app/irc: general rewrite (#103)

+ Refactor initialization process.
+ Refactor for consistency.
+ Add +irc-defer-notifications (for ZNC users).
+ Rewrote =irc (opens separate workspace + auto-connects to registered
  networks).
+ Add +irc/connect (connect to specific network).
+ Add +irc/quit (kill whole circe session).
+ Add +irc/ivy-jump-to-channel command.
+ Rewrite README.
+ Silence QUIT/PART default messages; they're cute, but no thanks.
+ Truncate nicks non-destructively.
+ Jump to prompt when entering insert mode (with evil).
+ Activate solaire-mde in channel buffers to visually distinguish them
  from server buffers.

modules/app/irc/README.org

@@ -1,19 +1,74 @@
 * :app irc
 
-This module makes Emacs an irc client, using [[https://github.com/jorgenschaefer/circe][~circe~]].
+This module turns adds an IRC client to Emacs ([[https://github.com/jorgenschaefer/circe][~circe~)]] with native notifications ([[https://github.com/eqyiel/circe-notifications][circe-notifications]]).
 
 ** Dependencies
+This module has no dependencies, besides =gnutls-cli= or =openssl= for secure connections.
 
-I use ~pass~ to not have the passwords written in my dotfiles. It's available under ~:tools~ modules.
-If you want to use TLS you also need =openssl= or =gnutls-cli=.
+** Configure
+Use the ~:irc~ setting to configure IRC servers. Its second argument (a plist) takes the same arguments as ~circe-network-options~.
 
-Configure Emacs to use your favorite irc servers:
 #+BEGIN_SRC emacs-lisp :tangle no
 (set! :irc "chat.freenode.net"
     `(:tls t
-      :nick "benny"
-      :sasl-username ,(password-store-get "irc/freenode")
-      :sasl-password ,(password-store-get "irc/freenode")
+      :nick "doom"
+      :sasl-username "myusername"
+      :sasl-password "mypassword"
+      :channels ("#emacs")))
+#+END_SRC
+
+*It is a obviously a bad idea to store auth-details in plaintext,* so here are some ways to avoid that:
+
+*** Pass: the unix password manager
+[[https://www.passwordstore.org/][Pass]] is my tool of choice. I use it to manage my passwords. If you activate the [[/modules/tools/password-store/README.org][:tools password-store]] module you get an elisp API through which to access your password store.
+
+~:irc~'s plist can use functions instead of strings. ~+pass-get-user~ and ~+pass-get-secret~ can help here:
+
+#+BEGIN_SRC emacs-lisp :tangle no
+(set! :irc "chat.freenode.net"
+    `(:tls t
+      :nick "doom"
+      :sasl-username ,(+pass-get-user   "irc/freenode.net")
+      :sasl-password ,(+pass-get-secret "irc/freenode.net")
+      :channels ("#emacs")))
+#+END_SRC
+
+But wait, there's more! This stores your password in a public variable which could be accessed or appear in backtraces. Not good! So we go a step further:
+
+#+BEGIN_SRC emacs-lisp :tangle no
+(set! :irc "chat.freenode.net"
+    `(:tls t
+      :nick "doom"
+      :sasl-username ,(+pass-get-user "irc/freenode.net")
+      :sasl-password (lambda (&rest _) (+pass-get-secret "irc/freenode.net"))
+      :channels ("#emacs")))
+#+END_SRC
+
+And you're good to go!
+
+*** Emacs' auth-source API
+~auth-source~ is built into Emacs. As suggested [[https://github.com/jorgenschaefer/circe/wiki/Configuration#safer-password-management][in the circe wiki]], you can store (and retrieve) encrypted passwords with it.
+
+#+BEGIN_SRC emacs-lisp :tangle no
+(setq auth-sources '("~/.authinfo.gpg"))
+
+(defun my-fetch-password (&rest params)
+  (require 'auth-source)
+  (let ((match (car (apply #'auth-source-search params))))
+    (if match
+        (let ((secret (plist-get match :secret)))
+          (if (functionp secret)
+              (funcall secret)
+            secret))
+      (error "Password not found for %S" params))))
+
+(defun my-nickserv-password (server)
+  (my-fetch-password :user "forcer" :host "irc.freenode.net"))
+
+(set! :irc "chat.freenode.net"
+    '(:tls t
+      :nick "doom"
+      :sasl-password my-nickserver-password
       :channels ("#emacs")))
 #+END_SRC