import 'package:lucide_icons_flutter/lucide_icons.dart';
import 'package:flutter/material.dart';
import '../core/theme/context_tokens.dart';
import '../core/utils/date_util.dart';

/// 可键入日期框 + 日历图标（替代旧的「年/月/日」三下拉）。
///
/// - **直接键入**：支持「2024」「2024-5」「2024-5-12」「20240512」等，归一为 `yyyy-MM-dd`，
///   缺的月/日补 `01`（老酒只知道年份，填 2024 即 2024-01-01）。失焦时把显示归一化。
/// - **日历图标**：弹 Material `showDatePicker`（input 模式可直接键入年份，选老年份方便）。
/// - 值以 `yyyy-MM-dd` 字符串进出（[value] / [onChanged]）；无有效年时回调 null。
class DatePickerField extends StatefulWidget {
  final String? value; // yyyy-MM-dd
  final ValueChanged<String?> onChanged;
  final bool isRequired;
  final String? label;

  const DatePickerField({
    super.key,
    this.value,
    required this.onChanged,
    this.isRequired = false,
    this.label,
  });

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

class _DatePickerFieldState extends State<DatePickerField> {
  late final TextEditingController _ctrl;
  final FocusNode _focus = FocusNode();

  @override
  void initState() {
    super.initState();
    _ctrl = TextEditingController(text: widget.value ?? '');
    _focus.addListener(() {
      // 失焦时把输入归一化显示（如 2024 → 2024-01-01）
      if (!_focus.hasFocus) {
        final n = _normalize(_ctrl.text);
        if (n != null && n != _ctrl.text) {
          _ctrl.text = n;
        }
      }
    });
  }

  @override
  void didUpdateWidget(DatePickerField old) {
    super.didUpdateWidget(old);
    // 仅在无焦点（非用户正在输入）时同步外部值，避免回流打断输入
    if (!_focus.hasFocus &&
        old.value != widget.value &&
        (widget.value ?? '') != _ctrl.text) {
      _ctrl.text = widget.value ?? '';
    }
  }

  @override
  void dispose() {
    _ctrl.dispose();
    _focus.dispose();
    super.dispose();
  }

  /// 归一用户输入为 `yyyy-MM-dd`（缺月/日补 01）；无有效年返回 null。
  static String? _normalize(String raw) {
    final s = raw.trim();
    if (s.isEmpty) return null;
    int? y, mo, d;
    if (RegExp(r'^[0-9]+$').hasMatch(s)) {
      // 纯数字串：yyyymmdd / yyyymm / yyyy
      if (s.length >= 8) {
        y = int.tryParse(s.substring(0, 4));
        mo = int.tryParse(s.substring(4, 6));
        d = int.tryParse(s.substring(6, 8));
      } else if (s.length == 6) {
        y = int.tryParse(s.substring(0, 4));
        mo = int.tryParse(s.substring(4, 6));
      } else {
        y = int.tryParse(s);
      }
    } else {
      final parts =
          s.split(RegExp(r'[^0-9]+')).where((e) => e.isNotEmpty).toList();
      if (parts.isNotEmpty) y = int.tryParse(parts[0]);
      if (parts.length >= 2) mo = int.tryParse(parts[1]);
      if (parts.length >= 3) d = int.tryParse(parts[2]);
    }
    if (y == null || y < 1900 || y > 2200) return null;
    mo ??= 1;
    d ??= 1;
    if (mo < 1 || mo > 12) return null;
    final maxDay = DateTime(y, mo + 1, 0).day;
    if (d < 1) d = 1;
    if (d > maxDay) d = maxDay;
    return '${y.toString().padLeft(4, '0')}-'
        '${mo.toString().padLeft(2, '0')}-'
        '${d.toString().padLeft(2, '0')}';
  }

  Future<void> _pickFromCalendar(FormFieldState<String> field) async {
    final init =
        parseYmd(_normalize(_ctrl.text) ?? widget.value) ?? DateTime.now();
    final picked = await showDatePicker(
      context: context,
      initialDate: init,
      firstDate: DateTime(1900),
      lastDate: DateTime(2200),
      initialEntryMode: DatePickerEntryMode.input,
    );
    if (picked != null) {
      final v = formatYmd(picked);
      _ctrl.text = v;
      field.didChange(v);
      widget.onChanged(v);
    }
  }

  @override
  Widget build(BuildContext context) {
    return FormField<String>(
      initialValue: widget.value,
      validator: widget.isRequired
          ? (_) => _normalize(_ctrl.text) == null ? '请输入日期' : null
          : null,
      builder: (field) {
        return TextField(
          controller: _ctrl,
          focusNode: _focus,
          keyboardType: TextInputType.datetime,
          style: const TextStyle(fontSize: 13),
          decoration: InputDecoration(
            isDense: true,
            hintText: '年-月-日',
            hintStyle: const TextStyle(fontSize: 12),
            contentPadding:
                const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
            errorText: field.errorText,
            suffixIcon: IconButton(
              icon: Icon(LucideIcons.calendar,
                  size: 16, color: context.tokens.muted),
              padding: EdgeInsets.zero,
              constraints: const BoxConstraints(minWidth: 34, minHeight: 34),
              tooltip: '选择日期',
              onPressed: () => _pickFromCalendar(field),
            ),
          ),
          onChanged: (v) {
            final n = _normalize(v);
            field.didChange(n);
            widget.onChanged(n);
          },
        );
      },
    );
  }
}