;;; gds.el -- frontend for Guile development in Emacs

;;;; Copyright (C) 2003 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 2.1 of the License, or (at your option) any later
;;;; version.
;;;; 
;;;; This library 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
;;;; Lesser General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free
;;;; Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
;;;; 02111-1307 USA


;;;; Prerequisites.

(require 'widget)
(require 'wid-edit)
(require 'scheme)


;;;; Debugging (of this code!).

(defsubst dmessage (msg &rest args)
  ;;(apply (function message) msg args)
  )


;;;; Customization group setup.

(defgroup gds nil
  "Customization options for Guile Emacs frontend."
  :group 'scheme)


;;;; Communication with the (ice-9 debugger ui-server) subprocess.

;; The subprocess object.
(defvar gds-process nil)

;; Subprocess output goes into the `*GDS Process*' buffer, and
;; is then read from there one form at a time.  `gds-read-cursor' is
;; the buffer position of the start of the next unread form.
(defvar gds-read-cursor nil)

(defun gds-start ()
  "Start (or restart, if already running) the GDS subprocess."
  (interactive)
  (if gds-process (gds-shutdown))
  (with-current-buffer (get-buffer-create "*GDS Process*")
    (erase-buffer)
    (setq gds-process
	  (let ((process-connection-type nil)) ; use a pipe
	    (start-process "gds"
			   (current-buffer)
			   "guile"
			   "-q"
			   "--debug"
			   "-e"
			   "run"
			   "-s"
			   "/home/neil/Guile/cvs/guile-core/ice-9/debugger/ui-server.scm"))))
  (setq gds-read-cursor (point-min))
  (set-process-filter gds-process (function gds-filter))
  (set-process-sentinel gds-process (function gds-sentinel))
  (set-process-coding-system gds-process 'latin-1-unix))

;; Shutdown the subprocess and cleanup all associated data.
(defun gds-shutdown ()
  "Shut down the GDS subprocess."
  (interactive)
  ;; Do cleanup for all clients.
  (while gds-names
    (gds-client-cleanup (caar gds-names)))
  ;; Reset any remaining variables.
  (setq gds-displayed-client nil
	gds-waiting nil)
  ;; If the timer is running, cancel it.
  (if gds-timer
      (cancel-timer gds-timer))
  (setq gds-timer nil)
  ;; Kill the subprocess.
  (process-kill-without-query gds-process)
  (condition-case nil
      (progn
	(kill-process gds-process)
	(accept-process-output gds-process 0 200))
    (error))
  (setq gds-process nil))

;; Subprocess output filter: inserts normally into the process buffer,
;; then tries to reread the output one form at a time and delegates
;; processing of each form to `gds-handle-input'.
(defun gds-filter (proc string)
  (with-current-buffer (process-buffer proc)
    (save-excursion
      (goto-char (process-mark proc))
      (insert-before-markers string))
    (goto-char gds-read-cursor)
    (while (let ((form (condition-case nil
			   (read (current-buffer))
			 (error nil))))
	     (if form
		 (save-excursion
		   (gds-handle-input form)))
	     form)
      (setq gds-read-cursor (point)))))

;; Subprocess sentinel: do nothing.  (Currently just here to avoid
;; inserting un-`read'able process status messages into the process
;; buffer.)
(defun gds-sentinel (proc event)
  )

;; Send input to the subprocess.
(defun gds-send (string)
  (process-send-string gds-process string))


;;;; Multiple application scheduling.

;; At any moment one Guile application has the focus of the frontend
;; code.  `gds-displayed-client' holds the port number of that client.
;; If there are no Guile applications wanting the focus - that is,
;; ready for instructions - `gds-displayed-client' is nil.
(defvar gds-displayed-client nil)

;; The list of other Guile applications waiting for focus, referenced
;; by their port numbers.
(defvar gds-waiting nil)

;; An idle timer that we use to avoid confusing any user work when
;; popping up debug buffers.  `gds-timer' is non-nil whenever the
;; timer is running and nil whenever it is not running.
(defvar gds-timer nil)

;; Debug the specified client.  If it already has the focus, do so
;; immediately, but using the idle timer to ensure that it doesn't
;; confuse any work the user may be doing.  Non-structural work is
;; delegated to `gds-display-state'.
(defun gds-debug (&optional client)
  (dmessage "gds-debug")
  ;; If `client' is specified, add it to the end of `gds-waiting',
  ;; unless that client is already the current client or it is already
  ;; in the waiting list.
  (if (and client
	   (not (eq client gds-displayed-client))
	   (not (memq client gds-waiting)))
      (setq gds-waiting (append gds-waiting (list client))))
  ;; Now update `client' to be the next client in the list.
  (setq client (or gds-displayed-client (car gds-waiting)))
  ;; If conditions are right, start the idle timer.
  (if (and client
	   (or (null gds-displayed-client)
	       (eq gds-displayed-client client)))
      (gds-display-state (or gds-displayed-client
			     (prog1 (car gds-waiting)
			       (setq gds-waiting
				     (cdr gds-waiting)))))))

