Implementation sans test

plugins/twitter.lisp

@@ -0,0 +1,45 @@
+(:eval-when (:compile-toplevel :load-toplevel)
+  (ql:quickload :chirp))
+
+(defpackage :coleslaw-twitter
+  (:use :cl)
+  (:export #:enable))
+
+(in-package :coleslaw-twitter)
+
+(defvar *tweet-format* '("~A" (title post) (text content))
+  "Controls what the tweet annoucing the post looks like. It is the made up of a format control string followed with the pertinent variables.")
+
+(defun enable (&key api-key api-secret access-token access-secret tweet-format)
+  (if (and api-key api-secret access-token access-secret)
+      (setf chirp:*oauth-api-key* api-key
+            chirp:*oauth-api-secret* api-secret
+            chirp:*oauth-access-token* access-token
+            chirp:*oauth-access-secret* access-secret)
+      (error 'plugin-conf-error :plugin "twitter"
+             :message "Credentials missing.")
+      ;; fallback to chirp for credential erros
+      (chirp:account/verify-credentials))
+  
+  (when tweet-format
+    (setf *tweet-format* tweet-format)))
+
+(defmethod render :after (post (eql (find-class 'coleslaw:post)))
+  (format-post post))
+
+(defun format-post (post)
+  "Take a post and return a string of 140 character length, at most. Urls have 23 len and are a must."
+ (chirp:statuses/update (%format-post post)))
+
+(defun %format-post (offset post)
+  "Garauntee that the tweet content is 140 chars at most."
+  (let* ((content-prefix (subseq (render-tweet post) 0 (- 117 offset)))
+         (content (format nil "~A ~A" content-prefix (coleslaw:page-url post)))
+         (content-length (chirp:compute-status-length content)))
+    (cond
+      ((>= 140 content-length) content)
+      ((< 140 content-length) (%format-post (1- offset) post)))))
+
+(defun render-tweet (post)
+  "Sans the url, which is a must."
+  (apply #'format (append '(nil) *tweet-format*)))