local Map = require"common.map".Map
local class = require"common.class"
local worldgen = require"worldgen"
local json = require"common.dkjson"

local MapS = class.extend(Map)
function MapS.obtain(self,cp)
	-- obtain chunk at chunkpos cp by any means necessary
	-- if already loaded, just return it
	-- if available on disk, load that then return it
	-- otherwise, generate a new chunk, load it, then return it.

	-- false is not used on serverside. yet.

	local ch = self:chunk(cp)
	if ch then return ch end

	local f = io.open(cp:filename(),"r")
	if f then
		local j = json.decode(f:read("a"))
		ch = Chunk:from_packet_data(j)
		f:close()
	else
		ch = worldgen.gen_chunk(cp)
	end

	self:add_chunk(ch)
	return ch
end
function MapS.save_chunk(self,cp)
	-- any attempt to save not-loaded chunks is silently ignored
	local ch = self:chunk(cp)
	if not ch then return end

	local f = io.open(cp:filename(),"w")
	f:write(ch:data_packet())
	f:flush()
	f:close()
end
function MapS.save_and_unload(self,cp)
	self:save_chunk(cp)
	self:remove_chunk(cp)
end

return {MapS=MapS}