ntopng/scripts/lua/modules/toasts/predicates_defined_toasts.lua

--
-- (C) 2020 - ntop.org
--
local dirs = ntop.getDirs()
package.path = dirs.installdir .. "/scripts/lua/modules/pools/?.lua;" .. package.path
package.path = dirs.installdir .. "/scripts/lua/modules/notifications/?.lua;" .. package.path

local pools = require("pools")
local check_utils = require("checks")
local endpoint_configs = require("endpoints")
local recipients_manager = require("recipients")
local page_utils = require('page_utils')
local toast_ui = require("toast_ui")
local stats_utils = require("stats_utils")
local delete_data_utils = require("delete_data_utils")
local prefs_factory_reset_utils = require("prefs_factory_reset_utils")
local configuration_utils = require "configuration_utils"
local recipients = require "recipients"
local alert_severities = require "alert_severities"

local info = ntop.getInfo()
local prefs = ntop.getPrefs()

local ToastLevel = toast_ui.ToastLevels

-- Constants
local ALARM_THRESHOLD_LOW = 80
local ALARM_THRESHOLD_HIGH = 90
local IS_ADMIN = isAdministrator()
local IS_SYSTEM_INTERFACE = page_utils.is_system_view()
local IS_PCAP_DUMP = interface.isPcapDumpInterface()
local IS_PACKET_INTERFACE = interface.isPacketInterface()
local UNEXPECTED_SCRIPTS_ENABLED_CACHE_KEY = "ntopng.cache.checks.unexpected_scripts_enabled"

local predicates = {}

-- ###############################################################

local function create_DHCP_range_missing_notification(toast)
    local title = i18n("about.configure_dhcp_range")
    local description = i18n("about.dhcp_range_missing_warning", {
        name = i18n("prefs.toggle_host_tskey_title"),
        url = ntop.getHttpPrefix() .. "/lua/if_stats.lua?page=config",
        dhcp_url = ntop.getHttpPrefix() .. "/lua/if_stats.lua?page=dhcp"
    })

    return toast_ui:new(toast.id, title, description, ToastLevel.WARNING, nil, toast.dismissable)

end

-- ###############################################################

local function create_DCHP_monitoring_toast(toast)
    local title = i18n("about.dhcp_monitoring_title")
    local description = i18n("about.host_identifier_warning", {
        name = i18n("prefs.toggle_host_tskey_title"),
        url = ntop.getHttpPrefix() .. "/lua/if_stats.lua?page=config"
    })

    local action = {
        url = ntop.getHttpPrefix() .. "/lua/if_stats.lua?page=config",
        title = i18n("configure")
    }

    return toast_ui:new(toast.id, title, description, ToastLevel.WARNING, action, toast.dismissable)
end

-- ###############################################################

local function create_DHCP_range_missing_toast(toast)
    local title = i18n("about.dhcp_monitoring_title")
    local description = i18n("about.dhcp_range_missing_warning", {
        name = i18n("prefs.toggle_host_tskey_title"),
        url = ntop.getHttpPrefix() .. "/lua/if_stats.lua?page=config",
        dhcp_url = ntop.getHttpPrefix() .. "/lua/if_stats.lua?page=dhcp"
    })

    local action = {
        url = ntop.getHttpPrefix() .. "/lua/if_stats.lua?page=dhcp",
        title = i18n("configure")
    }

    return toast_ui:new(toast.id, title, description, ToastLevel.WARNING, action, toast.dismissable)

end

-- ###############################################################

local function create_geo_ip_toast_ui(toast)
    local title = i18n("geolocation_unavailable_title")
    local description = i18n("geolocation_unavailable", {
        url = "https://github.com/ntop/ntopng/blob/dev/doc/README.geolocation.md",
        target = "_blank",
        icon = "fas fa-external-link-alt"
    })

    return toast_ui:new(toast.id, title, description, ToastLevel.WARNING, nil, toast.dismissable)
end

-- ###############################################################

local function create_forced_community_toast(toast)
    local title = i18n("about.licence")
    local description = i18n("about.forced_community_notification")

    return toast_ui:new(toast.id, title, description, ToastLevel.WARNING, nil --[[ no action --]] , toast.dismissable)
end

