Display summary of Ruby datetimes as range or as single day.

datetime_range_formatter.rb

def formatted_datetime_range(start_datetime, end_datetime)
	start_date = start_datetime.to_date rescue nil
	end_date = end_datetime.to_date rescue nil

	return "" if start_date.nil?

	is_all_day = (start_datetime == start_datetime.beginning_of_day)
	is_this_year = (start_datetime.year == Time.zone.today.year)

	if end_date && start_date != end_date
		if start_date.year == end_date.year
			# Jan 14 - 15
			# Jan 14 - 15, 2053
			# Jan 14 - Feb 15
			# Jan 14 - Feb 15, 2053
			start_date.strftime("%b %-d") + " - " + end_date.strftime("#{'%b ' if start_date.month != end_date.month}%-d#{', %Y' unless is_this_year}")
		else
			# Jan 14, 2052 - Jan 15, 2053
			# Jan 14, 2052 - Feb 15, 2053
			start_date.strftime("%b %-d, %Y") + " - " + end_date.strftime("%b %-d, %Y")
		end
	else
		# Tue, Jan 14
		# Tue, Jan 14, 2053
		# Tue, Jan 14 - 9:00am
		# Tue, Jan 14, 2053 - 9:00am
		start_datetime.strftime("%a, %b %-d#{', %Y' unless is_this_year}#{' - %l:%M%P' unless is_all_day}")
	end
end