add special things to variable blacklist

lib/farmbot/celery_script/ast/node/read_pin.ex

@@ -3,10 +3,15 @@ defmodule Farmbot.CeleryScript.AST.Node.ReadPin do
   use Farmbot.CeleryScript.AST.Node
   allow_args [:pin_number, :label, :pin_mode]
 
-  def execute(%{pin_number: pin_num, pin_mode: mode}, _, env) do
+  def execute(%{pin_number: pin_num, pin_mode: mode, label: label}, _, env) do
     env = mutate_env(env)
     case Farmbot.Firmware.read_pin(pin_num, mode) do
-      :ok -> {:ok, env}
+      :ok ->
+        case Farmbot.BotState.get_pin_value(pin_num) do
+          {:ok, val} ->
+            Farmbot.CeleryScript.var(env, label, val)
+          {:error, reason} -> {:error, reason, env}
+        end
       {:error, reason} -> {:error, reason, env}
     end
   end

lib/farmbot/celery_script/ast/node/send_message.ex

@@ -7,7 +7,7 @@ defmodule Farmbot.CeleryScript.AST.Node.SendMessage do
   def execute(%{message: m, message_type: type}, channels, env) do
     env = mutate_env(env)
     {:ok, env, channels} = do_reduce(channels, env, [])
-    bindings = fetch_bindings()
+    bindings = fetch_bindings(env)
     case sanatize(m) do
       {:ok, sanatized} ->
         msg = EEx.eval_string(sanatized, bindings)
@@ -88,11 +88,11 @@ defmodule Farmbot.CeleryScript.AST.Node.SendMessage do
     end
   end
 
-  defp fetch_bindings do
+  defp fetch_bindings(env) do
     bot_state = Farmbot.BotState.force_state_push()
     pins = Enum.map(bot_state.pins, fn({pin, %{value: value}}) -> {:"pin#{pin}", value} end)
     location = Enum.map(bot_state.location_data.position, fn({axis, val}) -> {axis, val} end)
-    pins ++ location
+    env.vars ++ pins ++ location
   end
 
   defp do_reduce([%{args: %{channel_name: channel}} | rest], env, acc) do

lib/farmbot/celery_script/celery_script.ex

@@ -37,4 +37,29 @@ defmodule Farmbot.CeleryScript do
     Module.split(kind) |> List.last() |> Macro.underscore()
   end
 
+  def var(env, dirty_label, val) do
+    case sanitize_var_name(dirty_label) do
+      {:ok, label} ->
+        new_vars = Keyword.put(env.vars, String.to_atom(label), val)
+        new_env = %{env | vars: new_vars}
+        {:ok, new_env}
+      {:error, reason} ->
+        {:error, reason, env}
+    end
+  end
+
+  defp sanitize_var_name(name) do
+    cond do
+      String.contains?(name, " ") ->
+        {:error, "variables may not contain special characters."}
+      match?(<<"__", _ :: binary>>, name) ->
+        {:error, "variables may not replace internal names."}
+      match?(<<"pin", _ :: binary>>, name) ->
+        {:error, "variables may not contain pattern: pin<number>."}
+      name in ["x", "y", "z"] ->
+        {:error, "variables may not be axis names."}
+      true -> {:ok, name}
+    end
+  end
+
 end