-- ###############################################################

local function create_tempdir_toast_ui(toast)
    local title = i18n("warning")
    local description = i18n("about.datadir_warning")
    local action = {
        url = "https://www.ntop.org/support/faq/migrate-the-data-directory-in-ntopng/",
        title = i18n("details.details")
    }

    return toast_ui:new(toast.id, title, description, ToastLevel.WARNING, action, toast.dismissable)
end

-- ###############################################################

local function create_update_ntopng_toast(toast, body)

    local title = i18n("update")
    return toast_ui:new(toast.id, title, body, ToastLevel.INFO, nil, toast.dismissable)
end

-- ###############################################################

local function create_mirrored_traffic_toast(toast, body)
    local title = i18n("mirrored_traffic")
    return toast_ui:new(toast.id, title, body, ToastLevel.INFO, nil, toast.dismissable)
end

-- ###############################################################

local function create_flows_limit_exceeded_toast(toast, level)
    local info = ntop.getInfo()
    local title = i18n("about.flows_limit_exceeded")
    local desc = i18n("about.flows_limit_exceeded_descr", {
        product = info["product"]
    })

    return toast_ui:new(toast.id, title, desc, level, action, toast.dismissable)
end

-- ###############################################################

local function create_hosts_limit_exceeded_toast(toast, level)
    local info = ntop.getInfo()
    local title = i18n("about.hosts_limit_exceeded")
    local desc = i18n("about.hosts_limit_exceeded_descr", {
        product = info["product"]
    })

    return toast_ui:new(toast.id, title, desc, level, action, toast.dismissable)
end

-- ###############################################################

local function create_too_many_flows_toast(toast, level, is_db_view)
    local info = ntop.getInfo()
    local title = i18n("too_many_flows")

    local desc
    if is_db_view then
        desc = i18n("about.you_have_too_many_flows_db", { product = info["product"] })
    else
        desc = i18n("about.you_have_too_many_flows", { product = info["product"] })
    end

    local action = {
        url = "#",
        additional_classes = "toast-config-change-flows",
        title = i18n("alert_messages.too_many_flows_title"),
        js = "toast-config-change-flows.js",
        dialog = {
            id = 'toast-config-change-modal-flows',
            action = 'toastConfigFlowChanges()',
            title = i18n("too_many_flows"),
            err_msg = i18n("alert_messages.too_many_flows_err"),
            message = i18n("alert_messages.too_many_flows_details"),
            custom_alert_class = 'alert alert-danger',
            confirm = i18n('increase_num_flows_hosts'),
            confirm_button = 'btn-danger'
        }
    }

    return toast_ui:new(toast.id, title, desc, level, action, toast.dismissable)
end

-- ###############################################################

local function create_too_many_hosts_toast(toast, level)
    local info = ntop.getInfo()
    local title = i18n("too_many_hosts")
    local desc = i18n("about.you_have_too_many_hosts", {
        product = info["product"]
    })
    local action = {
        url = "#",
        additional_classes = "toast-config-change-hosts",
        title = i18n("alert_messages.too_many_hosts_title"),
        js = "toast-config-change-hosts.js",
        dialog = {
            id = 'toast-config-change-modal-hosts',
            action = 'toastConfigHostChanges()',
            title = i18n("too_many_hosts"),
            err_msg = i18n("alert_messages.too_many_hosts_err"),
            message = i18n("alert_messages.too_many_hosts_details"),
            custom_alert_class = 'alert alert-danger',
            confirm = i18n('increase_num_flows_hosts'),
            confirm_button = 'btn-danger'
        }
    }

    return toast_ui:new(toast.id, title, desc, level, action, toast.dismissable)
end

-- ###############################################################

local function create_remote_probe_clock_drift_toast(toast, level, local_time, remote_time)
    local title = i18n("remote_probe_clock_drift")
    local desc = i18n("about.you_need_to_sync_remote_probe_time", {
        url = ntop.getHttpPrefix() .. "/lua/if_stats.lua"
    })
    local desc_times = i18n("about.remote_probe_times", {
        local_time = formatEpoch(local_time),
        remote_time = formatEpoch(remote_time)
    })
    desc = string.format("%s<br>%s.", desc, desc_times)

    return toast_ui:new(toast.id, title, desc, level, nil, toast.dismissable)
end

-- ##################################################################

local function create_flow_dump_toast_ui(toast)
    local title = i18n("flow_dump_not_working_title")
    local description = i18n("flow_dump_not_working", {
        icon = "fas fa-external-link-alt"
    })

    return toast_ui:new(toast.id, title, description, ToastLevel.WARNING, nil, toast.dismissable)
end

