require 'socket'
require 'http11'
require 'tempfile'
require 'yaml'
require 'time'
require 'etc'
require 'uri'
require 'stringio'

begin
  require 'fastthread'
rescue LoadError, RuntimeError
  require 'rubygems' and retry
ensure
  require 'thread'
end

begin
  require 'cgi_multipart_eof_fix'
rescue LoadError
  require 'rubygems' and retry
end

require 'mongrel/cgi'
require 'mongrel/handlers'
require 'mongrel/command'
require 'mongrel/tcphack'
require 'mongrel/configurator'
require 'mongrel/uri_classifier'
require 'mongrel/const'
require 'mongrel/http_request'
require 'mongrel/header_out'
require 'mongrel/http_response'

# Mongrel module containing all of the classes (include C extensions) for running
# a Mongrel web server.  It contains a minimalist HTTP server with just enough
# functionality to service web application requests fast as possible.
module Mongrel

  # Used to stop the HttpServer via Thread.raise.
  class StopServer < Exception; end

  # Thrown at a thread when it is timed out.
  class TimeoutError < Exception; end

  # A Hash with one extra parameter for the HTTP body, used internally.
  class HttpParams < Hash
    attr_accessor :http_body
  end


  # This is the main driver of Mongrel, while the Mongrel::HttpParser and Mongrel::URIClassifier
  # make up the majority of how the server functions.  It's a very simple class that just
  # has a thread accepting connections and a simple HttpServer.process_client function
  # to do the heavy lifting with the IO and Ruby.  
  #
  # You use it by doing the following:
  #
  #   server = HttpServer.new("0.0.0.0", 3000)
  #   server.register("/stuff", MyNiftyHandler.new)
  #   server.run.join
  #
  # The last line can be just server.run if you don't want to join the thread used.
  # If you don't though Ruby will mysteriously just exit on you.
  #
  # Ruby's thread implementation is "interesting" to say the least.  Experiments with
  # *many* different types of IO processing simply cannot make a dent in it.  Future
  # releases of Mongrel will find other creative ways to make threads faster, but don't
  # hold your breath until Ruby 1.9 is actually finally useful.
  class HttpServer
    attr_reader :acceptor
    attr_reader :workers
    attr_reader :classifier
    attr_reader :host
    attr_reader :port
    attr_reader :throttle
    attr_reader :timeout
    attr_reader :num_processors

    # Creates a working server on host:port (strange things happen if port isn't a Number).
    # Use HttpServer::run to start the server and HttpServer.acceptor.join to 
    # join the thread that's processing incoming requests on the socket.
    #
    # The num_processors optional argument is the maximum number of concurrent
    # processors to accept, anything over this is closed immediately to maintain
    # server processing performance.  This may seem mean but it is the most efficient
    # way to deal with overload.  Other schemes involve still parsing the client's request
    # which defeats the point of an overload handling system.
    # 
    # The throttle parameter is a sleep timeout (in hundredths of a second) that is placed between 
    # socket.accept calls in order to give the server a cheap throttle time.  It defaults to 0 and
    # actually if it is 0 then the sleep is not done at all.
    def initialize(host, port, num_processors=950, throttle=0, timeout=60)
      
      tries = 0
      @socket = TCPServer.new(host, port) 
      
      @classifier = URIClassifier.new
      @host = host
      @port = port
      @workers = ThreadGroup.new
      @throttle = throttle
      @num_processors = num_processors
      @timeout = timeout
    end

    # Does the majority of the IO processing.  It has been written in Ruby using
    # about 7 different IO processing strategies and no matter how it's done 
    # the performance just does not improve.  It is currently carefully constructed
    # to make sure that it gets the best possible performance, but anyone who
    # thinks they can make it faster is more than welcome to take a crack at it.
    def process_client(client)
      begin
        parser = HttpParser.new
        params = HttpParams.new
        request = nil
        data = client.readpartial(Const::CHUNK_SIZE)
        nparsed = 0

