--
-- (C) 2021 - ntop.org
--
-- This file contains the alert constants

local clock_start = os.clock()

local dirs = ntop.getDirs()
package.path = dirs.installdir .. "/scripts/lua/modules/alert_keys/?.lua;" .. package.path
package.path = dirs.installdir .. "/scripts/lua/modules/pools/?.lua;" .. package.path

local alert_severities = require "alert_severities"
local alert_entities = require "alert_entities"
local alert_consts = {}
local os_utils = require("os_utils")
local lua_path_utils = require "lua_path_utils"
require("ntop_utils")

if(ntop.isPro()) then
  package.path = dirs.installdir .. "/pro/scripts/lua/modules/?.lua;" .. package.path
  -- NOTE: import snmp_utils below to avoid import cycles
end

alert_consts.SEPARATOR = ';'

-- NOTE: sqlite can handle about 10-50 alerts/sec
alert_consts.MAX_NUM_QUEUED_ALERTS_PER_MODULE = 1024 -- should match ALERTS_MANAGER_MAX_ENTITY_ALERTS

alert_consts.MAX_NUM_QUEUED_ALERTS_PER_RECIPIENT = 4096

alert_consts.ALL_ALERT_KEY = 0 -- Special ID to select 'all' alerts

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

-- Groups for alert severities to obtain coarser-grained groups of finer-grained alert severities.
-- Used when grouping flow status severities into groups (shown in the UI header bar and flows page drilldown)
--
-- NOTE: keep it in sync with ntop_typedefs.h AlertLevelGroup
--
alert_consts.severity_groups = {
  group_none = {
    severity_group_id = 0,
    i18n_title = "severity_groups.group_none",
  },
  notice_or_lower = {
    severity_group_id = 1,
    i18n_title = "severity_groups.group_notice_or_lower",
  },
  warning = {
    severity_group_id = 2,
    i18n_title = "severity_groups.group_warning",
  },
  error = {
    severity_group_id = 3,
    i18n_title = "severity_groups.group_error",
  },
  critical = {
    severity_group_id = 4,
    i18n_title = "severity_groups.group_critical",
  },
  emergency = {
    severity_group_id = 5,
    i18n_title = "severity_groups.group_emergency",
},
}

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

alert_consts.alert_entities = alert_entities

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

-- Keep in sync with C
alert_consts.alerts_granularities = {
   ["min"] = {
      granularity_id = 1,
      granularity_seconds = 60,
      i18n_title = "show_alerts.minute",
      i18n_description = "alerts_thresholds_config.every_minute",
   },
   ["5mins"] = {
      granularity_id = 2,
      granularity_seconds = 300,
      i18n_title = "show_alerts.5_min",
      i18n_description = "alerts_thresholds_config.every_5_minutes",
   },
   ["hour"] = {
      granularity_id = 3,
      granularity_seconds = 3600,
      i18n_title = "show_alerts.hourly",
      i18n_description = "alerts_thresholds_config.hourly",
   },
   ["day"] = {
      granularity_id = 4,
      granularity_seconds = 86400,
      i18n_title = "show_alerts.daily",
      i18n_description = "alerts_thresholds_config.daily",
   }
}

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

-- This status is written in Clickhouse/SQLite column `alert_status`
alert_consts.alert_status = {
   ["historical"] = {
      -- Alerts written to the database that require attention
      alert_status_id = 0,
   },
   ["acknowledged"] = {
      -- Acknowledged (automatically or from the user) alerts written to the database
      alert_status_id = 1,
   },
   ["engaged"] = {
      -- Engaged (not actually used in the database as engaged alerts are in memory)
      alert_status_id = 2,
   },
   ["any"] = {
      -- Not actually used in the database (historical | acknowledged)
      alert_status_id = 3,
   },
}

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

alert_consts.ids_rule_maker = {
  GPL = "GPL",
  SURICATA = "Suricata",
  ET = "Emerging Threats",
}

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

local alert_entities_id_to_key = {}
local alert_severities_id_to_key = {}
local alerts_granularities_id_to_key = {}
local alerts_granularities_seconds_to_key = {}

local function initMappings()
  -- alert_entities_id_to_key
  for key, entity_info in pairs(alert_consts.alert_entities) do
    alert_entities_id_to_key[entity_info.entity_id] = key
  end

  -- alert_severities_id_to_key 
  for key, severity_info in pairs(alert_severities) do
    if severity_info.severity_id ~= 0 then
      alert_severities_id_to_key[severity_info.severity_id] = key
    end
  end

