class Rack::Handler::FastCGI

def self.run(app, **options)
  if options[:File]
    STDIN.reopen(UNIXServer.new(options[:File]))
  elsif options[:Port]
    STDIN.reopen(TCPServer.new(options[:Host], options[:Port]))
  end
  FCGI.each { |request|
    serve request, app
  }
end

def self.send_body(out, body)
  body.each { |part|
    out.print part
    out.flush
  }
end

def self.send_headers(out, status, headers)
  out.print "Status: #{status}\r\n"
  headers.each { |k, vs|
    vs.split("\n").each { |v|
      out.print "#{k}: #{v}\r\n"
    }
  }
  out.print "\r\n"
  out.flush
end

def self.serve(request, app)
  env = request.env
  env.delete "HTTP_CONTENT_LENGTH"
  env[SCRIPT_NAME] = ""  if env[SCRIPT_NAME] == "/"
  rack_input = RewindableInput.new(request.in)
  env.update(
    RACK_VERSION      => Rack::VERSION,
    RACK_INPUT        => rack_input,
    RACK_ERRORS       => request.err,
    RACK_MULTITHREAD  => false,
    RACK_MULTIPROCESS => true,
    RACK_RUNONCE      => false,
    RACK_URL_SCHEME   => ["yes", "on", "1"].include?(env[HTTPS]) ? "https" : "http"
  )
  env[QUERY_STRING] ||= ""
  env[HTTP_VERSION] ||= env[SERVER_PROTOCOL]
  env[REQUEST_PATH] ||= "/"
  env.delete "CONTENT_TYPE"  if env["CONTENT_TYPE"] == ""
  env.delete "CONTENT_LENGTH"  if env["CONTENT_LENGTH"] == ""
  begin
    status, headers, body = app.call(env)
    begin
      send_headers request.out, status, headers
      send_body request.out, body
    ensure
      body.close  if body.respond_to? :close
    end
  ensure
    rack_input.close
    request.finish
  end
end

def self.valid_options
  environment  = ENV['RACK_ENV'] || 'development'
  default_host = environment == 'development' ? 'localhost' : '0.0.0.0'
  {
    "Host=HOST" => "Hostname to listen on (default: #{default_host})",
    "Port=PORT" => "Port to listen on (default: 8080)",
    "File=PATH" => "Creates a Domain socket at PATH instead of a TCP socket. Ignores Host and Port if set.",
  }
end