### usage examples
# RubyVersion
### check for the main version with a Float
# RubyVersion.is? 1.8
### use strings for exacter checking
# RubyVersion.is.above '1.8.7'
# RubyVersion.is.at_least '1.8.7' # or below, at_most, not
### you can use the common comparison operators
# RubyVersion >= '1.8.7'
# RubyVersion.is.between? '1.8.6', '1.8.7'
### relase date checks
# RubyVersion.is.older_than Date.today
# RubyVersion.is.newer_than '2009-08-19'
### accessors
# RubyVersion.major # e.g. => 1
# RubyVersion.minor # e.g. => 8
# RubyVersion.tiny  # e.g. => 7
# RubyVersion.patchlevel # e.g. => 249
# RubyVersion.description # e.g. => "ruby 1.8.7 (2010-01-10 patchlevel 249) [i486-linux]"

require 'date'
require 'time'

module Quandl
module Utility
module RubyVersion
  class << self
    def to_s
      RUBY_VERSION
    end
    
    def full_version
      "#{RUBY_VERSION}-p#{patchlevel}"
    end

    # comparable
    def <=>(other)
      value = case other
        when Integer
          RUBY_VERSION.to_i
        when Float
          RUBY_VERSION.to_f
        when String
          RUBY_VERSION
        when Date,Time
          other.class.parse(RUBY_RELEASE_DATE)
        else 
          other = other.to_s
          RUBY_VERSION
        end  
      value <=> other
    end  
    include Comparable

    # chaining for dsl-like language
    def is?(other = nil)
      if other
        RubyVersion == other
      else
        RubyVersion
      end
    end
    alias is is?

    # aliases
    alias below     <
    alias below?    <
    alias at_most   <=
    alias at_most?  <=
    alias above     >
    alias above?    >
    alias at_least  >=
    alias at_least? >=
    alias exactly   ==
    alias exactly?  ==
    def not(other)
      self != other
    end
    alias not?     not
    alias between between?

    # compare dates
    def newer_than(other)
      if other.is_a? Date or other.is_a? Time
        RubyVersion > other
      else
        RUBY_RELEASE_DATE > other.to_s
      end
    end
    alias newer_than? newer_than

    def older_than(other)
      if other.is_a? Date or other.is_a? Time
        RubyVersion < other
      else
        RUBY_RELEASE_DATE < other.to_s
      end
    end
    alias older_than? older_than

    def released_today
      RubyVersion.date == Date.today
    end
    alias released_today? released_today

    # accessors

    def major
      RUBY_VERSION.to_i
    end
    alias main major

    def minor
      RUBY_VERSION.split('.')[1].to_i
    end
    alias mini minor

    def tiny
      RUBY_VERSION.split('.')[2].to_i
    end
    
    alias teeny tiny

    def patchlevel
      RUBY_PATCHLEVEL
    end

    def platform
      RUBY_PLATFORM
    end

    def release_date
      Date.parse RUBY_RELEASE_DATE
    end
    alias date release_date

    def description
      RUBY_DESCRIPTION
    end
  end
end
end
end