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

import 'labels.dart';

/// Edit form for the fields of an instrument a person may correct. Returns a patch holding
/// only what changed, or null when cancelled or nothing changed.
class InstrumentEditDialog extends StatefulWidget {
  const InstrumentEditDialog({required this.instrument, super.key});

  final InstrumentOut instrument;

  @override
  State<InstrumentEditDialog> createState() => _InstrumentEditDialogState();
}

class _InstrumentEditDialogState extends State<InstrumentEditDialog> {
  final _formKey = GlobalKey<FormState>();
  late final _name = TextEditingController(text: widget.instrument.name);
  late final _board = TextEditingController(
    text: widget.instrument.board ?? '',
  );
  late final _lot = TextEditingController(text: '${widget.instrument.lot}');
  late final _sector = TextEditingController(
    text: widget.instrument.sector ?? '',
  );
  late String _assetClass = widget.instrument.assetClass;

  @override
  void dispose() {
    _name.dispose();
    _board.dispose();
    _lot.dispose();
    _sector.dispose();
    super.dispose();
  }

  InstrumentPatch? _patch() {
    final i = widget.instrument;
    final name = _name.text.trim();
    final board = _board.text.trim();
    final sector = _sector.text.trim();
    final lot = int.parse(_lot.text.trim());
    final patch = InstrumentPatch(
      name: name != i.name ? name : null,
      assetClass: _assetClass != i.assetClass ? _assetClass : null,
      // an empty field means "leave as is": the wire format cannot express "clear"
      board: board.isNotEmpty && board != (i.board ?? '') ? board : null,
      lot: lot != i.lot ? lot : null,
      sector: sector.isNotEmpty && sector != (i.sector ?? '') ? sector : null,
    );
    final changed =
        patch.name != null ||
        patch.assetClass != null ||
        patch.board != null ||
        patch.lot != null ||
        patch.sector != null;
    return changed ? patch : null;
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: Text('Инструмент ${widget.instrument.ticker ?? ''}'.trim()),
      content: SizedBox(
        width: 420,
        child: Form(
          key: _formKey,
          child: SingleChildScrollView(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                TextFormField(
                  controller: _name,
                  decoration: const InputDecoration(labelText: 'Название'),
                  validator: (v) =>
                      (v ?? '').trim().isEmpty ? 'Обязательное поле' : null,
                ),
                const SizedBox(height: 12),
                DropdownButtonFormField<String>(
                  initialValue: assetClassLabels.containsKey(_assetClass)
                      ? _assetClass
                      : null,
                  isExpanded: true,
                  decoration: const InputDecoration(labelText: 'Класс актива'),
                  items: [
                    for (final e in assetClassLabels.entries)
                      DropdownMenuItem(
                        value: e.key,
                        child: Text('${e.value} (${e.key})'),
                      ),
                  ],
                  onChanged: (v) =>
                      setState(() => _assetClass = v ?? _assetClass),
                ),
                const SizedBox(height: 12),
                TextFormField(
                  controller: _board,
                  textCapitalization: TextCapitalization.characters,
                  decoration: const InputDecoration(
                    labelText: 'Доска (TQBR, TQTF…)',
                    helperText: 'По ней синк Мосбиржи находит котировки',
                  ),
                ),
                const SizedBox(height: 12),
                TextFormField(
                  controller: _lot,
                  keyboardType: TextInputType.number,
                  decoration: const InputDecoration(
                    labelText: 'Лот',
                    helperText:
                        'Ребалансировка округляет сделки до целого числа лотов',
                    helperMaxLines: 2,
                  ),
                  validator: (v) {
                    final n = int.tryParse((v ?? '').trim());
                    return n == null || n < 1
                        ? 'Целое число не меньше 1'
                        : null;
                  },
                ),
                const SizedBox(height: 12),
                TextFormField(
                  controller: _sector,
                  decoration: const InputDecoration(labelText: 'Сектор'),
                ),
              ],
            ),
          ),
        ),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.of(context).pop(),
          child: const Text('Отмена'),
        ),
        FilledButton(
          onPressed: () {
            if (!(_formKey.currentState?.validate() ?? false)) return;
            Navigator.of(context).pop(_patch());
          },
          child: const Text('Сохранить'),
        ),
      ],
    );
  }
}