calorimeter/lib/perdate/perdate_pageview_controller.dart

import 'dart:developer';

import 'package:barcode_scan2/barcode_scan2.dart';
import 'package:calorimeter/food_entry/food_entry_bloc.dart';
import 'package:calorimeter/perdate/perdate_pageview.dart';
import 'package:calorimeter/utils/app_drawer.dart';
import 'package:calorimeter/utils/calendar_floating_button.dart';
import 'package:calorimeter/utils/date_time_helper.dart';
import 'package:calorimeter/utils/rectangular_notch_shape.dart';
import 'package:calorimeter/utils/scan_food_floating_button.dart';
import 'package:calorimeter/utils/sum_widget.dart';
import 'package:calorimeter/utils/theme_switcher_button.dart';
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:provider/provider.dart';

class PerDatePageViewController extends StatelessWidget {
  // this is the date for which the PerDate widget will be shown on screen
  // left of it will be yesterday's PerDate widget
  // right of it will be tomorrow's PerDate widget
  final DateTime initialDate;
  final PageController pageController;
  static final int initialOffset = 36500000;

  const PerDatePageViewController._(
      {required this.initialDate, required this.pageController});

  factory PerDatePageViewController({required initialDate}) {
    return PerDatePageViewController._(
        initialDate: initialDate,
        pageController: PageController(initialPage: initialOffset));
  }

  @override
  Widget build(BuildContext context) {
    return BackButtonListener(
      onBackButtonPressed: () async {
        var visitedIndexes =
            context.read<PageViewStateProvider>().visitedIndexes;
        if (visitedIndexes.length == 1) {
          return false;
        }

        visitedIndexes.removeLast();

        pageController.jumpToPage(visitedIndexes.last);

        return true;
      },
      child: ChangeNotifierProvider(
        create: (context) => PageViewStateProvider(
          initialDate: initialDate,
          initialOffset: initialOffset,
        ),
        child: Builder(builder: (context) {
          return Scaffold(
            appBar: AppBar(
              title: Builder(builder: (context) {
                return Text(DateFormat.yMMMMd('de').format(
                    context.watch<PageViewStateProvider>().displayedDate));
              }),
              actions: const [ThemeSwitcherButton()],
            ),
            bottomNavigationBar: BottomAppBar(
                shape: const RectangularNotchShape(),
                color: Theme.of(context).colorScheme.secondary,
                child: SumWidget(foodEntries: [])),
            drawer: const AppDrawer(),
            floatingActionButton: OverflowBar(children: [
              ScanFoodFAB(
                onPressed: () {
                  var result = BarcodeScanner.scan();
                  context
                      .read<FoodEntryBloc>()
                      .add(BarcodeScanned(scanResultFuture: result));
                },
              ),
              const SizedBox(width: 8),
              CalendarFAB(
                startFromDate: DateTimeHelper.now(),
                onDateSelected: (dateSelected) {
                  if (dateSelected == null) return;

                  var dateDiff = dateSelected.difference(initialDate).inDays;

                  log("dateDiff = $dateDiff");
                  pageController.jumpToPage(initialOffset - dateDiff);
                },
              ),
            ]),
            floatingActionButtonLocation:
                FloatingActionButtonLocation.endDocked,
            body: PerDatePageView(
              pageController: pageController,
              initialDate: initialDate,
            ),
          );
        }),
      ),
    );
  }
}

class PageViewStateProvider with ChangeNotifier {
  DateTime _displayedDate;
  List<int> visitedIndexes = [];
  bool _backButtonWasPressed = false;

  PageViewStateProvider({required DateTime initialDate, int initialOffset = 0})
      : _displayedDate = initialDate {
    visitedIndexes.add(initialOffset);
  }

  set backButtonWasPressed(val) => _backButtonWasPressed = val;
  get backButtonWasPressed => _backButtonWasPressed;

  get displayedDate => _displayedDate;
  void setDisplayedDate(date) {
    _displayedDate = date;
    notifyListeners();
  }

  void addVisitedindex(int index) {
    visitedIndexes.add(index);
  }
}