local format = string.format;

local setmetatable, type = setmetatable, type;

local pairs = pairs;

local char = string.char;

local loadfile, setfenv, pcall = loadfile, setfenv, pcall;

local log = log;

local io_open = io.open;

local tostring = tostring;

module "datamanager"

---- utils -----

local encode, decode;

local log = function (type, msg) return log(type, "datamanager", msg); end

do 

	local urlcodes = setmetatable({}, { __index = function (t, k) t[k] = char(tonumber("0x"..k)); return t[k]; end });

	decode = function (s)

		return s and (s:gsub("+", " "):gsub("%%([a-fA-F0-9][a-fA-F0-9])", urlcodes));

	end

	encode = function (s)

		return s and (s:gsub("%W", function (c) return format("%%%x", c:byte()); end));

	end

end

local function basicSerialize (o)

  if type(o) == "number" or type(o) == "boolean" then

    return tostring(o)

  else -- assume it is a string

    return format("%q", tostring(o))

  end

end

local function simplesave (f, o)

      if type(o) == "number" then

        f:write(o)

      elseif type(o) == "string" then

        f:write(format("%q", o))

      elseif type(o) == "table" then

        f:write("{\n")

        for k,v in pairs(o) do

          f:write(" [", basicSerialize(k), "] = ")

          simplesave(f, v)

          f:write(",\n")

        end

        f:write("}\n")

      else

        error("cannot serialize a " .. type(o))

      end

    end

------- API -------------

function getpath(username, host, datastore)

	if username then

		return format("data/%s/%s/%s.dat", encode(host), datastore, encode(username));

	elseif host then

		return format("data/%s/%s.dat", encode(host), datastore);

	else

		return format("data/%s.dat", datastore);

	end

end

function load(username, host, datastore)

	local data, ret = loadfile(getpath(username, host, datastore));

	if not data then

		log("warn", "Failed to load "..datastore.." storage ('"..ret.."') for user: "..(username or nil).."@"..(host or nil));

		return nil;

	end

	setfenv(data, {});

	local success, ret = pcall(data);

	if not success then

		log("error", "Unable to load "..datastore.." storage ('"..ret.."') for user: "..(username or nil).."@"..(host or nil));

		return nil;

	end

	return ret;

end

function store(username, host, datastore, data)

	local f, msg = io_open(getpath(username, host, datastore), "w+");

	if not f then

		log("error", "Unable to write to "..datastore.." storage ('"..msg.."') for user: "..(username or nil).."@"..(host or nil));

		return nil;

	end

	f:write("return ");

	simplesave(f, data);

	f:close();

	return true;

end

return _M;