        # Assumption: nparsed will always be less since data will get filled with more
        # after each parsing.  If it doesn't get more then there was a problem
        # with the read operation on the client socket.  Effect is to stop processing when the
        # socket can't fill the buffer for further parsing.
        while nparsed < data.length
          nparsed = parser.execute(params, data, nparsed)

          if parser.finished?
            if not params[Const::REQUEST_PATH]
              # it might be a dumbass full host request header
              uri = URI.parse(params[Const::REQUEST_URI])
              params[Const::REQUEST_PATH] = uri.path
            end

            raise "No REQUEST PATH" if not params[Const::REQUEST_PATH]

            script_name, path_info, handlers = @classifier.resolve(params[Const::REQUEST_PATH])

            if handlers
              params[Const::PATH_INFO] = path_info
              params[Const::SCRIPT_NAME] = script_name

              # From http://www.ietf.org/rfc/rfc3875 :
              # "Script authors should be aware that the REMOTE_ADDR and REMOTE_HOST
              #  meta-variables (see sections 4.1.8 and 4.1.9) may not identify the
              #  ultimate source of the request.  They identify the client for the
              #  immediate request to the server; that client may be a proxy, gateway,
              #  or other intermediary acting on behalf of the actual source client."
              params[Const::REMOTE_ADDR] = client.peeraddr.last

              # select handlers that want more detailed request notification
              notifiers = handlers.select { |h| h.request_notify }
              request = HttpRequest.new(params, client, notifiers)

              # in the case of large file uploads the user could close the socket, so skip those requests
              break if request.body == nil  # nil signals from HttpRequest::initialize that the request was aborted

              # request is good so far, continue processing the response
              response = HttpResponse.new(client)

              # Process each handler in registered order until we run out or one finalizes the response.
              handlers.each do |handler|
                handler.process(request, response)
                break if response.done or client.closed?
              end

              # And finally, if nobody closed the response off, we finalize it.
              unless response.done or client.closed? 
                response.finished
              end
            else
              # Didn't find it, return a stock 404 response.
              client.write(Const::ERROR_404_RESPONSE)
            end

            break #done
          else
            # Parser is not done, queue up more data to read and continue parsing
            chunk = client.readpartial(Const::CHUNK_SIZE)
            break if !chunk or chunk.length == 0  # read failed, stop processing

            data << chunk
            if data.length >= Const::MAX_HEADER
              raise HttpParserError.new("HEADER is longer than allowed, aborting client early.")
            end
          end
        end
      rescue EOFError,Errno::ECONNRESET,Errno::EPIPE,Errno::EINVAL,Errno::EBADF
        client.close rescue nil
      rescue HttpParserError => e
        STDERR.puts "#{Time.now}: HTTP parse error, malformed request (#{params[Const::HTTP_X_FORWARDED_FOR] || client.peeraddr.last}): #{e.inspect}"
        STDERR.puts "#{Time.now}: REQUEST DATA: #{data.inspect}\n---\nPARAMS: #{params.inspect}\n---\n"
      rescue Errno::EMFILE
        reap_dead_workers('too many files')
      rescue Object => e
        STDERR.puts "#{Time.now}: Read error: #{e.inspect}"
        STDERR.puts e.backtrace.join("\n")
      ensure
        begin
          client.close
        rescue IOError
          # Already closed
        rescue Object => e
          STDERR.puts "#{Time.now}: Client error: #{e.inspect}"
          STDERR.puts e.backtrace.join("\n")
        end
        request.body.delete if request and request.body.class == Tempfile
      end
    end

    # Used internally to kill off any worker threads that have taken too long
    # to complete processing.  Only called if there are too many processors
    # currently servicing.  It returns the count of workers still active
    # after the reap is done.  It only runs if there are workers to reap.
    def reap_dead_workers(reason='unknown')
      if @workers.list.length > 0
        STDERR.puts "#{Time.now}: Reaping #{@workers.list.length} threads for slow workers because of '#{reason}'"
        error_msg = "Mongrel timed out this thread: #{reason}"
        mark = Time.now
        @workers.list.each do |worker|
          worker[:started_on] = Time.now if not worker[:started_on]

          if mark - worker[:started_on] > @timeout + @throttle
            STDERR.puts "Thread #{w.inspect} is too old, killing."
            worker.raise(TimeoutError.new(error_msg))
          end
        end
      end

