Fixes attempts to call nil alert format functions

17/Apr/2018 12:24:00 [Lua.cpp:7662] WARNING: Script failure [/Users/simone/code/ntopng/scripts/callbacks/interface/minute.lua][...s/simone/code/ntopng/scripts/lua/modules/alert_utils.lua:1757: attempt to call field 'fmt' (a nil value)]
2018-04-17 12:24:00.360600+0200 ntopng[34202:3875024] [Lua.cpp:7662] WARNING: Script failure [/Users/simone/code/ntopng/scripts/callbacks/interface/minute.lua][...s/simone/code/ntopng/scripts/lua/modules/alert_utils.lua:1757: attempt to call field 'fmt' (a nil value)]

By implementing a format_utils module

scripts/lua/modules/format_utils.lua

@@ -0,0 +1,197 @@
+--
+-- (C) 2014-18 - ntop.org
+--
+
+local format_utils = {}
+
+function format_utils.round(num, idp)
+   if(num == nil) then return(0) end
+   return tonumber(string.format("%." .. (idp or 0) .. "f", num))
+end
+local round = format_utils.round
+
+function format_utils.secondsToTime(seconds)
+   local seconds = tonumber(seconds)
+   if(seconds == nil) then return "" end
+   if(seconds == 0) then
+      return("0 sec")
+   end
+   if(seconds < 1) then
+      return("< 1 sec")
+   end
+
+   local days = math.floor(seconds / 86400)
+   local hours =  math.floor((seconds / 3600) - (days * 24))
+   local minutes = math.floor((seconds / 60) - (days * 1440) - (hours * 60))
+   local sec = seconds % 60
+   local msg = ""
+
+   if(days > 0) then
+      years = math.floor(days/365)
+
+      if(years > 0) then
+	 days = days % 365
+
+	 msg = years .. " year"
+	 if(years > 1) then msg = msg .. "s" end
+      end
+
+      if(days > 0) then
+	 if(string.len(msg) > 0) then  msg = msg .. ", " end
+	 msg = msg .. days .. " day"
+	 if(days > 1) then msg = msg .. "s" end
+      end
+   end
+
+   if(hours > 0) then
+      if(string.len(msg) > 0) then  msg = msg .. ", " end
+      msg = msg .. string.format("%d ", hours)
+      if(hours > 1) then
+	 msg = msg .. "h"
+      else
+	 msg = msg .. "h"
+      end
+
+      --if(hours > 1) then msg = msg .. "s" end
+   end
+
+   if(minutes > 0) then
+      if(string.len(msg) > 0) then msg = msg .. ", " end
+      msg = msg .. string.format("%d min", minutes)
+   end
+
+   if(sec > 0) then
+      if(string.len(msg) > 0) then msg = msg .. ", " end
+      msg = msg .. string.format("%d sec", sec);
+   end
+
+   return msg
+end
+
+function format_utils.msToTime(ms)
+   if(ms > 1000) then
+      return format_utils.secondsToTime(ms/1000)
+   else
+      if(ms < 1) then
+	 return("< 1 ms")
+      else
+	 return(round(ms, 4).." ms")
+      end
+   end
+end
+
+-- Convert bytes to human readable format
+function format_utils.bytesToSize(bytes)
+   if(bytes == nil) then
+      return("0")
+   else
+      local precision = 2
+      local kilobyte = 1024;
+      local megabyte = kilobyte * 1024;
+      local gigabyte = megabyte * 1024;
+      local terabyte = gigabyte * 1024;
+
+      bytes = tonumber(bytes)
+      if bytes == 1 then return "1 Byte"
+      elseif((bytes >= 0) and (bytes < kilobyte)) then
+	 return round(bytes, precision) .. " Bytes";
+      elseif((bytes >= kilobyte) and (bytes < megabyte)) then
+	 return round(bytes / kilobyte, precision) .. ' KB';
+      elseif((bytes >= megabyte) and (bytes < gigabyte)) then
+	 return round(bytes / megabyte, precision) .. ' MB';
+      elseif((bytes >= gigabyte) and (bytes < terabyte)) then
+	 return round(bytes / gigabyte, precision) .. ' GB';
+      elseif(bytes >= terabyte) then
+	 return round(bytes / terabyte, precision) .. ' TB';
+      else
+	 return round(bytes, precision) .. ' Bytes';
+      end
+   end
+end
+
+function format_utils.formatValue(amount)
+   local formatted = amount
+
+   if(formatted == nil) then return(0) end
+   while true do
+      formatted, k = string.gsub(formatted, "^(-?%d+)(%d%d%d)", '%1,%2')
+      if(k==0) then
+	 break
+      end
+   end
+   return formatted
+end
+
+function format_utils.formatPackets(amount)
+   local amount = tonumber(amount)
+   if (amount == 1) then return "1 Pkt" end
+   return format_utils.formatValue(amount).." Pkts"
+end
+
+function format_utils.formatFlows(amount)
+   local amount = tonumber(amount)
+   if (amount == 1) then return "1 Flow" end
+   return format_utils.formatValue(amount).." Flows"
+end
+
+-- Convert packets to pps readable format
+function format_utils.pktsToSize(pkts)
+   local precision = 2
+   if(pkts >= 1000000) then
+      return round(pkts/1000000, precision)..' Mpps';
+   elseif(pkts >= 1000) then
+      return round(pkts/1000, precision)..' Kpps';
+   else
+      return round(pkts, precision)..' pps';
+   end
+end
+
+-- Convert bits to human readable format
+
+function format_utils.bitsToSizeMultiplier(bits, multiplier)
+   if(bits == nil) then return(0) end
+
+   local precision = 2
+   local kilobit = 1000;
+   local megabit = kilobit * multiplier;
+   local gigabit = megabit * multiplier;
+   local terabit = gigabit * multiplier;
+
+   if((bits >= kilobit) and (bits < megabit)) then
+      return round(bits / kilobit, precision) .. ' kbit/s';
+   elseif((bits >= megabit) and (bits < gigabit)) then
+      return round(bits / megabit, precision) .. ' Mbit/s';
+   elseif((bits >= gigabit) and (bits < terabit)) then
+      return round(bits / gigabit, precision) .. ' Gbit/s';
+   elseif(bits >= terabit) then
+      return round(bits / terabit, precision) .. ' Tbit/s';
+   else
+      return round(bits, precision) .. ' bit/s';
+   end
+end
+
+function format_utils.bitsToSize(bits)
+   return(bitsToSizeMultiplier(bits, 1000))
+end
+
+-- maxRateToString
+function format_utils.maxRateToString(max_rate)
+   if((max_rate == nil) or (max_rate == "")) then max_rate = -1 end
+   max_rate = tonumber(max_rate)
+
+   if(max_rate < 1000) then
+      return(max_rate.." Kbit/s")
+   else
+      local mr
+      mr = round(max_rate / 1000, 2)
+
+      if(mr < 1000) then
+	 return(mr.." Mbit/s")
+      else
+	 gbit = mr /1000
+	 return(gbit.." Gbit/s")
+      end
+   end
+end
+
+return format_utils