info_tren/lib/components/select_train_suggestions/select_train_suggestions.dart

import 'dart:convert';

import 'package:flutter/widgets.dart';
import 'package:info_tren/components/select_train_suggestions/select_train_suggestions_cupertino.dart';
import 'package:info_tren/components/select_train_suggestions/select_train_suggestions_material.dart';
import 'package:info_tren/models.dart';
import 'package:info_tren/utils/default_ui_design.dart';
import 'package:tuple/tuple.dart';

class SelectTrainSuggestions extends StatefulWidget {
  final UiDesign? uiDesign;
  final List<TrainsResult> choices;
  final String? currentInput;
  final void Function(String trainNumber) onTrainSelected;

  const SelectTrainSuggestions({Key? key, required this.uiDesign, required this.choices, this.currentInput, required this.onTrainSelected }) : super(key: key);

  @override
  SelectTrainSuggestionsState createState() {
    final uiDesign = this.uiDesign ?? defaultUiDesign;
    switch(uiDesign) {
      case UiDesign.MATERIAL:
        return SelectTrainSuggestionsStateMaterial();
      case UiDesign.CUPERTINO:
        return SelectTrainSuggestionsStateCupertino();
      default:
        throw UnmatchedUiDesignException(uiDesign);
    }
  }
}

abstract class SelectTrainSuggestionsState extends State<SelectTrainSuggestions> {
  String getUseCurrentInputWidgetText(String currentInput) => 'Caută trenul cu numărul ${widget.currentInput}';
  Widget getUseCurrentInputWidget(String currentInput, void Function(String) onTrainSelected);

  @override
  Widget build(BuildContext context) {
    var slivers = widget.choices.map((c) => c.company).toSet().map((operator) => OperatorAutocompleteSliver(
      uiDesign: widget.uiDesign,
      operatorName: operator, 
      trains: widget.choices.where((c) => c.company == operator).toList(), 
      onTrainSelected: widget.onTrainSelected,
    )).toList();

    return CustomScrollView(
      slivers: <Widget>[
        ...slivers,
        SliverToBoxAdapter(
          child: widget.currentInput != null && int.tryParse(widget.currentInput!) != null ? getUseCurrentInputWidget(widget.currentInput!, widget.onTrainSelected) : Container(),
        ),
        SliverToBoxAdapter(
          child: Container(
            height: MediaQuery.of(context).viewPadding.bottom,
          ),
        ),
      ],
    );
  }
}

class OperatorAutocompleteSliver extends StatelessWidget {
  final UiDesign? uiDesign;
  final String operatorName;
  final List<TrainsResult> trains;
  final void Function(String) onTrainSelected;

  const OperatorAutocompleteSliver({ Key? key, required this.uiDesign, required this.operatorName, required this.trains, required this.onTrainSelected }) : super(key: key);

  Widget mapTrainToItem(TrainsResult train) {
    final uiDesign = this.uiDesign ?? defaultUiDesign;
    switch (uiDesign) {
      case UiDesign.MATERIAL:
        return OperatorAutocompleteTileMaterial(
          onTrainSelected: onTrainSelected,
          operatorName: operatorName,
          train: train,
        );
      case UiDesign.CUPERTINO:
        return OperatorAutocompleteTileCupertino(
          onTrainSelected: onTrainSelected,
          operatorName: operatorName,
          train: train,
        );
      default:
        throw UnmatchedUiDesignException(uiDesign);
    }
  }

  @override
  Widget build(BuildContext context) {
    if (trains.isEmpty) {
      return SliverToBoxAdapter(child: Container(),);
    }

    return SliverPrototypeExtentList(
      prototypeItem: Column(
        children: <Widget>[
          mapTrainToItem(TrainsResult(company: 'Company', number: '123', rank: 'R')),
        ],
      ),
      delegate: SliverChildBuilderDelegate(
        (context, index) {
          return Column(
            children: <Widget>[
              mapTrainToItem(trains[index]),
            ],
          );
        },
        childCount: trains.length,
        addSemanticIndexes: true,
      ),
    );
  }
}

abstract class OperatorAutocompleteTile extends StatelessWidget {
  final String operatorName;
  final TrainsResult train;
  final void Function(String) onTrainSelected;

  const OperatorAutocompleteTile({ Key? key, required this.onTrainSelected, required this.operatorName, required this.train }) : super(key: key);
}