--
-- (C) 2014-17 - ntop.org
--

-- This file contains the description of all functions
-- used to trigger host alerts

local verbose = ntop.getCache("ntopng.prefs.alerts.debug") == "1"
local callback_utils = require "callback_utils"
local template = require "template_utils"

alerts_granularity = {
   { "min", i18n("alerts_thresholds_config.every_minute"), 60 },
   { "5mins", i18n("alerts_thresholds_config.every_5_minutes"), 300 },
   { "hour", i18n("alerts_thresholds_config.hourly"), 3600 },
   { "day", i18n("alerts_thresholds_config.daily"), 86400 }
}

alarmable_metrics = {'bytes', 'dns', 'active', 'idle', 'packets', 'p2p', 'throughput',
    'ingress', 'egress', 'inner',
    'flows'}

alert_functions_info = {
   ["active"] = {
      label = i18n("alerts_thresholds_config.activity_time"),
      fmt = secondsToTime,
   }, ["bytes"] = {
      label = i18n("traffic"),
      fmt = bytesToSize,
   }, ["dns"] = {
      label = i18n("alerts_thresholds_config.dns_traffic"),
      fmt = bytesToSize,
   }, ["idle"] = {
      label = i18n("alerts_thresholds_config.idle_time"),
      fmt = secondsToTime,
   }, ["packets"] = {
      label = i18n("packets"),
      fmt = formatPackets,
   }, ["p2p"] = {
      label = i18n("alerts_thresholds_config.p2p_traffic"),
      fmt = bytesToSize,
   }, ["throughput"] = {
      label = i18n("alerts_thresholds_config.throughput"),
      fmt = bytesToSize,
   }, ["flows"] = {
      label = i18n("flows"),
      fmt = formatFlows,
   }, ["inner"] = {
      label = i18n("alerts_thresholds_config.inner_traffic"),
      fmt = bytesToSize
   }, ["ingress"] = {
      label = i18n("alerts_thresholds_config.ingress_traffic"),
      fmt = bytesToSize
   }, ["egress"] = {
      label = i18n("alerts_thresholds_config.egress_traffic"),
      fmt = bytesToSize
   },
}

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

local function ndpival_bytes(json, protoname)
   key = "ndpiStats"

   -- Host
   if((json[key] == nil) or (json[key][protoname] == nil)) then
      if(verbose) then print("## ("..protoname..") Empty<br>\n") end
      return(0)
   else
      local v = (json[key][protoname]["bytes"]["sent"] or 0) + (json[key][protoname]["bytes"]["rcvd"] or 0)
      if(verbose) then print("##  ("..protoname..") "..v.."<br>\n") end
      return(v)
   end
end

local function proto_bytes(old, new, protoname)
   return(ndpival_bytes(new, protoname) - ndpival_bytes(old, protoname))
end

--
-- NOTE
--
-- These functions are called by the loadstring function to evaluate
-- threshold crosses.
-- When reading a field from the "old" parameter, an "or" operator should be used
-- to avoid working on nil value. Nil values can be found, for example, when a
-- new entity appear and it has not previous dump or across ntopng reboot.
--

function bytes(old, new, interval)
   -- io.write(debug.traceback().."\n")
   if(verbose) then print("bytes("..interval..")") end

   if(new["sent"] ~= nil) then
      -- Host
      return((new["sent"]["bytes"] + new["rcvd"]["bytes"]) - ((old["sent"] and old["sent"]["bytes"] or 0) + (old["rcvd"] and old["rcvd"]["bytes"] or 0)))
   else
      -- Interface
      return(new.stats.bytes - (old.stats and old.stats.bytes or 0))
   end
end

function packets(old, new, interval)
   if(verbose) then print("packets("..interval..")") end
   if(new["sent"] ~= nil) then
      -- Host
      return((new["sent"]["packets"] + new["rcvd"]["packets"]) - ((old["sent"] and old["sent"]["packets"] or 0) + (old["rcvd"] and old["rcvd"]["packets"] or 0)))
   else
      -- Interface
      return(new.stats.packets - (old.stats and old.stats.packets or 0))
   end
end

function active(old, new, interval)
   if(verbose) then print("active("..interval..")") end
   local diff = (new["total_activity_time"] or 0) - (old["total_activity_time"] or 0)
   return(diff)
end

function idle(old, new, interval)
   if(verbose) then print("idle("..interval..")") end
   local diff = os.time()-new["seen.last"]
   return(diff)
end

function dns(old, new, interval)
   if(verbose) then print("dns("..interval..")") end
   return(proto_bytes(old, new, "DNS"))
end

function p2p(old, new, interval)
   if(verbose) then print("p2p("..interval..")") end
   return(proto_bytes(old, new, "eDonkey") + proto_bytes(old, new, "BitTorrent") + proto_bytes(old, new, "Skype"))
end

function throughput(old, new, interval)
   if(verbose) then print("throughput("..interval..")") end

   return((bytes(old, new, interval) * 8)/ (interval*1000000))
end

function ingress(old, new, interval)
   return new["ingress"] - (old["ingress"] or 0)
end

function egress(old, new, interval)
   return new["egress"] - (old["egress"] or 0)
end

function inner(old, new, interval)
   return new["inner"] - (old["inner"] or 0)
end

function flows(old, new, interval)
   local new_flows = new["flows.as_client"] + new["flows.as_server"]
   local old_flows = (old["flows.as_client"] or 0) + (old["flows.as_server"] or 0)
   return new_flows - old_flows
end

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

if ntop.isEnterprise() then
   local dirs = ntop.getDirs()
   package.path = dirs.installdir .. "/pro/scripts/lua/enterprise/modules/?.lua;" .. package.path
   require "enterprise_alert_utils"
end

j = require("dkjson")
require "persistence"

function is_allowed_timespan(timespan)
   for _, granularity in pairs(alerts_granularity) do
      granularity = granularity[1]
      if timespan == granularity then
	 return true
      end
   end
   return false
end

function is_allowed_alarmable_metric(metric)
   for _, allowed_metric in pairs(alarmable_metrics) do
      if metric == allowed_metric then
	 return true
      end
   end
   return false
end

function get_alerts_hash_name(timespan, ifname)
   local ifid = getInterfaceId(ifname)
   if not is_allowed_timespan(timespan) or tonumber(ifid) == nil then
      return nil
   end

   return "ntopng.prefs.alerts_"..timespan..".ifid_"..tostring(ifid)
end

-- Get the hash key used for saving global settings
function get_global_alerts_hash_key(entity_type, alert_source)
   if entity_type == "host" then
      return "local_hosts"
   elseif entity_type == "interface" then
      return "interfaces"
   elseif entity_type == "network" then
      return "local_networks"
   else
      return "*"
   end
end

function get_make_room_keys(ifId)
   return {flows="ntopng.prefs.alerts.ifid_"..ifId..".make_room_flow_alerts",
	   entities="ntopng.prefs.alerts.ifid_"..ifId..".make_room_closed_alerts"}
end

-- =====================================================

function get_alerts_suppressed_hash_name(ifid)
   local hash_name = "ntopng.prefs.alerts.ifid_"..ifid
   return hash_name
end

function are_alerts_suppressed(observed, ifid)
   local suppressAlerts = ntop.getHashCache(get_alerts_suppressed_hash_name(ifid), observed)
   --[[
      tprint("are_alerts_suppressed ".. suppressAlerts)
      tprint("are_alerts_suppressed observed: ".. observed)
      tprint("are_alerts_suppressed ifname: "..ifname)
   --]]
   if((suppressAlerts == "") or (suppressAlerts == nil) or (suppressAlerts == "true")) then
      return false  -- alerts are not suppressed
   else
      if(verbose) then print("Skipping alert check for("..observed.."): disabled in preferences<br>\n") end
      return true -- alerts are suppressed
   end
end

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

-- Note: see getConfiguredAlertsThresholds for threshold object format
local function entity_threshold_crossed(granularity, old_table, new_table, threshold)
   -- Needed because Lua. loadstring() won't work otherwise.
   old = old_table
   new = new_table
   duration = granularity2sec(granularity)

   local op = op2jsop(threshold.operator)

   -- This is where magic happens: loadstring() evaluates the string
   local what = "val = "..threshold.metric.."(old, new, duration); if(val ".. op .. " " .. threshold.edge .. ") then return(true) else return(false) end"

   local f = loadstring(what)
   local rc = f()

   local threshold_info = table.clone(threshold)
   threshold_info.value = val

   return rc, threshold_info
end

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

function granularity2sec(g)
   for _, granularity in pairs(alerts_granularity) do
      if(granularity[1] == g) then
	 return(granularity[3])
      end
   end

   return(0)
end

function op2jsop(op)
   if op == "gt" then
      return ">"
   elseif op == "lt" then
      return "<"
   else
      return "=="
   end
end

function performAlertsQuery(statement, what, opts, force_query)
   local wargs = {"WHERE", "1=1"}

   if tonumber(opts.row_id) ~= nil then
      wargs[#wargs+1] = 'AND rowid = '..(opts.row_id)
   end

   if (not isEmptyString(opts.entity)) and (not isEmptyString(opts.entity_val)) then
      if((what == "historical-flows") and (alertEntityRaw(opts.entity) == "host")) then
         -- need to handle differently for flows table
         local info = hostkey2hostinfo(opts.entity_val)
         wargs[#wargs+1] = 'AND (cli_addr="'..(info.host)..'" OR srv_addr="'..(info.host)..'")'
         wargs[#wargs+1] = 'AND vlan_id='..(info.vlan)
      else
         wargs[#wargs+1] = 'AND alert_entity = "'..(opts.entity)..'"'
         wargs[#wargs+1] = 'AND alert_entity_val = "'..(opts.entity_val)..'"'
      end
   end

