Optionally use auth-source-search for fetching and saving password. (#181)

* Use auth-source-search for fetching and saving password

This gives users the ability to save their password to either the gpg-encrypted ~/.authinfo.gpg or
~/.authinfo so that they don't have to provide username/password each time

* Add a new custom var to decide whether to use the auth-source package or not.

3 files changed, 89 insertions, 15 deletions

diff --git a/README.org b/README.org
index 5b8b676..a5e5819 100644
--- a/README.org
+++ b/README.org
@@ -65,6 +65,10 @@ Set =mastodon-instance-url= in your =.emacs= or =customize=. Defaults to the [[h
     (setq mastodon-instance-url "https://my.instance.url")
 #+END_SRC
 
+There is an option to have your user credentials (email address and password) saved to disk so you don't have to re-enter them on every restart.
+The default is not to do this because if not properly configured it would save these unencrypted which is not a good default to have.
+Customize the variable =mastodon-auth-source-file= if you want to enable this feature.
+
 *** Timelines
 
 =M-x mastodon=
diff --git a/lisp/mastodon-auth.el b/lisp/mastodon-auth.el
index 17f19e3..aa83fae 100644
--- a/lisp/mastodon-auth.el
+++ b/lisp/mastodon-auth.el
@@ -30,6 +30,7 @@
 ;;; Code:
 
 (require 'plstore)
+(require 'auth-source)
 
 (autoload 'mastodon-client "mastodon-client")
 (autoload 'mastodon-http--api "mastodon-http")
@@ -42,6 +43,15 @@
   :prefix "mastodon-auth-"
   :group 'mastodon)
 
+(defcustom mastodon-auth-source-file ""
+  "Filename to use to store user names and passwords.
+
+Leave empty to not permanently store any secrets.
+Otherwise set to e.g. \"~/.authinfo.gpg\" to have encrypted storage, or
+if you are happy with unencryped storage use e.g. \"~/authinfo\"."
+  :group 'mastodon-auth
+  :type 'string)
+
 (defvar mastodon-auth--token-alist nil
   "Alist of User access tokens keyed by instance url.")
 
@@ -50,6 +60,13 @@
 
 (defun mastodon-auth--generate-token ()
   "Make POST to generate auth token."
+  (if (or (null mastodon-auth-source-file)
+	  (string= "" mastodon-auth-source-file))
+      (mastodon-auth--generate-token-no-storing-credentials)
+    (mastodon-auth--generate-token-and-store)))
+
+(defun mastodon-auth--generate-token-no-storing-credentials ()
+  "Make POST to generate auth token."
   (mastodon-http--post
    (concat mastodon-instance-url "/oauth/token")
    `(("client_id" . ,(plist-get (mastodon-client) :client_id))
@@ -61,6 +78,36 @@
    nil
    :unauthenticated))
 
+(defun mastodon-auth--generate-token-and-store ()
+  "Make POST to generate auth token.
+
+Reads and/or stores secres in `MASTODON-AUTH-SOURCE-FILE'."
+  (let* ((auth-sources (list mastodon-auth-source-file))
+	 (auth-source-creation-prompts
+          '((user . "Enter email for %h: ")
+            (secret . "Password: ")))
+         (credentials-plist (nth 0 (auth-source-search
+                                    :create t
+                                    :host mastodon-instance-url
+                                    :port 443
+                                    :require '(:user :secret)))))
+    (prog1
+        (mastodon-http--post
+         (concat mastodon-instance-url "/oauth/token")
+         `(("client_id" . ,(plist-get (mastodon-client) :client_id))
+           ("client_secret" . ,(plist-get (mastodon-client) :client_secret))
+           ("grant_type" . "password")
+           ("username" . ,(plist-get credentials-plist :user))
+           ("password" . ,(let ((secret (plist-get credentials-plist :secret)))
+                            (if (functionp secret)
+                                (funcall secret)
+                              secret)))
+           ("scope" . "read write follow"))
+         nil
+	 :unauthenticated)
+      (when (functionp (plist-get credentials-plist :save-function))
+        (funcall (plist-get credentials-plist :save-function))))))
+
 (defun mastodon-auth--get-token ()
   "Make auth token request and return JSON response."
   (with-current-buffer (mastodon-auth--generate-token)
diff --git a/test/mastodon-auth-tests.el b/test/mastodon-auth-tests.el
index 719a56c..5108f9a 100644
--- a/test/mastodon-auth-tests.el
+++ b/test/mastodon-auth-tests.el
@@ -1,22 +1,45 @@
 (require 'el-mock)
 
-(ert-deftest generate-token ()
+(ert-deftest generate-token--no-storing-credentials ()
   "Should make `mastdon-http--post' request to generate auth token."
   (with-mock
-    (let ((mastodon-instance-url "https://instance.url"))
-      (mock (mastodon-client) => '(:client_id "id" :client_secret "secret"))
-      (mock (read-string "Email: ") => "foo@bar.com")
-      (mock (read-passwd "Password: ") => "password")
-      (mock (mastodon-http--post "https://instance.url/oauth/token"
-                                 '(("client_id" . "id")
-                                   ("client_secret" . "secret")
-                                    ("grant_type" . "password")
-                                    ("username" . "foo@bar.com")
-                                    ("password" . "password")
-                                    ("scope" . "read write follow"))
-                                 nil
-                                 :unauthenticated))
-      (mastodon-auth--generate-token))))
+   (let ((mastodon-auth-source-file "")
+	 (mastodon-instance-url "https://instance.url"))
+     (mock (mastodon-client) => '(:client_id "id" :client_secret "secret"))
+     (mock (read-string "Email: ") => "foo@bar.com")
+     (mock (read-passwd "Password: ") => "password")
+     (mock (mastodon-http--post "https://instance.url/oauth/token"
+                                '(("client_id" . "id")
+                                  ("client_secret" . "secret")
+                                  ("grant_type" . "password")
+                                  ("username" . "foo@bar.com")
+                                  ("password" . "password")
+                                  ("scope" . "read write follow"))
+                                nil
+                                :unauthenticated))
+     (mastodon-auth--generate-token))))
+
+(ert-deftest generate-token--storing-credentials ()
+  "Should make `mastdon-http--post' request to generate auth token."
+  (with-mock
+   (let ((mastodon-auth-source-file "~/.authinfo")
+	 (mastodon-instance-url "https://instance.url"))
+     (mock (mastodon-client) => '(:client_id "id" :client_secret "secret"))
+     (mock (auth-source-search :create t
+                               :host "https://instance.url"
+                               :port 443
+                               :require '(:user :secret))
+           => '((:user "foo@bar.com" :secret (lambda () "password"))))
+     (mock (mastodon-http--post "https://instance.url/oauth/token"
+                                '(("client_id" . "id")
+                                  ("client_secret" . "secret")
+                                  ("grant_type" . "password")
+                                  ("username" . "foo@bar.com")
+                                  ("password" . "password")
+                                  ("scope" . "read write follow"))
+                                nil
+				:unauthenticated))
+     (mastodon-auth--generate-token))))
 
 (ert-deftest get-token ()
   "Should generate token and return JSON response."