Add methods [days, weeks, months, years]_between

Inspired by rails/rails#27966

Gemfile

@@ -1,4 +1,3 @@
 source 'https://rubygems.org'
 
-# Specify your gem's dependencies in general_time.gemspec
 gemspec

README.md

@@ -1,9 +1,5 @@
 # GeneralTime
 
-Welcome to your new gem! In this directory, you'll find the files you need to be able to package up your Ruby library into a gem. Put your Ruby code in the file `lib/general_time`. To experiment with that code, run `bin/console` for an interactive prompt.
-
-TODO: Delete this and the text above, and describe your gem
-
 ## Installation
 
 Add this line to your application's Gemfile:
@@ -22,18 +18,141 @@ Or install it yourself as:
 
 ## Usage
 
-TODO: Write usage instructions here
+### #days_between
 
-## Development
+Formula: `((date2.yday - date1.yday) + 365 * (date2.year - date1.year)).abs`
 
-After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
+```ruby
+require "date"
 
-To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+Date.new(2017, 2, 10).days_between(Date.new(2017, 2, 10)) # => 0
 
-## Contributing
+Date.new(2017, 2, 10).days_between(Date.new(2017, 2, 10)) # => 0
+Date.new(2017, 2, 10).days_between(Date.new(2017, 2, 10)) # => 0
+
+Date.new(2017, 2, 9).days_between(Date.new(2017, 2, 10)) # => 1
+Date.new(2017, 2, 10).days_between(Date.new(2017, 2, 9)) # => 1
+Date.new(2017, 2, 1).days_between(Date.new(2017, 2, 10)) # => 9
+Date.new(2017, 2, 10).days_between(Date.new(2017, 2, 1)) # => 9
+Date.new(2016, 2, 10).days_between(Date.new(2017, 2, 10)) # => 365
+Date.new(2017, 2, 10).days_between(Date.new(2016, 2, 10)) # => 365
+```
+
+```ruby
+Time.new(2017, 2, 10, 10, 10, 10).days_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+
+Time.new(2017, 2, 10, 9, 10, 10).days_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+Time.new(2017, 2, 10, 10, 10, 10).days_between(Time.new(2017, 2, 10, 9, 10, 10)) # => 0
+
+Time.new(2017, 2, 9, 10, 10, 10).days_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 1
+Time.new(2017, 2, 10, 10, 10, 10).days_between(Time.new(2017, 2, 9, 10, 10, 10)) # => 1
+Time.new(2017, 2, 1, 10, 10, 10).days_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 9
+Time.new(2017, 2, 10, 10, 10, 10).days_between(Time.new(2017, 2, 1, 10, 10, 10)) # => 9
+Time.new(2016, 2, 10, 10, 10, 10).days_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 365
+Time.new(2017, 2, 10, 10, 10, 10).days_between(Time.new(2016, 2, 10, 10, 10, 10)) # => 365
+```
+
+### #weeks_between
+
+Formula: `((date2.cweek - date1.cweek) + 52 * (date2.year - date1.year)).abs`
+
+```ruby
+require "date"
+
+Date.new(2017, 2, 10).weeks_between(Date.new(2017, 2, 10)) # => 0
+
+Date.new(2017, 2, 10).weeks_between(Date.new(2017, 2, 10)) # => 0
+Date.new(2017, 2, 10).weeks_between(Date.new(2017, 2, 10)) # => 0
+
+Date.new(2017, 2, 3).weeks_between(Date.new(2017, 2, 10)) # => 1
+Date.new(2017, 2, 10).weeks_between(Date.new(2017, 2, 3)) # => 1
+Date.new(2016, 12, 9).weeks_between(Date.new(2017, 2, 10)) # => 9
+Date.new(2017, 2, 10).weeks_between(Date.new(2016, 12, 9)) # => 9
+Date.new(2016, 2, 10).weeks_between(Date.new(2017, 2, 10)) # => 52
+Date.new(2017, 2, 10).weeks_between(Date.new(2016, 2, 10)) # => 52
+```
+
+```ruby
+Time.new(2017, 2, 10, 10, 10, 10).weeks_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+
+Time.new(2017, 2, 10, 9, 10, 10).weeks_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+Time.new(2017, 2, 10, 10, 10, 10).weeks_between(Time.new(2017, 2, 10, 9, 10, 10)) # => 0
+
+Time.new(2017, 2, 3, 10, 10, 10).weeks_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 1
+Time.new(2017, 2, 10, 10, 10, 10).weeks_between(Time.new(2017, 2, 3, 10, 10, 10)) # => 1
+Time.new(2016, 12, 9, 10, 10, 10).weeks_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 9
+Time.new(2017, 2, 10, 10, 10, 10).weeks_between(Time.new(2016, 12, 9, 10, 10, 10)) # => 9
+Time.new(2016, 2, 10, 10, 10, 10).weeks_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 52
+Time.new(2017, 2, 10, 10, 10, 10).weeks_between(Time.new(2016, 2, 10, 10, 10, 10)) # => 52
+```
+
+### #months_between
+
+Formula: `((date2.month - date1.month) + 12 * (date2.year - date1.year)).abs`
 
-Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/general_time. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.
+```ruby
+require "date"
+
+Date.new(2017, 2, 10).months_between(Date.new(2017, 2, 10)) # => 0
+
+Date.new(2017, 2, 9).months_between(Date.new(2017, 2, 10)) # => 0
+Date.new(2017, 2, 10).months_between(Date.new(2017, 2, 9)) # => 0
+
+Date.new(2017, 1, 10).months_between(Date.new(2017, 2, 10)) # => 1
+Date.new(2017, 2, 10).months_between(Date.new(2017, 1, 10)) # => 1
+Date.new(2016, 5, 10).months_between(Date.new(2017, 2, 10)) # => 9
+Date.new(2017, 2, 10).months_between(Date.new(2016, 5, 1)) # => 9
+Date.new(2016, 2, 10).months_between(Date.new(2017, 2, 10)) # => 12
+Date.new(2017, 2, 10).months_between(Date.new(2016, 2, 10)) # => 12
+```
+
+```ruby
+Time.new(2017, 2, 10, 10, 10, 10).months_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+
+Time.new(2017, 2, 9, 10, 10, 10).months_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+Time.new(2017, 2, 10, 10, 10, 10).months_between(Time.new(2017, 2, 9, 10, 10, 10)) # => 0
+
+Time.new(2017, 1, 10, 10, 10, 10).months_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 1
+Time.new(2017, 2, 10, 10, 10, 10).months_between(Time.new(2017, 1, 10, 10, 10, 10)) # => 1
+Time.new(2016, 5, 10, 10, 10, 10).months_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 9
+Time.new(2017, 2, 10, 10, 10, 10).months_between(Time.new(2016, 5, 1, 10, 10, 10)) # => 9
+Time.new(2016, 2, 10, 10, 10, 10).months_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 12
+Time.new(2017, 2, 10, 10, 10, 10).months_between(Time.new(2016, 2, 10, 10, 10, 10)) # => 12
+```
+
+### #years_between
+
+Formula: `(date2.year - date1.year).abs`
+
+```ruby
+require "date"
+
+Date.new(2017, 2, 10).years_between(Date.new(2017, 2, 10)) # => 0
+
+Date.new(2017, 1, 10).years_between(Date.new(2017, 2, 10)) # => 0
+Date.new(2017, 2, 10).years_between(Date.new(2017, 1, 10)) # => 0
+
+Date.new(2016, 2, 10).years_between(Date.new(2017, 2, 10)) # => 1
+Date.new(2017, 2, 10).years_between(Date.new(2016, 2, 10)) # => 1
+Date.new(2008, 2, 10).years_between(Date.new(2017, 2, 10)) # => 9
+Date.new(2017, 2, 10).years_between(Date.new(2008, 2, 10)) # => 9
+```
+
+```ruby
+Time.new(2017, 2, 10, 10, 10, 10).years_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+
+Time.new(2017, 1, 10, 10, 10, 10).years_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 0
+Time.new(2017, 2, 10, 10, 10, 10).years_between(Time.new(2017, 1, 10, 10, 10, 10)) # => 0
+
+Time.new(2016, 2, 10, 10, 10, 10).years_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 1
+Time.new(2017, 2, 10, 10, 10, 10).years_between(Time.new(2016, 2, 10, 10, 10, 10)) # => 1
+Time.new(2008, 2, 10, 10, 10, 10).years_between(Time.new(2017, 2, 10, 10, 10, 10)) # => 9
+Time.new(2017, 2, 10, 10, 10, 10).years_between(Time.new(2008, 2, 10, 10, 10, 10)) # => 9
+```
+
+## Contributing
 
+Bug reports and pull requests are welcome on GitHub at https://github.com/bogdanvlviv/general_time. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.
 
