require 'JSON'
require 'socket'
require 'websocket/driver'

module SlackRTM

  class Client
    attr_accessor :stop

    def initialize(conf = {})
      if conf[:websocket_url].nil?
        raise ArgumentError.new 'conf[:websocket_url] should be provided'
      else
        @url = init_url conf[:websocket_url]
      end

      @socket = conf[:socket]
      @driver = conf[:websocket_driver]
      @msg_queue = conf[:msg_queue] || []
      @has_been_init = false
      @stop = false
    end

    VALID = [:open, :message, :error]
    def on(type, &block)
      unless VALID.include? type
        raise ArgumentError.new "Client#on accept one of #{VALID.inspect}"
      end

      @callbacks ||= {}
      @callbacks[type] = block
    end

    def send(data)
      data[:id] ||= SecureRandom.random_number 9999999
      @msg_queue << data.to_json
    end

    # This init has been delayed because the SSL handshake is a blocking and
    # expensive call
    def init
      return if @has_been_init

      @socket = init_socket(@socket)
      @socket.connect # costly and blocking !

      internalWrapper = (Struct.new :url, :socket do
        def write(*args)
          self.socket.write(*args)
        end
      end).new @url.to_s, @socket

      # this, also, is costly and blocking
      @driver = WebSocket::Driver.client internalWrapper
      @driver.on :open do
        @connected = true
        unless @callbacks[:open].nil?
          @callbacks[:open].call
        end
      end

      @driver.on :error do |event|
        @connected = false
        unless @callbacks[:error].nil?
          @callbacks[:error].call
        end
      end

      @driver.on :message do |event|
        data = JSON.parse event.data
        unless @callbacks[:message].nil?
          @callbacks[:message].call data
        end
      end
      @driver.start
      @has_been_init = true
    end

    def connected?
      @connected || false
    end

    # All the polling work is done here
    def inner_loop
      return if @stop
      data = @socket.readpartial 4096
      return if data.nil? or data.empty?

      @driver.parse data
      @msg_queue.each {|msg| driver.text msg}
      @msg_queue.clear
    end

    # A dumb simple main loop.
    def main_loop
      init
      loop do
        inner_loop
      end
    end

    private

    def init_url(url)
      url = if url.kind_of? URI then url else URI(url) end
      if url.scheme != 'wss'
        raise ArgumentError.new "config[:websocket_url] should be a valid websocket secure url !"
      end

      url
    end

    def init_socket(socket = nil)
      if socket.kind_of? OpenSSL::SSL::SSLSocket
        socket
      elsif socket.kind_of? TCPSocket
        OpenSSL::SSL::SSLSocket.new socket
      else
        OpenSSL::SSL::SSLSocket.new TCPSocket.new @url.host, 443
      end
    end
  end
  
end