-- ##################################################################

--- 
local function create_restart_required_toast(toast, description)
    local title = i18n("restart.restart_required")
    local action = nil
    -- only the ntop packed can be restarted
    if IS_ADMIN and ntop.isPackage() and not ntop.isWindows() then
        action = {
            title = i18n("restart.restart_now"),
            additional_classes = "restart-service",
            url = "#"
        }
    end

    return toast_ui:new(toast.id, title, description, ToastLevel.DANGER, action, toast.dismissable)

end

-- ##################################################################

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.restart_required(toast, container)

    if not IS_ADMIN then
        return
    end

    if prefs.active_monitoring_pref and not prefs.active_monitoring then
        table.insert(container, create_restart_required_toast(toast, i18n("prefs.restart_needed", { product = info.product })))
    end

    if not ntop.isPackage() or ntop.isWindows() then
        return
    end

    -- ifname is defined globally
    local delete_active_interface_requested = delete_data_utils.delete_active_interface_data_requested(ifname)
    if delete_active_interface_requested then
        table.insert(container, create_restart_required_toast(toast, i18n("delete_data.restart_product_toast", {
            product = ntop.getInfo()["product"]
        })))
    end
    if prefs_factory_reset_utils.is_prefs_factory_reset_requested() then
        table.insert(container, create_restart_required_toast(toast, i18n("manage_configurations.after_reset_request", {
            product = ntop.getInfo()["product"]
        })))
    end
    if configuration_utils.restart_required() then
        table.insert(container, create_restart_required_toast(toast, i18n("manage_configurations.restart_request", {
            product = ntop.getInfo()["product"]
        })))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.DHCP(toast, container)
    if not IS_ADMIN then
        return
    end

    -- In System Interface we can't collect the required data
    if (IS_SYSTEM_INTERFACE) then
        return false
    end

    local ifs = interface.getStats()

    if (not (ifs.has_seen_dhcp_addresses and IS_ADMIN and (not IS_PCAP_DUMP) and IS_PACKET_INTERFACE)) then
        return
    end

    local lbd_serialize_by_mac = (_POST["lbd_hosts_as_macs"] == "1") or
                                     (ntop.getPref(
            string.format("ntopng.prefs.ifid_%u.serialize_local_broadcast_hosts_as_macs", ifs.id)) == "1")

    if (not lbd_serialize_by_mac) and
        (ntop.getPref(string.format("ntopng.prefs.ifid_%u.disable_host_identifier_message", ifs.id)) ~= "1") then

        table.insertIfNotPresent(container, create_DCHP_monitoring_toast(toast), function(n)
            return n.id == toast.id
        end)

    elseif isEmptyString(_POST["dhcp_ranges"]) then

        local dhcp_utils = require("dhcp_utils")
        local ranges = dhcp_utils.listRanges(ifs.id)

        if (table.empty(ranges)) then
            table.insertIfNotPresent(container, create_DHCP_range_missing_toast(toast), function(n)
                return n.id == toast.id
            end)
        end
    end

end

--- Create an instance for the geoip alert toast
--- if the user doesn't have geoIP installed
--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.geo_ip(toast, container)
    if IS_ADMIN and not ntop.hasGeoIP() then
        table.insert(container, create_geo_ip_toast_ui(toast))
    end
end

--- Create an instance for the temp working directory alert
--- if ntopng is running inside /var/tmp
--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.temp_working_dir(toast, container)
    if not IS_ADMIN or ntop.isWindows() then
        return
    end

    if (dirs.workingdir == "/var/tmp/ntopng") then
        table.insert(container, create_tempdir_toast_ui(toast))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.update_ntopng(toast, container)
    if not IS_ADMIN or not ntop.isPackage() or ntop.isWindows() then
        return
    end

    -- check if ntopng is oem and the user is an Administrator
    local is_not_oem_and_administrator = IS_ADMIN and not info.oem
    local message = check_latest_major_release()

    if is_not_oem_and_administrator and not isEmptyString(message) then
        table.insert(container, create_update_ntopng_toast(toast, message))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.mirrored_traffic(toast, container)
    if not IS_ADMIN or not IS_PACKET_INTERFACE or ntop.isWindows() then
        return
    end

