class WWW::Mechanize::Chain::URIResolver

def handle(ctx, params)
  raise ArgumentError.new('uri must be specified') unless params[:uri]
  uri     = params[:uri]
  referer = params[:referer]
  unless uri.is_a?(URI)
    uri = uri.to_s.strip.gsub(/[^#{0.chr}-#{126.chr}]/) { |match|
      sprintf('%%%X', match.unpack($KCODE == 'UTF8' ? 'U' : 'c')[0])
    }
    escaped_uri = Util.html_unescape(
      uri.split(/(?:%[0-9A-Fa-f]{2})+|#/).zip(
        uri.scan(/(?:%[0-9A-Fa-f]{2})+|#/)
      ).map { |x,y|
        "#{URI.escape(x)}#{y}"
      }.join('')
    )
    begin
      uri = URI.parse(escaped_uri)
    rescue
      uri = URI.parse(URI.escape(escaped_uri))
    end
  end
  uri = @scheme_handlers[
    uri.relative? ? 'relative' : uri.scheme.downcase
  ].call(uri, params[:referer])
  if params[:referer] && params[:referer].uri
    if uri.path.length == 0 && uri.relative?
      uri.path = params[:referer].uri.path
    end
  end
  uri.path = '/' if uri.path.length == 0
  if uri.relative?
    raise 'need absolute URL' unless referer && referer.uri
    base = referer.respond_to?(:bases) ? referer.bases.last : nil
    uri = ((base && base.uri && base.uri.absolute?) ?
            base.uri :
            referer.uri) + uri
    uri = referer.uri + uri
    # Strip initial "/.." bits from the path
    uri.path.sub!(/^(\/\.\.)+(?=\/)/, '')
  end
  unless ['http', 'https', 'file'].include?(uri.scheme.downcase)
    raise "unsupported scheme: #{uri.scheme}"
  end
  params[:uri] = uri
  super
end

def initialize(scheme_handlers)
  @scheme_handlers = scheme_handlers
end