   if not isEmptyString(opts.origin) then
      local info = hostkey2hostinfo(opts.origin)
      wargs[#wargs+1] = 'AND cli_addr="'..(info.host)..'"'
      wargs[#wargs+1] = 'AND vlan_id='..(info.vlan)
   end

   if not isEmptyString(opts.target) then
      local info = hostkey2hostinfo(opts.target)
      wargs[#wargs+1] = 'AND srv_addr="'..(info.host)..'"'
      wargs[#wargs+1] = 'AND vlan_id='..(info.vlan)
   end

   if tonumber(opts.epoch_begin) ~= nil then
      wargs[#wargs+1] = 'AND alert_tstamp >= '..(opts.epoch_begin)
   end

   if tonumber(opts.epoch_end) ~= nil then
      wargs[#wargs+1] = 'AND alert_tstamp <= '..(opts.epoch_end)
   end

   if not isEmptyString(opts.flowhosts_type) then
      if opts.flowhosts_type ~= "all_hosts" then
         local cli_local, srv_local = 0, 0

         if opts.flowhosts_type == "local_only" then cli_local, srv_local = 1, 1
         elseif opts.flowhosts_type == "remote_only" then cli_local, srv_local = 0, 0
         elseif opts.flowhosts_type == "local_origin_remote_target" then cli_local, srv_local = 1, 0
         elseif opts.flowhosts_type == "remote_origin_local_target" then cli_local, srv_local = 0, 1
         end

         if what == "historical-flows" then
            wargs[#wargs+1] = "AND cli_localhost = "..cli_local
            wargs[#wargs+1] = "AND srv_localhost = "..srv_local
         end
         -- TODO cannot apply it to other tables right now
      end
   end

   if tonumber(opts.alert_type) ~= nil then
      wargs[#wargs+1] = "AND alert_type = "..(opts.alert_type)
   end

   if tonumber(opts.alert_severity) ~= nil then
      wargs[#wargs+1] = "AND alert_severity = "..(opts.alert_severity)
   end

   if tonumber(opts.alert_engine) ~= nil then
      wargs[#wargs+1] = "AND alert_engine = "..(opts.alert_engine)
   end

   if((not isEmptyString(opts.sortColumn)) and (not isEmptyString(opts.sortOrder))) then
      local order_by

      if opts.sortColumn == "column_date" then
         order_by = "alert_tstamp"
      elseif opts.sortColumn == "column_severity" then
         order_by = "alert_severity"
      elseif opts.sortColumn == "column_type" then
         order_by = "alert_type"
      elseif((opts.sortColumn == "column_duration") and (what == "historical")) then
         order_by = "(alert_tstamp_end - alert_tstamp)"
      else
         -- default
         order_by = "alert_tstamp"
      end

      wargs[#wargs+1] = "ORDER BY "..order_by
      wargs[#wargs+1] = string.upper(opts.sortOrder)
   end

   -- pagination
   if((tonumber(opts.perPage) ~= nil) and (tonumber(opts.currentPage) ~= nil)) then
      local to_skip = (tonumber(opts.currentPage)-1) * tonumber(opts.perPage)
      wargs[#wargs+1] = "LIMIT"
      wargs[#wargs+1] = to_skip..","..(opts.perPage)
   end

   local query = table.concat(wargs, " ")
   local res

   -- Uncomment to debug the queries
   --~ tprint(statement.." (from "..what..") "..query)

   if what == "engaged" then
      res = interface.queryAlertsRaw(true, statement, query, force_query)
   elseif what == "historical" then
      res = interface.queryAlertsRaw(false, statement, query, force_query)
   elseif what == "historical-flows" then
      res = interface.queryFlowAlertsRaw(statement, query, force_query)
   else
      error("Invalid alert subject: "..what)
   end

   return res
end

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

function getNumAlerts(what, options)
   local num = 0
   local opts = getUnpagedAlertOptions(options or {})
   local res = performAlertsQuery("SELECT COUNT(*) AS count", what, opts)
   if((res ~= nil) and (#res == 1) and (res[1].count ~= nil)) then num = tonumber(res[1].count) end

   return num
end

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

function getAlerts(what, options)
   return performAlertsQuery("SELECT rowid, *", what, options)
end

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

function deleteAlerts(what, options)
   local opts = getUnpagedAlertOptions(options or {})
   performAlertsQuery("DELETE", what, opts)
   invalidateEngagedAlertsCache(getInterfaceId(ifname))
end

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

-- this function returns an object with parameters specific for one tab
function getTabParameters(_get, what)
   local opts = {}
   for k,v in pairs(_get) do opts[k] = v end

   -- these options are contextual to the current tab (status)
   if _get.status ~= what then
      opts.alert_type = nil
      opts.alert_severity = nil
   end
   if not isEmptyString(what) then opts.status = what end
   return opts
end

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

-- Remove pagination options from the options
function getUnpagedAlertOptions(options)
   local res = {}

   local paged_option = { currentPage=1, perPage=1, sortColumn=1, sortOrder=1 }

   for k,v in pairs(options) do
      if not paged_option[k] then
         res[k] = v
      end
   end

   return res
end

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

function checkDeleteStoredAlerts()
   _GET["status"] = _GET["status"] or _POST["status"]

   if((_POST["id_to_delete"] ~= nil) and (_GET["status"] ~= nil)) then
      if(_POST["id_to_delete"] ~= "__all__") then
         _GET["row_id"] = tonumber(_POST["id_to_delete"])
      end

      deleteAlerts(_GET["status"], _GET)
      -- to avoid performing the delete again
      _POST["id_to_delete"] = nil
      -- to avoid filtering by id
      _GET["row_id"] = nil
      -- in case of delete "older than" button, resets the time period after the delete took place
      if isEmptyString(_GET["epoch_begin"]) then _GET["epoch_end"] = nil end

      local new_num = getNumAlerts(_GET["status"], _GET)
      if new_num == 0 then
         -- reset the filter to avoid hiding the tab
         _GET["alert_severity"] = nil
         _GET["alert_type"] = nil
      end
   end
end

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

--
-- This function should be updated whenever a new alert entity type is available.
-- If entity_info is nil, then no links will be provided.
--
local function formatAlertEntity(ifid, entity_type, entity_value, entity_info)
  local value

  if entity_type == "host" then
    value = resolveAddress(hostkey2hostinfo(entity_value))

    if entity_info ~= nil then
      value = "<a href='"..ntop.getHttpPrefix().."/lua/host_details.lua?ifid="..ifid
      .."&host="..hostinfo2hostkey({host=entity_info.ip.ip, vlan=entity_info.vlan_id}).."'>"..value.."</a>"
    end
  elseif entity_type == "interface" then
    value = getInterfaceName(ifid)

    if entity_info ~= nil then
      value = "<a href='"..ntop.getHttpPrefix().."/lua/if_stats.lua?ifid="..ifid.."'>"..value.."</a>"
    end
  elseif entity_type == "network" then
    value = hostkey2hostinfo(entity_value)["host"]

    if entity_info ~= nil then
      value = "<a href='"..ntop.getHttpPrefix().."/lua/network_details.lua?network="..(entity_info.network_id).."&page=historical'>"
        ..value.."</a>"
    end
  else
    -- fallback
    value = entity_value
  end

  -- try to get a localized message
  local localized = i18n("alert_messages."..entity_type.."_entity", {entity_value=value})

  if localized ~= nil then
    return localized
  else
    -- fallback
    return entity_type.." "..value
  end
end

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

local function drawDropdown(status, selection_name, active_entry, entries_table)
   -- alert_level_keys and alert_type_keys are defined in lua_utils
   local id_to_label
   if selection_name == "severity" then
      id_to_label = alertSeverityLabel
   elseif selection_name == "type" then
      id_to_label = alertTypeLabel
   end

   -- compute counters to avoid printing items that have zero entries in the database
   local actual_entries = {}
   if status == "historical-flows" then

      if selection_name == "severity" then
	 actual_entries = interface.queryFlowAlertsRaw("select alert_severity id, count(*) count", "group by alert_severity")
      elseif selection_name == "type" then
	 actual_entries = interface.queryFlowAlertsRaw("select alert_type id, count(*) count", "group by alert_type")
      end

   else -- dealing with non flow alerts (engaged and closed)
      local engaged
      if status == "engaged" then
	 engaged = true
      elseif status == "historical" then
	 engaged = false
      end

      if selection_name == "severity" then
	 actual_entries = interface.queryAlertsRaw(engaged, "select alert_severity id, count(*) count", "group by alert_severity")
      elseif selection_name == "type" then
	 actual_entries = interface.queryAlertsRaw(engaged, "select alert_type id, count(*) count", "group by alert_type")
      end

   end

   local buttons = '<div class="btn-group">'

   local button_label = firstToUpper(selection_name)
   if active_entry ~= nil and active_entry ~= "" then
      button_label = firstToUpper(active_entry)..'<span class="glyphicon glyphicon-filter"></span>'
   end

   buttons = buttons..'<button class="btn btn-link dropdown-toggle" data-toggle="dropdown">'..button_label
   buttons = buttons..'<span class="caret"></span></button>'

   buttons = buttons..'<ul class="dropdown-menu dropdown-menu-right" role="menu">'

   local class_active = ""
   if active_entry == nil then class_active = ' class="active"' end
   buttons = buttons..'<li'..class_active..'><a href="?status='..status..'">All</a></i>'

   for _, entry in pairs(actual_entries) do
      local id = tonumber(entry["id"])
      local count = entry["count"]
      local label = id_to_label(id, true)

      class_active = ""
      if label == active_entry then class_active = ' class="active"' end
      -- buttons = buttons..'<li'..class_active..'><a href="'..ntop.getHttpPrefix()..'/lua/show_alerts.lua?status='..status
      buttons = buttons..'<li'..class_active..'><a href="?status='..status
      buttons = buttons..'&alert_'..selection_name..'='..id..'">'
      buttons = buttons..firstToUpper(label)..' ('..count..')</a></li>'
   end

   buttons = buttons..'</ul></div>'

   return buttons
end

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

function getGlobalAlertsConfigurationHash(granularity, entity_type, alert_source)
   return 'ntopng.prefs.alerts_global.'..granularity.."."..get_global_alerts_hash_key(entity_type, alert_source)
end

local global_redis_thresholds_key = "thresholds"

