Looking for an efficient way to detect birthday ranges using Ruby - ruby

Question

Currently working on an app that needs to show the operator a list of staff that have birthdays that fall in the past 7 days or the next 21 days.
We have a staff database that contains the date of births, and selecting them by date range is fairly straightforward. However, we then have to show how many days in the future/past the birthday is from today.
The code currently looks something like:
today = Date.today
dob = staff.dob
days = Date.new(today.year, dob.month, dob.day) - today
if days < 0
"#{ days.abs } days ago"
else
"in #{ days } days"
end
This all works well in nearly every case, except when it comes to late December, or very early January. Because we are using today.year as the year comparator, if the 21 days ahead spills over into the new year, I get a false "days ago" reading. e.g.
Today's date is 20th December 2015, and the staff member's birthday is on 2nd January, instead of getting "in 13 days", I am getting "352 days ago".
I know I can probably wrap the code in another if/then/else clause that checks if the current date is after December 10th, to cater for this edge case, but there is a possibility that the date ranges will change dynamically, and also, the code is starting to look messy and inelegant - not like how I would like ruby code to look.
Does anyone have a better suggestion as to how to handle this issue?
(Note: This is in a Sinatra based project, so I don't have all the ActiveSupport or Rails based magic, although I am not averse to using a gem if it will get me the results I need.)

Answer 1

to get the smallest days for this year, next year and last year
today = Date.today
dob = staff.dob
this_dob = Date.new(today.year, dob.month, dob.day)
next_dob = this_dob.next_year
prev_dob = this_dob.prev_year
days = [this_dob - today, next_dob - today, prev_dob - today].min_by{|i| i.to_i.abs}
if days < 0
"#{ days.abs } days ago"
else
"in #{ days } days"
end

Answer 2

require 'date'
class BirthDates
attr_reader :year, :month, :day
def initialize(year, month, day)
#year = year
#month = month
#day = day
end
end
def count_days(dob)
today = Date.today
this_year = today.year
days = [this_year-1, this_year, this_year+1].map { |year|
(Date.new(year, dob.month, dob.day) - today) }.min_by(&:abs)
if days < 0
"#{ -days } days ago"
elsif days > 0
"in #{ days } days"
else
"Happy Birthday!"
end
end
Let's try it. (Today is 29 Oct 15)
dob = BirthDates.new(1908, 12, 28)
count_days(dob) #=> "in 60 days"
dob = BirthDates.new(1999, 10, 27)
count_days(dob) #=> "2 days ago"
dob = BirthDates.new(2014, 10, 29)
count_days(dob) #=> "Happy Birthday"
If today were 5 Jan 16:
dob = BirthDates.new(1908, 12, 28)
count_days(dob) #=> "8 days ago"
dob = BirthDates.new(1999, 3, 27)
count_days(dob) #=> "in 82 days"