import 'package:flutter/material.dart';

/// 드롭다운 기능이 있는 재사용 가능한 TextFormField 위젯
class CustomDropdownField extends StatefulWidget {
  final String label;
  final String hint;
  final bool required;
  final TextEditingController controller;
  final FocusNode focusNode;
  final List<String> items;
  final Function(String) onChanged;
  final Function(String)? onFieldSubmitted;
  final String? Function(String)? getAutocompleteSuggestion;
  final VoidCallback onDropdownPressed;
  final LayerLink layerLink;
  final GlobalKey fieldKey;

  const CustomDropdownField({
    Key? key,
    required this.label,
    required this.hint,
    required this.required,
    required this.controller,
    required this.focusNode,
    required this.items,
    required this.onChanged,
    this.onFieldSubmitted,
    this.getAutocompleteSuggestion,
    required this.onDropdownPressed,
    required this.layerLink,
    required this.fieldKey,
  }) : super(key: key);

  @override
  State<CustomDropdownField> createState() => _CustomDropdownFieldState();
}

class _CustomDropdownFieldState extends State<CustomDropdownField> {
  bool _isProgrammaticChange = false;
  OverlayEntry? _overlayEntry;

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

  void _showDropdown() {
    _removeDropdown();
    
    final RenderBox renderBox = widget.fieldKey.currentContext!.findRenderObject() as RenderBox;
    final size = renderBox.size;
    
    _overlayEntry = OverlayEntry(
      builder: (context) => Positioned(
        width: size.width,
        child: CompositedTransformFollower(
          link: widget.layerLink,
          showWhenUnlinked: false,
          offset: const Offset(0, 45),
          child: Material(
            elevation: 4,
            borderRadius: BorderRadius.circular(4),
            child: Container(
              decoration: BoxDecoration(
                color: Colors.white,
                border: Border.all(color: Colors.grey.shade300),
                borderRadius: BorderRadius.circular(4),
                boxShadow: [
                  BoxShadow(
                    color: Colors.grey.withValues(alpha: 0.3),
                    spreadRadius: 1,
                    blurRadius: 3,
                    offset: const Offset(0, 1),
                  ),
                ],
              ),
              constraints: const BoxConstraints(maxHeight: 200),
              child: SingleChildScrollView(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: widget.items.map((item) {
                    return GestureDetector(
                      behavior: HitTestBehavior.opaque,
                      onTap: () {
                        setState(() {
                          _isProgrammaticChange = true;
                          widget.controller.text = item;
                        });
                        widget.onChanged(item);
                        WidgetsBinding.instance.addPostFrameCallback((_) {
                          _isProgrammaticChange = false;
                        });
                        _removeDropdown();
                      },
                      child: Container(
                        padding: const EdgeInsets.symmetric(
                          horizontal: 16,
                          vertical: 12,
                        ),
                        width: double.infinity,
                        child: Text(item),
                      ),
                    );
                  }).toList(),
                ),
              ),
            ),
          ),
        ),
      ),
    );
    
    Overlay.of(context).insert(_overlayEntry!);
  }

  void _removeDropdown() {
    if (_overlayEntry != null) {
      _overlayEntry!.remove();
      _overlayEntry = null;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        CompositedTransformTarget(
          link: widget.layerLink,
          child: TextFormField(
            key: widget.fieldKey,
            controller: widget.controller,
            focusNode: widget.focusNode,
            decoration: InputDecoration(
              labelText: widget.label,
              hintText: widget.hint,
              suffixIcon: IconButton(
                icon: const Icon(Icons.arrow_drop_down),
                onPressed: () {
                  widget.onDropdownPressed();
                  _showDropdown();
                },
              ),
            ),
            onChanged: (value) {
              if (!_isProgrammaticChange) {
                widget.onChanged(value);
              }
            },
            onFieldSubmitted: widget.onFieldSubmitted,
          ),
        ),
        // 자동완성 후보 표시
        if (widget.getAutocompleteSuggestion != null)
          Builder(
            builder: (context) {
              final suggestion = widget.getAutocompleteSuggestion!(widget.controller.text);
              if (suggestion != null && suggestion.length > widget.controller.text.length) {
                return Padding(
                  padding: const EdgeInsets.only(left: 12, top: 2),
                  child: Text(
                    suggestion,
                    style: const TextStyle(
                      color: Color(0xFF1976D2),
                      fontWeight: FontWeight.bold,
                      fontSize: 13,
                    ),
                  ),
                );
              }
              return const SizedBox.shrink();
            },
          ),
      ],
    );
  }
}