-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local lxp = require "lxp";

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

local stanza_mt = st.stanza_mt;

local error = error;

local tostring = tostring;

local t_insert = table.insert;

local t_concat = table.concat;

local t_remove = table.remove;

local setmetatable = setmetatable;

-- COMPAT: w/LuaExpat 1.1.0

local lxp_supports_doctype = pcall(lxp.new, { StartDoctypeDecl = false });

local lxp_supports_xmldecl = pcall(lxp.new, { XmlDecl = false });

local lxp_supports_bytecount = not not lxp.new({}).getcurrentbytecount;

local default_stanza_size_limit = 1024*1024*1; -- 1MB

local _ENV = nil;

-- luacheck: std none

local new_parser = lxp.new;

local xml_namespace = {

	["http://www.w3.org/XML/1998/namespace\1lang"] = "xml:lang";

	["http://www.w3.org/XML/1998/namespace\1space"] = "xml:space";

	["http://www.w3.org/XML/1998/namespace\1base"] = "xml:base";

	["http://www.w3.org/XML/1998/namespace\1id"] = "xml:id";

};

local xmlns_streams = "http://etherx.jabber.org/streams";

local ns_separator = "\1";

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

local function dummy_cb() end

local function new_sax_handlers(session, stream_callbacks, cb_handleprogress)

	local xml_handlers = {};

	local cb_streamopened = stream_callbacks.streamopened;

	local cb_streamclosed = stream_callbacks.streamclosed;

	local cb_error = stream_callbacks.error or

		function(_, e, stanza)

			error("XML stream error: "..tostring(e)..(stanza and ": "..tostring(stanza) or ""),2);

		end;

	local cb_handlestanza = stream_callbacks.handlestanza;

	cb_handleprogress = cb_handleprogress or dummy_cb;

	local stream_ns = stream_callbacks.stream_ns or xmlns_streams;

	local stream_tag = stream_callbacks.stream_tag or "stream";

	if stream_ns ~= "" then

		stream_tag = stream_ns..ns_separator..stream_tag;

	end

	local stream_error_tag = stream_ns..ns_separator..(stream_callbacks.error_tag or "error");

	local stream_default_ns = stream_callbacks.default_ns;

	local stream_lang = "en";

	local stack = {};

	local chardata, stanza = {};

	local stanza_size = 0;

	local non_streamns_depth = 0;

	function xml_handlers:StartElement(tagname, attr)

		if stanza and #chardata > 0 then

			-- We have some character data in the buffer

			t_insert(stanza, t_concat(chardata));

			chardata = {};

		end

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

		if name == "" then

			curr_ns, name = "", curr_ns;

		end

		if curr_ns ~= stream_default_ns or non_streamns_depth > 0 then

			attr.xmlns = curr_ns;

			non_streamns_depth = non_streamns_depth + 1;

		end

		for i=1,#attr do

			local k = attr[i];

			attr[i] = nil;

			local xmlk = xml_namespace[k];

			if xmlk then

				attr[xmlk] = attr[k];

				attr[k] = nil;

			end

		end

		if not stanza then --if we are not currently inside a stanza

			if lxp_supports_bytecount then

				stanza_size = self:getcurrentbytecount();

			end

			if session.notopen then

				if tagname == stream_tag then

					non_streamns_depth = 0;

					stream_lang = attr["xml:lang"] or stream_lang;

					if cb_streamopened then

						if lxp_supports_bytecount then

							cb_handleprogress(stanza_size);

							stanza_size = 0;

						end

						cb_streamopened(session, attr);

					end

				else

					-- Garbage before stream?

					cb_error(session, "no-stream", tagname);

				end

				return;

			end

			if curr_ns == "jabber:client" and name ~= "iq" and name ~= "presence" and name ~= "message" then

				cb_error(session, "invalid-top-level-element");

			end

			stanza = setmetatable({ name = name, attr = attr, tags = {} }, stanza_mt);

		else -- we are inside a stanza, so add a tag

			if lxp_supports_bytecount then

				stanza_size = stanza_size + self:getcurrentbytecount();

			end

			t_insert(stack, stanza);

			local oldstanza = stanza;

			stanza = setmetatable({ name = name, attr = attr, tags = {} }, stanza_mt);

			t_insert(oldstanza, stanza);

			t_insert(oldstanza.tags, stanza);

		end

	end

	function xml_handlers:StartCdataSection()

		if lxp_supports_bytecount then

			if stanza then

				stanza_size = stanza_size + self:getcurrentbytecount();

			else

				cb_handleprogress(self:getcurrentbytecount());

			end

		end

	end

	function xml_handlers:EndCdataSection()

		if lxp_supports_bytecount then

			if stanza then

				stanza_size = stanza_size + self:getcurrentbytecount();

			else

				cb_handleprogress(self:getcurrentbytecount());

			end

		end

	end

	function xml_handlers:CharacterData(data)