    -- check if ntopng is oem and the user is an Administrator
    local is_not_oem_and_administrator = IS_ADMIN and not info.oem
    local ifstats = interface.getStats()
    local message = i18n('check_mirrored_traffic', {
        id = ifstats.id
    })
    local upload_traffic = 0
    local download_traffic = 0
    local num_tot_traffic_points = 0

    for _, traffic in pairs(ifstats.download_stats) do
        download_traffic = download_traffic + traffic
        if traffic > 0 then
            num_tot_traffic_points = num_tot_traffic_points + 1
        end
    end

    for _, traffic in pairs(ifstats.upload_stats) do
        upload_traffic = upload_traffic + traffic
    end

    local is_mirrored_traffic_pref = ntop.getPref(string.format("ntopng.prefs.ifid_%d.is_traffic_mirrored",
        interface.getId())) == "0"

    if is_not_oem_and_administrator and not isEmptyString(message) and (num_tot_traffic_points > 10) and
        (upload_traffic == 0 and download_traffic > 0 and is_mirrored_traffic_pref) then
        table.insert(container, create_mirrored_traffic_toast(toast, message))
    end
end

-- ###############################################

local function create_emergency_notifications_toast(toast, message)
    local title = i18n("emergency_notifications")
    return toast_ui:new(toast.id, title, message, ToastLevel.INFO, nil, toast.dismissable)
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.emergency_recipient(toast, container)
    if not IS_ADMIN then
        return
    end

    -- check if ntopng is oem and the user is an Administrator
    local is_not_oem_and_administrator = IS_ADMIN and not info.oem
    local message = i18n('check_emergency_recipient', {
        http_prefix = ntop.getHttpPrefix()
    })
    local emergency_recipient_configured = false

    for _, recipient in pairs(recipients.get_all_recipients()) do
        if recipients.isAlertsRecipient(recipient) and 
            not recipients.isBuiltinRecipient(recipient) and
            recipient.minimum_severity >= alert_severities.notice.severity_id then
            emergency_recipient_configured = true
            break
        end
    end

    if is_not_oem_and_administrator and not isEmptyString(message) and not emergency_recipient_configured then
        table.insert(container, create_emergency_notifications_toast(toast, message))
        return true
    end
end

-- ###############################################

local function hide_warn_on_limit_exceeeded()
    return ntop.getCache("ntopng.prefs.ignore_limit_exceeded") == "1"
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.flows_limit_exceeded(toast, container)
    if not IS_ADMIN then
        return
    end

    -- In System Interface we can't get the flows number from `interface.getNumFlows()`
    if (IS_SYSTEM_INTERFACE) then
        return
    end

    if hide_warn_on_limit_exceeeded() then
        return
    end

    local level = nil
    local flows = interface.getNumFlows()

    if flows > prefs.flows_limit then
        level = ToastLevel.WARNING
    end

    if (level ~= nil) then
        table.insert(container, create_flows_limit_exceeded_toast(toast, level))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.hosts_limit_exceeded(toast, container)
    if not IS_ADMIN then
        return
    end

    -- In System Interface we can't get the hosts number from `interface.getNumHosts()`
    if (IS_SYSTEM_INTERFACE) then
        return
    end

    if hide_warn_on_limit_exceeeded() then
        return
    end

    local level = nil
    local hosts = interface.getNumLocalHosts()

    local rxonly_hosts = interface.getNumLocalRxOnlyHosts()
    if hosts >= rxonly_hosts then -- Safety check
        hosts = hosts - rxonly_hosts -- Do not consider non-existing hosts
    end

    if hosts > prefs.hosts_limit then
        level = ToastLevel.WARNING
    end

    if (level ~= nil) then
        table.insert(container, create_hosts_limit_exceeded_toast(toast, level))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.too_many_hosts(toast, container)
    if not IS_ADMIN or not ntop.isPackage() or ntop.isWindows() then
        return
    end

