feat: support for Goth modules for FCM

config/test.exs

@@ -33,6 +33,6 @@ config :pigeon, PigeonTest.LegacyFCM,
 config :pigeon, PigeonTest.FCM,
   adapter: Pigeon.FCM,
   project_id: System.get_env("FCM_PROJECT"),
-  service_account_json: System.get_env("FCM_SERVICE_ACCOUNT_JSON")
+  goth: PigeonTest.Goth
 
 config :pigeon, PigeonTest.Sandbox, adapter: Pigeon.Sandbox

lib/pigeon/fcm.ex

@@ -75,11 +75,11 @@ defmodule Pigeon.FCM do
   ```
   n = Pigeon.FCM.Notification.new({:token, "reg ID"}, %{"body" => "test message"})
   ```
-   
-  5. Send the notification. 
 
-  On successful response, `:name` will be set to the name returned from the FCM 
-  API and `:response` will be `:success`. If there was an error, `:error` will 
+  5. Send the notification.
+
+  On successful response, `:name` will be set to the name returned from the FCM
+  API and `:response` will be `:success`. If there was an error, `:error` will
   contain a JSON map of the response and `:response` will be an atomized version
   of the error type.
 
@@ -92,46 +92,37 @@ defmodule Pigeon.FCM do
 
   defstruct config: nil,
             queue: Pigeon.NotificationQueue.new(),
-            refresh_before: 5 * 60,
             retries: @max_retries,
             socket: nil,
-            stream_id: 1,
-            token: nil
+            stream_id: 1
 
   @behaviour Pigeon.Adapter
 
   alias Pigeon.{Configurable, NotificationQueue}
   alias Pigeon.Http2.{Client, Stream}
 
-  @refresh :"$refresh"
-  @retry_after 1000
-
-  @scopes [
-    "https://www.googleapis.com/auth/cloud-platform",
-    "https://www.googleapis.com/auth/firebase.messaging"
-  ]
-
-  @impl true
+  @impl Pigeon.Adapter
   def init(opts) do
     config = Pigeon.FCM.Config.new(opts)
+
     Configurable.validate!(config)
 
     state = %__MODULE__{config: config}
 
-    with {:ok, socket} <- connect_socket(config),
-         {:ok, token} <- fetch_token(config) do
-      Configurable.schedule_ping(config)
-      schedule_refresh(state, token)
-      {:ok, %{state | socket: socket, token: token}}
-    else
-      {:error, reason} -> {:stop, reason}
+    case connect_socket(config) do
+      {:ok, socket} ->
+        Configurable.schedule_ping(config)
+        {:ok, %{state | socket: socket}}
+
+      {:error, reason} ->
+        {:stop, reason}
     end
   end
 
-  @impl true
+  @impl Pigeon.Adapter
   def handle_push(notification, state) do
-    %{config: config, queue: queue, token: token} = state
-    headers = Configurable.push_headers(config, notification, token: token)
+    %{config: config, queue: queue} = state
+    headers = Configurable.push_headers(config, notification, [])
     payload = Configurable.push_payload(config, notification, [])
 
     Client.default().send_request(state.socket, headers, payload)
@@ -146,7 +137,7 @@ defmodule Pigeon.FCM do
     {:noreply, state}
   end
 
-  @impl true
+  @impl Pigeon.Adapter
   def handle_info(:ping, state) do
     Client.default().send_ping(state.socket)
     Configurable.schedule_ping(state.config)
@@ -171,22 +162,6 @@ defmodule Pigeon.FCM do
     end
   end
 
-  def handle_info(@refresh, %{config: config} = state) do
-    case fetch_token(config) do
-      {:ok, token} ->
-        schedule_refresh(state, token)
-        {:noreply, %{state | retries: @max_retries, token: token}}
-
-      {:error, exception} ->
-        if state.retries > 0 do
-          Process.send_after(self(), @refresh, @retry_after)
-          {:noreply, %{state | retries: state.retries - 1}}
-        else
-          raise "too many failed attempts to refresh, last error: #{inspect(exception)}"
-        end
-    end
-  end
-
   def handle_info(msg, state) do
     case Client.default().handle_end_stream(msg, state) do
       {:ok, %Stream{} = stream} -> process_end_stream(stream, state)
@@ -210,18 +185,6 @@ defmodule Pigeon.FCM do
     end
   end
 