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

function drawAlertSourceSettings(entity_type, alert_source, delete_button_msg, delete_confirm_msg, page_name, page_params, alt_name, show_entity)
   local num_engaged_alerts, num_past_alerts, num_flow_alerts = 0,0,0
   local tab = _GET["tab"]

   -- This code controls which entries to show under the tabs Every Minute/Hourly/Daily
   local descr
   if entity_type == "network" then
      descr = network_alert_functions_description
   elseif entity_type == "interface" then
      -- interface
      descr = table.clone(alert_functions_description)
      descr["active"] = nil
      descr["flows"] = nil
   else
      -- host
      descr = alert_functions_description
   end

   local flow_rate_attacker_key = "flow_attacker_threshold"
   local flow_rate_victim_key = "flow_victim_threshold"
   local syn_attacker_key = "syn_attacker_threshold"
   local syn_victim_key = "syn_victim_threshold"
   local anomaly_config_key = nil
   local flow_rate_alert_thresh, syn_alert_thresh

   if entity_type == "host" then
      anomaly_config_key = 'ntopng.prefs.'..host_ip..':'..tostring(host_vlan)..'.alerts_config'
   end

   print('<ul class="nav nav-tabs">')

   local function printTab(tab, content, sel_tab)
      if(tab == sel_tab) then print("\t<li class=active>") else print("\t<li>") end
      print("<a href=\""..ntop.getHttpPrefix().."/lua/"..page_name.."?page=alerts&tab="..tab)
      for param, value in pairs(page_params) do
         print("&"..param.."="..value)
      end
      print("\">"..content.."</a></li>\n")
   end

   if(show_entity) then
      -- these fields will be used to perform queries
      _GET["entity"] = alertEntity(show_entity)
      _GET["entity_val"] = alert_source
   end

   if(show_entity) then
      -- possibly process pending delete arguments
      checkDeleteStoredAlerts()

      -- possibly add a tab if there are alerts configured for the host
      num_engaged_alerts = getNumAlerts("engaged", getTabParameters(_GET, "engaged"))
      num_past_alerts = getNumAlerts("historical", getTabParameters(_GET, "historical"))
      num_flow_alerts = getNumAlerts("historical-flows", getTabParameters(_GET, "historical-flows"))

      if num_past_alerts > 0 or num_engaged_alerts > 0 or num_flow_alerts > 0 then
         if(tab == nil) then
            -- if no tab is selected and there are alerts, we show them by default
            tab = "alert_list"
         end

         printTab("alert_list", "Detected Alerts", tab)
      else
         -- if there are no alerts, we show the alert settings
         if(tab=="alert_list") then tab = nil end
      end
   end

   -- Default tab
   if(tab == nil) then tab = "min" end

   if(tab ~= "alert_list") then
      local granularity_label = alertEngineLabel(alertEngine(tab))

      print(
        template.gen("modal_confirm_dialog.html", {
          dialog={
            id      = "deleteAlertSourceSettings",
            action  = "deleteAlertSourceSettings()",
            title   = i18n("show_alerts.delete_alerts_configuration"),
            message = i18n(delete_confirm_msg, {granularity=granularity_label}) .. " <span style='white-space: nowrap;'>" .. ternary(alt_name ~= nil, alt_name, alert_source).."</span>?",
            confirm = i18n("delete")
          }
        })
      )

      print(
        template.gen("modal_confirm_dialog.html", {
          dialog={
            id      = "deleteGlobalAlertConfig",
            action  = "deleteGlobalAlertConfig()",
            title   = i18n("show_alerts.delete_alerts_configuration"),
            message = i18n("show_alerts.delete_config_message", {conf = entity_type, granularity=granularity_label}).."?",
            confirm = i18n("delete")
          }
        })
      )
   end

   for _,e in pairs(alerts_granularity) do
      local k = e[1]
      local l = e[2]
      l = '<i class="fa fa-cog" aria-hidden="true"></i>&nbsp;'..l
      printTab(k, l, tab)
   end

   local anomalies_config = {
      {
         title = i18n("entity_thresholds.flow_attacker_title"),
         descr = i18n("entity_thresholds.flow_attacker_description"),
         key = flow_rate_attacker_key,
         global_default = 25, step = 1
      }, {
         title = i18n("entity_thresholds.flow_victim_title"),
         descr = i18n("entity_thresholds.flow_victim_description"),
         key = flow_rate_victim_key,
         global_default = 25, step = 1
      }, {
         title = i18n("entity_thresholds.syn_attacker_title"),
         descr = i18n("entity_thresholds.syn_attacker_description"),
         key = syn_attacker_key,
         global_default = 10, step = 5
      }, {
         title = i18n("entity_thresholds.syn_victim_title"),
         descr = i18n("entity_thresholds.syn_victim_description"),
         key = syn_victim_key,
         global_default = 10, step = 5
      }
   }

   local global_redis_hash = getGlobalAlertsConfigurationHash(tab, entity_type, alert_source)

   print('</ul>')

   if((show_entity) and (tab == "alert_list")) then
      drawAlertTables(num_past_alerts, num_engaged_alerts, num_flow_alerts, _GET, true)
   else
      -- Before doing anything we need to check if we need to save values

      vals = { }
      alerts = ""
      global_alerts = ""
      anomalies = {}
      global_anomalies = {}
      to_save = false

      if((_POST["to_delete"] ~= nil) and (_POST["SaveAlerts"] == nil)) then
         if _POST["to_delete"] == "local" then
            -- Delete threshold configuration
            ntop.delHashCache(get_alerts_hash_name(tab, ifname), alert_source)

            -- Delete specific settings
            if entity_type == "host" then
               ntop.delCache(anomaly_config_key)
               interface.refreshHostsAlertsConfiguration()
            end
            alerts = nil

            -- Load the global settings normally
            global_alerts = ntop.getHashCache(global_redis_hash, global_redis_thresholds_key)
         else
            -- Only delete global configuration
            ntop.delCache(global_redis_hash)
         end
      end

      if _POST["to_delete"] ~= "local" then
         for k,_ in pairs(descr) do
	    value    = _POST["value_"..k]
	    operator = _POST["op_"..k]

	    if((value ~= nil) and (operator ~= nil)) then
	       --io.write("\t"..k.."\n")
	       to_save = true
	       value = tonumber(value)
	       if(value ~= nil) then
		  if(alerts ~= "") then alerts = alerts .. "," end
		  alerts = alerts .. k .. ";" .. operator .. ";" .. value
	       end

         -- Handle global settings
         local global_value = tonumber(_POST["value_global_"..k])
         local global_operator = _POST["op_global_"..k]

         if (global_value ~= nil) and (global_operator ~= nil) then
            if(global_alerts ~= "") then global_alerts = global_alerts .. "," end
            global_alerts = global_alerts..k..";"..global_operator..";"..global_value
         end
	    end
         end --END for k,_ in pairs(descr) do

         -- Save source specific anomalies
         if (entity_type == "host") and (tab == "min") and (to_save or (_POST["to_delete"] ~= nil)) then
            local config_to_dump = {}

            for _, config in ipairs(anomalies_config) do
               local value = _POST[config.key]
               local global_value = _POST["global_"..config.key]

               if isEmptyString(global_value) then
                  global_value = config.global_default
               end
	       global_anomalies["global_"..config.key] = global_value
               ntop.setHashCache(global_redis_hash, config.key, global_value)

	       if not isEmptyString(value) then
		  anomalies[config.key] = value
	       else
		  value = "global"
	       end
               config_to_dump[#config_to_dump + 1] = value

            end

            -- Serialize the settings
	    local configdump = table.concat(config_to_dump, "|")
            ntop.setCache(anomaly_config_key, configdump)
            interface.refreshHostsAlertsConfiguration()
         end

         --print(alerts)

         if(to_save) then
            -- This specific entity alerts
            if(alerts == "") then
               ntop.delHashCache(get_alerts_hash_name(tab, ifname), alert_source)
            else
               ntop.setHashCache(get_alerts_hash_name(tab, ifname), alert_source, alerts)
            end

            -- Global alerts
            if(global_alerts ~= "") then
               ntop.setHashCache(global_redis_hash, global_redis_thresholds_key, global_alerts)
            else
               ntop.delHashCache(global_redis_hash, global_redis_thresholds_key)
            end
         else
            alerts = ntop.getHashCache(get_alerts_hash_name(tab, ifname), alert_source)
            global_alerts = ntop.getHashCache(global_redis_hash, global_redis_thresholds_key)
         end
      end -- END if _POST["to_delete"] ~= nil

         --print(alerts)
         --tokens = string.split(alerts, ",")
      for _, al in pairs({
         {prefix = "", config = alerts},
         {prefix = "global_", config = global_alerts},
      }) do
       if al.config ~= nil then
         tokens = split(al.config, ",")

