class Gem::Commands::DependencyCommand

def arguments # :nodoc:
  "REGEXP        show dependencies for gems whose names start with REGEXP"
end

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

def description # :nodoc:
  <<-EOF
e dependency commands lists which other gems a given gem depends on.  For
cal gems only the reverse dependencies can be shown (which gems depend on
e named gem).
e dependency list can be displayed in a format suitable for piping for
e with other commands.
  EOF
end

def display_pipe specs # :nodoc:
  specs.each do |spec|
    unless spec.dependencies.empty? then
      spec.dependencies.sort_by { |dep| dep.name }.each do |dep|
        say "#{dep.name} --version '#{dep.requirement}'"
      end
    end
  end
end

def display_readable specs, reverse # :nodoc:
  response = String.new
  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

def ensure_local_only_reverse_dependencies # :nodoc:
  if options[:reverse_dependencies] and remote? and not local? then
    alert_error 'Only reverse dependencies for local gems are supported.'
    terminate_interaction 1
  end
end

def ensure_specs specs # :nodoc:
  return unless specs.empty?
  patterns = options[:args].join ','
  say "No gems found matching #{patterns} (#{options[:version]})" if
    Gem.configuration.verbose
  terminate_interaction 1
end

def execute
  ensure_local_only_reverse_dependencies
  pattern = name_pattern options[:args]
  dependency =
    gem_dependency pattern, options[:version], options[:prerelease]
  specs = fetch_specs pattern, dependency
  reverse = reverse_dependencies specs
  if options[:pipe_format] then
    display_pipe specs
  else
    display_readable specs, reverse
  end
end

def fetch_remote_specs dependency # :nodoc:
  fetcher = Gem::SpecFetcher.fetcher
  ss, = fetcher.spec_for_dependency dependency
  ss.map { |spec, _| spec }
end

def fetch_specs name_pattern, dependency # :nodoc:
  specs = []
  if local?
    specs.concat Gem::Specification.stubs.find_all { |spec|
      name_pattern =~ spec.name and
        dependency.requirement.satisfied_by? spec.version
    }.map(&:to_spec)
  end
  specs.concat fetch_remote_specs dependency if remote?
  ensure_specs specs
  specs.uniq.sort
end

def find_reverse_dependencies spec # :nodoc:
  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 gem_dependency pattern, version, prerelease # :nodoc:
  dependency = Gem::Deprecate.skip_during {
    Gem::Dependency.new pattern, version
  }
  dependency.prerelease = prerelease
  dependency
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 name_pattern args
  args << '' if args.empty?
  if args.length == 1 and args.first =~ /\A\/(.*)\/(i)?\z/m then
    flags = $2 ? Regexp::IGNORECASE : nil
    Regexp.new $1, flags
  else
    /\A#{Regexp.union(*args)}/
  end
end

def print_dependencies(spec, level = 0) # :nodoc:
  response = String.new
  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 remote_specs dependency # :nodoc:
  fetcher = Gem::SpecFetcher.fetcher
  ss, _ = fetcher.spec_for_dependency dependency
  ss.map { |s,o| s }
end

def reverse_dependencies specs # :nodoc:
  reverse = Hash.new { |h, k| h[k] = [] }
  return reverse unless options[:reverse_dependencies]
  specs.each do |spec|
    reverse[spec.full_name] = find_reverse_dependencies spec
  end
  reverse
end

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