  -- alerts_granularities_id_to_key 
  for key, granularity_info in pairs(alert_consts.alerts_granularities) do
    alerts_granularities_id_to_key[granularity_info.granularity_id] = key
  end

  -- alerts_granularities_seconds_to_key
  for key, granularity_info in pairs(alert_consts.alerts_granularities) do
    alerts_granularities_seconds_to_key[granularity_info.granularity_seconds] = key
  end
end

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

function alert_consts.formatHostAlert(ifid, host, vlan)
   return hostinfo2label({host = host, vlan = vlan}, vlan)
end

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

function alert_consts.formatAlertEntity(ifid, entity_type, entity_value)
   require "flow_utils"
   local value
   local epoch_begin, epoch_end = getAlertTimeBounds({alert_tstamp = os.time()})

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

      if host_info ~= nil then
         if hostinfo2hostkey(host_info) ~= value then
            -- Avoid overwriting the IP
            value = string.format("%s [%s]", hostinfo2hostkey(host_info), value)
         end

         value = hostinfo2detailshref(host_info, {page = "historical", epoch_begin = epoch_begin, epoch_end = epoch_end}, value, nil, true --[[ check if the link brings to an active page]])
      end
   elseif entity_type == "interface" then
      value = "<a href='"..ntop.getHttpPrefix().."/lua/if_stats.lua?ifid="..ifid..
        "&page=historical&epoch_begin="..epoch_begin .."&epoch_end=".. epoch_end ..
        "'>"..getHumanReadableInterfaceName(getInterfaceName(ifid)).."</a>"
   elseif entity_type == "network" then
      value = getLocalNetworkAlias(hostkey2hostinfo(entity_value)["host"])

      value = "<a href='"..ntop.getHttpPrefix().."/lua/network_details.lua?network_cidr="..
        entity_value.."&page=historical&epoch_begin=".. epoch_begin
         .."&epoch_end=".. epoch_end .."'>" ..value.."</a>"
   elseif entity_type == "host_pool" then
      local host_pools = require "host_pools"

      -- Instantiate host pools
      local host_pools_instance = host_pools:create()

      value = host_pools_instance:get_pool_name(entity_value)
   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 value
   end
end

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

function getMacUrl(mac)
   if not mac then
      tprint("getMacUrl(nil)")
      tprint(debug.traceback()) 
      return "" 
   end
   return ntop.getHttpPrefix() .. "/lua/mac_details.lua?host=" .. mac
end

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

function getHostUrl(host, vlan_id)
   return hostinfo2detailsurl({host = host, vlan = vlan_id})
end

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

function getHostPoolUrl(pool_id)
   if not pool_id then
      tprint(debug.traceback())
      return ""
   end
   return ntop.getHttpPrefix() .. "/lua/hosts_stats.lua?pool=" .. pool_id
end

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

function getNedgeHostPoolUrl(pool_name)
   if not pool_name then
      tprint(debug.traceback())
      return ""
   end
   return ntop.getHttpPrefix() .. "/lua/pro/nedge/admin/nf_edit_user.lua?username=" .. pool_name
end

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

local function showSnmpUrl(snmp_device)
   local show_url = true

   if ntop.isPro() then
      local snmp_config = require "snmp_config"
      local device_config = snmp_config.get_device_config(snmp_device)

      if not device_config then
         show_url = false
      end
   elseif not snmp_device then
      show_url = false
   end

   return show_url
end

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

function snmpDeviceUrl(snmp_device)
   if showSnmpUrl(snmp_device) then
      return ntop.getHttpPrefix()..string.format("/lua/pro/enterprise/snmp_device_details.lua?host=%s", snmp_device)
   end

   return "#"
end

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

function snmpIfaceUrl(snmp_device, interface_idx)
   if showSnmpUrl(snmp_device) then
      return ntop.getHttpPrefix()..string.format("/lua/pro/enterprise/snmp_interface_details.lua?host=%s&snmp_port_idx=%d", snmp_device, interface_idx)
   end

   return "#"
end

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

function alert_consts.getDefinititionDirs()
   local dirs = ntop.getDirs()

   return({
         -- Path for ntopng-defined builtin alerts
         os_utils.fixPath(dirs.installdir .. "/scripts/lua/modules/alert_definitions/flow"),
         os_utils.fixPath(dirs.installdir .. "/scripts/lua/modules/alert_definitions/host"),
         os_utils.fixPath(dirs.installdir .. "/scripts/lua/modules/alert_definitions/other"),
          }
   )
end

