require 'dionysus'
require 'active_support/core_ext/kernel/reporting'
require 'active_support/core_ext/module/delegation'

module Dionysus
  ##
  # = VersonString
  #
  #     require 'dionysus/version_string'
  #
  # VersionString is a proxy to Gem::Version that modifies the comparable 
  # interface on String to compare based on the Gem::Version comparator.  
  # It also adds a +satisfies?+ method to check for a Gem::Requirement.
  #
  # In addition, requiring VersionString changes the +RUBY_VERSION+ constant 
  # into a VersionString. Because VersionString "is a" String, there should be
  # no ill-effects with this change since only the Comparable interface is 
  # overriden and this does not change the original operation of the == method.
  #
  # The comparator works by converting strings into Gem::Version objects, so 
  # this still works as you would expect:
  #
  #     RUBY_VERSION < '1.9'
  class VersionString < String
    include Comparable

    ##
    # Initializes a VersionString and freezes itself.
    def initialize(*args)
      super(*args)
      to_rubygem_version
      freeze
    end

    ##
    # Compares this VersionString to another String, VersionString, or 
    # Gem::Version.
    #
    # Examples:
    #
    #     Dionysus::VersionString.new('1.0') > '1.0' => false
    #     Dionysus::VersionString.new('1.0') == Gem::Version('1.0') => true
    #     Dionysus::VersionString.new('1.0') <=> Dionysus::VersionString.new('1.0') => 0
    #
    # See http://rubygems.rubyforge.org/rubygems-update/Gem/Version.html
    def <=>( obj )
      obj = obj.dup
      if obj.is_a?(String) or obj.is_a?(Gem::Version)
        obj = Gem::Version.create(obj)
      else
        raise ArgumentError, "Can only compare to a Dionysus::VersionString/String or Gem::Version"
      end

      self.to_rubygem_version <=> obj
    end
    alias_method :"eql?", :"=="

    ##
    # Determines if the given requirement String or Gem::Requirement is 
    # satisfied by this version.
    #
    # Examples:
    #
    #   Dionysus::VersionString.new('1.6.7').satisfies? '~> 1.6.0' => true
    #   Dionysus::VersionString.new('1.6.7').satisfies? Gem::Requirement('< 1.6') => false
    #
    # See http://rubygems.rubyforge.org/rubygems-update/Gem/Requirement.html
    def satisfies?( requirement )
      requirement = requirement.dup
      if requirement.is_a?(String) or requirement.is_a?(Gem::Requirement)
        requirement = Gem::Requirement.create(requirement)
      else
        raise ArgumentError, "Can only compare to a String or Gem::Requirement"
      end

      requirement.satisfied_by?(to_rubygem_version)
    end

    ##
    # Converts this VersionString into a Gem::Version
    def to_rubygem_version
      @rubygem_version ||= Gem::Version.create(self)
    end
    alias_method :to_gem_version, :to_rubygem_version

    ##
    # Indicates whether this VersionString is a prerelease.
    #
    # See http://rubygems.rubyforge.org/rubygems-update/Gem/Version.html#method-i-prerelease%3F
    def prerelease?() to_rubygem_version.prerelease?; end
  end
end

silence_warnings do
  RUBY_VERSION = Dionysus::VersionString.new(RUBY_VERSION)
end