i3.el

(require 'bindat)
(require 'json)

(defconst i3-process-name "*i3-process*"
  "Name of the buffer associated with i3 
IPC process")

(defun i3-get-tree-layout ()
  "Returns a layout tree. See i3 wm IPC 
docs for details."
  (i3-command 4))

(defun i3-get-workspaces ()
  "Returns a list of current workspaces. 
See i3 wm IPC docs for details."
  (i3-command 1))

(defun i3-command (command &optional 
payload)
  "Sends command to i3 and returns the 
response. See i3 wm IPC docs for 
details."
  (let ((proc (i3-get-or-make-client))
        (length (length payload)))
    (process-put proc 'response nil)
    (process-put proc 'partial-response 
nil)
    (process-send-string proc (concat 
(bindat-pack i3-msg-spec `((:magic . 
"i3-ipc")
                                                                 
(:length . ,length)
                                                                 
(:command . ,command)))
                                      
payload))
    (while (not (process-get proc 
'response))
      (accept-process-output proc))
    (let ((response (process-get proc 
'response)))
      (process-put proc 'response nil)
      (json-read-from-string response))))

(defun i3-get-or-make-client ()
  "Creates or returns a current process 
connected to i3 wm IPC."
  (unless (boundp 'i3-client)
    (setq i3-client (make-network-process 
:name i3-process-name :buffer 
(get-buffer-create i3-process-name)
                                          
:coding '(raw-text-unix . raw-text-unix)
                                          
:family 'local
                                          
:filter 'i3-response-filter
                                          
:sentinel 'i3-sentinel
                                          
:service (i3-chomp 
(shell-command-to-string "i3 
--get-socketpath")))))
  i3-client)

;;; Internal functions and data 
structures.

(defvar i3-msg-spec
  '((:magic str 6)
    (:length u32r)
    (:command u32r)))

(defun i3-response-filter (proc resp)
  (if (not (process-get proc 
'partial-response))
      (let ((length (cdr (assq :length 
(bindat-unpack i3-msg-spec resp))))
            (payload (substring resp 
14)))
        (process-put proc 
'partial-response-length length)
        (process-put proc 
'partial-response payload))
    (process-put proc 'partial-response 
(concat (process-get proc 
'partial-response) resp)))
  (when (>= (length (process-get proc 
'partial-response)) (process-get proc 
'partial-response-length))
    (process-put proc 'response 
(process-get proc 'partial-response))
    (process-put proc 'partial-response 
nil)))

(defun i3-sentinel (proc event)
  (setq i3-client nil))

(defun i3-chomp (string)
  (replace-regexp-in-string "\n$" "" 
string))

(provide 'i3)