
                          right: 16,
                        ),
                        title: Text(
                          option.node.name,
                          style: option.selectable
                              ? baseStyle?.copyWith(
                                  color: selected
                                      ? theme.colorScheme.primary
                                      : null,
                                  fontWeight: selected
                                      ? FontWeight.bold
                                      : FontWeight.normal,
                                )
                              : baseStyle?.copyWith(
                                  color: theme.disabledColor,
                                ),
                        ),
                        trailing: selected
                            ? Icon(
                                Icons.check_circle,
                                color: theme.colorScheme.primary,
                              )
                            : null,
                        selected: selected,
                        selectedTileColor: theme.colorScheme.primaryContainer
                            .withOpacity(0.38),
                        onTap: option.selectable
                            ? () => _onSelect(option)
                            : null,
                      );
                    },
                  ),
          ),
          // 底部安全区
          SizedBox(height: MediaQuery.of(context).padding.bottom),
        ],
      ),
    );
  }
}

/// 表单中的「组织选择」输入框：点击后弹出 [OrgPickerSheet]，
/// 进入页面时自动展开选择器并高亮已选项。
class OrgPickerFormField extends StatefulWidget {
  const OrgPickerFormField({
    super.key,
    this.value,
    required this.labelText,
    required this.options,
    required this.onChanged,
    this.validator,
    this.autoOpen = true,
    this.searchHint,
    this.emptyHint,
  });

  final String? value;
  final String labelText;
  final List<OrgPickerOption> options;
  final ValueChanged<String?> onChanged;
  final String? Function(String?)? validator;
  final bool autoOpen;
  final String? searchHint;
  final String? emptyHint;

  @override
  State<OrgPickerFormField> createState() => _OrgPickerFormFieldState();
}

class _OrgPickerFormFieldState extends State<OrgPickerFormField> {
  bool _autoOpened = false;
  FormFieldState<String>? _field;

  @override
  void initState() {
    super.initState();
    _scheduleAutoOpen();
  }

  @override
  void didUpdateWidget(covariant OrgPickerFormField oldWidget) {
    super.didUpdateWidget(oldWidget);
    // 外部 value 变更时同步到 FormField 状态。
    if (oldWidget.value != widget.value) {
      _field?.didChange(widget.value);
    }
    // 选项从空变为有值时（异步加载完成），立即自动展开选择器。
    if (oldWidget.options.isEmpty && widget.options.isNotEmpty) {
      _scheduleAutoOpen();
    }
  }

  void _scheduleAutoOpen() {
    if (!_shouldAutoOpen) return;
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted && _shouldAutoOpen) {
        _autoOpened = true;
        _openPicker();
      }
    });
  }

  bool get _shouldAutoOpen =>
      widget.autoOpen && widget.options.isNotEmpty && !_autoOpened;

  Future<void> _openPicker() async {
    if (!mounted) return;
    final selected = await showModalBottomSheet<OrgPickerOption>(
          useSafeArea: true,
      context: context,
      isScrollControlled: true,
      builder: (ctx) => OrgPickerSheet(
        title: widget.labelText,
        searchHint: widget.searchHint ?? '搜索组织名称',
        emptyHint: widget.emptyHint ?? '未找到匹配组织',
        options: widget.options,
        selectedId: widget.value,
      ),
    );
    if (selected != null && mounted) {
      _field?.didChange(selected.node.id);
      widget.onChanged(selected.node.id);
    }
  }

  String? _displayName(String? value) {
    if (value == null || value.isEmpty) return null;
    for (final option in widget.options) {
      if (option.node.id == value) return option.node.name;
    }
    return value;
  }

  @override
  Widget build(BuildContext context) {
    return FormField<String>(
      initialValue: widget.value,
      validator: widget.validator,
      builder: (field) {
        _field = field;
        final displayName = _displayName(field.value);
        final theme = Theme.of(context);
        return InkWell(
          onTap: _openPicker,
          borderRadius: BorderRadius.circular(8),
          child: InputDecorator(
            decoration: InputDecoration(
              labelText: widget.labelText,
              border: const OutlineInputBorder(),
              prefixIcon: const Icon(Icons.account_tree),
              suffixIcon: const Icon(Icons.arrow_drop_down),
              errorText: field.errorText,
            ),
            child: Text(
              displayName ?? widget.labelText,
              style: TextStyle(
                color: displayName == null ? theme.hintColor : null,
              ),
            ),
          ),
        );
      },
    );
  }
}