         --print(tokens)
         if(tokens ~= nil) then
	    for _,s in pairs(tokens) do
	       t = string.split(s, ";")
	       --print("-"..t[1].."-")
	       if(t ~= nil) then vals[(al.prefix)..t[1]] = { t[2], t[3] } end
	    end
         end
       end
      end


      print [[
       </ul>
       <form method="post">
       <table id="user" class="table table-bordered table-striped" style="clear: both"> <tbody>
       <tr><th>]] print(i18n("alerts_thresholds_config.threshold_type")) print[[</th><th width=30%>]] print(i18n("alerts_thresholds_config.thresholds_single_source", {source=firstToUpper(entity_type),alt_name=ternary(alt_name ~= nil, alt_name, alert_source)})) print[[</th><th width=30%>]] print(i18n("alerts_thresholds_config.common_thresholds_local_sources", {source=firstToUpper(entity_type)}))
       print[[</th></tr>]]
      print('<input id="csrf" name="csrf" type="hidden" value="'..ntop.getRandomCSRFValue()..'" />\n')

      for key,v in pairsByKeys(descr, asc) do
         print("<tr><td><b>".. alert_functions_info[key].label .."</b><br>")
         print("<small>"..v.."</small>\n")

        for _, prefix in pairs({"", "global_"}) do
         local k = prefix..key
         print("</td><td>")
         print("<select name=op_".. k ..">\n")
         if((vals[k] ~= nil) and (vals[k][1] == "gt")) then print("<option selected=\"selected\"") else print("<option ") end
         print("value=\"gt\">&gt;</option>\n")

         if((vals[k] ~= nil) and (vals[k][1] == "lt")) then print("<option selected=\"selected\"") else print("<option ") end
         print("value=\"lt\">&lt;</option>\n")
         print("</select>\n")
         print("<input type=number min=1 step=1 class=\"text-right form-control\" style=\"display:inline; width:12em;\" name=\"value_"..k.."\" value=\"")
         if(vals[k] ~= nil) then print(vals[k][2]) end
         print("\">\n")
        end
         print("</td></tr>\n")
      end

      if (entity_type == "host") and (tab == "min") then
         local vals = table.merge(anomalies, global_anomalies)

	 -- Possibly load old config
	 local serialized_config = ntop.getCache(anomaly_config_key)
	 local deserialized_config
	 if isEmptyString(serialized_config) then
	    deserialized_config = {}
	 else
	    deserialized_config = split(serialized_config, "|")
	 end

	 for idx, config in ipairs(anomalies_config) do
	    if isEmptyString(vals[config.key]) then
	       if idx <= #deserialized_config
		  and deserialized_config[idx] ~= "global"
	          and not isEmptyString(deserialized_config[idx]) then
		  vals[config.key] = deserialized_config[idx]
	       end
	    end

	 if isEmptyString(vals["global_"..config.key]) then
	       vals["global_"..config.key] = ntop.getHashCache(global_redis_hash, config.key)
	       if isEmptyString(vals["global_"..config.key]) then
		  vals["global_"..config.key] = config.global_default
	       end
	    end
	 end

	 -- Print the config
         for _, config in ipairs(anomalies_config) do
            print("<tr><td><b>"..(config.title).."</b><br>\n")
            print("<small>"..(config.descr)..".</small>")

            for _, prefix in pairs({"", "global_"}) do
               local key = prefix..config.key

               print("</td><td>\n")
               print('<input type="number" class=\"text-right form-control\" name="'..key..'" style="display:inline; width:7em;" placeholder="" min="'..(config.step)..'" step="'..(config.step)..'" max="100000" value="')
               print(tostring(vals[key] or ""))
               print[["></input>]]
            end

            print("</td></tr>")
         end

      end

      print [[
      </tbody> </table>
      <input type="hidden" name="SaveAlerts" value="">
      
      <button class="btn btn-primary" style="float:right; margin-right:1em;" disabled="disabled" type="submit">]] print(i18n("save_configuration")) print[[</button>
      </form>

      <button class="btn btn-default" onclick="$('#deleteGlobalAlertConfig').modal('show');" style="float:right; margin-right:1em;"><i class="fa fa-trash" aria-hidden="true" data-original-title="" title=""></i> ]] print(i18n("show_alerts.delete_config_btn",{conf=firstToUpper(entity_type)})) print[[</button>
      <button class="btn btn-default" onclick="$('#deleteAlertSourceSettings').modal('show');" style="float:right; margin-right:1em;"><i class="fa fa-trash" aria-hidden="true" data-original-title="" title=""></i> ]] print(delete_button_msg) print[[</button>
      ]]

      print("<div style='margin-top:4em;'><b>" .. i18n("alerts_thresholds_config.notes") .. ":</b><ul>")

      print("<li>" .. i18n("alerts_thresholds_config.note_control_threshold_checks_periods") .. "</li>")
      print("<li>" .. i18n("alerts_thresholds_config.note_thresholds_expressed_as_delta") .. "</li>")
      print("<li>" .. i18n("alerts_thresholds_config.note_consecutive_checks") .. "</li>")

      if (entity_type == "host") then
         print("<li>" .. i18n("alerts_thresholds_config.note_deltas_of_idle_host_become_active") .. "</li>")
	 print("<li>" .. i18n("alerts_thresholds_config.note_attacker_victime_threshold") .. "</li>")
      end
      print("</ul></div>")

      print[[
      <script>
         function deleteAlertSourceSettings() {
            var params = {};

            params.to_delete = "local";
            params.csrf = "]] print(ntop.getRandomCSRFValue()) print[[";

            var form = paramsToForm('<form method="post"></form>', params);
            form.appendTo('body').submit();
         }

         function deleteGlobalAlertConfig() {
            var params = {};

            params.to_delete = "global";
            params.csrf = "]] print(ntop.getRandomCSRFValue()) print[[";

            var form = paramsToForm('<form method="post"></form>', params);
            form.appendTo('body').submit();
         }

         aysHandleForm("form", {
            handle_tabs: true,
         });
      </script>
      ]]
   end
end

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

function housekeepingAlertsMakeRoom(ifId)
   local prefs = ntop.getPrefs()
   local max_num_alerts_per_entity = prefs.max_num_alerts_per_entity
   local max_num_flow_alerts = prefs.max_num_flow_alerts

   local k = get_make_room_keys(ifId)

   if ntop.getCache(k["entities"]) == "1" then
      ntop.delCache(k["entities"])
      local res = interface.queryAlertsRaw(false,
					   "SELECT alert_entity, alert_entity_val, count(*) count",
					   "GROUP BY alert_entity, alert_entity_val HAVING COUNT >= "..max_num_alerts_per_entity)

      for _, e in pairs(res) do
	 local to_keep = (max_num_alerts_per_entity * 0.8) -- deletes 20% more alerts than the maximum number
	 to_keep = round(to_keep, 0)
	 -- tprint({e=e, total=e.count, to_keep=to_keep, to_delete=to_delete, to_delete_not_discounted=(e.count - max_num_alerts_per_entity)})
	 local cleanup = interface.queryAlertsRaw(false,
						  "DELETE",
						  "WHERE rowid NOT IN (SELECT rowid FROM closed_alerts WHERE alert_entity="..e.alert_entity.." AND alert_entity_val=\""..e.alert_entity_val.."\""..
						     "ORDER BY alert_tstamp DESC LIMIT "..to_keep..")")
	 -- TODO: possibly raise a too many alerts for entity e
      end
   end

   if ntop.getCache(k["flows"]) == "1" then
      ntop.delCache(k["flows"])
      local res = interface.queryFlowAlertsRaw("SELECT count(*) count", "WHERE 1=1")
      local count = tonumber(res[1].count)
      if count ~= nil and count >= max_num_flow_alerts then
	 local to_keep = (max_num_flow_alerts * 0.8)
	 to_keep = round(to_keep, 0)
	 local cleanup = interface.queryFlowAlertsRaw("DELETE",
						      "WHERE rowid NOT IN (SELECT rowid FROM flows_alerts ORDER BY alert_tstamp DESC LIMIT "..to_keep..")")
	 --tprint({total=count, to_delete=to_delete, cleanup=cleanup})
	 --tprint(cleanup)
	 -- TODO: possibly raise a too many flow alerts
      end
   end

end

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

function drawAlertTables(num_past_alerts, num_engaged_alerts, num_flow_alerts, get_params, hide_extended_title, alt_nav_tabs)
   local alert_items = {}
   local url_params = {}

   print(
     template.gen("modal_confirm_dialog.html", {
       dialog={
         id      = "delete_alert_dialog",
         action  = "deleteAlertById(delete_alert_id)",
         title   = i18n("show_alerts.delete_alert"),
         message = i18n("show_alerts.confirm_delete_alert").."?",
         confirm = i18n("delete"),
       }
     })
   )

   print(
     template.gen("modal_confirm_dialog.html", {
       dialog={
         id      = "myModal",
         action  = "checkModalDelete()",
         title   = "",
         message = 'Do you really want to purge all the<span id="modalDeleteContext"></span> alerts<span id="modalDeleteAlertsMsg"></span>?',
         confirm = i18n("show_alerts.purge_num_alerts", {
            num_alerts = '<img id="alerts-summary-wait" src="'..ntop.getHttpPrefix()..'/img/loading.gif"/><span id="alerts-summary-body"></span>'
         }),
       }
     })
   )

   for k,v in pairs(get_params) do if k ~= "csrf" then url_params[k] = v end end
      if not alt_nav_tabs then
	 print[[
<br>
<ul class="nav nav-tabs" role="tablist" id="alert-tabs">
<!-- will be populated later with javascript -->
</ul>
]]
	 nav_tab_id = "alert-tabs"
      else
	 nav_tab_id = alt_nav_tabs
      end

      print[[
<script>

function checkAlertActionsPanel() {
   /* check if this tab is handled by this script */
   if(getCurrentStatus() == "" || getCurrentStatus() == "engaged")
      $("#alertsActionsPanel").css("display", "none");
   else
      $("#alertsActionsPanel").css("display", "");
}

function setActiveHashTab(hash) {
   $('#]] print(nav_tab_id) --[[ see "clicked" below for the other part of this logic ]] print[[ a[href="' + hash + '"]').tab('show');
}

