class RSpec::Mocks::MessageChain

def chain_on(object, *chain, &block)
  initialize(object, *chain, &block)
  setup_chain
end

def expectation(object, message, &return_block)
  raise NotImplementedError.new
end

def find_matching_expectation
  ::RSpec::Mocks.space.proxy_for(object).
    __send__(:find_matching_expectation, chain.first.to_sym)
end

def find_matching_stub
  ::RSpec::Mocks.space.proxy_for(object).
    __send__(:find_matching_method_stub, chain.first.to_sym)
end

def format_chain(*chain, &blk)
  if Hash === chain.last
    hash = chain.pop
    hash.each do |k,v|
      chain << k
      blk = Proc.new { v }
    end
  end
  return chain.join('.').split('.'), blk
end

def initialize(object, *chain, &blk)
  @object = object
  @chain, @block = format_chain(*chain, &blk)
end

def setup_chain
  if chain.length > 1
    if matching_stub = find_matching_stub
      chain.shift
      chain_on(matching_stub.invoke(nil), *chain, &@block)
    elsif matching_expectation = find_matching_expectation
      chain.shift
      chain_on(matching_expectation.invoke_without_incrementing_received_count(nil), *chain, &@block)
    else
      next_in_chain = Double.new
      expectation(object, chain.shift) { next_in_chain }
      chain_on(next_in_chain, *chain, &@block)
    end
  else
    expectation(object, chain.shift, &@block)
  end
end