-  defp fetch_token(config) do
-    source = {:service_account, config.service_account_json, [scopes: @scopes]}
-    Goth.Token.fetch(%{source: source})
-  end
-
-  defp schedule_refresh(state, token) do
-    time_in_seconds =
-      max(token.expires - System.system_time(:second) - state.refresh_before, 0)
-
-    Process.send_after(self(), @refresh, time_in_seconds * 1000)
-  end
-
   @doc false
   def process_end_stream(%Stream{id: stream_id} = stream, state) do
     %{queue: queue, config: config} = state

lib/pigeon/fcm/config.ex

@@ -1,16 +1,21 @@
 defmodule Pigeon.FCM.Config do
   @moduledoc false
 
-  defstruct port: 443,
+  defstruct goth: nil,
             project_id: nil,
-            service_account_json: nil,
-            uri: 'fcm.googleapis.com'
+            uri: "fcm.googleapis.com",
+            port: 443
+
+  @typedoc """
+  TODO - the name or via-tuple of your Goth implementation, e.g. `YourApp.Goth`
+  """
+  @type goth_name :: module() | term()
 
   @type t :: %__MODULE__{
-          port: pos_integer,
-          project_id: binary,
-          service_account_json: binary,
-          uri: charlist
+          goth: nil | goth_name(),
+          project_id: nil | String.t(),
+          uri: String.t(),
+          port: pos_integer()
         }
 
   @doc ~S"""
@@ -20,70 +25,41 @@ defmodule Pigeon.FCM.Config do
 
       iex> Pigeon.FCM.Config.new(
       ...>   project_id: "example-project",
-      ...>   service_account_json: "{\"dummy\":\"contents\"}"
+      ...>   goth: YourApp.Goth
       ...> )
       %Pigeon.FCM.Config{
         port: 443,
         project_id: "example-project",
-        service_account_json: %{"dummy" => "contents"},
-        uri: 'fcm.googleapis.com'
+        goth: YourApp.Goth,
+        uri: "fcm.googleapis.com"
       }
   """
-  def new(opts) when is_list(opts) do
-    project_id =
-      opts
-      |> Keyword.get(:project_id)
-      |> decode_bin()
-
-    service_account_json =
-      opts
-      |> Keyword.get(:service_account_json)
-      |> decode_json()
+  def new(opts) do
+    opts = Map.new(opts)
 
     %__MODULE__{
-      port: Keyword.get(opts, :port, 443),
-      project_id: project_id,
-      service_account_json: service_account_json,
-      uri: Keyword.get(opts, :uri, 'fcm.googleapis.com')
+      goth: opts[:goth],
+      project_id: opts[:project_id],
+      uri: Map.get(opts, :uri, "fcm.googleapis.com"),
+      port: Map.get(opts, :port, 443)
     }
   end
-
-  def decode_bin(bin) when is_binary(bin) do
-    bin
-  end
-
-  def decode_bin(other) do
-    {:error, {:invalid, other}}
-  end
-
-  def decode_json(bin) when is_binary(bin) do
-    case Pigeon.json_library().decode(bin) do
-      {:ok, json} -> json
-      {:error, _reason} -> {:error, {:invalid, bin}}
-    end
-  end
-
-  def decode_json(other) do
-    {:error, {:invalid, other}}
-  end
 end
 
 defimpl Pigeon.Configurable, for: Pigeon.FCM.Config do
   @moduledoc false
 
-  require Logger
-
   import Pigeon.Tasks, only: [process_on_response: 1]
 
   alias Pigeon.Encodable
-  alias Pigeon.FCM.{Config, Error}
+  alias Pigeon.FCM.Error
 
   @type sock :: {:sslsocket, any, pid | {any, any}}
 
   # Configurable Callbacks
 
   @spec connect(any) :: {:ok, sock} | {:error, String.t()}
-  def connect(%Config{uri: uri} = config) do
+  def connect(%@for{uri: uri} = config) do
     case connect_socket_options(config) do
       {:ok, options} ->
         Pigeon.Http2.Client.default().connect(uri, :https, options)
@@ -104,18 +80,20 @@ defimpl Pigeon.Configurable, for: Pigeon.FCM.Config do
     {:ok, opts}
   end
 
-  def add_port(opts, %Config{port: 443}), do: opts
-  def add_port(opts, %Config{port: port}), do: [{:port, port} | opts]
+  def add_port(opts, %@for{port: 443}), do: opts
+  def add_port(opts, %@for{port: port}), do: [{:port, port} | opts]
 
   def push_headers(
-        %Config{project_id: project_id},
+        config,
         _notification,
-        opts
+        _opts
       ) do
+    token = Goth.fetch!(config.goth)
+
     [
       {":method", "POST"},
-      {":path", "/v1/projects/#{project_id}/messages:send"},
-      {"authorization", "Bearer #{opts[:token].token}"},
+      {":path", "/v1/projects/#{config.project_id}/messages:send"},
+      {"authorization", "#{token.type} #{token.token}"},
       {"content-type", "application/json"},
       {"accept", "application/json"}
     ]
@@ -148,19 +126,26 @@ defimpl Pigeon.Configurable, for: Pigeon.FCM.Config do
   def close(_config) do
   end
 