;; Give up focus because debugging is done for now.  Display detail in
;; case of no waiting clients is delegated to `gds-clear-display'.
(defun gds-focus-done ()
  (gds-clear-display)
  (gds-debug))

;; Although debugging of this client isn't done, yield focus to the
;; next waiting client.
(defun gds-focus-yield ()
  (interactive)
  (if (and (null gds-waiting)
	   (y-or-n-p "No other clients waiting - bury *Guile* buffer? "))
      (bury-buffer)
    (or (memq gds-displayed-client gds-waiting)
	(setq gds-waiting (append gds-waiting (list gds-displayed-client))))
    (gds-focus-done)))


;;;; Per-client state information.

;; Alist mapping client port numbers to application names.  The names
;; in this list have been uniquified by `gds-uniquify'.
(defvar gds-names nil)

;; Return unique form of NAME.
(defun gds-uniquify (name)
  (let ((count 1)
	(maybe-unique name))
    (while (member maybe-unique (mapcar (function cdr) gds-names))
      (setq count (1+ count)
	    maybe-unique (concat name "<" (number-to-string count) ">")))
    maybe-unique))

;; Alist mapping client port numbers to last known status.
;;
;; Status is one of the following symbols.
;;
;;   `running' - application is running.
;;
;;   `waiting-for-input' - application is blocked waiting for
;;   instruction from the frontend.
;;
;;   `ready-for-input' - application is not blocked but can also
;;   accept asynchronous instructions from the frontend.
;;
(defvar gds-statuses nil)

;; Alist mapping client port numbers to last printed outputs.
(defvar gds-outputs nil)

;; Alist mapping client port numbers to last known stacks.
(defvar gds-stacks nil)

;; Alist mapping client port numbers to module information.  This
;; looks like:
;;
;; ((4 ((guile) t sym1 sym2 ...) ((guile-user)) ((ice-9 debug) nil sym3 sym4) ...) ...)
;;
;; So, for example:
;;
;; (assq client gds-modules)
;; =>
;; (4 ((guile) t sym1 sym2 ...) ((guile-user)) ((ice-9 debug) nil sym3 sym4) ...)
;;
;; The t or nil after the module name indicates whether the module is
;; displayed in expanded form (that is, showing the bindings in that
;; module).
;;
;; The syms are actually all strings, because some Guile symbols are
;; not readable by Emacs.
(defvar gds-modules nil)


;;;; Handling debugging instructions.

;; General dispatch function called by the subprocess filter.
(defun gds-handle-input (form)
  (dmessage "Form: %S" form)
  (let ((client (car form)))
    (cond ((eq client '*))
	  (t
	   (let ((proc (cadr form)))

	     (cond ((eq proc 'name)
		    ;; (name ...) - Application's name.
		    (setq gds-names
			  (cons (cons client (gds-uniquify (caddr form)))
				gds-names)))

		   ((eq proc 'stack)
		    ;; (stack ...) - Stack at an error or breakpoint.
		    (gds-set gds-stacks client (cddr form)))

		   ((eq proc 'modules)
		    ;; (modules ...) - Application's loaded modules.
		    (gds-set gds-modules client
			     (mapcar (function list) (cddr form))))

		   ((eq proc 'output)
		    ;; (output ...) - Last printed output.
		    (gds-set gds-outputs client (caddr form)))

		   ((eq proc 'status)
		    ;; (status ...) - Application status indication.
		    (let ((status (caddr form)))
		      (gds-set gds-statuses client status)
		      (cond ((eq status 'waiting-for-input)
			     (gds-debug client))
			    ((or (eq status 'running)
				 (eq status 'ready-for-input))
			     (if (eq client gds-displayed-client)
				 (gds-display-state client)))
			    (t
			     (error "Unexpected status: %S" status)))))

		   ((eq proc 'module)
		    ;; (module MODULE ...) - The specified module's bindings.
		    (let* ((modules (assq client gds-modules))
			   (minfo (assoc (caddr form) modules)))
		      (if minfo
			  (setcdr (cdr minfo) (cdddr form)))))