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

function alert_consts.alertEntityRaw(entity_id)
   entity_id = tonumber(entity_id)
   return alert_entities_id_to_key[entity_id]
end

function alert_consts.alertEntityById(entity_id)
   entity_id = tonumber(entity_id)
   return alert_consts.alert_entities[alert_entities_id_to_key[entity_id]]
end

function alert_consts.alertEntity(v)
   return(alert_consts.alert_entities[v].entity_id)
end

function alert_consts.alertEntityLabel(v)
  local entity_id = alert_consts.alertEntityRaw(v)

  if(entity_id) then
    return i18n(alert_consts.alert_entities[entity_id].i18n_label)
  end
end

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

-- See alert_consts.resetDefinitions()
alert_consts.alert_types = {}
local alerts_by_id = {} -- All available alerts keyed by entity_id and alert_id

local function loadAlertsDefs()
   if(false) then
      if(string.find(debug.traceback(), "second.lua")) then
         traceError(TRACE_WARNING, TRACE_CONSOLE, "second.lua is loading alert_consts.lua. This will slow it down!")
      end
   end

   local defs_dirs = alert_consts.getDefinititionDirs()

   for _, defs_dir in pairs(defs_dirs) do
      lua_path_utils.package_path_prepend(defs_dir)

      for fname in pairs(ntop.readdir(defs_dir)) do
         if string.ends(fname, ".lua") then
            local mod_fname = string.sub(fname, 1, string.len(fname) - 4)
            local def_script = require(mod_fname)

            if(def_script == nil) then
               traceError(TRACE_ERROR, TRACE_CONSOLE, string.format("Error loading alert definition from %s", mod_fname))
               goto next_script
            end

            if not loadDefinition(def_script, mod_fname, defs_dir) then
               -- Retry reload
               package.loaded[mod_fname] = nil
            end
         end

         ::next_script::
      end

      if defs_dir:ends(os_utils.fixPath("/flow")) then
         -- Load flow alerts for flows with nDPI risks that don't have an alert .lua file explicitly defined under alert_definitions/
         local flow_risk_alerts = ntop.getFlowRiskAlerts()
         for mod_fname, flow_risk_alert in pairs(flow_risk_alerts) do
            local alert_type = alert_consts.getAlertType(flow_risk_alert.alert_id, alert_entities.flow.entity_id)

            -- Make sure the alert hasn't already been loaded via a dedicated alert_definition .lua file
            if not alert_type then
               -- Can't use the require. Require always returns the same table and this would result in overwritten alert_key and title
               local def_script = dofile(os_utils.fixPath(string.format("%s/scripts/lua/modules/flow_risk_simple_alert_definition.lua", dirs.installdir)))

               -- Add the mandatory fields according to what arrives from C++
               def_script.meta.alert_key = flow_risk_alert.alert_id
               def_script.meta.i18n_title = flow_risk_alert.risk_name

               if not loadDefinition(def_script, mod_fname, defs_dir) then
                  -- Retry reload
                  package.loaded[mod_fname] = nil
               end
            end
         end
      end
   end
end

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

function loadDefinition(def_script, mod_fname, script_path)
   local required_fields = {"alert_key", "i18n_title", "icon"}

   -- Check the required meta table
   if(def_script.meta == nil) then
      traceError(TRACE_ERROR, TRACE_CONSOLE, string.format("Missing required table 'meta' in %s from %s", mod_fname, script_path))
      return(false)
   end

   -- Check the required metadata fields
   for _, k in pairs(required_fields) do
      if(def_script.meta[k] == nil) then
         traceError(TRACE_ERROR, TRACE_CONSOLE, string.format("Missing required field '%s' in %s from %s", k, mod_fname, script_path))
         return(false)
      end
   end

   local alert_entity
   if script_path:ends(os_utils.fixPath("/flow")) then
      alert_entity = alert_entities.flow
   elseif script_path:ends(os_utils.fixPath("/host")) then
      alert_entity = alert_entities.host
   else
      -- TODO: migrate all. currently assumes other for non-flow non-host
      alert_entity = alert_entities.other
   end

   local alert_key = def_script.meta.alert_key

   if not alert_entity or not alert_key then
      traceError(TRACE_ERROR, TRACE_CONSOLE, string.format("Invalid alert key specified %s in %s from %s", status, mod_fname, script_path))
      return(false)
   end

