;;; -*- Mode: Emacs-Lisp -*-
;;;
;;; Registration of the default Tooltalk patterns and handlers.
;;;
;;; @(#)tooltalk-init.el 1.8 94/02/22


(defvar tooltalk-eval-pattern
  '(category TT_HANDLE
       scope TT_SESSION
          op "emacs-eval"
    callback tooltalk-eval-handler))

(defvar tooltalk-load-file-pattern
  '(category TT_HANDLE
       scope TT_SESSION
          op "emacs-load-file"
    callback tooltalk-load-file-handler))

(defvar tooltalk-make-client-screen-pattern 
  '(category TT_HANDLE
       scope TT_SESSION
          op "emacs-make-client-screen"
    callback tooltalk-make-client-screen-handler))

(defvar tooltalk-status-pattern 
  '(category TT_HANDLE
       scope TT_SESSION
          op "emacs-status"
    callback tooltalk-status-handler))


(defvar initial-tooltalk-patterns ())

(defun dispatch-initial-tooltalk-message (m)
  (let ((opsym (intern (get-tooltalk-message-attribute m 'op)))
	(patterns initial-tooltalk-patterns))
    (while patterns
      (let ((p (car patterns)))
	(if (eq opsym (tooltalk-pattern-prop-get p 'opsym))
	    (let ((callback (tooltalk-pattern-prop-get p 'callback)))
	      (if callback (funcall callback m p))
	      (setq patterns '()))
	  (setq patterns (cdr patterns)))))))

(defun make-initial-tooltalk-pattern (args)
  (let ((opcdr (cdr (memq 'op args)))
	(cbcdr (cdr (memq 'callback args))))
    (if (and (consp opcdr) (consp cbcdr))
	(let ((plist (list 'opsym (intern (car opcdr)) 'callback (car cbcdr))))
	  (make-tooltalk-pattern (append args (list 'plist plist))))
      (make-tooltalk-pattern args))))

(defun register-initial-tooltalk-patterns ()
  (mapcar #'register-tooltalk-pattern 
	  (setq initial-tooltalk-patterns
		(mapcar #'make-initial-tooltalk-pattern
			(list tooltalk-eval-pattern
			      tooltalk-load-file-pattern
			      tooltalk-make-client-screen-pattern
			      tooltalk-status-pattern))))
  (add-hook 'tooltalk-unprocessed-message-hook 'dispatch-initial-tooltalk-message))


(defun unregister-initial-tooltalk-patterns ()
  (mapcar 'destroy-tooltalk-pattern initial-tooltalk-patterns)
  (setq initial-tooltalk-patterns ())
  (remove-hook 'tooltalk-unprocessed-message-hook 'dispatch-initial-tooltalk-message))


(defun tooltalk:prin1-to-string (form)
  "Like prin1-to-string except: if the string contains embedded nulls (unlikely
but possible) then replace each one with \"\\000\"."
  (let ((string (prin1-to-string form)))
    (let ((parts '())
	  index)
      (while (setq index (string-match "\0" string))
	(setq parts 
	      (apply 'list "\\000" (substring string 0 index) parts))
	(setq string (substring string (1+ index))))
      (if (not parts)
	  string
	(setq parts (apply 'list string parts))
	(apply 'concat (nreverse parts))))))

;; Backwards compatibility
(fset 'tooltalk::prin1-to-string-carefully 'tooltalk:prin1-to-string)


(defun tooltalk:read-from-string (str)
  "Like read-from-string except: an error is signalled if the entire 
string can't be parsed."
  (let ((res (read-from-string str)))
    (if (< (cdr res) (length str))
	(error "Parse of input string ended prematurely."
	       str))
    (car res)))


(defun tooltalk::eval-string (str)
  (let ((result (eval (car (read-from-string str)))))
    (tooltalk:prin1-to-string result)))


(defun tooltalk-eval-handler (msg pat)
  (let ((str (get-tooltalk-message-attribute msg 'arg_val 0))
	(result-str nil)
	(failp t))
    (unwind-protect
	(cond
	 ;; Assume That the emacs debugger will handle errors.
	 ;; If the user throws from the debugger to the cleanup
	 ;; form below, failp will remain t.
	 (debug-on-error   
	  (setq result-str (tooltalk::eval-string str)
		failp nil))

	 ;; If an error occurs as a result of evaluating
	 ;; the string or printing the result, then we'll return 
	 ;; a string version of error-info.
	 (t
	  (condition-case error-info
	      (setq result-str (tooltalk::eval-string str)
		    failp nil)
	    (error 
	     (let ((error-str (tooltalk:prin1-to-string error-info)))
	       (setq result-str error-str
		     failp t))))))

      ;; If we get to this point and result-str is still nil, the
      ;; user must have thrown out of the debuggger
      (let ((reply-type (if failp 'fail 'reply))
	    (reply-value (or result-str "(debugger exit)")))
	(set-tooltalk-message-attribute reply-value msg 'arg_val 0)
	(return-tooltalk-message msg reply-type)))))


(defun tooltalk-make-client-screen-handler (m p)
  (let ((nargs (get-tooltalk-message-attribute m 'args_count)))
    (if (not (= 3 nargs))
	(progn
	  (set-tooltalk-message-attribute "wrong number of arguments" m 'status_string)
	  (return-tooltalk-message m 'fail))))

  ;; Note: relying on the fact that arg_ival is returned as a string

  (let* ((name   (get-tooltalk-message-attribute m 'arg_val 0))
	 (window (get-tooltalk-message-attribute m 'arg_ival 1))
	 (args (list (cons 'name name)))
	 (screen (x-create-screen args window)))
    (set-tooltalk-message-attribute (screen-name screen) m 'arg_val 2)
    (return-tooltalk-message m 'reply)))



(defun tooltalk-load-file-handler (m p)
  (let ((path (get-tooltalk-message-attribute m 'file)))
    (condition-case error-info 
	(progn
	  (load-file path)
	  (return-tooltalk-message m 'reply))
      (error 
       (let ((error-string (tooltalk:prin1-to-string error-info)))
	(set-tooltalk-message-attribute error-string m 'status_string)
	(return-tooltalk-message m 'fail))))))


(defun tooltalk-status-handler (m p)
  (return-tooltalk-message m 'reply))


;; Hack the command-line.

(defun command-line-do-tooltalk (arg)
  "Connect to the ToolTalk server."
;  (setq command-line-args-left
;	(cdr (tooltalk-open-connection (cons (car command-line-args)
;					     command-line-args-left))))
  (if (tooltalk-open-connection)
      (register-initial-tooltalk-patterns)
    (beep)
    (message "Warning: unable to connect to a ToolTalk server.")))

(setq command-switch-alist
      (append command-switch-alist
	      '(("-tooltalk" . command-line-do-tooltalk))))