dateapp/lib/pages/day.dart

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import '../utils/gregorian_date.dart';

class DayScreen extends StatefulWidget {
  const DayScreen({Key? key}) : super(key: key);

  @override
  State<DayScreen> createState() => _DayScreenState();
}

class _DayScreenState extends State<DayScreen> {
  DateTime? _selectedDate;
  dynamic period;

  @override
  Widget build(BuildContext context) {
    void showDateDialog() async {
      final DateTime? pickedDate = await showDatePicker(
        context: context,
        initialDate: DateTime.now(),
        firstDate: DateTime(1970),
        lastDate: DateTime(2100),
        locale: const Locale("en", "GB"),
      );

      if (pickedDate != null) {
        setState(() {
          _selectedDate = pickedDate;
        });
      }
    }

    final pickedDate = _selectedDate ?? DateTime.now();
    // List<int> diffYMD = GregorianDate.differenceInYearsMonthsDays(DateTime.now(), pickedDate);
    int diffD = GregorianDate.differenceInDays(DateTime.now(), pickedDate);
    List<int> diffYMD = GregorianDate.differenceInYearsMonthsDays(diffD);

    if (pickedDate.isBefore(DateTime.now())) {
      period = "in the past";
    } else {
      period = "to the future";
    }

    dynamic pickedDateString =
        DateFormat("EEEE, d MMM yyyy").format(pickedDate).toString();
    dynamic todayString =
        DateFormat("EEEE, d MMM yyyy").format(DateTime.now()).toString();

    return Scaffold(
      appBar: AppBar(
        title: const Text("Day Calculator"),
        elevation: 4,
        shadowColor: Theme.of(context).shadowColor,
      ),
      body: _selectedDate == null
          ? const Padding(
              padding: EdgeInsets.all(30),
              child: Center(
                child: Text('Select the date by using the date picker button'),
              ),
            )
          : Padding(
              padding: const EdgeInsets.all(30),
              child: Center(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    const Text("Dates",
                        style: TextStyle(
                            fontSize: 30, fontWeight: FontWeight.bold)),
                    const Text("Chosen Date", style: TextStyle(fontSize: 14)),
                    Text(
                      pickedDateString,
                      style: const TextStyle(
                          fontSize: 22, fontWeight: FontWeight.bold),
                    ),
                    const SizedBox(height: 5),
                    const Text("Today", style: TextStyle(fontSize: 14)),
                    Text(
                      todayString,
                      style: const TextStyle(
                          fontSize: 22, fontWeight: FontWeight.bold),
                    ),
                    const SizedBox(height: 20),
                    const Text("Difference",
                        style: TextStyle(
                            fontSize: 30, fontWeight: FontWeight.bold)),
                    Text(pickedDateString,
                        style: const TextStyle(fontSize: 14)),
                    Text(
                        "${diffYMD[3]} days \n${diffYMD[2]} weeks \n${diffYMD[1]} months\n${diffYMD[0]} years",
                        style: const TextStyle(
                            fontSize: 24, fontWeight: FontWeight.bold)),
                    Text(period, style: const TextStyle(fontSize: 14)),
                    const SizedBox(
                      height: 20,
                    ),
                    const Text("Or in total is",
                        style: TextStyle(fontSize: 14)),
                    Text("$diffD days $period",
                        style: const TextStyle(
                            fontSize: 24, fontWeight: FontWeight.bold)),
                  ],
                ),
              )),
      // This button is used to show the date range picker
      floatingActionButton: FloatingActionButton(
        onPressed: showDateDialog,
        child: const Icon(Icons.today),
      ),
    );
  }
}