   -- Coherence check: make sure the alert key is not redefined
   local alert_entity_id = alert_entity.entity_id
  
   if alerts_by_id[alert_entity_id] and alerts_by_id[alert_entity_id][alert_key] then
      traceError(TRACE_ERROR, TRACE_CONSOLE, string.format("Alert key %d redefined, skipping in %s from %s", alert_key, mod_fname, script_path))
      return(false)
   end

   -- Add alert metadata to the script
   alert_consts.alert_types[mod_fname] = def_script

   if not alerts_by_id[alert_entity_id] then
      alerts_by_id[alert_entity_id] = {}
   end
   alerts_by_id[alert_entity_id][alert_key] = mod_fname

   -- Handle 'other' alerts
   -- Note: some are used by multiple entities, defined under
   -- meta in the alert definition
   if def_script.meta['entities'] then
      for _, entity in ipairs(def_script.meta['entities']) do
         if not alerts_by_id[entity.entity_id] then
            alerts_by_id[entity.entity_id] = {}
         end
         alerts_by_id[entity.entity_id][alert_key] = mod_fname
      end
   end

   -- Success
   return(true)
end
 
-- ##############################################

function alert_consts.alertTypeLabel(alert_id, nohtml, alert_entity_id, nil_on_not_found)
   local alert_key = alert_consts.getAlertType(alert_id, alert_entity_id)

   if alert_key then
      local type_info = alert_consts.alert_types[alert_key]
      -- TODO: .meta is the new format, OR are for compatibility and can be removed when migration is done
      local title = i18n(type_info.i18n_title or type_info.meta.i18n_title) or type_info.i18n_title or type_info.meta.i18n_title

      if nohtml then
        return title
      else
        -- return(string.format('<i class="%s"></i> %s', type_info.icon or type_info.meta.icon, shortenString(title)))
        return string.format('<i class="%s"></i> %s', type_info.icon or type_info.meta.icon, title)
      end

   elseif nil_on_not_found then
      return nil

   else
      return(i18n("unknown"))
   end
end

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

-- @brief Given a flow status identified by `status_key`, returns an icon associated to the severity
-- @param `status info`, A human readable (localized) status info
-- @param `alerted_severity`, Integer severity of the alert associated to this status
-- @return The HTML with icon and ALT text, or empty if no icon is available
function alert_consts.alertTypeIcon(alert_info, alerted_severity, icon_size)
  local severity = alert_consts.alertSeverityById(alerted_severity)
  local icon = ''

  if severity then
    local severity_icon = (icon_size or 'fa-fw') .. " " .. severity.icon
    icon = "<i class='"..severity_icon.."' title='"..noHtml(alert_consts.alertTypeLabel(alert_info, true)) .."'></i> "
  end

  return icon
end

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

function alert_consts.alertType(v)
   if(alert_consts.alert_types[v] == nil) then
      tprint(debug.traceback())
   end

   local res = alert_consts.alert_types[v].alert_key

   if not res and alert_consts.alert_types[v].meta then
      -- TODO AM: attempt at looking inside new implementation `meta`
      res = alert_consts.alert_types[v].meta.alert_key
   end

   return res
 end

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

function alert_consts.getAlertType(alert_key, alert_entity_id)
   -- Make sure we are working with numbers
   alert_key = tonumber(alert_key)
   alert_entity_id = tonumber(alert_entity_id)

   -- If the alert entity has been explicity submitted and is one among 'flow' or 'host', then
   -- this method return if no alert is found. Otherwise, fallbacks are tried.
   -- NOTE: This is because 'flow' and 'host' alert entities have their explicit alert definitions
   -- under modules/alert_definitions. All other entities currently fall under the 'other' entity.
   if alert_entity_id and (alert_entity_id == alert_entities.flow.entity_id or alert_entity_id == alert_entities.host.entity_id) then
      if alerts_by_id[alert_entity_id] and alerts_by_id[alert_entity_id][alert_key] then
         return alerts_by_id[alert_entity_id][alert_key]
      end

      -- Alert entity explicitly submitted and no alert found. Returning.
      return
   end

   -- TODO: remove fallbacks when all alerts in alert_keys.lua will be migrated and will have their own entity specified

   -- Fallback 01: if no alert_entity_id is passed, alert_entity is assumed to be flow.
   if alerts_by_id[alert_entities.flow.entity_id][alert_key] then
      return alerts_by_id[alert_entities.flow.entity_id][alert_key]
   end
   
