# -*- encoding: binary -*-
require 'revactor'
Revactor::VERSION >= '0.1.5' or abort 'revactor 0.1.5 is required'

module Rainbows

  # Enables use of the Actor model through
  # {Revactor}[http://revactor.org] under Ruby 1.9.  It spawns one
  # long-lived Actor for every listen socket in the process and spawns a
  # new Actor for every client connection accept()-ed.
  # +worker_connections+ will limit the number of client Actors we have
  # running at any one time.
  #
  # Applications using this model are required to be reentrant, but do
  # not have to worry about race conditions unless they use threads
  # internally.  \Rainbows! does not spawn threads under this model.
  # Multiple instances of the same app may run in the same address space
  # sequentially (but at interleaved points).  Any network dependencies
  # in the application using this model should be implemented using the
  # \Revactor library as well, to take advantage of the networking
  # concurrency features this model provides.

  module Revactor
    require 'rainbows/revactor/tee_input'

    include Base

    # once a client is accepted, it is processed in its entirety here
    # in 3 easy steps: read request, call app, write app response
    def process_client(client)
      buf = client.read or return # this probably does not happen...
      hp = HttpParser.new
      env = {}
      alive = true
      remote_addr = ::Revactor::TCP::Socket === client ?
                    client.remote_addr : LOCALHOST

      begin
        while ! hp.headers(env, buf)
          buf << client.read
        end

        env[Const::RACK_INPUT] = 0 == hp.content_length ?
                 HttpRequest::NULL_IO :
                 Rainbows::Revactor::TeeInput.new(client, env, hp, buf)
        env[Const::REMOTE_ADDR] = remote_addr
        response = app.call(env.update(RACK_DEFAULTS))

        if 100 == response.first.to_i
          client.write(Const::EXPECT_100_RESPONSE)
          env.delete(Const::HTTP_EXPECT)
          response = app.call(env)
        end

        alive = hp.keepalive? && G.alive
        out = [ alive ? CONN_ALIVE : CONN_CLOSE ] if hp.headers?
        HttpResponse.write(client, response, out)
      end while alive and hp.reset.nil? and env.clear
      client.close
    # if we get any error, try to write something back to the client
    # assuming we haven't closed the socket, but don't get hung up
    # if the socket is already closed or broken.  We'll always ensure
    # the socket is closed at the end of this function
    rescue EOFError,Errno::ECONNRESET,Errno::EPIPE,Errno::EINVAL,Errno::EBADF
      emergency_response(client, Const::ERROR_500_RESPONSE)
    rescue HttpParserError # try to tell the client they're bad
      buf.empty? or emergency_response(client, Const::ERROR_400_RESPONSE)
    rescue Object => e
      emergency_response(client, Const::ERROR_500_RESPONSE)
      logger.error "Read error: #{e.inspect}"
      logger.error e.backtrace.join("\n")
    end

    # runs inside each forked worker, this sits around and waits
    # for connections and doesn't die until the parent dies (or is
    # given a INT, QUIT, or TERM signal)
    def worker_loop(worker)
      init_worker_process(worker)

      root = Actor.current
      root.trap_exit = true

      limit = worker_connections
      revactorize_listeners!
      clients = {}

      listeners = LISTENERS.map do |s|
        Actor.spawn(s) do |l|
          begin
            while clients.size >= limit
              logger.info "busy: clients=#{clients.size} >= limit=#{limit}"
              Actor.receive { |filter| filter.when(:resume) {} }
            end
            actor = Actor.spawn(l.accept) { |c| process_client(c) }
            clients[actor.object_id] = actor
            root.link(actor)
          rescue Errno::EAGAIN, Errno::ECONNABORTED
          rescue Object => e
            listen_loop_error(e)
          end while G.alive
        end
      end

      m = 0
      check_quit = lambda do
        worker.tmp.chmod(m = 0 == m ? 1 : 0)
        G.alive = false if master_pid != Process.ppid
      end

      begin
        Actor.receive do |filter|
          filter.after(1, &check_quit)
          filter.when(Case[:exit, Actor, Object]) do |_,actor,_|
            orig = clients.size
            clients.delete(actor.object_id)
            orig >= limit and listeners.each { |l| l << :resume }
            check_quit.call
          end
        end
      end while G.alive || clients.size > 0
    end

  private

    # write a response without caring if it went out or not
    # This is in the case of untrappable errors
    def emergency_response(client, response_str)
      client.instance_eval do
        # this is Revactor implementation dependent
        @_io.write_nonblock(response_str) rescue nil
      end
      client.close rescue nil
    end

    def revactorize_listeners!
      LISTENERS.map! do |s|
        case s
        when TCPServer
          ::Revactor::TCP.listen(s, nil)
        when UNIXServer
          ::Revactor::UNIX.listen(s)
        end
      end
    end

  end
end