import 'package:test/test.dart';
import 'package:intl/intl.dart';
import 'package:timezone/timezone.dart';
import 'package:timezone/data/latest.dart';

// A DateTime in dart contains the TimezoneOffset from UTC/GMT
// This was modified to ommit the `:` so we actually have implemented the Z
// Timezone formatter in dart.
//
// See: https://github.com/dart-lang/intl/issues/19 for more details.
Future<void> main() async {
  initializeTimeZones();

  test('format date that includes offset', () {
    var date = TZDateTime.now(getLocation('Asia/Taipei'));
    var formattedDate = formatDateWithOffset(date);

    expect(formattedDate, contains("+0800"));
  });

  test('double digit offset hours', () {
    var brisbane = getLocation('Australia/Brisbane');
    var date = TZDateTime.now(brisbane);
    var formattedDate = formatDateWithOffset(date);

    expect(formattedDate, contains("+1000"));
  });

  test('single digit offset hours', () {
    final chicago = getLocation('America/Chicago');
    var date = TZDateTime.now(chicago);
    var formattedDate = formatDateWithOffset(date);

    expect(formattedDate, contains("-0500"));
  });

  test('30 minute offset', () {
    final brokenHill = getLocation('Australia/Broken_Hill');
    var date = TZDateTime.now(brokenHill);
    var formattedDate = formatDateWithOffset(date);

    expect(formattedDate, contains("30"));
  });

  test('across several different timezones', () {
    final chicago = getLocation('America/Chicago');
    var date = TZDateTime.now(chicago);
    var formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("-0500"));

    final detroit = getLocation('America/Detroit');
    date = TZDateTime.now(detroit);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("-0400"));

    // Phoenix
    final phoenix = getLocation('America/Phoenix');
    date = TZDateTime.now(phoenix);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("-0700"));

    // Denver
    final denver = getLocation('America/Denver');
    date = TZDateTime.now(denver);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("-0600"));

    final la = getLocation('America/Los_Angeles');
    date = TZDateTime.now(la);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("-0700"));

    final kolkata = getLocation('Asia/Kolkata');
    date = TZDateTime.now(kolkata);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("+0530"));

    final brisbane = getLocation('Australia/Brisbane');
    date = TZDateTime.now(brisbane);
    formattedDate = formatDateWithOffset(date);
    print(formattedDate);
    expect(formattedDate, contains("+1000"));

    final mexicoCity = getLocation('America/Mexico_City');
    date = TZDateTime.now(mexicoCity);
    formattedDate = formatDateWithOffset(date);
    print("mexicoCity formattedDate $formattedDate");
    expect(formattedDate, contains("-0600"));

    final honolulu = getLocation('Pacific/Honolulu');
    date = TZDateTime.now(honolulu);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("-1000"));

    final zurich = getLocation('Europe/Zurich');
    date = TZDateTime.now(zurich);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("+0200"));

    final london = getLocation('Europe/London');
    date = TZDateTime.now(london);
    formattedDate = formatDateWithOffset(date);
    expect(formattedDate, contains("+0100"));
  });
}

/// Formats Date and includes the time zone offset in iso8601 format
String formatDateWithOffset(DateTime date) {
  String twoDigits(int n) => n >= 10 ? "$n" : "0$n";

  var hours = twoDigits(date.timeZoneOffset.inHours.abs());
  var minutes = twoDigits(date.timeZoneOffset.inMinutes.remainder(60));
  var sign = date.timeZoneOffset.inHours > 0 ? "+" : "-";
  var formattedDate = DateFormat("yyyy-MM-ddTHH:mm:ss").format(date);

  return "$formattedDate$sign$hours$minutes";
}