/* Handle the current tab */
$(function() {
 $("ul.nav-tabs > li > a").on("shown.bs.tab", function(e) {
      var id = $(e.target).attr("href").substr(1);
      history.replaceState(null, null, "#"+id);
      updateDeleteLabel(id);
      checkAlertActionsPanel();
   });

  var hash = window.location.hash;
  if (! hash && ]] if(isEmptyString(status) and not isEmptyString(_GET["tab"])) then print("true") else print("false") end print[[)
    hash = "#]] print(_GET["tab"] or "") print[[";

  if (hash)
    setActiveHashTab(hash)

  $(function() { checkAlertActionsPanel(); });
});

function getActiveTabId() {
   return $("#]] print(nav_tab_id) print[[ > li.active > a").attr('href').substr(1);
}

function updateDeleteLabel(tabid) {
   var label = $("#purgeBtnLabel");
   var prefix = "]]
      if not isEmptyString(_GET["entity"]) then print(alertEntityLabel(_GET["entity"], true).." ") end
      print [[";
   var val = "";

   if (tabid == "tab-table-engaged-alerts")
      val = "Engaged ";
   else if (tabid == "tab-table-alerts-history")
      val = "Past ";
   else if (tabid == "tab-table-flow-alerts-history")
      val = "Past Flow ";

   label.html(prefix + val);
}

function getCurrentStatus() {
   var tabid = getActiveTabId();

   if (tabid == "tab-table-engaged-alerts")
      val = "engaged";
   else if (tabid == "tab-table-alerts-history")
      val = "historical";
   else if (tabid == "tab-table-flow-alerts-history")
      val = "historical-flows";
   else
      val = "";

   return val;
}
</script>
]]
      if not alt_nav_tabs then print [[<div class="tab-content">]] end

      local status = _GET["status"]
      local status_reset = (status == nil)

      if num_engaged_alerts > 0 then
	 alert_items[#alert_items + 1] = {["label"] = i18n("show_alerts.engaged_alerts"),
	    ["div-id"] = "table-engaged-alerts",  ["status"] = "engaged"}
      elseif status == "engaged" then
	 status = nil; status_reset = 1
      end

      if num_past_alerts > 0 then
	 alert_items[#alert_items +1] = {["label"] = i18n("show_alerts.past_alerts"),
	    ["div-id"] = "table-alerts-history",  ["status"] = "historical"}
      elseif status == "historical" then
	 status = nil; status_reset = 1
      end

      if num_flow_alerts > 0 then
	 alert_items[#alert_items +1] = {["label"] = i18n("show_alerts.flow_alerts"),
	    ["div-id"] = "table-flow-alerts-history",  ["status"] = "historical-flows"}
      elseif status == "historical-flows" then
	 status = nil; status_reset = 1
      end

      for k, t in ipairs(alert_items) do
	 local clicked = "0"
	 if((not alt_nav_tabs) and ((k == 1 and status == nil) or (status ~= nil and status == t["status"]))) then
	    clicked = "1"
	 end
	 print [[
      <div class="tab-pane fade in" id="tab-]] print(t["div-id"]) print[[">
        <div id="]] print(t["div-id"]) print[["></div>
      </div>

      <script type="text/javascript">
         function deleteAlertById(alert_id) {
            var params = {};
            params.id_to_delete = alert_id;
            params.status = getCurrentStatus();
            params.csrf = "]] print(ntop.getRandomCSRFValue()) print[[";

            var form = paramsToForm('<form method="post"></form>', params);
            form.appendTo('body').submit();
         }

         $("#]] print(nav_tab_id) print[[").append('<li><a href="#tab-]] print(t["div-id"]) print[[" clicked="]] print(clicked) print[[" role="tab" data-toggle="tab">]] print(t["label"]) print[[</a></li>')

         $('a[href="#tab-]] print(t["div-id"]) print[["]').on('shown.bs.tab', function (e) {
         // append the li to the tabs

	 $("#]] print(t["div-id"]) print[[").datatable({
			url: "]] print(ntop.getHttpPrefix()) print [[/lua/get_alerts_data.lua?" + $.param(]] print(tableToJsObject(getTabParameters(url_params, t["status"]))) print [[),
               showFilter: true,
	       showPagination: true,
               buttons: [']]

	 local title = t["label"]

	 -- TODO this condition should be removed and page integration support implemented
	 if((isEmptyString(_GET["entity"])) and isEmptyString(_GET["epoch_begin"]) and isEmptyString(_GET["epoch_end"])) then
	    -- alert_level_keys and alert_type_keys are defined in lua_utils
	    local alert_severities = {}
	    for _, s in pairs(alert_level_keys) do alert_severities[#alert_severities +1 ] = s[3] end
	    local alert_types = {}
	    for _, s in pairs(alert_type_keys) do alert_types[#alert_types +1 ] = s[3] end

	    local a_type, a_severity = nil, nil
	    if clicked == "1" then
	       if tonumber(_GET["alert_type"]) ~= nil then a_type = alertTypeLabel(_GET["alert_type"], true) end
	       if tonumber(_GET["alert_severity"]) ~= nil then a_severity = alertSeverityLabel(_GET["alert_severity"], true) end
	    end

	    print(drawDropdown(t["status"], "type", a_type, alert_types))
	    print(drawDropdown(t["status"], "severity", a_severity, alert_severities))
	 elseif((not isEmptyString(_GET["entity_val"])) and (not hide_extended_title)) then
	    if entity == "host" then
	       title = title .. " - " .. firstToUpper(formatAlertEntity(getInterfaceId(ifname), entity, _GET["entity_val"], nil))
	    end
	 end

	 print[['],
/*
               buttons: ['<div class="btn-group"><button class="btn btn-link dropdown-toggle" data-toggle="dropdown">Severity<span class="caret"></span></button><ul class="dropdown-menu" role="menu"><li>test severity</li></ul></div><div class="btn-group"><button class="btn btn-link dropdown-toggle" data-toggle="dropdown">Type<span class="caret"></span></button><ul class="dropdown-menu" role="menu"><li>test type</li></ul></div>'],
*/
]]

	 if(_GET["currentPage"] ~= nil and _GET["status"] == t["status"]) then
	    print("currentPage: ".._GET["currentPage"]..",\n")
	 end
	 if(_GET["perPage"] ~= nil and _GET["status"] == t["status"]) then
	    print("perPage: ".._GET["perPage"]..",\n")
	 end
	 print ('sort: [ ["' .. getDefaultTableSort("alerts") ..'","' .. getDefaultTableSortOrder("alerts").. '"] ],\n')
	 print [[
	        title: "]] print(title) print[[",
      columns: [
	 {
	    title: "]]print(i18n("show_alerts.alert_datetime"))print[[",
	    field: "column_date",
            sortable: true,
	    css: {
	       textAlign: 'center',
          whiteSpace: 'nowrap',
	    }
	 },

	 {
	    title: "]]print(i18n("show_alerts.alert_duration"))print[[",
	    field: "column_duration",
            sortable: true,
       ]]

   if t["status"] == "historical-flows" then
      print("hidden: true,")
   end

   print[[
	    css: {
	       textAlign: 'center',
          whiteSpace: 'nowrap',
	    }
	 },

	 {
	    title: "]]print(i18n("show_alerts.alert_severity"))print[[",
	    field: "column_severity",
            sortable: true,
	    css: {
	       textAlign: 'center'
	    }
	 },

	 {
	    title: "]]print(i18n("show_alerts.alert_type"))print[[",
	    field: "column_type",
            sortable: true,
	    css: {
	       textAlign: 'center',
          whiteSpace: 'nowrap',
	    }
	 },

	 {
	    title: "]]print(i18n("show_alerts.alert_description"))print[[",
	    field: "column_msg",
	    css: {
	       textAlign: 'left',
	    }
	 },

    {
      field: "column_key",
      hidden: true
    },

    {
	    title: "]]print(i18n("show_alerts.alert_actions")) print[[",
       ]]
   if t["status"] == "engaged" then
      print("hidden: true,")
   end
   print[[
	    css: {
	       textAlign: 'center',
	    }
	 }
      ], tableCallback: function() {
            datatableForEachRow("#]] print(t["div-id"]) print[[", function(row_id) {
               var alert_key = $("td:nth(5)", this).html().split("|");
               var alert_id = alert_key[0];
               var historical_url = alert_key[1];

               if (typeof(historical_url) === "string")
                  datatableAddLinkButtonCallback.bind(this)(7, historical_url, "]] print(i18n("show_alerts.explorer")) print[[");
               datatableAddDeleteButtonCallback.bind(this)(7, "delete_alert_id ='" + alert_id + "'; $('#delete_alert_dialog').modal('show');", "]] print(i18n('delete')) print[[");