 ## License
 

bin/console

@@ -3,12 +3,5 @@
 require "bundler/setup"
 require "general_time"
 
-# You can add fixtures and/or initialization code here to make experimenting
-# with your gem easier. You can also use a different console, if you like.
-
-# (If you use this, don't forget to add pry to your Gemfile!)
-# require "pry"
-# Pry.start
-
 require "irb"
 IRB.start

bin/setup

@@ -4,5 +4,3 @@ IFS=$'\n\t'
 set -vx
 
 bundle install
-
-# Do any other automated setup that you need to do here

general_time.gemspec

@@ -9,25 +9,12 @@ Gem::Specification.new do |spec|
   spec.authors       = ["bogdanvlviv"]
   spec.email         = ["bogdanvlviv@gmail.com"]
 
-  spec.summary       = %q{TODO: Write a short summary, because Rubygems requires one.}
-  spec.description   = %q{TODO: Write a longer description or delete this line.}
-  spec.homepage      = "TODO: Put your gem's website or public repo URL here."
+  spec.summary       = "Allows getting general time between two instances of Date/Time classes"
+  spec.description   = ""
+  spec.homepage      = "https://github.com/bogdanvlviv/general_time"
   spec.license       = "MIT"
 
-  # Prevent pushing this gem to RubyGems.org. To allow pushes either set the 'allowed_push_host'
-  # to allow pushing to a single host or delete this section to allow pushing to any host.
-  if spec.respond_to?(:metadata)
-    spec.metadata['allowed_push_host'] = "TODO: Set to 'http://mygemserver.com'"
-  else
-    raise "RubyGems 2.0 or newer is required to protect against " \
-      "public gem pushes."
-  end
-
-  spec.files         = `git ls-files -z`.split("\x0").reject do |f|
-    f.match(%r{^(test|spec|features)/})
-  end
-  spec.bindir        = "exe"
-  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.files         = `git ls-files -z`.split("\x0")
   spec.require_paths = ["lib"]
 
   spec.add_development_dependency "bundler", "~> 1.13"

lib/general_time.rb

@@ -1,5 +1,5 @@
 require "general_time/version"
+require "general_time/time"
 
 module GeneralTime
-  # Your code goes here...
 end

lib/general_time/core_ext/date.rb

@@ -0,0 +1 @@
+require "general_time/core_ext/date/calculations"

lib/general_time/core_ext/date/calculations.rb

@@ -0,0 +1,6 @@
+require "date"
+require "general_time/core_ext/date_and_time/calculations"
+
+class Date
+  include DateAndTime::Calculations
+end

lib/general_time/core_ext/date_and_time/calculations.rb

@@ -0,0 +1,35 @@
+module DateAndTime
+  module Calculations
+    AMOUNT_DAYS_PER_YEAR = 365
+    AMOUNT_WEEKS_PER_YEAR = 52
+    AMOUNT_MONTHS_PER_YEAR = 12
+
+    # Returns the number of days to given date, default to +Date.current+.
+    def days_between(date = ::Date.current)
+      date1, date2 = self.to_date, date.to_date
+
+      ((date2.yday - date1.yday) + AMOUNT_DAYS_PER_YEAR * (date2.year - date1.year)).abs
+    end
+
+    # Returns the number of weeks to given date, default to +Date.current+.
+    def weeks_between(date = ::Date.current)
+      date1, date2 = self.to_date, date.to_date
+
+      ((date2.cweek - date1.cweek) + AMOUNT_WEEKS_PER_YEAR * (date2.year - date1.year)).abs
+    end
+
+    # Returns the number of months to given date, default to +Date.current+.
+    def months_between(date = ::Date.current)
+      date1, date2 = self.to_date, date.to_date
+
+      ((date2.month - date1.month) + AMOUNT_MONTHS_PER_YEAR * (date2.year - date1.year)).abs
+    end
+
+    # Returns the number of years to given date, default to +Date.current+.
+    def years_between(date = ::Date.current)
+      date1, date2 = self.to_date, date.to_date
+
+      (date2.year - date1.year).abs
+    end
+  end
+end

lib/general_time/core_ext/time.rb

@@ -0,0 +1 @@
+require "general_time/core_ext/time/calculations"

lib/general_time/core_ext/time/calculations.rb

@@ -0,0 +1,5 @@
+require "general_time/core_ext/date_and_time/calculations"
+
+class Time
+  include DateAndTime::Calculations
+end

lib/general_time/time.rb

@@ -0,0 +1,5 @@
+require "date"
+require "time"
+
+require "general_time/core_ext/date"
+require "general_time/core_ext/time"