import 'package:flutter/material.dart';
import '../../formula_models.dart';
import '../../corpus.dart';

class UnitDropdown extends StatelessWidget {
  final Corpus corpus;
  final VariableSpec variable;
  final String? selectedUnit;
  final ValueChanged<String?> onUnitChanged;

  const UnitDropdown({
    super.key,
    required this.corpus,
    required this.variable,
    required this.selectedUnit,
    required this.onUnitChanged,
  });

  @override
  Widget build(BuildContext context) {
    final unitNames = corpus.unitsOfSameMagnitude(variable.unit);
    final availableUnits = unitNames.map((name) => corpus.getUnit(name)).toList();

    return SizedBox(
      width: 50, // Constrain dropdown width
      child: DropdownButton<String>(
        value: selectedUnit ?? variable.unit,
        selectedItemBuilder: (context) => availableUnits
            .map((unit) => SizedBox(width: 50, child: Text(unit.symbol, overflow: TextOverflow.ellipsis)))
            .toList(),
        icon: const Icon(Icons.arrow_drop_down),
        elevation: 16,
        style: TextStyle(color: Theme.of(context).colorScheme.primary, fontSize: 14),
        underline: Container(height: 1, color: Theme.of(context).dividerColor),
        onChanged: onUnitChanged,
        items: availableUnits.map<DropdownMenuItem<String>>((UnitSpec unit) {
          return DropdownMenuItem<String>(
            value: unit.name,
            child: SizedBox(
              width: 300, // Fixed width for all items
              child: Text(
                "${unit.symbol} - ${unit.name}",
                style: const TextStyle(fontSize: 14),
                overflow: TextOverflow.ellipsis,
              ),
            ),
          );
        }).toList(),
        menuWidth: 300,
        menuMaxHeight: 400,
        isExpanded: true,
      ),
    );
  }
}