begin
  require 'em-redis'
rescue LoadError => error
  raise 'Missing EM-Synchrony dependency: gem install em-redis'
end

module EventMachine
  module Protocols
    module Redis
      attr_reader :connected

      class << self
        alias :aconnect :connect
      end

      def self.connect(*args)
        f = Fiber.current

        conn = self.aconnect(*args)
        conn.callback { f.resume(conn) }

        Fiber.yield
      end

      alias :old_call_command :call_command

      SYNC = ['add', 'auth']
      def call_command(argv, &blk)
        # async commands are 'a' prefixed
        if (argv.first[0] == 'a') && !SYNC.include?(argv.first.to_s)
          argv[0] = argv[0].to_s.slice(1,argv[0].size)
          old_call_command(argv, &blk)

        else
          # wrap response blocks into fiber callbacks
          # to emulate the sync api
          f = Fiber.current
          blk = proc { |v| v } if !block_given?
          clb = proc { |v| f.resume(blk.call(v)) }

          old_call_command(argv, &clb)
          Fiber.yield
        end
      end

      # adapted from em-redis' implementation to use
      # the asynchronous version of mget
      def amapped_mget(*keys)
        self.amget(*keys) do |response|
          result = {}
          response.each do |value|
            key = keys.shift
            result.merge!(key => value) unless value.nil?
          end
          yield result if block_given?
        end
      end

      def mapped_mget(*keys)
        f = Fiber.current

        self.amapped_mget(*keys) do |values|
          f.resume(values)
        end

        Fiber.yield
      end
    end
  end
end