    -- In System Interface we can't get the hosts number from `interface.getNumHosts()`
    if (IS_SYSTEM_INTERFACE) then
        return
    end

    local level = nil
    local hosts = interface.getNumHosts()
    local hosts_pctg = math.floor(1 + ((hosts * 100) / prefs.max_num_hosts))

    if (hosts_pctg >= ALARM_THRESHOLD_LOW and hosts_pctg <= ALARM_THRESHOLD_HIGH) then
        level = ToastLevel.WARNING
    elseif (hosts_pctg > ALARM_THRESHOLD_HIGH) then
        level = ToastLevel.DANGER
    end

    if (level ~= nil) then
        table.insert(container, create_too_many_hosts_toast(toast, level))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.too_many_flows(toast, container)
    if not IS_ADMIN or not ntop.isPackage() or ntop.isWindows() then
        return
    end

    -- In System Interface we can't get the flows number from `interface.getNumFlows()`
    if (IS_SYSTEM_INTERFACE) then
        return
    end

    local level = nil
    local is_db_view = false
    local flows = interface.getNumFlows()
    local max_flows = prefs.max_num_flows

    local ifstats = interface.getStats()
    if ifstats['type'] == 'db' then
        is_db_view = true
        if flows >= max_flows then
            level = ToastLevel.WARNING
        end
    else
        local flows_pctg = math.floor(1 + ((flows * 100) / prefs.max_num_flows))

        if (flows_pctg >= ALARM_THRESHOLD_LOW and flows_pctg <= ALARM_THRESHOLD_HIGH) then
            level = ToastLevel.WARNING
        elseif (flows_pctg > ALARM_THRESHOLD_HIGH) then
            level = ToastLevel.DANGER
        end
    end

    if (level ~= nil) then
        table.insert(container, create_too_many_flows_toast(toast, level, is_db_view))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.remote_probe_clock_drift(toast, container)
    if not IS_ADMIN then
        return
    end

    -- In System Interface we can't collect the stats from `interface.getStats()`
    if (IS_SYSTEM_INTERFACE) then
        return
    end

    local ifstats = interface.getStats()

    if ifstats["probe.remote_time"] ~= nil and ifstats["probe.local_time"] ~= nil then

        local tdiff = math.abs(ifstats["probe.local_time"] - ifstats["probe.remote_time"])
        local level = nil

        if (tdiff >= 10 and tdiff <= 30) then
            level = ToastLevel.WARNING
        elseif (tdiff > 30) then
            level = ToastLevel.DANGER
        end

        if (level ~= nil) then
            table.insert(container, create_remote_probe_clock_drift_toast(toast, level, ifstats["probe.local_time"],
                ifstats["probe.remote_time"]))
        end
    end
end

--- Create an instance for the flow dump alert toast
--- if flow dump is not able to start/run/dump
--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.flow_dump(toast, container)
    if not IS_ADMIN or not ntop.isPackage() or ntop.isWindows() then
        return
    end

    -- In System Interface we can't collect the stats from `interface.getStats()`
    if (IS_SYSTEM_INTERFACE) then
        return
    end

    local ifstats = interface.getStats()

    if IS_ADMIN and prefs.is_dump_flows_enabled and prefs.is_dump_flows_runtime_enabled and
        not ifstats.isFlowDumpDisabled and not ifstats.isFlowDumpRunning and not ifstats.isViewed then

        table.insert(container, create_flow_dump_toast_ui(toast))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.about_page(toast, container)
    if not IS_ADMIN then
        return
    end

    if (_POST["ntopng_license"] ~= nil) then

        ntop.setCache('ntopng.license', trimSpace(_POST["ntopng_license"]))
        ntop.checkLicense()

        info = ntop.getInfo()

        if (info["version.enterprise_l_edition"] and info["pro.license"] ~= "") then
            table.insert(container,
                toast_ui:new(toast.id, i18n("info"), i18n("about.create_license_l"), ToastLevel.INFO, {
                    url = "https://www.ntop.org/support/faq/what-is-included-in-ntopng-enterprise-l/",
                    title = i18n("details.details")
                }))
        elseif (not info["version.enterprise_l_edition"] and info["pro.license"] ~= "") then
            table.insert(container, toast_ui:new(toast.id, i18n("info"), i18n("about.create_license"), ToastLevel.INFO))
        end

