local t_insert = table.insert;

local st = require "util.stanza";

local lxp = require "lxp";

local setmetatable = setmetatable;

local pairs = pairs;

local error = error;

local s_gsub = string.gsub;

local print = print;

module("template")

local function process_stanza(stanza, ops)

	-- process attrs

	for key, val in pairs(stanza.attr) do

		if val:match("{[^}]*}") then

			t_insert(ops, {stanza.attr, key, val});

		end

	end

	-- process children

	local i = 1;

	while i <= #stanza do

		local child = stanza[i];

		if child.name then

			process_stanza(child, ops);

		elseif child:match("{[^}]*}") then -- text

			t_insert(ops, {stanza, i, child});

		end

		i = i + 1;

	end

end

local parse_xml = (function()

	local ns_prefixes = {

		["http://www.w3.org/XML/1998/namespace"] = "xml";

	};

	local ns_separator = "\1";

	local ns_pattern = "^([^"..ns_separator.."]*)"..ns_separator.."?(.*)$";

	return function(xml)

		local handler = {};

		local stanza = st.stanza("root");

		function handler:StartElement(tagname, attr)

			local curr_ns,name = tagname:match(ns_pattern);

			if name == "" then

				curr_ns, name = "", curr_ns;

			end

			if curr_ns ~= "" then

				attr.xmlns = curr_ns;

			end

			for i=1,#attr do

				local k = attr[i];

				attr[i] = nil;

				local ns, nm = k:match(ns_pattern);

				if nm ~= "" then

					ns = ns_prefixes[ns]; 

					if ns then 

						attr[ns..":"..nm] = attr[k];

						attr[k] = nil;

					end

				end

			end

			stanza:tag(name, attr);

		end

		function handler:CharacterData(data)

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

			stanza:text(data);

		end

		function handler:EndElement(tagname)

			stanza:up();

		end

		local parser = lxp.new(handler, "\1");

		local ok, err, line, col = parser:parse(xml);

		if ok then ok, err, line, col = parser:parse(); end

		--parser:close();

		if ok then

			return stanza.tags[1];

		else

			return ok, err.." (line "..line..", col "..col..")";

		end

	end;

end)();

local function create_template(text)

	local stanza, err = parse_xml(text);

	if not stanza then error(err); end

	local ops = {};

	process_stanza(stanza, ops);

	local template = {};

	function template.apply(data)

		end

	end

	return template;

end

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

return function(text)

	local template = templates[text];

	if not template then

		template = create_template(text);

		templates[text] = template;

	end

	return template;

end;