class HTTPClient::SessionManager

def add_cached_session(sess)
  @sess_pool_mutex.synchronize do
    (@sess_pool[sess.dest] ||= []).unshift(sess)
  end
end

def close(dest)
  if cached = get_cached_session(Site.new(dest))
    cached.close
    true
  else
    false
  end
end

def close_all
  @sess_pool_mutex.synchronize do
    @sess_pool.each do |site, pool|
      pool.each do |sess|
        sess.close
      end
    end
  end
  @sess_pool.clear
end

def get_cached_session(site)
  if Thread.current[:HTTPClient_AcquireNewConnection]
    return nil
  end
  @sess_pool_mutex.synchronize do
    now = Time.now
    if now > @sess_pool_last_checked + @keep_alive_timeout
      scrub_cached_session(now)
      @sess_pool_last_checked = now
    end
    if pool = @sess_pool[site]
      pool.each_with_index do |sess, idx|
        if valid_session?(sess, now)
          return pool.slice!(idx)
        end
      end
    end
  end
  nil
end

def get_session(req, via_proxy = false)
  uri = req.header.request_uri
  if uri.scheme.nil?
    raise ArgumentError.new("Request URI must have schema. Possibly add 'http://' to the request URI?")
  end
  site = Site.new(uri)
  if cached = get_cached_session(site)
    cached
  else
    open(uri, via_proxy)
  end
end

def initialize(client)
  @client = client
  @proxy = client.proxy
  @agent_name = nil
  @from = nil
  @protocol_version = nil
  @debug_dev = client.debug_dev
  @socket_sync = true
  @tcp_keepalive = false
  @chunk_size = ::HTTP::Message::Body::DEFAULT_CHUNK_SIZE
  @connect_timeout = 60
  @connect_retry = 1
  @send_timeout = 120
  @receive_timeout = 60        # For each read_block_size bytes
  @keep_alive_timeout = 15     # '15' is from Apache 2 default
  @read_block_size = 1024 * 16 # follows net/http change in 1.8.7
  @protocol_retry_count = 5
  @ssl_config = nil
  @test_loopback_http_response = []
  @transparent_gzip_decompression = false
  @strict_response_size_check = false
  @socket_local = Site.new
  @sess_pool = {}
  @sess_pool_mutex = Mutex.new
  @sess_pool_last_checked = Time.now
end

def keep(sess)
  add_cached_session(sess)
end

def open(uri, via_proxy = false)
  site = Site.new(uri)
  sess = Session.new(@client, site, @agent_name, @from)
  sess.proxy = via_proxy ? @proxy : nil
  sess.socket_sync = @socket_sync
  sess.tcp_keepalive = @tcp_keepalive
  sess.requested_version = @protocol_version if @protocol_version
  sess.connect_timeout = @connect_timeout
  sess.connect_retry = @connect_retry
  sess.send_timeout = @send_timeout
  sess.receive_timeout = @receive_timeout
  sess.read_block_size = @read_block_size
  sess.protocol_retry_count = @protocol_retry_count
  sess.ssl_config = @ssl_config
  sess.debug_dev = @debug_dev
  sess.strict_response_size_check = @strict_response_size_check
  sess.socket_local = @socket_local
  sess.test_loopback_http_response = @test_loopback_http_response
  sess.transparent_gzip_decompression = @transparent_gzip_decompression
  sess
end

def proxy=(proxy)
  if proxy.nil?
    @proxy = nil
  else
    @proxy = Site.new(proxy)
  end
end

def query(req, via_proxy)
  req.http_body.chunk_size = @chunk_size if req.http_body
  sess = get_session(req, via_proxy)
  begin
    sess.query(req)
  rescue
    sess.close
    raise
  end
  sess
end

def reset(uri)
  site = Site.new(uri)
  close(site)
end

def reset_all
  close_all
end

def scrub_cached_session(now)
  @sess_pool.each do |site, pool|
    pool.replace(pool.select { |sess|
      if valid_session?(sess, now)
        true
      else
        sess.close # close & remove from the pool
        false
      end
    })
  end
end

def valid_session?(sess, now)
  (now <= sess.last_used + @keep_alive_timeout)
end