local heartbeats = module:shared("/*/host_status_check/heartbeats");

local events = module:shared("/*/host_status_check/connection_events");

local host_status_ok = module:shared("host_status_ok");

local time = require "socket".gettime;

local template = require "util.interpolation".new("%b{}", function (s) return s end)

module:depends "http"

local threshold = module:get_option_number("status_check_heartbeat_threshold", 10);

local function status_string(status, duration, comment)

	local string_timestamp;

	if duration then

		string_timestamp = ("(%0.2fs%s)"):format(duration, comment or "");

	elseif comment then

		string_timestamp = ("(%s)"):format(comment);

	else

		return status and "UP" or "DOWN";

	end

	return (status and "UP " or "DOWN ")..string_timestamp;

end

local function string_pad(s, len)

	return s..(" "):rep(len-#s);

end

local status_page_template = [[

STATUS {status}

{host_statuses%HOST {item} {idx}

}]];

function status_page()

	local host_statuses = {};

	local current_time = time();

	local all_ok = true;

	local failed_hosts = {};

	for host in pairs(hosts) do

		local last_heartbeat_time = heartbeats[host];

		local ok, status_text = true;

		local is_component = hosts[host].type == "component" and hosts[host].modules.component;

		if is_component then

			local current_status = hosts[host].modules.component.connected;

			if events[host] then

				local tracked_status = events[host].connected;

				if tracked_status == current_status then

					status_text = status_string(current_status, time() - events[host].timestamp);

				else

					status_text = status_string(current_status, nil, "!");

				end

			else

				status_text = status_string(current_status, nil, "?");

			end

			if not current_status then

				ok = false;

			end

		else

			local event_info = events[host];

			local connected = true;

			if event_info then

				connected = event_info.connected;

			end

			status_text = status_string(connected, event_info and (time() - events[host].timestamp), not event_info and "?");

		end

		if last_heartbeat_time then

			local time_since_heartbeat = current_time - last_heartbeat_time;

			if ok then

				if time_since_heartbeat > threshold then

					status_text = ("TIMEOUT (%0.2fs)"):format(time_since_heartbeat);

					ok = false;

				else

					status_text = status_text:gsub("^%S+", "GOOD");

				end

			end

		end

		if not ok then

			all_ok = false;

			table.insert(failed_hosts, host);

		end

		if not ok or is_component or last_heartbeat_time then

			host_statuses[host] = string_pad(status_text, 20);

		end

		local last_ok = host_status_ok[host];

		if last_ok ~= ok then

			if last_ok ~= nil then

				module:log("warn", "Host status check %s (%s)", ok and "OK" or "FAILED", status_text);

			end

			host_status_ok[host] = ok;

		end

	end

	local page = template(status_page_template, {

		status = all_ok and "OK" or ("FAIL: "..table.concat(failed_hosts, ", "));

		host_statuses = host_statuses;

	});

	return page;

end

module:provides("http", {

	route = {

		GET = status_page;

	};

})