		   ((eq proc 'closed)
		    ;; (closed) - Client has gone away.
		    (gds-client-cleanup client))

		   ((eq proc 'eval-results)
		    ;; (eval-results ...) - Results of evaluation.
		    (gds-display-results client (cddr form)))

		   ))))))

(defun gds-display-results (client results)
  (let ((buf (get-buffer-create "*Guile Results*")))
    (save-excursion
      (set-buffer buf)
      (erase-buffer)
      (while results
	(insert (car results))
	(mapcar (function (lambda (value)
			    (insert " => " value "\n")))
		(cadr results))
	(insert "\n")
	(setq results (cddr results))))
    (pop-to-buffer buf)))

;; Store latest status, stack or module list for the specified client.
(defmacro gds-set (alist client val)
  `(let ((existing (assq ,client ,alist)))
     (if existing
	 (setcdr existing ,val)
       (setq ,alist
	     (cons (cons client ,val) ,alist)))))

;; Cleanup processing when CLIENT goes away.
(defun gds-client-cleanup (client)
  (if (eq client gds-displayed-client)
      (gds-focus-done))
  (setq gds-names
	(delq (assq client gds-names) gds-names))
  (setq gds-stacks
	(delq (assq client gds-stacks) gds-stacks))
  (setq gds-modules
	(delq (assq client gds-modules) gds-modules)))


;;;; Displaying debugging information.

(defvar gds-client-buffer nil)

(define-derived-mode gds-mode
  fundamental-mode
  "Guile"
  "Major mode for Guile information buffers.")

(defun gds-set-client-buffer (&optional client)
  (if (and gds-client-buffer
	   (buffer-live-p gds-client-buffer))
      (set-buffer gds-client-buffer)
    (setq gds-client-buffer (get-buffer-create "*Guile*"))
    (set-buffer gds-client-buffer)
    (gds-mode))
  ;; Rename to something we don't want first.  Otherwise, if the
  ;; buffer is already correctly named, we get a confusing change
  ;; from, say, `*Guile: REPL*' to `*Guile: REPL*<2>'.
  (rename-buffer "*Guile Fake Buffer Name*" t)
  (rename-buffer (if client
		     (concat "*Guile: "
			     (cdr (assq client gds-names))
			     "*")
		   "*Guile*")
		 t)			; Rename uniquely if needed,
					; although it shouldn't be.
  (force-mode-line-update t))

(defun gds-clear-display ()
  ;; Clear the client buffer.
  (gds-set-client-buffer)
  (let ((inhibit-read-only t))
    (erase-buffer)
    (insert "Stack:\nNo clients ready for debugging.\n")
    (goto-char (point-min)))
  (setq gds-displayed-stack 'no-clients)
  (setq gds-displayed-modules nil)
  (setq gds-displayed-client nil)
  (bury-buffer))

;; Determine whether the client display buffer is visible in the
;; currently selected frame (i.e. where the user is editing).
(defun gds-buffer-visible-in-selected-frame-p ()
  (let ((visible-p nil))
    (walk-windows (lambda (w)
		    (if (eq (window-buffer w) gds-client-buffer)
			(setq visible-p t))))
    visible-p))

;; Cached display variables for `gds-display-state'.
(defvar gds-displayed-stack nil)
(defvar gds-displayed-modules nil)

;; Types of display areas in the *Guile* buffer.
(defvar gds-display-types '("Status" "Stack" "Modules"))
(defvar gds-display-type-regexp
  (concat "^\\("
	  (substring (apply (function concat)
			    (mapcar (lambda (type)
				      (concat "\\|" type))
				    gds-display-types))
		     2)
	  "\\):"))

(defun gds-maybe-delete-region (type)
  (let ((beg (save-excursion
	       (goto-char (point-min))
	       (and (re-search-forward (concat "^"
					       (regexp-quote type)
					       ":")
				       nil t)
		    (match-beginning 0)))))
    (if beg
	(delete-region beg
		       (save-excursion
			 (goto-char beg)
			 (end-of-line)
			 (or (and (re-search-forward gds-display-type-regexp
						     nil t)
				  (match-beginning 0))
			     (point-max)))))))

(defun gds-maybe-skip-region (type)
  (if (looking-at (regexp-quote type))
      (if (re-search-forward gds-display-type-regexp nil t 2)
	  (beginning-of-line)
	(goto-char (point-max)))))