-  def validate!(%{project_id: {:error, _}} = config) do
+  def validate!(config) do
+    config
+    |> Map.from_struct()
+    |> Enum.each(&do_validate!(&1, config))
+  end
+
+  defp do_validate!({:goth, mod}, config)
+       when not is_atom(mod) or is_nil(mod) do
     raise Pigeon.ConfigError,
-      reason: "attempted to start without valid :project_id",
+      reason: "attempted to start without valid :goth module",
       config: redact(config)
   end
 
-  def validate!(%{service_account_json: {:error, _}} = config) do
+  defp do_validate!({:project_id, value}, config) when not is_binary(value) do
     raise Pigeon.ConfigError,
-      reason: "attempted to start without valid :service_account_json",
+      reason: "attempted to start without valid :project_id",
       config: redact(config)
   end
 
-  def validate!(_config), do: :ok
+  defp do_validate!({_key, _value}, _config), do: :ok
 
   @doc false
   def redact(config) when is_map(config) do

test/pigeon/fcm_test.exs

@@ -9,7 +9,7 @@ defmodule Pigeon.FCMTest do
 
   @data %{"message" => "Test push"}
   @invalid_project_msg ~r/^attempted to start without valid :project_id/
-  @invalid_service_account_json_msg ~r/^attempted to start without valid :service_account_json/
+  @invalid_goth_msg ~r/^attempted to start without valid :goth module/
 
   defp valid_fcm_reg_id do
     Application.get_env(:pigeon, :test)[:valid_fcm_reg_id]
@@ -18,14 +18,14 @@ defmodule Pigeon.FCMTest do
   describe "init/1" do
     test "raises if configured with invalid project" do
       assert_raise(Pigeon.ConfigError, @invalid_project_msg, fn ->
-        [project_id: nil, service_account_json: "{}"]
+        [project_id: nil, goth: PigeonTest.Goth]
         |> Pigeon.FCM.init()
       end)
     end
 
-    test "raises if configured with invalid service account JSON" do
-      assert_raise(Pigeon.ConfigError, @invalid_service_account_json_msg, fn ->
-        [project_id: "example", service_account_json: nil]
+    test "raises if configured with invalid goth module" do
+      assert_raise(Pigeon.ConfigError, @invalid_goth_msg, fn ->
+        [project_id: "example", goth: nil]
         |> Pigeon.FCM.init()
       end)
     end
@@ -52,6 +52,7 @@ defmodule Pigeon.FCMTest do
       assert n.response == :success
     end
 
+    @tag :focus
     test "successfully sends a valid push with a dynamic dispatcher" do
       target = {:token, valid_fcm_reg_id()}
       n = Notification.new(target, %{}, @data)

test/support/fcm.ex

@@ -7,3 +7,51 @@ defmodule PigeonTest.LegacyFCM do
   @moduledoc false
   use Pigeon.Dispatcher, otp_app: :pigeon
 end
+
+defmodule PigeonTest.GothHttpClient.Stub do
+  @moduledoc """
+  A collection of functions that can be used as custom `:http_client` values. Used to avoid
+  calling out to GCP during tests.
+  """
+
+  @doc """
+  Always returns a stub access_token response, as if being requested of a Google Metadata Server
+
+  ## Usage
+  ```
+  goth_opts = [
+    name: PigeonTest.Goth,
+    source: {:metadata, []}
+    http_client: {&PigeonTest.GothHttpClient.Stub.access_token_response/1, []}
+  ]
+
+  fcm_opts = [
+    adapter: Pigeon.Sandbox,
+    project_id: "example-123",
+    goth: PigeonTest.Goth
+  ]
+
+  children = [
+    {Goth, goth_opts}
+    {PigeonTest.FCM, fcm_opts}
+  ]
+
+  Supervisor.start_link(children, strategy: :one_for_one)
+  """
+  @spec access_token_response(keyword()) ::
+          {:ok,
+           %{
+             status: pos_integer(),
+             headers: list(),
+             body: String.t()
+           }}
+  def access_token_response(_) do
+    body = %{
+      "access_token" => "FAKE_APPLICATION_DEFAULT_CREDENTIALS_ACCESS_TOKEN",
+      "expires_in" => :timer.minutes(30),
+      "token_type" => "Bearer"
+    }
+
+    {:ok, %{status: 200, headers: [], body: Jason.encode!(body)}}
+  end
+end