From 8404b1c908ac890925496ce839e5b2b2b407a6f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= <essen@ninenines.eu>
Date: Tue, 11 Sep 2018 14:33:58 +0200
Subject: Add a commands-based interface to Websocket handlers

This feature is currently experimental. It will become the
preferred way to use Websocket handlers once it becomes
documented.

A commands-based interface enables adding commands without
having to change the interface much. It mirrors the interface
of stream handlers or gen_statem. It will enable adding
commands that have been needed for some time but were not
implemented for fear of making the interface too complex.
---
 test/handlers/ws_handle_commands_h.erl | 31 +++++++++++++++++++++++++++++++
 test/handlers/ws_info_commands_h.erl   | 32 ++++++++++++++++++++++++++++++++
 test/handlers/ws_init_commands_h.erl   | 30 ++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 test/handlers/ws_handle_commands_h.erl
 create mode 100644 test/handlers/ws_info_commands_h.erl
 create mode 100644 test/handlers/ws_init_commands_h.erl

(limited to 'test/handlers')

diff --git a/test/handlers/ws_handle_commands_h.erl b/test/handlers/ws_handle_commands_h.erl
new file mode 100644
index 0000000..da3ffad
--- /dev/null
+++ b/test/handlers/ws_handle_commands_h.erl
@@ -0,0 +1,31 @@
+%% This module takes commands from the x-commands header
+%% and returns them in the websocket_handle/2 callback.
+
+-module(ws_handle_commands_h).
+-behavior(cowboy_websocket).
+
+-export([init/2]).
+-export([websocket_init/1]).
+-export([websocket_handle/2]).
+-export([websocket_info/2]).
+
+init(Req=#{pid := Pid}, RunOrHibernate) ->
+	Commands0 = cowboy_req:header(<<"x-commands">>, Req),
+	Commands = binary_to_term(base64:decode(Commands0)),
+	case Commands of
+		bad -> ct_helper_error_h:ignore(Pid, cowboy_websocket, handler_call, 6);
+		_ -> ok
+	end,
+	{cowboy_websocket, Req, {Commands, RunOrHibernate}}.
+
+websocket_init(State) ->
+	{[], State}.
+
+websocket_handle(_, State={Commands, run}) ->
+	{Commands, State};
+websocket_handle(_, State={Commands, hibernate}) ->
+	{Commands, State, hibernate}.
+
+websocket_info(_, State) ->
+	{[], State}.
+
diff --git a/test/handlers/ws_info_commands_h.erl b/test/handlers/ws_info_commands_h.erl
new file mode 100644
index 0000000..d596473
--- /dev/null
+++ b/test/handlers/ws_info_commands_h.erl
@@ -0,0 +1,32 @@
+%% This module takes commands from the x-commands header
+%% and returns them in the websocket_info/2 callback.
+%% This callback is triggered via a message.
+
+-module(ws_info_commands_h).
+-behavior(cowboy_websocket).
+
+-export([init/2]).
+-export([websocket_init/1]).
+-export([websocket_handle/2]).
+-export([websocket_info/2]).
+
+init(Req=#{pid := Pid}, RunOrHibernate) ->
+	Commands0 = cowboy_req:header(<<"x-commands">>, Req),
+	Commands = binary_to_term(base64:decode(Commands0)),
+	case Commands of
+		bad -> ct_helper_error_h:ignore(Pid, cowboy_websocket, handler_call, 6);
+		_ -> ok
+	end,
+	{cowboy_websocket, Req, {Commands, RunOrHibernate}}.
+
+websocket_init(State) ->
+	self() ! shoot,
+	{[], State}.
+
+websocket_handle(_, State) ->
+	{[], State}.
+
+websocket_info(_, State={Commands, run}) ->
+	{Commands, State};
+websocket_info(_, State={Commands, hibernate}) ->
+	{Commands, State, hibernate}.
diff --git a/test/handlers/ws_init_commands_h.erl b/test/handlers/ws_init_commands_h.erl
new file mode 100644
index 0000000..8bae352
--- /dev/null
+++ b/test/handlers/ws_init_commands_h.erl
@@ -0,0 +1,30 @@
+%% This module takes commands from the x-commands header
+%% and returns them in the websocket_init/1 callback.
+
+-module(ws_init_commands_h).
+-behavior(cowboy_websocket).
+
+-export([init/2]).
+-export([websocket_init/1]).
+-export([websocket_handle/2]).
+-export([websocket_info/2]).
+
+init(Req=#{pid := Pid}, RunOrHibernate) ->
+	Commands0 = cowboy_req:header(<<"x-commands">>, Req),
+	Commands = binary_to_term(base64:decode(Commands0)),
+	case Commands of
+		bad -> ct_helper_error_h:ignore(Pid, cowboy_websocket, handler_call, 6);
+		_ -> ok
+	end,
+	{cowboy_websocket, Req, {Commands, RunOrHibernate}}.
+
+websocket_init(State={Commands, run}) ->
+	{Commands, State};
+websocket_init(State={Commands, hibernate}) ->
+	{Commands, State, hibernate}.
+
+websocket_handle(_, State) ->
+	{[], State}.
+
+websocket_info(_, State) ->
+	{[], State}.
-- 
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