local jid_bare = require "util.jid".bare;

local os_time = os.time;

local t_concat = table.concat;

prosody.unlock_globals(); -- LuaSocket wants to pollute the global scope

local smtp = require "socket.smtp";

prosody.lock_globals();

local smtp_server = module:get_option_string("smtp_server", "localhost");

local smtp_user = module:get_option_string("smtp_username");

local smtp_pass = module:get_option_string("smtp_password");

local smtp_address = module:get_option("smtp_from") or ((smtp_user or "xmpp").."@"..(smtp_server or module.host));

local queue_offline_emails = module:get_option("queue_offline_emails");

if queue_offline_emails == true then queue_offline_emails = 300; end

local send_message_as_email;

module:hook("message/offline/handle", function(event)

	local stanza = event.stanza;

	local text = stanza:get_child_text("body");

	if text then

		return send_message_as_email(jid_bare(stanza.attr.to), jid_bare(stanza.attr.from), text);

	end

end, 1);

function send_message_as_email(address, from_address, message_text, subject)

	module:log("info", "Forwarding offline message to %s via email", address);

	local rcpt = "<"..address..">";

	local mesgt = {

		headers = {

			["content-type"] = 'text/plain; charset=utf-8';

			to = address;

			subject = subject or ("Offline message from "..jid_bare(from_address));

		};

		body = message_text;

	};

	local ok, err = smtp.send{ from = smtp_address, rcpt = rcpt, source = smtp.message(mesgt),

		server = smtp_server, user = smtp_user, password = smtp_pass };

	if not ok then

		module:log("error", "Failed to deliver to %s: %s", tostring(address), tostring(err));

		return;

	end

	return true;

end

if queue_offline_emails then

	local queues = {};

	local real_send_message_as_email = send_message_as_email;

	function send_message_as_email(address, from_address, message_text)

		local pair_key = address.."\0"..from_address;

		local queue = queues[pair_key];

		if not queue then

			queue = { from = smtp_address, to = address, messages = {} };

			queues[pair_key] = queue;

			module:add_timer(queue_offline_emails+5, function ()

				module:log("info", "Checking on %s", from_address);

				local current_time = os_time();

				local diff = current_time - queue.last_message_time;

				if diff > queue_offline_emails then

					module:log("info", "Enough silence, sending...");

					real_send_message_as_email(address, from_address, t_concat(queue.messages, "\n"), "You have "..#queue.messages.." offline message"..(#queue.messages == 1 and "" or "s").." from "..from_address)

				else

					module:log("info", "Next check in %d", queue_offline_emails - diff + 5);

					return queue_offline_emails - diff + 5;

				end

			end);

		end

		queue.last_message_time = os_time();

		local messages = queue.messages;

		messages[#messages+1] = message_text;

		return true;

	end

end