DatePicker.kt

//firstDayOfWeek contains when the week starts in the locale.
//For example, UK locale will have Monday as first day of week
//English locale will have Sunday as first day of week.
val firstDayOfWeek = currentMonth.firstDayOfWeek

//weekDayList contains a list of week days with size 7 
//that starts with the firstDayOfWeek.
//For example, the UK locale has MONDAY as first day of week.
//The value of Calendar.MONDAY is 2.
//So the list contains [2, 3, 4, 5, 6, 7, 1]
val weekDayList = (0..6).map { ((firstDayOfWeek + it) % 7).takeIf { it > 0 } ?: 7  }

//firstDayOfMonth contains the week day in which the month starts.
//For Example November 2023 starts in Wednesday.
//So the value will be 4.
val firstDayOfMonth = remember (year, month, locale){
    Calendar.getInstance(locale).apply {
        set(Calendar.YEAR, year)
        set(Calendar.MONTH, month - 1)
        set(Calendar.DAY_OF_MONTH, 1)
    }.get(Calendar.DAY_OF_WEEK)
}

//initialDayInWeek of the week will contain the positoin in the row 
//where the month should start.
//For example, In UK locale, since wednesday is the third day of week,
//November 2023 should start at the third position in Row
//In English locale, wednesday is at the fourth day so the same month should
//start at fourth position.
val initialDayInWeek = weekDayList.indexOf(firstDayOfMonth) + 1

//Number of days in current month, 
//31 in Jan, Mar etc, 30 in Apr, Jun etc
//28 or 29 in Feb
val totalDaysOfMonth = currentMonth.getActualMaximum(Calendar.DAY_OF_MONTH)