Merge pull request #3 from redwirelabs/use-port

Use erlang term based port instead of a c-node

lib/bacnet.ex

@@ -3,18 +3,73 @@ defmodule BACNet do
   BACNet client.
   """
 
+  use GenServer
+
   require Logger
 
-  defmodule Device do
-    @typedoc "Placeholder"
-    @type t :: term
+  defmodule State do
+    @doc false
+
+    defstruct [:port]
+  end
+
+  @doc """
+  Start the BACnet client.
+  """
+  @spec start_link(any, GenServer.options()) :: GenServer.on_start()
+  def start_link(args, opts \\ []) do
+    GenServer.start_link(__MODULE__, args, opts)
   end
 
-  @spec add_device(device :: Device.t) :: :ok | {:error, term}
-  def add_device(device) do
-    GenServer.call({:global, :bacnetd}, {:add_device, device})
+  @impl GenServer
+  def init(_args) do
+    bacnetd_exe = "#{:code.priv_dir(:bacnet)}/bacnetd"
+
+    port = Port.open(
+      {:spawn, bacnetd_exe},
+      [
+        :binary,
+        :use_stdio,
+        packet: 4,
+        env: [],
+      ]
+    )
+
+    state = %State{port: port}
+
+    {:ok, state}
   end
 
-  @doc false
-  defdelegate ei_log(level, term), to: Logger, as: :log
+  @impl GenServer
+  def handle_call(cmd, from, state) do
+    encoded_term = :erlang.term_to_binary({:"$gen_call", from, cmd})
+    Port.command(state.port, encoded_term)
+
+    {:noreply, state}
+  end
+
+  @impl GenServer
+  def handle_info({_port, {:data, data}}, state) do
+    try do
+      data
+      |> :erlang.binary_to_term
+      |> process_message
+    catch
+      _ -> nil
+    end
+
+    {:noreply, state}
+  end
+
+  defp process_message({:log, level, message}) do
+    Logger.log(level, message)
+  end
+
+  defp process_message({:"$gen_reply", to, result}) do
+    GenServer.reply(to, result)
+  end
+
+  defp process_message(unknown) do
+    Logger.warning("Unknown message received #{inspect(unknown)}")
+  end
 end

mix.exs

@@ -15,7 +15,6 @@ defmodule BACNet.MixProject do
       start_permanent: Mix.env() == :prod,
       test_coverage: [tool: ExCoveralls, test_task: "espec"],
       dialyzer: [
-        ignore_warnings: "dialyzer.ignore.exs",
         list_unused_filters: true,
         plt_file: {:no_warn, plt_file_path()},
       ],
@@ -33,7 +32,6 @@ defmodule BACNet.MixProject do
   def application do
     [
       extra_applications: [:logger],
-      mod: {BACNet.Application, []}
     ]
   end
 
@@ -71,7 +69,7 @@ defmodule BACNet.MixProject do
 
   defp package do
     [
-      licenses: ["Apache-2.0"],
+      licenses: ["MIT"],
       links: %{"GitHub" => "https://github.com/redwirelabs/bacnet_ex"},
       maintainers: ["Abelino Romo"],
       files: [