--

-- XEP-0295: JSON Encodings for XMPP

--

module.host = "*"

local httpserver = require "net.httpserver";

local filters = require "util.filters"

local json = require "util.json"

local json_escapes = {

	["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b", ["\f"] = "\\f",

	["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};

local s_char = string.char;

for i=0,31 do

	local ch = s_char(i);

	if not json_escapes[ch] then json_escapes[ch] = ("\\u%.4X"):format(i); end

end

local state_out = 0;

local state_key_before = 1;

local state_key_in = 2;

local state_key_escape = 3;

local state_key_after = 4;

local state_val_before = 5;

local state_val_in = 6;

local state_val_escape = 7;

local state_val_after = 8;

local whitespace = { [" "] = true, ["\n"] = true, ["\r"] = true, ["\t"] = true };

function json_decoder()

	local state = state_out;

	local quote;

	local output = "";

	local buffer = "";

	return function(input)

		for ch in input:gmatch(".") do

			module:log("debug", "%s | %d", ch, state)

			local final = false;

			if state == state_out then

				if whitespace[ch] then

				elseif ch ~= "{" then return nil, "{ expected";

				else state = state_key_before end

			elseif state == state_key_before then

				if whitespace[ch] then

				elseif ch ~= "'" and ch ~= "\"" then return nil, "\" expected";

				else quote = ch; state = state_key_in; end

			elseif state == state_key_in then

				if ch == quote then state = state_key_after;

				elseif ch ~= "s" then return nil, "invalid key, 's' expected"; -- only s as key allowed

				else end -- ignore key

			elseif state == state_key_after then

				if whitespace[ch] then

				elseif ch ~= ":" then return nil, ": expected";

				else state = state_val_before; end

			elseif state == state_val_before then

				if whitespace[ch] then

				elseif ch ~= "'" and ch ~= "\"" then return nil, "\" expected";

				else quote = ch; state = state_val_in; end

			elseif state == state_val_in then

				if ch == quote then state = state_val_after;

				elseif ch == "\\" then state = state_val_escape;

				else end

			elseif state == state_val_after then

				if whitespace[ch] then

				elseif ch ~= "}" then return nil, "} expected";

				else state = state_out;

					final = true;

				end

			elseif state == state_val_escape then

				state = state_val_in;

			else

				module:log("error", "Unhandled state: "..state);

				return nil, "Unhandled state in parser"

			end

			buffer = buffer..ch;

			if final then

				module:log("debug", "%s", buffer)

				local tmp;

				pcall(function() tmp = json.decode(buffer); end);

				if not tmp then return nil, "Invalid JSON"; end

				output, buffer = output..tmp.s, "";

			end

		end

		local _ = output; output = "";

		return _;

	end;

end

function filter_hook(session)

	local determined = false;

	local is_json = false;

	local function in_filter(t)

		if not determined then

			is_json = (t:sub(1,1) == "{") and json_decoder();

			determined = true;

		end

		if is_json then

			local s, err = is_json(t);

			if not err then return s; end

			session:close("not-well-formed");

			return;

		end

		return t;

	end

	local function out_filter(t)

		if is_json then

			return '{"s":"' .. t:gsub(".", json_escapes) .. '"}'; -- encode

		end

		return t;

	end

	filters.add_filter(session, "bytes/in", in_filter,   100);

	filters.add_filter(session, "bytes/out", out_filter, 100);

end

function module.load()

	filters.add_filter_hook(filter_hook);

end

function module.unload()

	filters.remove_filter_hook(filter_hook);

end

function encode(data)

	if type(data) == "string" then

		data = json.encode({ s = data });

	elseif type(data) == "table" and data.body then

		data.body = json.encode({ s = data.body });

		data.headers["Content-Type"] = "application/json";

	end

	return data;

end

function handle_request(method, body, request)

	local mod_bosh = modulemanager.get_module("*", "bosh")

	if mod_bosh then

		if body and method == "POST" then

			pcall(function() body = json.decode(body).s; end);

		end

		local _send = request.send;

		function request:send(data) return _send(self, encode(data)); end

		return encode(mod_bosh.handle_request(method, body, request));

	end

	return "<html><body>mod_bosh not loaded</body></html>";

end

local function setup()

	local ports = module:get_option("jsonstreams_ports") or { 5280 };

	httpserver.new_from_config(ports, handle_request, { base = "jsonstreams" });

end

if prosody.start_time then -- already started

	setup();

else

	prosody.events.add_handler("server-started", setup);

end