               $("form", this).submit(function() {
                  // add "status" parameter to the form
                  var get_params = paramsExtend(]] print(tableToJsObject(getTabParameters(url_params, nil))) print[[, {status:getCurrentStatus()});
                  $(this).attr("action", "?" + $.param(get_params));

                  return true;
               });
         });
      }
   });
   });
   ]]
	 if (clicked == "1") then
	    print[[
         // must wait for modalDeleteAlertsStatus to be created
         $(function() {
            var status_reset = ]] print(tostring(status_reset)) --[[ this is necessary because of status parameter inconsistency after tab switch ]] print[[;
            var tabid;

            if ((status_reset) || (getCurrentStatus() == "")) {
               tabid = "]] print("tab-"..t["div-id"]) print[[";
               history.replaceState(null, null, "#"+tabid);
            } else {
               tabid = getActiveTabId();
            }

            updateDeleteLabel(tabid);
         });
      ]]
	 end
	 print[[
   </script>
	      ]]

      end

      local zoom_vals = {
	 { "5 min",  5*60*1, i18n("show_alerts.older_5_minutes_ago") },
	 { "30 min", 30*60*1, i18n("show_alerts.older_30_minutes_ago") },
	 { "1 hour",  60*60*1, i18n("show_alerts.older_1_hour_ago") },
	 { "1 day",  60*60*24, i18n("show_alerts.older_1_day_ago") },
	 { "1 week",  60*60*24*7, i18n("show_alerts.older_1_week_ago") },
	 { "1 month",  60*60*24*31, i18n("show_alerts.older_1_month_ago") },
	 { "6 months",  60*60*24*31*6, i18n("show_alerts.older_6_months_ago") },
	 { "1 year",  60*60*24*366 , i18n("show_alerts.older_1_year_ago") }
      }

      if (num_past_alerts > 0 or num_flow_alerts > 0 or num_engaged_alerts > 0) then
	 -- trigger the click on the right tab to force table load
	 print[[
<script type="text/javascript">
$("[clicked=1]").trigger("click");
</script>
]]

	 if not alt_nav_tabs then print [[</div> <!-- closes tab-content -->]] end
	 local has_fixed_period = ((not isEmptyString(_GET["epoch_begin"])) or (not isEmptyString(_GET["epoch_end"])))

	 print('<div id="alertsActionsPanel">')
	 print('<br>Alerts to Purge: ')
	 print[[<select id="deleteZoomSelector" class="form-control" style="display:]] if has_fixed_period then print("none") else print("inline") end print[[; width:14em; margin:0 1em;">]]
	 local all_msg = ""

	 if not has_fixed_period then
	    print('<optgroup label="older than">')
	    for k,v in ipairs(zoom_vals) do
	       print('<option data-older="'..(os.time() - zoom_vals[k][2])..'" data-msg="'.." "..zoom_vals[k][3].. '">'..zoom_vals[k][1]..'</option>\n')
	    end
	    print('</optgroup>')
	 else
	    all_msg = " in the selected time period"
	 end

	 print('<option selected="selected" data-older="0" data-msg="') print(all_msg) print('">All</option>\n')


	 print[[</select>
       <form id="modalDeleteForm" class="form-inline" style="display:none;" method="post" onsubmit="return checkModalDelete();">
         <input type="hidden" id="modalDeleteAlertsOlderThan" value="-1" />
         <input id="csrf" name="csrf" type="hidden" value="]] print(ntop.getRandomCSRFValue()) print[[" />
      </form>
    ]]

    -- we need to dynamically modify parameters at js-time because we switch tab
	 local delete_params = getTabParameters(url_params, nil)
	 delete_params.epoch_end = -1

	 print[[<button id="buttonOpenDeleteModal" data-toggle="modal" data-target="#myModal" class="btn btn-default"><i type="submit" class="fa fa-trash-o"></i> <span id="purgeBtnMessage">Purge <span id="purgeBtnLabel"></span>Alerts</span></button>
   </div> <!-- closes alertsActionsPanel -->

<script>

paramsToForm('#modalDeleteForm', ]] print(tableToJsObject(delete_params)) print[[);

function getTabSpecificParams() {
   var tab_specific = {status:getCurrentStatus()};
   var period_end = $('#modalDeleteAlertsOlderThan').val();
   if (parseInt(period_end) > 0)
      tab_specific.epoch_end = period_end;

   if (tab_specific.status == "]] print(_GET["status"]) print[[") {
      tab_specific.alert_severity = ]] if tonumber(_GET["alert_severity"]) ~= nil then print(_GET["alert_severity"]) else print('""') end print[[;
      tab_specific.alert_type = ]] if tonumber(_GET["alert_type"]) ~= nil then print(_GET["alert_type"]) else print('""') end print[[;
   }

   // merge the general parameters to the tab specific ones
   return paramsExtend(]] print(tableToJsObject(getTabParameters(url_params, nil))) print[[, tab_specific);
}

function checkModalDelete() {
   var get_params = getTabSpecificParams();
   var post_params = {};
   post_params.csrf = "]] print(ntop.getRandomCSRFValue()) print[[";
   post_params.id_to_delete = "__all__";

   // this actually performs the request
   var form = paramsToForm('<form method="post"></form>', post_params);
   form.attr("action", "?" + $.param(get_params));
   form.appendTo('body').submit();
   return false;
}

var cur_alert_num_req = null;

/* This acts before shown.bs.modal event, avoiding visual fields substitution glitch */
$('#buttonOpenDeleteModal').on('click', function() {
   var lb = $("#purgeBtnLabel");
   var zoomsel = $("#deleteZoomSelector").find(":selected");
   $("#myModal h3").html($("#purgeBtnMessage").html());

   $(".modal-body #modalDeleteAlertsMsg").html(zoomsel.data('msg') + ']]
	 if tonumber(_GET["alert_severity"]) ~= nil then
	    print(' with severity "'..alertSeverityLabel(_GET["alert_severity"], true)..'" ')
	 elseif tonumber(_GET["alert_type"]) ~= nil then
	    print(' with type "'..alertTypeLabel(_GET["alert_type"], true)..'" ')
	 end
	 print[[');
   if (lb.length == 1)
      $(".modal-body #modalDeleteContext").html(" " + lb.html());

   $('#modalDeleteAlertsOlderThan').val(zoomsel.data('older'));

   cur_alert_num_req = $.ajax({
      type: 'GET',
      ]] print("url: '"..ntop.getHttpPrefix().."/lua/get_num_alerts.lua'") print[[,
       data: getTabSpecificParams(),
       complete: function() {
         $("#alerts-summary-wait").hide();
       }, error: function() {
         $("#alerts-summary-body").html("?");
       }, success: function(count){
         $("#alerts-summary-body").html(count);
         if (count == 0)
            $('#myModal button[type="submit"]').attr("disabled", "disabled");
       }
    });
});

$('#myModal').on('hidden.bs.modal', function () {
   if(cur_alert_num_req) {
      cur_alert_num_req.abort();
      cur_alert_num_req = null;
   }

   $("#alerts-summary-wait").show();
   $("#alerts-summary-body").html("");
   $('#myModal button[type="submit"]').removeAttr("disabled");
})
</script>]]
      end

end

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

local function getEngagedAlertsCacheKey(ifid, granularity)
   return "ntopng.cache.engaged_alerts_cache_ifid_"..ifid.."_".. granularity
end

local function getConfiguredAlertsThresholds(ifname, granularity)
  local thresholds_key = get_alerts_hash_name(granularity, ifname)
  local thresholds_config = {}
  local res = {}

  -- Handle the global configuration
  local global_conf_keys = ntop.getKeysCache(getGlobalAlertsConfigurationHash(granularity, "*", "*")) or {}
  
  for alert_key in pairs(global_conf_keys) do
    local thresholds_str = ntop.getHashCache(alert_key, global_redis_thresholds_key)

    if not isEmptyString(thresholds_str) then
      -- extract only the last part of the key
      local k = string.sub(alert_key, string.find(alert_key, "%.[^%.]*$")+1)
      thresholds_config[k] = thresholds_str
    end
  end

  for entity_val, thresholds_str in pairs(table.merge(thresholds_config, ntop.getHashAllCache(thresholds_key) or {})) do
    local thresholds = split(thresholds_str, ",")
    res[entity_val] = {}

    for _, threshold in pairs(thresholds) do
      local parts = string.split(threshold, ";")
      if #parts == 3 then
        local alert_key = granularity .. "_" .. parts[1] -- the alert key is the concatenation of the granularity and the metric
        res[entity_val][parts[1]] = {metric=parts[1], operator=parts[2], edge=parts[3], key=alert_key}
      end
    end
  end

  return res
end

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

-- Extracts the configured thresholds for the entity, global and local
local function getEntityThresholds(configured_thresholds, entity_type, entity)
   local res = {}
   local global_conf_key = get_global_alerts_hash_key(entity_type, entity)

   if configured_thresholds[global_conf_key] ~= nil then
      -- Global configuration exists
      for k, v in pairs(configured_thresholds[global_conf_key]) do
         res[k] = v
      end
   end