		if stanza then

			if lxp_supports_bytecount then

				stanza_size = stanza_size + self:getcurrentbytecount();

			end

			t_insert(chardata, data);

		elseif lxp_supports_bytecount then

			cb_handleprogress(self:getcurrentbytecount());

		end

	end

	function xml_handlers:EndElement(tagname)

		if lxp_supports_bytecount then

			stanza_size = stanza_size + self:getcurrentbytecount()

		end

		if non_streamns_depth > 0 then

			non_streamns_depth = non_streamns_depth - 1;

		end

		if stanza then

			if #chardata > 0 then

				-- We have some character data in the buffer

				t_insert(stanza, t_concat(chardata));

				chardata = {};

			end

			-- Complete stanza

			if #stack == 0 then

				if lxp_supports_bytecount then

					cb_handleprogress(stanza_size);

				end

				stanza_size = 0;

				if stanza.attr["xml:lang"] == nil then

					stanza.attr["xml:lang"] = stream_lang;

				end

				if tagname ~= stream_error_tag then

					cb_handlestanza(session, stanza);

				else

					cb_error(session, "stream-error", stanza);

				end

				stanza = nil;

			else

				stanza = t_remove(stack);

			end

		else

			if lxp_supports_bytecount then

				cb_handleprogress(stanza_size);

			end

			if cb_streamclosed then

				cb_streamclosed(session);

			end

		end

	end

	local function restricted_handler(parser)

		cb_error(session, "parse-error", "restricted-xml", "Restricted XML, see RFC 6120 section 11.1.");

		if not parser.stop or not parser:stop() then

			error("Failed to abort parsing");

		end

	end

	if lxp_supports_xmldecl then

		function xml_handlers:XmlDecl(version, encoding, standalone)

			if lxp_supports_bytecount then

				cb_handleprogress(self:getcurrentbytecount());

			end

			if (encoding and encoding:lower() ~= "utf-8")

			or (standalone == "no")

			or (version and version ~= "1.0") then

				return restricted_handler(self);

			end

		end

	end

	if lxp_supports_doctype then

		xml_handlers.StartDoctypeDecl = restricted_handler;

	end

	xml_handlers.Comment = restricted_handler;

	xml_handlers.ProcessingInstruction = restricted_handler;

	local function reset()

		stanza, chardata, stanza_size = nil, {}, 0;

		stack = {};

	end

	local function set_session(stream, new_session) -- luacheck: ignore 212/stream

		session = new_session;

	end

	return xml_handlers, { reset = reset, set_session = set_session };

end

local function new(session, stream_callbacks, stanza_size_limit)

	-- Used to track parser progress (e.g. to enforce size limits)

	local n_outstanding_bytes = 0;

	local handle_progress;

	if lxp_supports_bytecount then

		function handle_progress(n_parsed_bytes)

			n_outstanding_bytes = n_outstanding_bytes - n_parsed_bytes;

		end

		stanza_size_limit = stanza_size_limit or default_stanza_size_limit;

	elseif stanza_size_limit then

		error("Stanza size limits are not supported on this version of LuaExpat")

	end

	local handlers, meta = new_sax_handlers(session, stream_callbacks, handle_progress);

	local parser = new_parser(handlers, ns_separator, false);

	local parse = parser.parse;

	function session.open_stream(session, from, to) -- luacheck: ignore 432/session

		local send = session.sends2s or session.send;

		local attr = {

			["xmlns:stream"] = "http://etherx.jabber.org/streams",

			["xml:lang"] = "en",

			xmlns = stream_callbacks.default_ns,

			version = session.version and (session.version > 0 and "1.0" or nil),

			id = session.streamid or "",

			from = from or session.host, to = to,

		};

		if session.stream_attrs then

			session:stream_attrs(from, to, attr)

		end

		send("<?xml version='1.0'?>"..st.stanza("stream:stream", attr):top_tag());

		return true;

	end

	return {

		reset = function ()

			parser = new_parser(handlers, ns_separator, false);

			parse = parser.parse;

			n_outstanding_bytes = 0;

			meta.reset();

		end,

		feed = function (self, data) -- luacheck: ignore 212/self

			if lxp_supports_bytecount then

				n_outstanding_bytes = n_outstanding_bytes + #data;

			end

			local _parser = parser;

			local ok, err = parse(_parser, data);

			if lxp_supports_bytecount and n_outstanding_bytes > stanza_size_limit then

				return nil, "stanza-too-large";

			end

			if parser ~= _parser then

				_parser:parse();

				_parser:close();

			end

			return ok, err;

		end,

		set_session = meta.set_session;

		set_stanza_size_limit = function (_, new_stanza_size_limit)

			stanza_size_limit = new_stanza_size_limit;

		end;

	};

end

return {

	ns_separator = ns_separator;

	ns_pattern = ns_pattern;

	new_sax_handlers = new_sax_handlers;

	new = new;

};