local stanza = require"util.stanza".stanza;

local tostring, tonumber = tostring, tonumber;

local type = type;

local pairs = pairs;

local xmlns_rsm = 'http://jabber.org/protocol/rsm';

local element_parsers;

do

	local function xs_int(st)

		return tonumber((st:get_text()));

	end

	local function xs_string(st)

		return st:get_text();

	end

	element_parsers = {

		after = xs_string;

		before = function(st)

			local text = st:get_text();

			return text == "" or text;

		end;

		max = xs_int;

		index = xs_int;

		first = function(st)

			return { index = tonumber(st.attr.index); st:get_text() };

		end;

		last = xs_string;

		count = xs_int;

	}

end

local element_generators = setmetatable({

	first = function(st, data)

		if type(data) == "table" then

			st:tag("first", { index = data.index }):text(data[1]):up();

		else

			st:tag("first"):text(tostring(data)):up();

		end

	end;

	before = function(st, data)

		if data == true then

			st:tag("before"):up();

		else

			st:tag("before"):text(tostring(data)):up();

		end

	end

}, {

	__index = function(_, name)

		return function(st, data)

			st:tag(name):text(tostring(data)):up();

		end

	end;

});

local function parse(stanza)

	local rs = {};

	for tag in stanza:childtags() do

		local name = tag.name;

		local parser = name and element_parsers[name];

		if parser then

			rs[name] = parser(tag);

		end

	end

	return rs;

end

local function generate(t)

	local st = stanza("set", { xmlns = xmlns_rsm });

	for k,v in pairs(t) do

		if element_parsers[k] then

			element_generators[k](st, v);

		end

	end

	return st;

end

local function get(st)

	local set = st:get_child("set", xmlns_rsm);

	if set and #set.tags > 0 then

		return parse(set);

	end

end

return { parse = parse, generate = generate, get = get };