Rework flow scripts into user scripts

scripts/callbacks/user_scripts/loader.lua

@@ -0,0 +1,45 @@
+--
+-- (C) 2016-17 - ntop.org
+--
+
+--
+-- This is the user scripts loader. It exposes to the C side the callbacks from
+-- the user scripts.
+--
+
+local dirs = ntop.getDirs()
+local scripts_dir = dirs.installdir .. "/scripts/callbacks/user_scripts/"..script_context
+
+local scripts_callbacks = {}
+
+if ntop.isdir(scripts_dir) then
+  package.path = scripts_dir.."/?.lua;" .. package.path
+
+  for _,script in pairs(ntop.readdir(scripts_dir)) do
+    if (script ~= nil) then
+      local module_name = script:match("([^.]+).lua")
+      if module_name ~= nil then
+        local module_callbacks = require(module_name)
+
+        for callback_name, callback in pairs(module_callbacks) do
+          if _G[callback_name] == nil then
+
+            -- Define the global hook called by the C side
+            _G[callback_name] = function (...)
+              -- Note: order is not currently preserved
+              for _, callback in pairs(scripts_callbacks[callback_name]) do
+                callback(unpack(arg or {}))
+              end
+            end
+
+            scripts_callbacks[callback_name] = {}
+          end
+
+          -- Add the callback to be called
+          scripts_callbacks[callback_name][#scripts_callbacks[callback_name] + 1] = callback
+        end
+      end
+    end
+  end
+end
+