      return @workers.list.length
    end

    # Performs a wait on all the currently running threads and kills any that take
    # too long.  It waits by @timeout seconds, which can be set in .initialize or
    # via mongrel_rails. The @throttle setting does extend this waiting period by
    # that much longer.
    def graceful_shutdown
      while reap_dead_workers("shutdown") > 0
        STDERR.puts "Waiting for #{@workers.list.length} requests to finish, could take #{@timeout + @throttle} seconds."
        sleep @timeout / 10
      end
    end

    def configure_socket_options
      case RUBY_PLATFORM
        when /linux/
          # 9 is currently TCP_DEFER_ACCEPT
          $tcp_defer_accept_opts = [Socket::SOL_TCP, 9, 1]
          $tcp_cork_opts = [Socket::SOL_TCP, 3, 1]
      end
    end

    # Runs the thing.  It returns the thread used so you can "join" it.  You can also
    # access the HttpServer::acceptor attribute to get the thread later.
    def run
      BasicSocket.do_not_reverse_lookup=true

      configure_socket_options

      if defined?($tcp_defer_accept_opts) and $tcp_defer_accept_opts
        @socket.setsockopt(*$tcp_defer_accept_opts) rescue nil
      end

      @acceptor = Thread.new do
        begin
          while true
            begin
              client = @socket.accept
  
              if defined?($tcp_cork_opts) and $tcp_cork_opts
                client.setsockopt(*$tcp_cork_opts) rescue nil
              end
  
              worker_list = @workers.list
  
              if worker_list.length >= @num_processors
                STDERR.puts "Server overloaded with #{worker_list.length} processors (#@num_processors max). Dropping connection."
                client.close rescue nil
                reap_dead_workers("max processors")
              else
                thread = Thread.new(client) {|c| process_client(c) }
                thread[:started_on] = Time.now
                @workers.add(thread)
  
                sleep @throttle/100.0 if @throttle > 0
              end
            rescue StopServer
              break
            rescue Errno::EMFILE
              reap_dead_workers("too many open files")
              sleep 0.5
            rescue Errno::ECONNABORTED
              # client closed the socket even before accept
              client.close rescue nil
            rescue Object => e
              STDERR.puts "#{Time.now}: Unhandled listen loop exception #{e.inspect}."
              STDERR.puts e.backtrace.join("\n")
            end
          end
          graceful_shutdown
        ensure
          @socket.close
          # STDERR.puts "#{Time.now}: Closed socket."
        end
      end

      return @acceptor
    end

    # Simply registers a handler with the internal URIClassifier.  When the URI is
    # found in the prefix of a request then your handler's HttpHandler::process method
    # is called.  See Mongrel::URIClassifier#register for more information.
    #
    # If you set in_front=true then the passed in handler will be put in the front of the list
    # for that particular URI. Otherwise it's placed at the end of the list.
    def register(uri, handler, in_front=false)
      begin
        @classifier.register(uri, [handler])
      rescue URIClassifier::RegistrationError
        handlers = @classifier.resolve(uri)[2]
        method_name = in_front ? 'unshift' : 'push'
        handlers.send(method_name, handler)
      end
      handler.listener = self
    end

    # Removes any handlers registered at the given URI.  See Mongrel::URIClassifier#unregister
    # for more information.  Remember this removes them *all* so the entire
    # processing chain goes away.
    def unregister(uri)
      @classifier.unregister(uri)
    end

    # Stops the acceptor thread and then causes the worker threads to finish
    # off the request queue before finally exiting.
    def stop(synchronous=false)
      @acceptor.raise(StopServer.new)

      if synchronous
        sleep(0.5) while @acceptor.alive?
      end
    end

  end
end

# Load experimental library, if present. We put it here so it can override anything
# in regular Mongrel.

begin  
  # Look for SVN version
  $LOAD_PATH.unshift 'projects/mongrel_experimental/lib/'
  require 'mongrel_experimental'  
rescue LoadError
  begin
    # Look for gem
    gem 'mongrel_experimental', '=1.1' if respond_to? 'gem'
    require 'mongrel_experimental'  
  rescue LoadError
    # Not found
  end
end