Add facebook

Author: scrogson

config/config.exs

@@ -31,4 +31,3 @@ config :phoenix, :generators,
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
 import_config "#{Mix.env}.exs"
-

config/dev.exs

@@ -51,3 +51,7 @@ config :oauth2_example, Google,
   client_secret: System.get_env("GOOGLE_CLIENT_SECRET"),
   redirect_uri: System.get_env("GOOGLE_REDIRECT_URI")
 
+config :oauth2_example, Facebook,
+  client_id: System.get_env("FACEBOOK_CLIENT_ID"),
+  client_secret: System.get_env("FACEBOOK_CLIENT_SECRET"),
+  redirect_uri: System.get_env("FACEBOOK_REDIRECT_URI")

web/controllers/auth_controller.ex

@@ -9,6 +9,13 @@ defmodule OAuth2Example.AuthController do
     redirect conn, external: authorize_url!(provider)
   end
 
+  def delete(conn, _params) do
+    conn
+    |> put_flash(:info, "You have been logged out!")
+    |> configure_session(drop: true)
+    |> redirect(to: "/")
+  end
+
   @doc """
   This action is reached via `/auth/:provider/callback` is the the callback URL that
   the OAuth2 provider will redirect the user back to with a `code` that will
@@ -20,7 +27,7 @@ defmodule OAuth2Example.AuthController do
     token = get_token!(provider, code)
 
     # Request the user's data with the access token
-    user = get_user!(provider, token).body
+    user = get_user!(provider, token)
 
     # Store the user in the session under `:current_user` and redirect to /.
     # In most cases, we'd probably just store the user's ID that can be used
@@ -35,15 +42,26 @@ defmodule OAuth2Example.AuthController do
     |> redirect(to: "/")
   end
 
-  defp authorize_url!("github"), do: GitHub.authorize_url!
-  defp authorize_url!("google"), do: Google.authorize_url!(scope: "https://www.googleapis.com/auth/userinfo.email")
+  defp authorize_url!("github"),   do: GitHub.authorize_url!
+  defp authorize_url!("google"),   do: Google.authorize_url!(scope: "https://www.googleapis.com/auth/userinfo.email")
+  defp authorize_url!("facebook"), do: Facebook.authorize_url!(scope: "user_photos")
   defp authorize_url!(_), do: raise "No matching provider available"
 
-  defp get_token!("github", code), do: GitHub.get_token!(code: code)
-  defp get_token!("google", code), do: Google.get_token!(code: code)
+  defp get_token!("github", code),   do: GitHub.get_token!(code: code)
+  defp get_token!("google", code),   do: Google.get_token!(code: code)
+  defp get_token!("facebook", code), do: Facebook.get_token!(code: code)
   defp get_token!(_, _), do: raise "No matching provider available"
 
-  defp get_user!("github", token), do: OAuth2.AccessToken.get!(token, "/user")
-  defp get_user!("google", token), do: OAuth2.AccessToken.get!(token, "https://www.googleapis.com/plus/v1/people/me/openIdConnect")
+  defp get_user!("github", token) do
+    {:ok, %{body: user}} = OAuth2.AccessToken.get(token, "/user")
+    %{name: user["name"], avatar: user["avatar_url"]}
+  end
+  defp get_user!("google", token) do
+    {:ok, %{body: user}} = OAuth2.AccessToken.get(token, "https://www.googleapis.com/plus/v1/people/me/openIdConnect")
+    %{name: user["name"], avatar: user["picture"]}
+  end
+  defp get_user!("facebook", token) do
+    {:ok, %{body: user}} = OAuth2.AccessToken.get(token, "/me", fields: "id,name")
+    %{name: user["name"], avatar: "https://graph.facebook.com/#{user["id"]}/picture"}
+  end
 end
-

web/oauth/facebook.ex

@@ -0,0 +1,43 @@
+defmodule Facebook do
+  @moduledoc """
+  An OAuth2 strategy for Facebook.
+  """
+  use OAuth2.Strategy
+
+  alias OAuth2.Strategy.AuthCode
+
+  defp config do
+    [strategy: Facebook,
+     site: "https://graph.facebook.com",
+     authorize_url: "https://www.facebook.com/dialog/oauth",
+     token_url: "/oauth/access_token"]
+  end
+
+  # Public API
+
+  def client do
+    Application.get_env(:oauth2_example, Facebook)
+    |> Keyword.merge(config())
+    |> OAuth2.Client.new()
+  end
+
+  def authorize_url!(params \\ []) do
+    OAuth2.Client.authorize_url!(client(), params)
+  end
+
+  def get_token!(params \\ [], headers \\ []) do
+    OAuth2.Client.get_token!(client(), params)
+  end
+
+  # Strategy Callbacks
+
+  def authorize_url(client, params) do
+    AuthCode.authorize_url(client, params)
+  end
+
+  def get_token(client, params, headers) do
+    client
+    |> put_header("Accept", "application/json")
+    |> AuthCode.get_token(params, headers)
+  end
+end

web/router.ex

@@ -21,6 +21,7 @@ defmodule OAuth2Example.Router do
 
     get "/:provider", AuthController, :index
     get "/:provider/callback", AuthController, :callback
+    delete "/logout", AuthController, :delete
   end
 
   # Fetch the current user from the session and add it to `conn.assigns`. This

web/templates/layout/app.html.eex

@@ -44,8 +44,9 @@
       <iframe src="https://ghbtns.com/github-btn.html?user=scrogson&repo=oauth2_example&type=watch&count=true&size=large&v=2" frameborder="0" scrolling="0" width="160px" height="30px"></iframe>
 
       <%= if @current_user do %>
-        <h2>Welcome, <%= @current_user["name"] %>!</h2>
-        <img src="<%= @current_user["avatar_url"] || @current_user["picture"] %>" class="img-circle"/>
+        <h2>Welcome, <%= @current_user.name %>!</h2>
+        <img src="<%= @current_user.avatar %>" class="img-circle"/>
+        <%= link "Logout", to: auth_path(@conn, :delete), method: :delete, class: "btn btn-danger" %>
       <% else %>
         <br>
         <br>
@@ -59,6 +60,11 @@
           <i class="fa fa-github"></i>
           Sign in with GitHub
         </a>
+
+        <a class="btn btn-primary btn-lg" href="<%= auth_path @conn, :index, "facebook" %>">
+          <i class="fa fa-facebook"></i>
+          Sign in with Facebook
+        </a>
       <% end %>
     </div>