    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.hosts_geomap(toast, container)
    if not IS_ADMIN then
        return
    end

    local hosts_stats = interface.getHostsInfo()
    local num = hosts_stats["numHosts"]
    if (num > 0) then
        table.insert(container, toast_ui:new(toast.id, i18n("warning"), i18n("geo_map.warning_accuracy"),
            ToastLevel.WARNING, nil, toast.dismissable))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.vulnerability_scan(toast, container)
    if not IS_ADMIN then
        return
    end

    if not ntop.isClickHouseEnabled() then
        local body = i18n("hosts_stats.page_scan_hosts.enable_clickhouse_toast_label", {
            link = "https://www.ntop.org/guides/ntopng/user_interface/network_interface/monitoring/vulnerability_scan.html#scan-reports"
        })
        table.insert(container, toast_ui:new(toast.id, i18n("info"),body,
            ToastLevel.INFO, nil, toast.dismissable))
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.service_map(toast, container)
    local service_map_status = interface.serviceMapLearningStatus()
    if ntop.isEnterprise() and service_map_status.service_map_learning_status == true then
        local body = i18n("map_page.learning")
        table.insert(container, toast_ui:new(toast.id, i18n("info"),body,
            ToastLevel.INFO, nil, toast.dismissable))       
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.enable_exporters_timeseries(toast, container)
    if ntop.isEnterprise() and not areFlowdevTimeseriesEnabled() then
        local body = i18n("prefs.enable_exporters_timeseries", {
            link = ntop.getHttpPrefix() .. "/lua/admin/prefs.lua?tab=on_disk_ts"
        })
        table.insert(container, toast_ui:new(toast.id, i18n("info"),body,
            ToastLevel.INFO, nil, toast.dismissable))       
    end
end

--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.configured_exporters_timeseries_resolution(toast, container)
    local service_map_status = interface.serviceMapLearningStatus()
    if ntop.isEnterprise() and areFlowdevTimeseriesEnabled() and not highExporterTimeseriesResolution() then
        local body = i18n("prefs.change_exporter_timeseries_resolution", {
            link = ntop.getHttpPrefix() .. "/lua/admin/prefs.lua?tab=on_disk_ts"
        })
        table.insert(container, toast_ui:new(toast.id, i18n("info"),body,
            ToastLevel.INFO, nil, toast.dismissable))       
    end
end


--- This is a simple placeholder for new toasts
--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.empty(toast, container)
    -- do nothing!
end

--- Generate two toasts if the SNMP ratio is not available for probes
--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.exporters_SNMP_ratio_column(toast, container)
    if not IS_ADMIN or not ntop.isPro() then
        return
    end

    local snmp_utils = require "snmp_utils"
    local snmp_cached_dev = require "snmp_cached_dev"

    local flow_device_ip = _GET["ip"]
    if (isEmptyString(flow_device_ip)) then
        return
    end

    local cached_device = snmp_cached_dev:create(flow_device_ip)

    local is_ratio_available = snmp_utils.is_snmp_ratio_available(cached_device)

    if (is_ratio_available) then
        return
    end

    local title = i18n("flow_devices.enable_flow_ratio")
    local body
    local action = nil

    -- Did the user add the device to the SNMP overview page?
    local device_exists = not (cached_device == nil)
    -- Are SNMP Timeseries enabled?
    local snmp_dev_creation = ntop.getPref("ntopng.prefs.snmp_devices_rrd_creation") == "1"
    -- Are Flow Probes Timseries enabled?
    local flow_dev_creation = ntop.getPref("ntopng.prefs.flow_device_port_rrd_creation") == "1"

    if not device_exists then
        -- Build the message to show
        local message_snmp = i18n("flow_devices.flow_ratio_snmp_instructions", {
            href = ntop.getHttpPrefix() .. "/lua/pro/enterprise/snmpdevices_stats.lua"
        })

        body = message_snmp

    elseif not flow_dev_creation or not snmp_dev_creation then
        -- Build the message to show
        local message_timeseries = i18n("flow_devices.flow_ratio_timeseries_instructions")

        body = message_timeseries
        action = {
            url = ntop.getHttpPrefix() .. "/lua/admin/prefs.lua?tab=on_disk_ts",
            title = i18n("enable_them")
        }
    end

    if body then
        table.insert(container, toast_ui:new(toast.id, title, body, ToastLevel.INFO, action, toast.dismissable))
    end

end

-- ###############################################

--- Create an instance for forced community toast
--- @param toast table The toast is the logic model defined in defined_toasts
--- @param container table Is the table where to put the new toast ui
function predicates.forced_community(toast, container)
    if (ntop.getInfo()["pro.forced_community"] and ntop.exists("/etc/ntopng.license")) then
        table.insert(container, create_forced_community_toast(toast))
    end
end

