class Gem::Dependency

def <=>(other)
  name <=> other.name
end

def ==(other) # :nodoc:
  Gem::Dependency === other &&
    name        == other.name &&
    type        == other.type &&
    requirement == other.requirement
end

def =~(other)
  unless Gem::Dependency === other
    return unless other.respond_to?(:name) && other.respond_to?(:version)
    other = Gem::Dependency.new other.name, other.version
  end
  return false unless name === other.name
  reqs = other.requirement.requirements
  return false unless reqs.length == 1
  return false unless reqs.first.first == "="
  version = reqs.first.last
  requirement.satisfied_by? version
end

def encode_with(coder) # :nodoc:
  coder.add "name", @name
  coder.add "requirement", @requirement
  coder.add "type", @type
  coder.add "prerelease", @prerelease
  coder.add "version_requirements", @version_requirements
end

def hash # :nodoc:
  name.hash ^ type.hash ^ requirement.hash
end

def identity
  if prerelease?
    if specific?
      :complete
    else
      :abs_latest
    end
  elsif latest_version?
    :latest
  else
    :released
  end
end

def initialize(name, *requirements)
  case name
  when String then # ok
  when Regexp then
    msg = ["NOTE: Dependency.new w/ a regexp is deprecated.",
           "Dependency.new called from #{Gem.location_of_caller.join(":")}"]
    warn msg.join("\n") unless Gem::Deprecate.skip
  else
    raise ArgumentError,
          "dependency name must be a String, was #{name.inspect}"
  end
  type         = Symbol === requirements.last ? requirements.pop : :runtime
  requirements = requirements.first if requirements.length == 1 # unpack
  unless TYPES.include? type
    raise ArgumentError, "Valid types are #{TYPES.inspect}, " \
                         "not #{type.inspect}"
  end
  @name        = name
  @requirement = Gem::Requirement.create requirements
  @type        = type
  @prerelease  = false
  # This is for Marshal backwards compatibility. See the comments in
  # +requirement+ for the dirty details.
  @version_requirements = @requirement
end

def inspect # :nodoc:
  if prerelease?
    format("<%s type=%p name=%p requirements=%p prerelease=ok>", self.class, type, name, requirement.to_s)
  else
    format("<%s type=%p name=%p requirements=%p>", self.class, type, name, requirement.to_s)
  end
end

def latest_version?
  @requirement.none?
end

def match?(obj, version=nil, allow_prerelease=false)
  if !version
    name = obj.name
    version = obj.version
  else
    name = obj
  end
  return false unless self.name === name
  version = Gem::Version.new version
  return true if requirement.none? && !version.prerelease?
  return false if version.prerelease? &&
                  !allow_prerelease &&
                  !prerelease?
  requirement.satisfied_by? version
end

def matches_spec?(spec)
  return false unless name === spec.name
  return true  if requirement.none?
  requirement.satisfied_by?(spec.version)
end

def matching_specs(platform_only = false)
  matches = Gem::Specification.find_all_by_name(name, requirement)
  if platform_only
    matches.reject! do |spec|
      spec.nil? || !Gem::Platform.match_spec?(spec)
    end
  end
  matches.reject(&:ignored?)
end

def merge(other)
  unless name == other.name
    raise ArgumentError,
          "#{self} and #{other} have different names"
  end
  default = Gem::Requirement.default
  self_req = requirement
  other_req = other.requirement
  return self.class.new name, self_req  if other_req == default
  return self.class.new name, other_req if self_req  == default
  self.class.new name, self_req.as_list.concat(other_req.as_list)
end

def prerelease?
  @prerelease || requirement.prerelease?
end

def pretty_print(q) # :nodoc:
  q.group 1, "Gem::Dependency.new(", ")" do
    q.pp name
    q.text ","
    q.breakable
    q.pp requirement
    q.text ","
    q.breakable
    q.pp type
  end
end

def requirement
  return @requirement if defined?(@requirement) && @requirement
  # @version_requirements and @version_requirement are legacy ivar
  # names, and supported here because older gems need to keep
  # working and Dependency doesn't implement marshal_dump and
  # marshal_load. In a happier world, this would be an
  # attr_accessor. The horrifying instance_variable_get you see
  # below is also the legacy of some old restructurings.
  #
  # Note also that because of backwards compatibility (loading new
  # gems in an old RubyGems installation), we can't add explicit
  # marshaling to this class until we want to make a big
  # break. Maybe 2.0.
  #
  # Children, define explicit marshal and unmarshal behavior for
  # public classes. Marshal formats are part of your public API.
  # REFACTOR: See above
  if defined?(@version_requirement) && @version_requirement
    version = @version_requirement.instance_variable_get :@version
    @version_requirement = nil
    @version_requirements = Gem::Requirement.new version
  end
  @requirement = @version_requirements if defined?(@version_requirements)
end

def requirements_list
  requirement.as_list
end

def runtime?
  @type == :runtime || !@type
end

def specific?
  @requirement.specific?
end

def to_s # :nodoc:
  if type != :runtime
    "#{name} (#{requirement}, #{type})"
  else
    "#{name} (#{requirement})"
  end
end

def to_spec
  matches = to_specs.compact
  active = matches.find(&:activated?)
  return active if active
  unless prerelease?
    # Consider prereleases only as a fallback
    pre, matches = matches.partition {|spec| spec.version.prerelease? }
    matches = pre if matches.empty?
  end
  matches.first
end

def to_specs
  matches = matching_specs true
  # TODO: check Gem.activated_spec[self.name] in case matches falls outside
  if matches.empty?
    specs = Gem::Specification.stubs_for name
    if specs.empty?
      raise Gem::MissingSpecError.new name, requirement
    else
      raise Gem::MissingSpecVersionError.new name, requirement, specs
    end
  end
  # TODO: any other resolver validations should go here
  matches
end

def type
  @type ||= :runtime
end