Cleanup work

lib/birdy_chat/dispatcher.ex

@@ -1,4 +1,18 @@
 defmodule BirdyChat.Dispatcher do
+  @moduledoc """
+  Main dispatcher of messages - decides to either write them to local file system or send them via
+  HTTP to peers.
+
+  It originally started as a websocket connection between servers, but then I decided to rip
+  it out and replace with simple HTTP request-response for the following reasons:
+
+  1. HTTP guarantees immediate feedback (request succeeds or not), making the addition of caching
+  or retries easy.
+  2. HTTP requests have well-know semantic so I can i.e use HTTP statuses for error signals
+  instead of inventing my own error language.
+  """
+
+  @spec dispatch(Ecto.Changeset.t()) :: :ok | {:error, String.t()}
   def dispatch(%Ecto.Changeset{changes: changes} = changeset) do
     case changes do
       %{routing: :local} -> BirdyChat.MessageWriter.write(changeset.changes)
@@ -6,13 +20,13 @@ defmodule BirdyChat.Dispatcher do
     end
   end
 
-  def send_to_remote(%{server: server, to: to} = message) do
-    {_name, base_url} =
+  defp send_to_remote(%{server: server, from: from} = message) do
+    {name, base_url} =
       BirdyChat.Identity.peers()
       |> Enum.find(fn {name, _url} -> name == server end)
 
     api_url = base_url <> "/api/internal"
-    token = Phoenix.Token.sign(BirdyChatWeb.Endpoint, "serverAuth", to)
+    token = Phoenix.Token.sign(BirdyChatWeb.Endpoint, "serverAuth", from)
 
     {_request, result} =
       Req.new(url: api_url, retry: false, method: :post)
@@ -24,6 +38,12 @@ defmodule BirdyChat.Dispatcher do
     # Handle more when you encounter errors
     case result do
       %Req.Response{status: 201} -> :ok
+      # This should never happen under normal circumstances so I am commenting this out but maybe
+      # needs a second look.
+      # %Req.Response{status: 403} -> {:error, "Unauthorised"}
+
+      # Peer is down.
+      %Req.TransportError{reason: :econnrefused} -> {:error, "peer #{name} is unreachable"}
     end
   end
 

lib/birdy_chat/identity.ex

@@ -55,6 +55,12 @@ defmodule BirdyChat.Identity do
           peers: %{"test2" => "http://localhost:4001"},
           mode: :test
         }
+
+      {identity, peers} ->
+        peers = parse_peers(peers)
+        identity = parse_identity(identity)
+
+        %__MODULE__{identity: identity, peers: peers, mode: :connected}
     end
   end
 end

lib/birdy_chat/message_writer.ex

@@ -1,5 +1,7 @@
 defmodule BirdyChat.MessageWriter do
-  @moduledoc false
+  @moduledoc """
+  Simple file writer that stores messages in priv folder of Elixir application/release.
+  """
 
   @spec write(%{to: String.t(), from: String.t(), message: String.t()}) :: :ok
   def write(message) do

lib/birdy_chat_web/api/messages/controller.ex

@@ -10,10 +10,10 @@ defmodule BirdyChatWeb.Api.Messages.Controller do
             |> put_status(:created)
             |> render(:create, message: changeset.changes)
 
-          :error ->
+          {:error, error} ->
             conn
             |> put_status(:unprocessable_entity)
-            |> render(:error, changeset: changeset)
+            |> render(:error, message: error)
         end
 
       {:error, changeset} ->

lib/birdy_chat_web/api/messages/json.ex

@@ -3,6 +3,10 @@ defmodule BirdyChatWeb.Api.Messages.JSON do
     message
   end
 
+  def render("error.json", %{message: message}) do
+    %{errors: %{"general" => Gettext.dgettext(BirdyChatWeb.Gettext, "errors", message, [])}}
+  end
+
   def render("error.json", %{changeset: changeset}) do
     errors = Ecto.Changeset.traverse_errors(changeset, &get_error/1)
     %{errors: errors}