Prepare to join servers

lib/birdy_chat/application.ex

@@ -10,6 +10,8 @@ defmodule BirdyChat.Application do
     children = [
       BirdyChatWeb.Telemetry,
       BirdyChat.Identity,
+      BirdyChat.PeerSupervisor,
+      {Registry, keys: :unique, name: BirdyChat.PeerRegistry},
       {DNSCluster, query: Application.get_env(:birdy_chat, :dns_cluster_query) || :ignore},
       {Phoenix.PubSub, name: BirdyChat.PubSub},
       # Start a worker by calling: BirdyChat.Worker.start_link(arg)

lib/birdy_chat/identity.ex

@@ -49,7 +49,12 @@ defmodule BirdyChat.Identity do
     peers = System.get_env("BIRDY_CHAT_PEERS")
 
     case {identity, peers} do
-      {nil, nil} -> %__MODULE__{identity: "test", peers: [], mode: :singleton}
+      {nil, nil} ->
+        %__MODULE__{
+          identity: "test1",
+          peers: %{"test2" => "http://localhost:4001"},
+          mode: :test
+        }
     end
   end
 end

lib/birdy_chat/message.ex

@@ -19,4 +19,21 @@ defmodule BirdyChat.Message do
       {:error, changeset}
     end
   end
+
+  def find_peer(%{to: to}) do
+    identity = BirdyChat.Identity.identity()
+
+    if String.starts_with?(to, identity) do
+      {:ok, :local}
+    else
+      result =
+        BirdyChat.Identity.peers()
+        |> Enum.find(fn {name, _url} -> String.starts_with?(to, name) end)
+
+      case result do
+        {name, _url} -> {:ok, name}
+        nil -> {:error, :not_found}
+      end
+    end
+  end
 end

lib/birdy_chat/peer_client.ex

@@ -0,0 +1,9 @@
+defmodule BirdyChat.PeerClient do
+  use Slipstream, restart: :temporary
+
+  def start_link(args) do
+    name = args[:peer_name]
+    name = {:via, BirdyChat.PeerRegistry, {:peers, name}}
+    Slipstream.start_link(__MODULE__, args, name: name)
+  end
+end

lib/birdy_chat/peer_supervisor.ex

@@ -0,0 +1,17 @@
+defmodule BirdyChat.PeerSupervisor do
+  use DynamicSupervisor
+
+  def start_link(init_arg) do
+    DynamicSupervisor.start_link(__MODULE__, init_arg, name: __MODULE__)
+  end
+
+  def start_child(peer_name, peer_address) do
+    spec = {BirdyChat.PeerClient, peer_name: peer_name, peer_address: peer_address}
+    DynamicSupervisor.start_child(__MODULE__, spec)
+  end
+
+  @impl true
+  def init(init_arg) do
+    DynamicSupervisor.init(strategy: :one_for_one, extra_arguments: [init_arg])
+  end
+end

lib/birdy_chat_web/api/messages/controller.ex

@@ -4,6 +4,8 @@ defmodule BirdyChatWeb.Api.Messages.Controller do
   def create(conn, params) do
     case BirdyChat.Message.validate(params) do
       {:ok, changeset} ->
+        case BirdyChat.Message.find_peer(changeset.changes) do
+          {:ok, :local} ->
             case BirdyChat.MessageWriter.write(changeset.changes) do
               :ok ->
                 conn
@@ -11,6 +13,23 @@ defmodule BirdyChatWeb.Api.Messages.Controller do
                 |> render(:create, message: changeset.changes)
             end
 
+          {:ok, peer_name} ->
+            BirdyChatWeb.ServerChannel.broadcast!(peer_name, changeset.changes)
+
+            conn
+            |> put_status(:created)
+            |> render(:create, message: changeset.changes)
+
+          {:error, :not_found} ->
+            changeset =
+              changeset
+              |> Ecto.Changeset.add_error(:to, "Unknown 'to' server")
+
+            conn
+            |> put_status(:unprocessable_entity)
+            |> render(:error, changeset: changeset)
+        end
+
       {:error, changeset} ->
         conn
         |> put_status(:unprocessable_entity)

lib/birdy_chat_web/channels/server_channel.ex

@@ -24,6 +24,13 @@ defmodule BirdyChatWeb.ServerChannel do
     end
   end
 
+  # This is how we send messages
+  def broadcast!(peer, message) do
+    channel = "server:#{peer}"
+    encoded_message = :erlang.term_to_binary(message)
+    BirdyChatWeb.Endpoint.broadcast!(channel, "new_message", {:binary, encoded_message})
+  end
+
   # Simple token-based authentication. Servers should use the same Phoenix secret key so they will
   # have the basis for generating tokens.
   defp authorised?(%{"token" => token}, server_id) do

test/birdy_chat/identity_test.exs

@@ -1,5 +1,5 @@
 defmodule BirdyChat.IdentityTest do
-  use BirdyChat.DataCase
+  use BirdyChat.DataCase, async: true
 
   setup do
     registry = start_supervised!({Registry, keys: :unique, name: __MODULE__})
@@ -11,7 +11,7 @@ defmodule BirdyChat.IdentityTest do
       name = {:via, Registry, {__MODULE__, "identity"}}
       {:ok, process} = BirdyChat.Identity.start_link(name: name)
       mode = BirdyChat.Identity.mode(process)
-      assert mode == :singleton
+      assert mode == :test
     end
 
     test "can be started by giving values like environment variables" do

test/birdy_chat/peer_test.exs

@@ -0,0 +1,3 @@
+defmodule BirdyChat.PeerTest do
+  use BirdyChat.DataCase, async: true
+end

test/birdy_chat_web/api/messages_test.exs

@@ -1,10 +1,12 @@
 defmodule BirdyChatWeb.Api.MessagesTest do
-  use BirdyChatWeb.ConnCase
+  use BirdyChatWeb.ConnCase, async: true
+
+  import Phoenix.ChannelTest
 
   setup %{conn: conn} do
     url = ~p"/api/messages"
 
