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

local setmetatable = setmetatable;

local pairs = pairs;

local ipairs = ipairs;

local error = error;

local loadstring = loadstring;

local debug = debug;

local t_remove = table.remove;

local parse_xml = require "util.xml".parse;

module("template")

local function trim_xml(stanza)

	for i=#stanza,1,-1 do

		local child = stanza[i];

		if child.name then

			trim_xml(child);

		else

			child = child:gsub("^%s*", ""):gsub("%s*$", "");

			stanza[i] = child;

			if child == "" then t_remove(stanza, i); end

		end

	end

end

local function create_string_string(str)

	str = ("%q"):format(str);

	str = str:gsub("{([^}]*)}", function(s)

		return '"..(data["'..s..'"]or"").."';

	end);

	return str;

end

local function create_attr_string(attr, xmlns)

	local str = '{';

	for name,value in pairs(attr) do

		if name ~= "xmlns" or value ~= xmlns then

			str = str..("[%q]=%s;"):format(name, create_string_string(value));

		end

	end

	return str..'}';

end

local function create_clone_string(stanza, lookup, xmlns)

	if not lookup[stanza] then

		local s = ('setmetatable({name=%q,attr=%s,tags={'):format(stanza.name, create_attr_string(stanza.attr, xmlns));

		-- add tags

		for i,tag in ipairs(stanza.tags) do

			s = s..create_clone_string(tag, lookup, stanza.attr.xmlns)..";";

		end

		s = s..'};';

		-- add children

		for i,child in ipairs(stanza) do

			if child.name then

				s = s..create_clone_string(child, lookup, stanza.attr.xmlns)..";";

			else

				s = s..create_string_string(child)..";"

			end

		end

		s = s..'}, stanza_mt)';

		s = s:gsub('%.%.""', ""):gsub('([=;])""%.%.', "%1"):gsub(';"";', ";"); -- strip empty strings

		local n = #lookup + 1;

		lookup[n] = s;

		lookup[stanza] = "_"..n;

	end

	return lookup[stanza];

end

local function create_cloner(stanza, chunkname)

	local lookup = {};

	local name = create_clone_string(stanza, lookup, "");

	local f = "local setmetatable,stanza_mt=...;return function(data)";

	for i=1,#lookup do

		f = f.."local _"..i.."="..lookup[i]..";";

	end

	f = f.."return "..name..";end";

	local f,err = loadstring(f, chunkname);

	if not f then error(err); end

	return f(setmetatable, stanza_mt);

end

local template_mt = { __tostring = function(t) return t.name end };

local function create_template(templates, text)

	local stanza, err = parse_xml(text);

	if not stanza then error(err); end

	trim_xml(stanza);

	local info = debug.getinfo(3, "Sl");

	info = info and ("template(%s:%d)"):format(info.short_src:match("[^\\/]*$"), info.currentline) or "template(unknown)";

	local template = setmetatable({ apply = create_cloner(stanza, info), name = info, text = text }, template_mt);

	templates[text] = template;

	return template;

end

local templates = setmetatable({}, { __mode = 'k', __index = create_template });

return function(text)

	return templates[text];

end;