Commit missing file

lib/farmbot/firmware/estop_timer.ex

@@ -0,0 +1,74 @@
+defmodule Farmbot.Firmware.EstopTimer do
+  @moduledoc """
+  Module responsible for timing emails about E stops.
+  """
+  use GenServer
+  use Farmbot.Logger
+
+  @msg "Farmbot has been E-Stopped for more than 10 minutes."
+  # Ten minutes.
+  @timer_ms 600000
+  # fifteen seconds.
+  # @timer_ms 15000
+
+  @doc "Checks if the timer is active."
+  def timer_active? do
+    GenServer.call(__MODULE__, :timer_active?)
+  end
+
+  @doc "Starts a new timer if one isn't started."
+  def start_timer do
+    GenServer.call(__MODULE__, :start_timer)
+  end
+
+  @doc "Cancels a timer if it exists."
+  def cancel_timer do
+    GenServer.call(__MODULE__, :cancel_timer)
+  end
+
+  @doc false
+  def start_link do
+    GenServer.start_link(__MODULE__, [], [name: __MODULE__])
+  end
+
+  @doc false
+  def init([]) do
+    {:ok, %{timer: nil, already_sent: false}}
+  end
+
+  def handle_call(:timer_active?, _, state) do
+    {:reply, is_timer_active?(state.timer), state}
+  end
+
+  def handle_call(:start_timer, _from, state) do
+    if !is_timer_active?(state.timer) do
+      {:reply, :ok, %{state | timer: do_start_timer(self())}}
+    else
+      {:reply, :ok, state}
+    end
+  end
+
+  def handle_call(:cancel_timer, _from, state) do
+    if is_timer_active?(state.timer) do
+      Process.cancel_timer(state.timer)
+    end
+    {:reply, :ok, %{state | timer: nil, already_sent: false}}
+  end
+
+  def handle_info(:timer, state) do
+    if state.already_sent do
+      {:noreply, %{state | timer: nil}}
+    else
+      Logger.warn 1, @msg, [channels: [:email]]
+      {:noreply, %{state | timer: nil, already_sent: true}}
+    end
+  end
+
+  defp is_timer_active?(timer) do
+    if timer, do: is_number(Process.read_timer(timer)), else: false
+  end
+
+  defp do_start_timer(pid) do
+    Process.send_after(pid, :timer, @timer_ms)
+  end
+end