local t_insert  =   table.insert;

local t_remove  =   table.remove;

local format    =  string.format;

local tostring  =       tostring;

local setmetatable= setmetatable;

local pairs     =          pairs;

local ipairs    =         ipairs;

module "stanza"

stanza_mt = {};

stanza_mt.__index = stanza_mt;

function stanza(name, attr)

	local stanza = { name = name, attr = attr or {}, last_add = {}};

	return setmetatable(stanza, stanza_mt);

end

function stanza_mt:iq(attrs)

	return self + stanza("iq", attrs)

end

function stanza_mt:message(attrs)

	return self + stanza("message", attrs)

end

function stanza_mt:presence(attrs)

	return self + stanza("presence", attrs)

end

function stanza_mt:query(xmlns)

	return self:tag("query", { xmlns = xmlns });

end

function stanza_mt:tag(name, attrs)

	local s = stanza(name, attrs);

	(self.last_add[#self.last_add] or self):add_child(s);

	t_insert(self.last_add, s);

	return self;

end

function stanza_mt:text(text)

	(self.last_add[#self.last_add] or self):add_child(text);

	return self; 

end

function stanza_mt:up()

	t_remove(self.last_add);

	return self;

end

function stanza_mt:add_child(child)

	t_insert(self, child);

end

function stanza_mt:child_with_name(name)

	for _, child in ipairs(self) do	

		if child.name == name then return child; end

	end

end

function stanza_mt.__tostring(t)

	local children_text = "";

	for n, child in ipairs(t) do

		children_text = children_text .. tostring(child);

	end

	local attr_string = "";

	if t.attr then

		for k, v in pairs(t.attr) do attr_string = attr_string .. format(" %s='%s'", k, tostring(v)); end

	end

	return format("<%s%s>%s</%s>", t.name, attr_string, children_text, t.name);

end

function stanza_mt.__add(s1, s2)

	return s:add_child(s2);

end

do

        local id = 0;

        function new_id()

                id = id + 1;

                return "lx"..id;

        end

end

function message(attr, body)

	if not body then

		return stanza("message", attr);

	else

		return stanza("message", attr):tag("body"):text(body);

	end

end

function iq(attr)

	if attr and not attr.id then attr.id = new_id(); end

	return stanza("iq", attr or { id = new_id() });

end

function reply(orig)

	return stanza(orig.name, orig.attr and { to = orig.attr.from, from = orig.attr.to, id = orig.attr.id, type = ((orig.name == "iq" and "result") or nil) });

end

function presence(attr)

	return stanza("presence", attr);

end