local error = error;

local setmetatable = setmetatable;

local config = require "core.configmanager";

local datamanager = require "util.datamanager";

local multitable = require "util.multitable";

local modulemanager = require "core.modulemanager";

local hosts = hosts;

local log = require "util.logger".init("storagemanager");

local olddm = {}; -- maintain old datamanager, for backwards compatibility

for k,v in pairs(datamanager) do olddm[k] = v; end

local driver_cache = multitable.new();

local store_cache = multitable.new();

module("storagemanager")

local default_driver_mt = {};

default_driver_mt.__index = default_driver_mt;

function default_driver_mt:open(store)

end

function default_driver_mt:get(user) return olddm.load(user, self.host, self.store); end

function default_driver_mt:set(user, data) return olddm.store(user, self.host, self.store, data); end

local function load_driver_for_host(host)

	if driver_cache:get(host) then return driver_cache:get(host); end

	local host_session = hosts[host];

	if not host_session then error("No such host"); end

	local driver_plugin = config.get(host, "core", "datastore");

	if not driver_plugin then return setmetatable({ host = host }, default_driver_mt); end

	local provider;

	local function handler(event) provider = event.item; end

	host_session.events.add_handler("item-added/data-driver", handler);

	local success, err = modulemanager.load(host, driver_plugin);

	host_session.events.remove_handler("item-added/data-driver", handler);

	if not success then error(err); end

	if not provider then error("Module didn't add a provider"); end

	driver_cache:set(host, provider);

	log("debug", "Data driver '%s' loaded for host '%s'", driver_plugin, host);

	return provider;

end

function open(host, store, typ)

	local ret = store_cache:get(host, store);

	if not ret then

		local driver = load_driver_for_host(host);

		ret = driver:open(store, typ);

		if not ret then ret = setmetatable({ host = host, store = store }, default_driver_mt); end -- default to default driver

		store_cache:set(host, store, ret);

	end

	return ret;

end

function datamanager.load(username, host, datastore)

	return open(host, datastore):get(username);

end

function datamanager.store(username, host, datastore, data)

	return open(host, datastore):set(username, data);

end

return _M;