tramp-virtualenv.el

(require 'tramp)

(if (boundp 'enable-remote-dir-locals)
    (setq enable-remote-dir-locals t))

(defun tramp-virtualenv-bin-dir ()
  (concat tramp-virtualenv-dir "/bin"))

(defun tramp-virtualenv (&optional dir)
  (progn
    ;;(message "entering tramp-virtualenv")
    (if (and (boundp 'dir) dir)
        (progn
          ;;(message "dir")
          (set (make-local-variable 'tramp-virtualenv-dir) dir)))
    (if (and (boundp 'tramp-virtualenv-dir) tramp-virtualenv-dir)
        (progn
          ;;(message "tramp-virtualenv-dir")
          (set (make-local-variable 'tramp-virtualenv-mode-line-string) (tramp-virtualenv-format-mode-line-string))
          (tramp-virtualenv-minor-mode t)
          (let ((vec (if (tramp-tramp-file-p (buffer-file-name))
                         (tramp-dissect-file-name (buffer-file-name))
                       nil)))
            (if (or
                 (not (boundp 'tramp-virtualenv-last-dir))
                 (not (equal tramp-virtualenv-dir tramp-virtualenv-last-dir))
                 (not (boundp 'tramp-virtualenv-last-vec))
                 (not (equal vec tramp-virtualenv-last-vec)))
                (progn
                  ;;(message "new tramp-virtualenv-dir")
                  (if vec
                      (let* ((proc (tramp-get-connection-process vec))
                             (new-remote-path (let ((path (tramp-get-remote-path vec)))
                                                (setq path (delete (tramp-virtualenv-bin-dir) path))
                                                (add-to-list 'path (tramp-virtualenv-bin-dir))
                                                path)))
                        ;;(message "tramp-virtualenv remote")
                        (tramp-send-command
                         vec (format "VIRTUAL_ENV=%s; export VIRTUAL_ENV" tramp-virtualenv-dir))
                        (setq tramp-remote-path (delete (tramp-virtualenv-bin-dir) tramp-remote-path))
                        (add-to-list 'tramp-remote-path (tramp-virtualenv-bin-dir))
                        (tramp-set-connection-property vec  "remote-path" new-remote-path)
                        (tramp-set-connection-property proc "remote-path" new-remote-path)
                        (tramp-set-remote-path vec))
                    (progn
                      ;;(message "tramp-virtualenv local")
                      (setenv "VIRTUAL_ENV" tramp-virtualenv-dir)
                      (setq exec-path (delete (tramp-virtualenv-bin-dir) exec-path))
                      (add-to-list 'exec-path (tramp-virtualenv-bin-dir))
                      (setenv "PATH" (mapconcat 'identity exec-path ":"))))
                  (setq tramp-virtualenv-last-dir tramp-virtualenv-dir)
                  (setq tramp-virtualenv-last-vec vec)))))
      (tramp-virtualenv-minor-mode -1))))

(add-hook 'post-command-hook 'tramp-virtualenv)

(defun tramp-virtualenv-format-mode-line-string ()
  (concat " " (nth 0 (reverse (split-string tramp-virtualenv-dir "/")))))

(define-minor-mode tramp-virtualenv-minor-mode
  nil                                   ; use default docstring
  nil                                   ; the initial value
  tramp-virtualenv-mode-line-string     ; mode line indicator
  nil                                   ; keymap
  :group 'tramp-virtualenv)             ; group

(provide 'tramp-virtualenv)