   -- Fallback 02: if no alert_entity_id is passed, alert_entity is assumed to be host.
   if alerts_by_id[alert_entities.host.entity_id][alert_key] then
      return alerts_by_id[alert_entities.host.entity_id][alert_key]
   end

   -- Fallback 03: if no alert_entity_id is passed, alert_entity is assumed to be other.
   if alerts_by_id[alert_entities.other.entity_id][alert_key] then
      return alerts_by_id[alert_entities.other.entity_id][alert_key]
   end
end

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

function alert_consts.getAlertTypes(alert_entity_id)
   return alerts_by_id[alert_entity_id]
end

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

function alert_consts.alert_type_info_asc(a, b)
   return (a.label:upper() < b.label:upper())
end

function alert_consts.getAlertTypesInfo(alert_entity_id)
   local alert_types = alert_consts.getAlertTypes(alert_entity_id)

   if not alert_types then
      return {}
   end

   local alert_types_info = {}
   for alert_id, alert_name in pairs(alert_types) do
      alert_types_info[alert_id] = {
         alert_id = alert_id,
         name = alert_name,
         label = alert_consts.alertTypeLabel(alert_id, true, alert_entity_id),
      }
   end

   return alert_types_info
end

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

function alert_consts.alertLevelToSyslogLevel(v)
   return alert_severities[alert_consts.alertSeverityRaw(v)].syslog_severity
end

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

function alert_consts.alertSeverityRaw(severity_id)
   severity_id = tonumber(severity_id)
   if not alert_severities_id_to_key[severity_id] then
      severity_id = 1 -- falling back to min severity
   end
   return alert_severities_id_to_key[severity_id] 
end

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

function alert_consts.get_printable_severities()
  local severities = {}

  for name, conf in pairs(alert_severities, "severity_id", asc) do
    if (conf.severity_id > 2) then
      severities[name] = conf
    end
  end

  return severities
end

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

function alert_consts.alertSeverityLabel(score, nohtml, emoji)
   local severity_id = alert_consts.alertSeverityRaw(map_score_to_severity(score))

   if(severity_id) then
      local severity_info = alert_severities[severity_id]
      local title = i18n(severity_info.i18n_title) or severity_info.i18n_title

      if(emoji) then
         title = (severity_info.emoji or "").. " " .. title
      end
      
      if(nohtml) then
        return(title)
      else
        return(string.format('<span class="badge %s" title="%s">%s</span>', severity_info.label, title, title))
      end
   end

   return "(unknown severity)"
end

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

function alert_consts.alertSeverity(v)
   return(alert_severities[v].severity_id)
end
 
-- ################################################################################

function alert_consts.alertSeverityById(severity_id)
   local key = alert_consts.alertSeverityRaw(severity_id)
   if key == nil then 
      return alert_severities.none
   end
   return(alert_severities[key])
end

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

-- Rename engine -> granulariy
local function alertEngineRaw(granularity_id)
   granularity_id = tonumber(granularity_id)
   return alerts_granularities_id_to_key[granularity_id] 
end
 
-- ################################################################################
 
function alert_consts.alertEngine(v)
   if(alert_consts.alerts_granularities[v] == nil) then
      tprint(debug.traceback())
   end

   return(alert_consts.alerts_granularities[v].granularity_id)
end

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

function alert_consts.alertEngineLabel(v)
   local granularity_id = alertEngineRaw(v)
 
   if(granularity_id ~= nil) then
     return(i18n(alert_consts.alerts_granularities[granularity_id].i18n_title))
   end
 end

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

function alert_consts.granularity2sec(v)
   if(alert_consts.alerts_granularities[v] == nil) then
      tprint(debug.traceback())
   end

  return(alert_consts.alerts_granularities[v].granularity_seconds)
end

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

-- See NetworkInterface::checkHostsAlerts()
function alert_consts.granularity2id(granularity)
   -- TODO replace alertEngine
   return(alert_consts.alertEngine(granularity))
end

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

function alert_consts.sec2granularity(seconds)
   seconds = tonumber(seconds)
   local key = alerts_granularities_seconds_to_key[seconds]
   if not key  then
      key = alerts_granularities_seconds_to_key[60]
   end
   return key
end
 
-- Load definitions now
loadAlertsDefs()
initMappings()

if(trace_script_duration ~= nil) then
  io.write(debug.getinfo(1,'S').source .." executed in ".. (os.clock()-clock_start)*1000 .. " ms\n")
end

return alert_consts
