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

/// 通用日期选择器组件
/// 支持功能：
/// - 初始日期设置
/// - 日期范围限制
/// - 自定义日期格式
/// - 主题适配
/// - 空值处理
/// - 验证支持
class DatePickerField extends StatefulWidget {
  final DateTime? initialDate;
  final DateTime? firstDate;
  final DateTime? lastDate;
  final ValueChanged<DateTime?> onDateSelected;
  final String labelText;
  final String? hintText;
  final bool isRequired;
  final TextStyle? textStyle;
  final InputDecoration? decoration;
  final DateFormat? dateFormat;
  final bool allowClear;
  final bool autoValidate;

  const DatePickerField({
    super.key,
    this.initialDate,
    this.firstDate,
    this.lastDate,
    required this.onDateSelected,
    this.labelText = '选择日期',
    this.hintText,
    this.isRequired = false,
    this.textStyle,
    this.decoration,
    this.dateFormat,
    this.allowClear = true,
    this.autoValidate = false,
  });

  @override
  State<DatePickerField> createState() => _DatePickerFieldState();
}

class _DatePickerFieldState extends State<DatePickerField> {
  late final TextEditingController _controller;
  DateTime? _selectedDate;
  final DateFormat _defaultFormat = DateFormat('yyyy-MM-dd');

  @override
  void initState() {
    super.initState();
    _selectedDate = widget.initialDate;
    _controller = TextEditingController(
      text: _selectedDate != null ? _getFormattedDate(_selectedDate!) : '',
    );
  }

  @override
  void didUpdateWidget(covariant DatePickerField oldWidget) {
    if (widget.initialDate != oldWidget.initialDate) {
      _updateDate(widget.initialDate);
    }
    super.didUpdateWidget(oldWidget);
  }

  String _getFormattedDate(DateTime date) {
    return (widget.dateFormat ?? _defaultFormat).format(date);
  }

  void _updateDate(DateTime? newDate) {
    setState(() {
      _selectedDate = newDate;
      _controller.text = newDate != null ? _getFormattedDate(newDate) : '';
    });
    widget.onDateSelected(newDate);
  }

  Future<void> _selectDate() async {
    final DateTime? picked = await showDatePicker(
      context: context,
      initialDate: _selectedDate ?? DateTime.now(),
      firstDate: widget.firstDate ?? DateTime(1900),
      lastDate: widget.lastDate ?? DateTime(2100),
      builder: (context, child) {
        return Theme(
          data: Theme.of(context).copyWith(
            colorScheme: ColorScheme.light(
              primary: Theme.of(context).primaryColor,
            ),
          ),
          child: child!,
        );
      },
    );

    if (picked != null && picked != _selectedDate) {
      _updateDate(picked);
    }
  }

  void _clearDate() {
    _updateDate(null);
  }

  String? _validateDate(String? value) {
    if (widget.isRequired && _selectedDate == null) {
      return '请选择日期';
    }
    return null;
  }

  @override
  Widget build(BuildContext context) {
    return TextFormField(
      controller: _controller,
      readOnly: true,
      style: widget.textStyle ?? Theme.of(context).textTheme.bodyMedium,
      decoration: (widget.decoration ?? InputDecoration(
        labelText: widget.labelText,
        hintText: widget.hintText,
        suffixIcon: _buildSuffixIcon(),
      )).copyWith(
        errorStyle: const TextStyle(height: 0.7),
      ),
      onTap: _selectDate,
      validator: widget.autoValidate ? _validateDate : null,
    );
  }

  Widget _buildSuffixIcon() {
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: [
        if (widget.allowClear && _selectedDate != null)
          IconButton(
            icon: const Icon(Icons.clear, size: 18),
            onPressed: _clearDate,
          ),
        const Padding(
          padding: EdgeInsets.only(right: 8),
          child: Icon(Icons.calendar_today, size: 18),
        ),
      ],
    );
  }

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