From a02ae8d1153560876e55e2a558ab6f7e44f240b8 Mon Sep 17 00:00:00 2001
From: Andrew Vy <andrew@andrewvy.com>
Date: Sat, 30 Sep 2017 20:29:26 -0700
Subject: [PATCH] :sparkles: Add `async` option to RPC

Ex: `ChromeRemoteInterface.RPC.Page.navigate(page_pid, %{url: "google.com"}, async: true)`

Instead of a blocking call, this will `cast` the RPC request and send a message back
to the current process.

This message will be in the format of:

`{:chrome_remote_interface, "Page.navigate", response}`
---
 lib/chrome_remote_interface.ex | 31 +++++++++++++---
 lib/page_session.ex            | 66 ++++++++++++++++++++++++++--------
 mix.exs                        |  2 +-
 3 files changed, 78 insertions(+), 21 deletions(-)

diff --git a/lib/chrome_remote_interface.ex b/lib/chrome_remote_interface.ex
index 47df490..3b1ab34 100644
--- a/lib/chrome_remote_interface.ex
+++ b/lib/chrome_remote_interface.ex
@@ -3,6 +3,8 @@ defmodule ChromeRemoteInterface do
   Documentation for ChromeRemoteInterface.
   """
 
+  alias ChromeRemoteInterface.PageSession
+
   protocol =
     File.read!("priv/protocol.json")
     |> Poison.decode!()
@@ -32,11 +34,30 @@ defmodule ChromeRemoteInterface do
         Parameters:
         #{arg_doc}
         """
-        def unquote(:"#{name}")(page_pid, parameters \\ %{}) do
-          page_pid |> ChromeRemoteInterface.PageSession.execute_command(
-             unquote("#{domain["domain"]}.#{name}"),
-             parameters
-           )
+        def unquote(:"#{name}")(page_pid) do
+          page_pid |> PageSession.call(
+            unquote("#{domain["domain"]}.#{name}"),
+            %{}
+          )
+        end
+        def unquote(:"#{name}")(page_pid, parameters) do
+          page_pid |> PageSession.call(
+            unquote("#{domain["domain"]}.#{name}"),
+            parameters
+          )
+        end
+        def unquote(:"#{name}")(page_pid, parameters, opts) when is_list(opts) do
+          if opts[:async] do
+            page_pid |> PageSession.cast(
+              unquote("#{domain["domain"]}.#{name}"),
+              parameters
+            )
+          else
+            page_pid |> PageSession.call(
+              unquote("#{domain["domain"]}.#{name}"),
+              parameters
+            )
+          end
         end
       end
     end
diff --git a/lib/page_session.ex b/lib/page_session.ex
index b72fbd2..3948c32 100644
--- a/lib/page_session.ex
+++ b/lib/page_session.ex
@@ -81,8 +81,16 @@ defmodule ChromeRemoteInterface.PageSession do
   @doc """
   Executes a raw JSON RPC command through Websockets.
   """
-  def execute_command(pid, method, params) do
-    GenServer.call(pid, {:execute_command, method, params})
+  def call(pid, method, params) do
+    GenServer.call(pid, {:call_command, method, params})
+  end
+
+  @doc """
+  Executes a raw JSON RPC command through Websockets, but sends the
+  response as a message to the requesting process.
+  """
+  def cast(pid, method, params, from \\ self()) do
+    GenServer.cast(pid, {:cast_command, method, params, from})
   end
 
   # ---
@@ -99,22 +107,24 @@ defmodule ChromeRemoteInterface.PageSession do
     {:ok, state}
   end
 
-  def handle_call({:execute_command, method, params}, from, state) do
-    message = %{
-      "id" => state.ref_id,
-      "method" => method,
-      "params" => params
-    }
+  def handle_cast({:cast_command, method, params, from}, state) do
+    send_rpc_request(state, method, params)
 
-    json = Poison.encode!(message)
-    WebSockex.send_frame(state.socket, {:text, json})
+    new_state =
+      state
+      |> add_callback({:cast, method, from})
+      |> increment_ref_id()
+
+    {:noreply, new_state}
+  end
+
+  def handle_call({:call_command, method, params}, from, state) do
+    send_rpc_request(state, method, params)
 
     new_state =
       state
-      |> Map.update(:callbacks, [{state.ref_id, from}], fn(callbacks) ->
-        [{state.ref_id, from} | callbacks]
-      end)
-      |> Map.update(:ref_id, 1, &(&1 + 1))
+      |> add_callback({:call, from})
+      |> increment_ref_id()
 
     {:noreply, new_state}
   end
@@ -185,6 +195,29 @@ defmodule ChromeRemoteInterface.PageSession do
     {:noreply, state}
   end
 
+  defp send_rpc_request(state, method, params) do
+    message = %{
+      "id" => state.ref_id,
+      "method" => method,
+      "params" => params
+    }
+
+    json = Poison.encode!(message)
+    WebSockex.send_frame(state.socket, {:text, json})
+  end
+
+  defp add_callback(state, from) do
+    state
+    |> Map.update(:callbacks, [{state.ref_id, from}], fn(callbacks) ->
+      [{state.ref_id, from} | callbacks]
+    end)
+  end
+
+  defp increment_ref_id(state) do
+    state
+    |> Map.update(:ref_id, 1, &(&1 + 1))
+  end
+
   defp send_rpc_response(callbacks, id, json) do
     error = json["error"]
 
@@ -192,7 +225,10 @@ defmodule ChromeRemoteInterface.PageSession do
       ref_id == id
     end)
     |> case do
-      {_ref_id, from} ->
+      {_ref_id, {:cast, method, from}} ->
+        event = {:chrome_remote_interface, method, json}
+        send(from, event)
+      {_ref_id, {:call, from}} ->
         status = if error, do: :error, else: :ok
         GenServer.reply(from, {status, json})
       _ -> :ok
diff --git a/mix.exs b/mix.exs
index f96bc32..5b1abb3 100644
--- a/mix.exs
+++ b/mix.exs
@@ -4,7 +4,7 @@ defmodule ChromeRemoteInterface.Mixfile do
   def project do
     [
       app: :chrome_remote_interface,
-      version: "0.0.2",
+      version: "0.0.3",
       elixir: "~> 1.5",
       start_permanent: Mix.env == :prod,
       deps: deps(),