-- ###############################################

--- Did the user create an non builtin endpoint?
local function user_has_created_endpoint()
    return ntop.getCache(endpoint_configs.FIRST_ENDPOINT_CREATED_CACHE_KEY) == "1"
end

--- Did the user create a recipient?
local function user_has_created_recipient()
    return ntop.getCache(recipients_manager.FIRST_RECIPIENT_CREATED_CACHE_KEY) == "1"
end

--- Generate a toast to adive the user about toast endpoints
function predicates.create_endpoint(toast, container)
    if (not IS_ADMIN) then
        return
    end
    if (user_has_created_endpoint()) then
        return
    end
    if IS_PCAP_DUMP then
        return
    end

    local title = i18n("endpoint_notifications.hints.create_endpoint.title")
    local body = i18n("endpoint_notifications.hints.create_endpoint.body", {
        link = "https://www.ntop.org/guides/ntopng/user_interface/shared/alerts/available_endpoints.html#available-endpoints"
    })
    local action = {
        title = i18n("endpoint_notifications.hints.create_endpoint.action"),
        url = ntop.getHttpPrefix() .. "/lua/admin/endpoint_notifications_list.lua"
    }

    local hint = toast_ui:new(toast.id, title, body, ToastLevel.INFO, action, toast.dismissable)

    table.insert(container, hint)

end

-- Generate a second toast to inform the user to create a recipient for the new endpoint
function predicates.create_recipients_for_endpoint(toast, container)
    if (not IS_ADMIN) then
        return
    end
    if IS_PCAP_DUMP then
        return
    end

    -- Did the user created a new endpoint? If not then return
    if (not user_has_created_endpoint()) then
        return
    end
    -- Did the user created the new recipient? If yes then return
    if (user_has_created_recipient()) then
        return
    end

    local title = i18n("endpoint_notifications.hints.create_recipients.title")
    local body = i18n("endpoint_notifications.hints.create_recipients.body", {
        link = "https://www.ntop.org/guides/ntopng/user_interface/shared/alerts/available_endpoints.html#available-endpoints"
    })
    local action = {
        url = ntop.getHttpPrefix() .. "/lua/admin/endpoint_notifications_list.lua?subdir=recipient",
        title = i18n("create")
    }

    local hint = toast_ui:new(toast.id, title, body, ToastLevel.INFO, action, toast.dismissable)
    table.insert(container, hint)
end

--- Check if unexpected scripts are disabled and notifiy the user
--- about their existance
function predicates.unexpected_scripts(toast, container)
    if (not IS_ADMIN) then
        return
    end
    if not isEmptyString(ntop.getCache(UNEXPECTED_SCRIPTS_ENABLED_CACHE_KEY)) then
        return
    end

    local url = ntop.getHttpPrefix() .. "/lua/admin/edit_configset.lua?subdir=flow&search_script=unexpected#disabled"

    -- TODO: missing documentation links
    local title = i18n("checks.hint.title")
    local body = i18n("checks.hint.body", {
        link_DHCP = "https://ntop.org",
        link_SMTP = "https://ntop.org",
        link_DNS = "https://ntop.org",
        link_NTP = "https://ntop.org",
        product = info["product"]
    })
    local action = {
        url = url,
        title = i18n("configure")
    }

    local hint = toast_ui:new(toast.id, title, body, ToastLevel.INFO, action, toast.dismissable)
    table.insert(container, hint)
end

-- ###############################################

function predicates.export_drops(toast, container)
    if (IS_SYSTEM_INTERFACE) then
        return
    end

    if ntop.isClickHouseEnabled() then
        local ifstats = interface.getStats()
        local total_flows = ifstats.stats_since_reset.db.flow_export_count
        local flow_export_drops = ifstats.stats_since_reset.db.flow_export_drops
        local severity = ToastLevels[stats_utils.get_severity_by_export_drops(flow_export_drops, total_flows)]

        -- for the info severity don't show anything
        if severity == ToastLevels.INFO then
            return
        end

        local body = i18n("about.too_many_exports", {
            product = "<b>" .. info.product .. "</b>"
        })
        local hint = toast_ui:new(toast.id, i18n("too_many_exports"), body, severity, nil, toast.dismissable)
        table.insert(container, hint)
    end

end

-- ###############################################

return predicates