   -- Possibly override global thresholds with local configured ones
   if configured_thresholds[entity] ~= nil then
      for k, v in pairs(configured_thresholds[entity]) do
         res[k] = v
      end
   end

   return res
end

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

local function formatThresholdCross(ifid, engine, entity_type, entity_value, entity_info, alert_key, threshold_info)
  if threshold_info.metric then
    local info = alert_functions_info[threshold_info.metric]
    local label = info and string.lower(info.label) or threshold_info.metric
    local value = info and info.fmt(threshold_info.value) or threshold_info.value
    local edge = info and info.fmt(threshold_info.edge) or threshold_info.edge

    return alertEngineLabel(engine).." <b>".. label .."</b> crossed by "..formatAlertEntity(ifid, entity_type, entity_value, entity_info)..
        " ["..value.." &"..(threshold_info.operator).."; "..edge.."]"
  end

  return ""
end

local function formatSynFlood(ifid, engine, entity_type, entity_value, entity_info, alert_key, alert_info)
  if entity_info.anomalies ~= nil then
    if (alert_key == "syn_flood_attacker") and (entity_info.anomalies.syn_flood_attacker ~= nil) then
      local anomaly_info = entity_info.anomalies.syn_flood_attacker

      return firstToUpper(formatAlertEntity(ifid, entity_type, entity_value, entity_info)).." is a SYN Flooder ("..
           (anomaly_info.last_trespassed_hits).." SYN sent in "..secondsToTime(anomaly_info.over_threshold_duration_sec)..")"
    elseif (alert_key == "syn_flood_victim") and (entity_info.anomalies.syn_flood_victim ~= nil) then
      local anomaly_info = entity_info.anomalies.syn_flood_victim

      return firstToUpper(formatAlertEntity(ifid, entity_type, entity_value, entity_info)).." is under SYN flood attack ("..
           (anomaly_info.last_trespassed_hits).." SYN received in "..secondsToTime(anomaly_info.over_threshold_duration_sec)..")"
    end
  end

  return ""
end

local function formatFlowsFlood(ifid, engine, entity_type, entity_value, entity_info, alert_key, alert_info)
  if entity_info.anomalies ~= nil then
    if (alert_key == "flows_flood_attacker") and (entity_info.anomalies.flows_flood_attacker) then
      local anomaly_info = entity_info.anomalies.flows_flood_attacker
      return firstToUpper(formatAlertEntity(ifid, entity_type, entity_value, entity_info)).." is a Flooder ("..
           (anomaly_info.last_trespassed_hits).." flows sent in "..secondsToTime(anomaly_info.over_threshold_duration_sec)..")"
    elseif (alert_key == "flows_flood_victim") and (entity_info.anomalies.flows_flood_victim) then
      local anomaly_info = entity_info.anomalies.flows_flood_victim
      return firstToUpper(formatAlertEntity(ifid, entity_type, entity_value, entity_info)).." is under flood attack ("..
           (anomaly_info.last_trespassed_hits).." flows received in "..secondsToTime(anomaly_info.over_threshold_duration_sec)..")"
    end
  end

  return ""
end

local function formatMisconfiguredApp(ifid, engine, entity_type, entity_value, entity_info, alert_key, alert_info)
  if entity_info.anomalies ~= nil then
    if alert_key == "too_many_flows" then
      return firstToUpper(formatAlertEntity(ifid, entity_type, entity_value, entity_info))..
          " has too many flows. Please extend the --max-num-flows/-X command line option"
    elseif alert_key == "too_many_hosts" then
      return firstToUpper(formatAlertEntity(ifid, entity_type, entity_value, entity_info))..
          " has too many hosts. Please extend the --max-num-hosts/-x command line option"
    end
  end

  return ""
end

-- returns the pair (message, severity)
local function formatAlertMessage(ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info)
  -- Defaults
  local msg = ""
  local severity = "error"

  if atype == "threshold_cross" then
    msg = formatThresholdCross(ifid, engine, entity_type, entity_value, entity_info, akey, alert_info)
  elseif atype == "tcp_syn_flood" then
    msg = formatSynFlood(ifid, engine, entity_type, entity_value, entity_info, akey, alert_info)
  elseif atype == "flows_flood" then
    msg = formatFlowsFlood(ifid, engine, entity_type, entity_value, entity_info, akey, alert_info)
  elseif atype == "misconfigured_app" then
    msg = formatMisconfiguredApp(ifid, engine, entity_type, entity_value, entity_info, akey, alert_info)
  end

  return msg, severity
end

local function engageReleaseAlert(engaged, ifid, engine, entity_type, entity_value, atype, alert_key, entity_info, alert_info)
  local alert_msg, alevel = formatAlertMessage(ifid, engine, entity_type, entity_value, atype, alert_key, entity_info, alert_info)
  local alert_type = alertType(atype)
  local alert_level = alertLevel(alevel)

  if entity_type == "interface" then
    if engaged then
      return interface.engageInterfaceAlert(engine, alert_key, alert_type, alert_level, alert_msg)
    else
      return interface.releaseInterfaceAlert(engine, alert_key, alert_type, alert_level, alert_msg)
    end
  elseif entity_type == "host" then
    if engaged then
      return interface.engageHostAlert(engine, entity_value, alert_key, alert_type, alert_level, alert_msg)
    else
      return interface.releaseHostAlert(engine, entity_value, alert_key, alert_type, alert_level, alert_msg)
    end
  elseif entity_type == "network" then
    if engaged then
      return interface.engageNetworkAlert(engine, entity_value, alert_key, alert_type, alert_level, alert_msg)
    else
      return interface.releaseNetworkAlert(engine, entity_value, alert_key, alert_type, alert_level, alert_msg)
    end
  end
end

local function engageAlert(ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info)
   if(verbose) then io.write("Engage Alert: "..entity_value.." "..atype.." "..akey.."\n") end

   engageReleaseAlert(true, ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info)

   if ntop.isPro() and hasNagiosSupport() then
      ntop.sendNagiosAlert(entity_value:gsub("@0", ""), akey, formatAlertMessage(ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info))
   end
end

local function releaseAlert(ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info)
   if(verbose) then io.write("Release Alert: "..entity_value.." "..atype.." "..akey.."\n") end

   engageReleaseAlert(false, ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info)

   if ntop.isPro() and hasNagiosSupport() then
      ntop.withdrawNagiosAlert(entity_value:gsub("@0", ""), akey, "Service OK.")
   end
end

local function getEngagedAlertsCache(ifid, granularity)
  local engaged_cache = ntop.getCache(getEngagedAlertsCacheKey(ifid, granularity))

  if isEmptyString(engaged_cache) then
    engaged_cache = {}
    local sql_res = performAlertsQuery("select *", "engaged", {alert_engine = alertEngine(granularity)})

    for _, res in pairs(sql_res) do
      local entity_type = alertEntityRaw(res.alert_entity)
      local entity_value = res.alert_entity_val
      local atype = alertTypeRaw(res.alert_type)
      local akey = res.alert_id

      engaged_cache[entity_type] = engaged_cache[entity_type] or {}
      engaged_cache[entity_type][entity_value] = engaged_cache[entity_type][entity_value] or {}
      engaged_cache[entity_type][entity_value][akey] = engaged_cache[entity_type][entity_value][akey] or {}
      engaged_cache[entity_type][entity_value][atype] = engaged_cache[entity_type][entity_value][atype] or {}
      engaged_cache[entity_type][entity_value][atype][akey] = true
    end

    ntop.setCache(getEngagedAlertsCacheKey(ifid, granularity), j.encode(engaged_cache))
  else
    engaged_cache = j.decode(engaged_cache, 1, nil)
  end

  return engaged_cache
end

function invalidateEngagedAlertsCache(ifid)
  local keys = ntop.getKeysCache(getEngagedAlertsCacheKey(ifid, "*")) or {}

  for key in pairs(keys) do
    ntop.delCache(key)
  end

  if(verbose) then io.write("Engaged Alerts Cache invalidated\n") end
end

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

local function check_entity_alerts(ifid, entity_type, entity_value, working_status, old_entity_info, entity_info)
  if are_alerts_suppressed(entity_value, ifid) then return end

  local engine = working_status.engine
  local granularity = working_status.granularity
  local engaged_cache = working_status.engaged_cache
  local current_alerts = {}
  local past_alert_info = {}
  local invalidate = false

  local function addAlertInfo(info_arr, atype, akey, alert_info)
    info_arr[atype] = info_arr[atype] or {}
    info_arr[atype][akey] = alert_info or {}
  end

  if granularity == "min" then
    -- Populate current_alerts with anomalies
    for anomal_name, anomaly in pairs(entity_info.anomalies or {}) do
      if starts(anomal_name, "syn_flood") then
        addAlertInfo(current_alerts, "tcp_syn_flood", anomal_name, anomaly)
      elseif starts(anomal_name, "flows_flood") then
        addAlertInfo(current_alerts, "flows_flood", anomal_name, anomaly)
      elseif starts(anomal_name, "too_many_") then
        addAlertInfo(current_alerts, "misconfigured_app", anomal_name, anomaly)
      else
        -- default anomaly - empty alert key
        addAlertInfo(current_alerts, anomal_name, "", anomaly)
      end
    end
  end

  -- Populate current_alerts with threshold crosses
  for _, threshold in pairs(getEntityThresholds(working_status.configured_thresholds, entity_type, entity_value)) do
    local atype = "threshold_cross"
    local akey = threshold.key
    local exceeded, alert_info = entity_threshold_crossed(granularity, old_entity_info, entity_info, threshold)

    if exceeded then
      addAlertInfo(current_alerts, atype, akey, alert_info)
    else
      -- save past alert information
      addAlertInfo(past_alert_info, atype, akey, alert_info)
    end
  end

  -- Engage logic
  for atype, akeys in pairs(current_alerts) do
    for akey, alert_info in pairs(akeys) do
      if ((engaged_cache[entity_type] == nil)
          or (engaged_cache[entity_type][entity_value] == nil)
          or (engaged_cache[entity_type][entity_value][atype] == nil)
          or (engaged_cache[entity_type][entity_value][atype][akey] == nil)) then
        engageAlert(ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info)
        working_status.dirty_cache = true
      end
    end
  end

