class Bundler::Resolver::Strategy

def initialize(source)
  @source = source
end

def most_preferred_version_of(package, range)
  versions = @source.versions_for(package, range)
  # Conditional avoids (among other things) calling
  # sort_versions_by_preferred with the root package
  if versions.size > 1
    @source.sort_versions_by_preferred(package, versions)
  else
    versions
  end
end

def next_package_and_version(unsatisfied)
  package, range = next_term_to_try_from(unsatisfied)
  [package, most_preferred_version_of(package, range).first]
end

def next_term_to_try_from(unsatisfied)
  unsatisfied.min_by do |package, range|
    matching_versions = @source.versions_for(package, range)
    higher_versions = @source.versions_for(package, range.upper_invert)
    [matching_versions.count <= 1 ? 0 : 1, higher_versions.count]
  end
end