local stm = require "skynet.stm"
  local sprotoloader = require "sprotoloader"
  local sproto = require "sproto"
  local setmetatable = setmetatable
  
  local sharemap = {}
  
  function sharemap.register(protofile)
  	-- use global slot 0 for type define
  	sprotoloader.register(protofile, 0)
  end
  
  local sprotoobj
  local function loadsp()
  	if sprotoobj == nil then
  		sprotoobj = sprotoloader.load(0)
  	end
  	return sprotoobj
  end
  
  function sharemap:commit()
  	self.__obj(sprotoobj:encode(self.__typename, self.__data))
  end
  
  function sharemap:copy()
  	return stm.copy(self.__obj)
  end
  
  function sharemap.writer(typename, obj)
  	local sp = loadsp()
  	obj = obj or {}
  	local stmobj = stm.new(sp:encode(typename,obj))
  	local ret = {
  		__typename = typename,
  		__obj = stmobj,
  		__data = obj,
  		commit = sharemap.commit,
  		copy = sharemap.copy,
  	}
  	return setmetatable(ret, { __index = obj, __newindex = obj })
  end
  
  local function decode(msg, sz, self)
  	local data = self.__data
  	for k in pairs(data) do
  		data[k] = nil
  	end
  	return sprotoobj:decode(self.__typename, msg, sz, data)
  end
  
  function sharemap:update()
  	return self.__obj(decode, self)
  end
  
  function sharemap.reader(typename, stmcpy)
  	local sp = loadsp()
  	local stmobj = stm.newcopy(stmcpy)
  	local _, data = stmobj(function(msg, sz)
  		return sp:decode(typename, msg, sz)
  	end)
  
  	local obj = {
  		__typename = typename,
  		__obj = stmobj,
  		__data = data,
  		update = sharemap.update,
  	}
  	return setmetatable(obj, { __index = data, __newindex = error })
  end
  
  return sharemap