englishDay method
Persian weekday names (with space, half-space or joined) → English. "دوشنبه" → "Monday"
Implementation
String englishDay() {
String day = this;
const Map<String, String> names = <String, String>{"یک": "Sunday", "دو": "Monday", "سه": "Tuesday", "چهار": "Wednesday", "پنج": "Thursday"};
names.forEach((String prefix, String english) => day = day.replaceAll(RegExp("$prefix[ ]?شنبه"), english));
return day.replaceAll("جمعه", "Friday").replaceAll("شنبه", "Saturday");
}