# -*- 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'

    RD_ARGS = {}

    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)
      defined?(Fcntl::FD_CLOEXEC) and
        client.instance_eval { @_io.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) }
      rd_args = [ nil ]
      remote_addr = if ::Revactor::TCP::Socket === client
        rd_args << RD_ARGS
        client.remote_addr
      else
        LOCALHOST
      end
      buf = client.read(*rd_args)
      hp = HttpParser.new
      env = {}
      alive = true

      begin
        while ! hp.headers(env, buf)
          buf << client.read(*rd_args)
        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
    rescue ::Revactor::TCP::ReadError
    rescue => e
      handle_error(client, e)
    ensure
      client.close
    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)
      RD_ARGS[:timeout] = G.kato if G.kato > 0

      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 => e
            Error.listen_loop(e)
          end while G.alive
        end
      end

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

    # 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
    def handle_error(client, e)
      # this is Revactor implementation dependent
      msg = Error.response(e) and
        client.instance_eval { @_io.write_nonblock(msg) }
      rescue
    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