facebook.el 0.0.1

[paul . huff]

I'm an amateur elisper.  If you see anything obviously bad, please,
let me know.

Right now, this just lets you update your facebook status, but it
requires heavy setup on the facebook side, because their API is pretty
awful that way.

Any comments at all would be much appreciated.

-Paul

;;; facebook.el --- Access the Facebook API from emacs
     
;;; Copyright (C) 2007 Paul Huff
     
;;; Author: Paul Huff <address@hidden>
;;; Maintainer: Paul Huff <address@hidden>
;;; Created: 5 Oct 2007
;;; Version: 0.0.1
;;; Package-Requires: ((json "0"))
;;; Keywords: facebook, frivolity

;; This file is NOT part of GNU Emacs.

;; This is free software; you can redistribute it and/or modify it under
;; the terms of the GNU General Public License as published by the Free
;; Software Foundation; either version 2, or (at your option) any later
;; version.

;; This file is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with Emacs; see the file COPYING, or type `C-h C-c'. If not,
;; write to the Free Software Foundation at this address:

;;   Free Software Foundation
;;   51 Franklin Street, Fifth Floor
;;   Boston, MA 02110-1301
;;   USA     

;;; Commentary:

;;;   First pass at interfacing with facebook.  You must add the "developers 
;;;   app" and get your own application api-key and application secret key to 
;;;   use this.  Also, facebook's authentication scheme is, well, ridiculous, 
;;;   so you've got to have gnutls or openssl installed, as well as a working
;;;   browser that handles https to log in and give your app permissions.
;;;   Also, it requires hober's excellent json.el which can be obtained here:
;;;   http://edward.oconnor.cx/elisp/json.el

;;;   To log into facebook, call (facebook-login)
;;;   To check credentials/optionally login call (facebook-check-creds)
;;;   To make api calls call (facebook-call-function "<funcname>" (list (cons 
"of" "args") (cons "more" "args")))

;;;   Only two actual api functions are present right now, (though you can 
;;;   use facebook-call-function to call whatever you'd like...):
;;;   facebook-users-has-app-permission = users.hasAppPermission
;;;   facebook-users-set-status = users.setStatus
;;;   facbeook-users-set-status checks for the applicable app permission 
;;;   redirects the user to the permission page if needed and then goes and 
;;;   updates the status.

;;;   The sf.net project homepage for this project can be found here:
;;;   http://sf.net/projects/facebook-el

;;; Code:
(require 'json)
(defcustom facebook-api-key "" "Your facebook api-key")
(defcustom facebook-api-secret "" "Your facebook api secret")
(defcustom facebook-session-info 'nil "Your facebook session info.  This will 
be set by facebook.el")

(defun facebook-call-function-post (method-name args)
  "Send ARGS to URL as a POST request."
  (let* ((url "http://api.facebook.com/restserver.php";)
         (url-request-method "POST")
         (url-request-extra-headers
          '(("Content-Type" . "application/x-www-form-urlencoded")))
         (full-args (append (list (cons "method" method-name) (cons "v" "1.0")
                                  (cons "format" "JSON") 
                                  (cons "api_key" facebook-api-key)) 
                            args))
         (full-args-call-id (cons (cons "call_id" 
                                        (mapconcat 'number-to-string 
                                                   (current-time) "")) 
                                  full-args))
         (sorted-full-args (sort full-args-call-id 'car-string<))
         (sig-full-args (cons (cons "sig" 
                                    (facebook-sig-creator sorted-full-args))
                              sorted-full-args))
         (url-request-data
          (mapconcat (lambda (arg)
                       (concat (url-hexify-string (car arg))
                               "="
                               (url-hexify-string (cdr arg))))
                     sig-full-args
                     "&"))
         (result 
          (save-excursion
            (set-buffer (url-retrieve-synchronously url))
            (progn (goto-char (point-min))
                   (delete-region (point-min) (search-forward "\n\n"))
                   (buffer-substring (point-min) (point-max))))))
    
    (setq facebook-last-raw-json-result result)
    (json-read-from-string result)))

(defun car-string< (a b)
  (string< (car a) (car b)))

(defun facebook-sig-creator (args-array &optional secret)
  (let* ((request-str (mapconcat (lambda (arg)
                                   (concat (car arg)
                                           "="
                                           (cdr arg)))
                                 args-array
                                 ""))
         (request-str-secret (if secret
                                 (concat request-str secret)
                               (if (and facebook-session-info
                                        (or (equal (assoc-default 'expires 
facebook-session-info) 0)
                                            (<= (map-concat 'number-to-string 
(current-time) "")
                                                (assoc-default 'expires 
facebook-session-info))))
                                   (concat request-str (assoc-default 'secret 
facebook-session-info))
                                 (concat request-str facebook-api-secret)))))
    (md5 request-str-secret)))

;;;###autoload
(defun facebook-login ()
  (interactive)
  (let* ((auth-token (facebook-call-function-post "auth.createToken" '()))
         (login-url (concat 
                     "https://login.facebook.com/login.php?v=1.0&api_key="; 
                     facebook-api-key "&auth_token=" auth-token)))
    (browse-url login-url)
    (read-string "Hit enter here after you've logged into facebook (this is 
their lame scheme, not facebook.el's")
    (customize-save-variable 'facebook-session-info 
                             (facebook-call-function-post "auth.getSession"  
                                                          (list (cons 
                                                                 "auth_token" 
                                                                 auth-token)))
                             )))


(defun facebook-check-creds ()
  (interactive)
  (let* ((session-expires 
          (assoc-default 'expires facebook-session-info 'nil -1))
         (current-time (mapconcat 'number-to-string (current-time) "")))
    (if (not (equal session-expires 0))
        (if (or (eq session-expires 'nil) 
                (<= session-expires current-time))
            (facebook-login)
          't)
      't)))

(defun facebook-users-has-app-permission (permission)
  (interactive)
  (let ((result 
         (facebook-call-function-post "users.hasAppPermission" 
                                      (list (cons "session_key" 
                                                  (assoc-default 
                                                   'session_key 
                                                   facebook-session-info)) 
                                            (cons "ext_perm" permission)))))
    (setq facebook-last-app-permission result)))


;;;###autoload
(defun facebook-users-set-status (status_message)
  (interactive)
  (progn
    (facebook-check-creds)
    (if (equal (facebook-users-has-app-permission "status_update") 0)
        (let* ((auth-url (concat 
                          "http://www.facebook.com/authorize.php?api_key=";
                          facebook-api-key "&v=1.0&ext_perm=status_update"))) 
          (progn
            (browse-url auth-url)
            (read-string "Hit enter here after you've granted your app_key 
permission to update your status (should only have to do this once... this is 
their lame scheme, not facebook.el's)")
            )))
    (message "Setting status to: %s" status_message)
    (let ((result 
           (facebook-call-function-post "users.setStatus" 
                                        (list 
                                         (cons "session_key" 
                                               (assoc-default 
                                                'session_key 
                                                facebook-session-info)) 
                                         (cons "status" status_message)))))
      (setq facebook-set-status-result result))))

;;;###autoload
(defun facebook-status (status_message)
  (interactive  "sStatus message: ")
  (facebook-users-set-status status_message))


(provide 'facebook)
;;; facebook.el ends here