local class = require"common.class"
local Chunk = require"common.chunk".Chunk
local json = require"common.dkjson"

local ChunkS = class.extend(Chunk)
function ChunkS.make(cls,...)
	local self = Chunk.make(cls,...)
	self.dirty = false
	return self
end
function ChunkS.load_from_disk(cls,cp)
	-- returns nil if not there
	local filename = cp:filename()
	local f = io.open(filename,"r")
	if not f then return nil end
	local j = json.decode(f:read("a"))
	self = cls:from_packet_data(j)
	f:close()
	return self
end
function ChunkS.save_if_dirty(self)
	if self.dirty then
		print("saving chunk",self.cp)
		local filename = self.cp:filename()
		local f = io.open(filename,"w")
		f:write(self:data_packet())
		f:flush()
		f:close()
		self.dirty = false
	end
end
function ChunkS.set_at(self,...)
	Chunk.set_at(self,...)
	self.dirty = true
end

return {ChunkS=ChunkS}