class Gem::Commands::DependencyCommand

def arguments # :nodoc:
  "GEMNAME       name of gem to show dependencies for"
end

def defaults_str # :nodoc:
  "--local --version '#{Gem::Requirement.default}' --no-reverse-dependencies"
end

def execute
  if options[:reverse_dependencies] and remote? and not local? then
    alert_error 'Only reverse dependencies for local gems are supported.'
    terminate_interaction 1
  end
  options[:args] << '' if options[:args].empty?
  pattern = if options[:args].length == 1 and
               options[:args].first =~ /\A\/(.*)\/(i)?\z/m then
              flags = $2 ? Regexp::IGNORECASE : nil
              Regexp.new $1, flags
            else
              /\A#{Regexp.union(*options[:args])}/
            end
  # TODO: deprecate for real damnit
  dependency = Gem::Deprecate.skip_during {
    Gem::Dependency.new pattern, options[:version]
  }
  dependency.prerelease = options[:prerelease]
  specs = []
  specs.concat dependency.matching_specs if local?
  if remote? and not options[:reverse_dependencies] then
    fetcher = Gem::SpecFetcher.fetcher
    ss, _ = fetcher.spec_for_dependency dependency
    ss.each { |s,o| specs << s }
  end
  if specs.empty? then
    patterns = options[:args].join ','
    say "No gems found matching #{patterns} (#{options[:version]})" if
      Gem.configuration.verbose
    terminate_interaction 1
  end
  specs = specs.uniq.sort
  reverse = Hash.new { |h, k| h[k] = [] }
  if options[:reverse_dependencies] then
    specs.each do |spec|
      reverse[spec.full_name] = find_reverse_dependencies spec
    end
  end
  if options[:pipe_format] then
    specs.each do |spec|
      unless spec.dependencies.empty?
        spec.dependencies.sort_by { |dep| dep.name }.each do |dep|
          say "#{dep.name} --version '#{dep.requirement}'"
        end
      end
    end
  else
    response = ''
    specs.each do |spec|
      response << print_dependencies(spec)
      unless reverse[spec.full_name].empty? then
        response << "  Used by\n"
        reverse[spec.full_name].each do |sp, dep|
          response << "    #{sp} (#{dep})\n"
        end
      end
      response << "\n"
    end
    say response
  end
end

def find_reverse_dependencies(spec)
  result = []
  Gem::Specification.each do |sp|
    sp.dependencies.each do |dep|
      dep = Gem::Dependency.new(*dep) unless Gem::Dependency === dep
      if spec.name == dep.name and
         dep.requirement.satisfied_by?(spec.version) then
        result << [sp.full_name, dep]
      end
    end
  end
  result
end

def initialize
  super 'dependency',
        'Show the dependencies of an installed gem',
        :version => Gem::Requirement.default, :domain => :local
  add_version_option
  add_platform_option
  add_prerelease_option
  add_option('-R', '--[no-]reverse-dependencies',
             'Include reverse dependencies in the output') do
    |value, options|
    options[:reverse_dependencies] = value
  end
  add_option('-p', '--pipe',
             "Pipe Format (name --version ver)") do |value, options|
    options[:pipe_format] = value
  end
  add_local_remote_options
end

def print_dependencies(spec, level = 0)
  response = ''
  response << '  ' * level + "Gem #{spec.full_name}\n"
  unless spec.dependencies.empty? then
    spec.dependencies.sort_by { |dep| dep.name }.each do |dep|
      response << '  ' * level + "  #{dep}\n"
    end
  end
  response
end

def usage # :nodoc:
  "#{program_name} GEMNAME"
end