  -- Release logic
  if (engaged_cache[entity_type] ~= nil) and (engaged_cache[entity_type][entity_value] ~= nil) then
    for atype, akeys in pairs(engaged_cache[entity_type][entity_value]) do
      for akey, _ in pairs(akeys) do
        -- mark the alert as processed
        engaged_cache[entity_type][entity_value][atype][akey] = "processed"

        if (current_alerts[atype] == nil) or (current_alerts[atype][akey] == nil) then
          local alert_info

          if (past_alert_info[atype] ~= nil) and (past_alert_info[atype][akey] ~= nil) then
            alert_info = past_alert_info[atype][akey]
          else
            alert_info = {}
          end

          releaseAlert(ifid, engine, entity_type, entity_value, atype, akey, entity_info, alert_info)
          working_status.dirty_cache = true
        end
      end
    end
  end
end

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

local function entity_threshold_status_rw(granularity, ifname_id, fname, use_persistance, to_write --[[nil if it's a read]], additional_path)
   local basedir = fixPath(dirs.workingdir .. "/" .. ifname_id .. "/json/" .. granularity .. (additional_path and ("/"..additional_path) or ""))
   local fpath = fixPath(basedir.."/"..fname)

   if to_write ~= nil then
      if not(ntop.exists(basedir)) then
         ntop.mkdir(basedir)
      end

      -- Write new version
      if use_persistance then
         persistence.store(fpath, to_write)
      else
         local f = io.open(fpath, "w")
         if f ~= nil then
            f:write(to_write)
            f:close()
         end
      end
   elseif ntop.exists(fpath) then
      -- Read old version
      local old_dump = nil

      if use_persistance then
         old_dump = persistence.load(fpath)
      else
         local f = io.open(fpath, "r")
         if(f ~= nil) then
            old_dump = f:read("*all")
            f:close()
            if not isEmptyString(old_dump) then
               old_dump = j.decode(old_dump, 1, nil)
            end
         end
      end

      if old_dump ~= nil then
         return old_dump
      end
   end
end

local function interface_threshold_status_rw(granularity, ifid,  to_write)
   return entity_threshold_status_rw(granularity, ifid, "iface_"..ifid.."_lastdump", true, to_write)
end

local function network_threshold_status_rw(granularity, ifid, network, to_write)
   return entity_threshold_status_rw(granularity, ifid, "alarmed_subnet_stats_lastdump", true, to_write, getPathFromKey(network))
end

local function host_threshold_status_rw(granularity, ifid, hostinfo, to_write)
   return entity_threshold_status_rw(granularity, ifid, hostinfo.ip .. ".json", false, to_write)
end

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

local function check_interface_alerts(ifid, working_status)
   local ifstats = interface.getStats()
   local entity_value = "iface_"..ifid
   
   local old_entity_info = interface_threshold_status_rw(working_status.granularity, ifid) -- read old json
   local new_entity_info = ifstats

   if (old_entity_info ~= nil) and (old_entity_info.stats ~= nil) and (old_entity_info.stats.bytes ~= nil) then
      -- wrap check
      if old_entity_info.stats.bytes > ifstats.stats.bytes then
         -- reset
         if(verbose) then print("entity '"..entity_value.."' stats reset("..working_status.granularity..")") end
         old_entity_info = {}
      end
   else
      -- empty
      old_entity_info = {}
   end

   check_entity_alerts(ifid, "interface", entity_value, working_status, old_entity_info, new_entity_info)

   interface_threshold_status_rw(working_status.granularity, ifid, new_entity_info) -- write new json
end

local function check_networks_alerts(ifid, working_status)
   local subnet_stats = interface.getNetworksStats()

   for subnet, sstats in pairs(subnet_stats) do
      local old_entity_info = network_threshold_status_rw(working_status.granularity, ifid, subnet) -- read old json
      local new_entity_info = sstats

      if (old_entity_info ~= nil) and (old_entity_info.ingress ~= nil) then
         -- wrap check
         if (old_entity_info["egress"] > new_entity_info["egress"])
          or (old_entity_info["ingress"] > new_entity_info["ingress"])
          or (old_entity_info["inner"] > new_entity_info["inner"]) then
            -- reset
            if(verbose) then print("entity '"..subnet.."' stats reset("..working_status.granularity..")") end
            old_entity_info = {}
         end
      else
         -- empty
         old_entity_info = {}
      end

      check_entity_alerts(ifid, "network", subnet, working_status, old_entity_info, new_entity_info)

      network_threshold_status_rw(working_status.granularity, ifid, subnet, new_entity_info) -- write new json
   end
end

local function check_hosts_alerts(ifid, working_status)
   local hosts = interface.getLocalHostsInfo(false)

   if hosts ~= nil then
      for host, hoststats in pairs(hosts["hosts"] or {}) do
         local hostinfo = interface.getHostInfo(host)
         if hostinfo ~= nil then
            local entity_value = hostinfo2hostkey({host=host, vlan=hostinfo.vlan}, nil, true --[[force vlan]])
            local old_entity_info = host_threshold_status_rw(working_status.granularity, ifid, hostinfo)  -- read old json
            local new_entity_info_json = hostinfo["json"]
            local new_entity_info = j.decode(new_entity_info_json, 1, nil)

            -- TODO this is little hack to make anomalies apper into the json
            new_entity_info["anomalies"] = hostinfo.anomalies

            if (old_entity_info ~= nil) and (old_entity_info.sent ~= nil) then
               -- wrap check
               if (old_entity_info["sent"]["packets"] > new_entity_info["sent"]["packets"])
                or (old_entity_info["rcvd"]["packets"] > new_entity_info["rcvd"]["packets"]) then
                  -- reset
                  if(verbose) then print("entity '"..entity_value.."' stats reset("..working_status.granularity..")") end
                  old_entity_info = {}
               end
            else
               -- empty
               old_entity_info = {}
            end

            check_entity_alerts(ifid, "host", entity_value, working_status, old_entity_info, new_entity_info)

            host_threshold_status_rw(working_status.granularity, ifid, hostinfo, new_entity_info_json) -- write new json
         end
      end
   end
end

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

function scanAlerts(granularity, ifname)
   if not areAlertsEnabled() then return end

   if(verbose) then print("[minute.lua] Scanning ".. granularity .." alerts for interface " .. ifname.."<p>\n") end
   local ifid = getInterfaceId(ifname)

   local working_status = {
      granularity = granularity,
      engine = alertEngine(granularity),
      engaged_cache = getEngagedAlertsCache(ifid, granularity),
      configured_thresholds = getConfiguredAlertsThresholds(ifname, granularity),
      dirty_cache = false,
   }

   check_interface_alerts(ifid, working_status)
   check_networks_alerts(ifid, working_status)
   check_hosts_alerts(ifid, working_status)

   -- Process the remaining alerts to release, e.g. related to expired hosts
   for entity_type, entity_values in pairs(working_status.engaged_cache) do
      for entity_value, alert_types in pairs(entity_values) do
         for atype, alert_keys in pairs(alert_types) do
            for akey, status in pairs(alert_keys) do
               if status ~= "processed" then
                  releaseAlert(ifid, working_status.engine, entity_type, entity_value, atype, akey, {}, {})
                  working_status.dirty_cache = true
               end
            end
         end
      end
   end

   if working_status.dirty_cache then
      invalidateEngagedAlertsCache(ifid)
   end
end


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

function flushAlertsData()
   if not haveAdminPrivileges() then
      return
   end

   local function deleteCachePattern(pattern)
      local keys = ntop.getKeysCache(pattern)

      for key in pairs(keys or {}) do
         ntop.delCache(key)
      end
   end

   local selected_interface = ifname
   local ifnames = interface.getIfNames()
   local force_query = true

   if(verbose) then io.write("[Alerts] Temporary disabling alerts generation...\n") end
   ntop.setAlertsTemporaryDisabled(true);
   os.execute("sleep 3")

   callback_utils.foreachInterface(ifnames, nil, function(ifname, ifstats)
      if(verbose) then io.write("[Alerts] Processing interface "..ifname.."...\n") end

      -- Clear hosts status
      interface.refreshHostsAlertsConfiguration(true --[[ with counters ]])

      if(verbose) then io.write("[Alerts] Flushing SQLite configuration...\n") end
      performAlertsQuery("DELETE", "engaged", {}, force_query)
      performAlertsQuery("DELETE", "historical", {}, force_query)
      performAlertsQuery("DELETE", "historical-flows", {}, force_query)
   end)

   if(verbose) then io.write("[Alerts] Flushing Redis configuration...\n") end
   deleteCachePattern("ntopng.prefs.*alert*")
   deleteCachePattern("ntopng.alerts.*")
   deleteCachePattern(getEngagedAlertsCacheKey("*", "*"))
   deleteCachePattern(getGlobalAlertsConfigurationHash("*", "*", "*"))
   ntop.delCache(get_alerts_suppressed_hash_name("*"))
   for _, key in pairs(get_make_room_keys("*")) do deleteCachePattern(key) end

   if(verbose) then io.write("[Alerts] Enabling alerts generation...\n") end
   ntop.setAlertsTemporaryDisabled(false);

   callback_utils.foreachInterface(ifnames, nil, function(_ifname, ifstats)
      -- Reload hosts status
      interface.refreshHostsAlertsConfiguration(true --[[ with counters ]])
   end)

   if(verbose) then io.write("[Alerts] Flush done\n") end
   interface.select(selected_interface)
end

-- DEBUG: uncomment this to test
--~ scanAlerts("min", "wlan0")