-    path = Application.app_dir(:birdy_chat, ["priv", "messages", "test-user.txt"])
+    path = Application.app_dir(:birdy_chat, ["priv", "messages", "test1-user.txt"])
     on_exit(fn -> File.rm(path) end)
 
     conn =
@@ -14,6 +16,45 @@ defmodule BirdyChatWeb.Api.MessagesTest do
     %{conn: conn, url: url}
   end
 
+  describe "POST /api/messages to other server" do
+    setup do
+      server_id = "test2"
+      token = Phoenix.Token.sign(BirdyChatWeb.Endpoint, "serverAuth", server_id)
+
+      {:ok, _, socket} =
+        BirdyChatWeb.ServerSocket
+        |> socket("server_socket", %{server_id: server_id})
+        |> subscribe_and_join(BirdyChatWeb.ServerChannel, "server:#{server_id}", %{token: token})
+
+      %{socket: socket}
+    end
+
+    test "returns error when a peer is unknown", %{conn: conn, url: url} do
+      message = %{from: "test1-user", to: "fake-user", message: "123"}
+
+      payload = Jason.encode!(message)
+      conn = post(conn, url, payload)
+      assert result = json_response(conn, :unprocessable_entity)
+
+      expected_result = %{"errors" => %{"to" => ["Unknown 'to' server"]}}
+
+      assert result == expected_result
+    end
+
+    test "broadcasts message to websocket", %{conn: conn, url: url} do
+      message = %{from: "test1-user", to: "test2-user", message: "123"}
+      string_message = %{"from" => "test1-user", "message" => "123", "to" => "test2-user"}
+
+      payload = Jason.encode!(message)
+      conn = post(conn, url, payload)
+      assert result = json_response(conn, :created)
+      assert result == string_message
+
+      assert_broadcast "new_message", {:binary, encoded_message}
+      assert :erlang.binary_to_term(encoded_message, [:safe]) == message
+    end
+  end
+
   describe "POST /api/messages" do
     test "returns errors for invalid message", %{conn: conn, url: url} do
       payload = Jason.encode!(%{})
@@ -32,7 +73,7 @@ defmodule BirdyChatWeb.Api.MessagesTest do
     end
 
     test "returns message and 201 when successful", %{conn: conn, url: url} do
-      message = %{"from" => "2-user", "to" => "1-user", "message" => "123"}
+      message = %{"from" => "test2-user", "to" => "test1-user", "message" => "123"}
       payload = Jason.encode!(message)
       conn = post(conn, url, payload)
       assert result = json_response(conn, :created)
@@ -40,30 +81,30 @@ defmodule BirdyChatWeb.Api.MessagesTest do
     end
 
     test "writes message to file", %{conn: conn, url: url} do
-      message = %{"from" => "2-user", "to" => "test-user", "message" => "123"}
+      message = %{"from" => "test2-user", "to" => "test1-user", "message" => "123"}
       payload = Jason.encode!(message)
       conn = post(conn, url, payload)
       assert result = json_response(conn, :created)
       assert result == message
 
-      path = Application.app_dir(:birdy_chat, ["priv", "messages", "test-user.txt"])
+      path = Application.app_dir(:birdy_chat, ["priv", "messages", "test1-user.txt"])
       contents = File.read!(path)
-      assert contents == "2-user: 123\n"
+      assert contents == "test2-user: 123\n"
     end
 
     test "appends message to file", %{conn: conn, url: url} do
-      message = %{"from" => "2-user", "to" => "test-user", "message" => "123"}
+      message = %{"from" => "test2-user", "to" => "test1-user", "message" => "123"}
       payload = Jason.encode!(message)
       post(conn, url, payload)
 
-      message = %{"from" => "2-user", "to" => "test-user", "message" => "456"}
+      message = %{"from" => "test2-user", "to" => "test1-user", "message" => "456"}
       payload = Jason.encode!(message)
       conn = post(conn, url, payload)
       assert json_response(conn, :created)
 
-      path = Application.app_dir(:birdy_chat, ["priv", "messages", "test-user.txt"])
+      path = Application.app_dir(:birdy_chat, ["priv", "messages", "test1-user.txt"])
       contents = File.read!(path)
-      assert contents == "2-user: 123\n2-user: 456\n"
+      assert contents == "test2-user: 123\ntest2-user: 456\n"
     end
   end
 end

test/birdy_chat_web/channels/server_channel_test.exs

@@ -1,5 +1,5 @@
 defmodule BirdyChatWeb.ServerChannelTest do
-  use BirdyChatWeb.ChannelCase
+  use BirdyChatWeb.ChannelCase, async: true
 
   setup do
     server_id = "test2"

test/birdy_chat_web/controllers/page_controller_test.exs

@@ -1,5 +1,5 @@
 defmodule BirdyChatWeb.PageControllerTest do
-  use BirdyChatWeb.ConnCase
+  use BirdyChatWeb.ConnCase, async: true
 
   test "GET /", %{conn: conn} do
     conn = get(conn, ~p"/")