local format = string.format;

local setmetatable, type = setmetatable, type;

local pairs, ipairs = pairs, ipairs;

local char = string.char;

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

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

local io_open = io.open;

local os_remove = os.remove;

local tostring, tonumber = tostring, tonumber;

local error = error;

local next = next;

local t_insert = table.insert;

local indent = function(f, i)

	for n = 1, i do

		f:write("\t");

	end

end

local data_path = "data";

module "datamanager"

---- utils -----

local encode, decode;

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 -- FIXME make sure it's a string. throw an error otherwise.

		return (format("%q", tostring(o)):gsub("\\\n", "\\n"));

	end

end

local function simplesave (f, o, ind)

	if type(o) == "number" then

		f:write(o)

	elseif type(o) == "string" then

		f:write((format("%q", o):gsub("\\\n", "\\n")))

	elseif type(o) == "table" then

		f:write("{\n")

		for k,v in pairs(o) do

			indent(f, ind);

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

			simplesave(f, v, ind+1)

			f:write(",\n")

		end

		indent(f, ind-1);

		f:write("}")

	elseif type(o) == "boolean" then

		f:write(o and "true" or "false");

	else

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

	end

end

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

function set_data_path(path)

	data_path = path;

end

function getpath(username, host, datastore, ext)

	ext = ext or "dat";

	if username then

		return format("%s/%s/%s/%s.%s", data_path, encode(host), datastore, encode(username), ext);

	elseif host then

		return format("%s/%s/%s.%s", data_path, encode(host), datastore, ext);

	else

		return format("%s/%s.%s", data_path, datastore, ext);

	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)

	if not data then

		data = {};

	end

	-- save the datastore

	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;

	end

	f:write("return ");

	simplesave(f, data, 1);

	f:close();

	if not next(data) then -- try to delete empty datastore

		os_remove(getpath(username, host, datastore));

	end

	-- we write data even when we are deleting because lua doesn't have a

	-- platform independent way of checking for non-exisitng files

	return true;

end

function list_append(username, host, datastore, data)

	if not data then return; end

	-- save the datastore

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

	if not f then

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

		return;

	end

	f:write("item(");

	simplesave(f, data, 1);

	f:write(");\n");

	f:close();

	return true;

end

function list_store(username, host, datastore, data)

	if not data then

		data = {};

	end

	-- save the datastore

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

	if not f then

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

		return;

	end

	for _, d in ipairs(data) do

		f:write("item(");

		simplesave(f, d, 1);

		f:write(");\n");

	end

	f:close();

	if not next(data) then -- try to delete empty datastore

		os_remove(getpath(username, host, datastore, "list"));

	end

	-- we write data even when we are deleting because lua doesn't have a

	-- platform independent way of checking for non-exisitng files

	return true;

end

function list_load(username, host, datastore)

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

	if not data then

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

		return nil;

	end

	local items = {};

	setfenv(data, {item = function(i) t_insert(items, i); end});

	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 items;

end

return _M;