(defun gds-display-state (client)
  (dmessage "gds-display-state")
  ;; Avoid continually popping up the last associated source buffer
  ;; unless it really is still current.
  (setq gds-selected-frame-source-buffer nil)
  (gds-set-client-buffer client)
  (let ((stack (cdr (assq client gds-stacks)))
	(modules (cdr (assq client gds-modules)))
	(inhibit-read-only t)
	(p (if (eq client gds-displayed-client)
	       (point)
	     (point-min)))
	stack-changed)
    ;; Start at top of buffer.
    (goto-char (point-min))
    ;; Display status; too simple to be worth caching.
    (gds-maybe-delete-region "Status")
    (widget-insert "Status: "
		   (cdr (assq (cdr (assq client gds-statuses))
			      '((running . "running (cannot accept input)")
				(waiting-for-input . "waiting for input")
				(ready-for-input . "running"))))
		   "\n\n")
    (let ((output (cdr (assq client gds-outputs))))
      (if (> (length output) 0)
	  (widget-insert output "\n\n")))
    ;; Display stack.
    (dmessage "insert stack")
    (if (equal stack gds-displayed-stack)
	(gds-maybe-skip-region "Stack")
      ;; Note that stack has changed.
      (if stack (setq stack-changed t))
      ;; Delete existing stack.
      (gds-maybe-delete-region "Stack")
      ;; Insert new stack.		       
      (if stack (gds-insert-stack stack))
      ;; Record displayed stack.
      (setq gds-displayed-stack stack))
    ;; Display module list.
    (dmessage "insert modules")
    (if (equal modules gds-displayed-modules)
	(gds-maybe-skip-region "Modules")
      ;; Delete existing module list.
      (gds-maybe-delete-region "Modules")
      ;; Insert new list.
      (if modules (gds-insert-modules modules))
      ;; Record displayed list.
      (setq gds-displayed-modules (copy-tree modules)))
    ;; Finish off.
    (dmessage "widget-setup")
    (widget-setup)
    (if stack-changed
	;; Stack is being seen for the first time, so make sure top of
	;; buffer is visible.
	(progn
	  (goto-char (point-min))
	  (re-search-forward "^Stack:")
	  (forward-line (+ 1 (cadr stack))))
      ;; Restore point from before buffer was redrawn.
      (goto-char p)))
  (setq gds-displayed-client client)
  (dmessage "consider display")
  (if (eq (window-buffer (selected-window)) gds-client-buffer)
      ;; *Guile* buffer already selected.
      (gds-display-buffers)
    (dmessage "Running GDS timer")
    (setq gds-timer
	  (run-with-idle-timer 0.5
			       nil
			       (lambda ()
				 (setq gds-timer nil)
				 (gds-display-buffers))))))

(defun gds-display-buffers ()
  ;; If there's already a window showing the *Guile* buffer, use
  ;; it.
  (let ((window (get-buffer-window gds-client-buffer t)))
    (if window
	(progn
	  (make-frame-visible (window-frame window))
	  (raise-frame (window-frame window))
	  (select-frame (window-frame window))
	  (select-window window))
      (switch-to-buffer gds-client-buffer)))
  ;; If there is an associated source buffer, display it as well.
  (if gds-selected-frame-source-buffer
      (let ((window (display-buffer gds-selected-frame-source-buffer)))
	(set-window-point window
			  (overlay-start gds-selected-frame-source-overlay))))
  ;; Force redisplay.
  (sit-for 0))

(defun old-stuff ()
  (if (gds-buffer-visible-in-selected-frame-p)
      ;; Buffer already visible enough.
      nil
    ;; Delete any views of the buffer in other frames - we don't want
    ;; views all over the place.
    (delete-windows-on gds-client-buffer)
    ;; Run idle timer to display the buffer as soon as user isn't in
    ;; the middle of something else.
    ))

(defun gds-insert-stack (stack)
  (let ((frames (car stack))
	(index (cadr stack))
	(flags (caddr stack))
	frame items)
    (widget-insert "Stack: " (prin1-to-string flags) "\n")
    (let ((i -1))
      (gds-show-selected-frame (caddr (nth index frames)))
      (while frames
	(setq frame (car frames)
	      frames (cdr frames)
	      i (+ i 1)
	      items (cons (list 'item
				(let ((s (cadr frame)))
				  (put-text-property 0 1 'index i s)
				  s))
			  items))))
    (setq items (nreverse items))
    (apply (function widget-create)
	     'radio-button-choice
	     :value (cadr (nth index items))
	     :notify (function gds-select-stack-frame)
	     items)
    (widget-insert "\n")))

(defun gds-select-stack-frame (widget &rest ignored)
  (let* ((s (widget-value widget))
	 (ind (memq 'index (text-properties-at 0 s))))
    (gds-send (format "(%S debugger-command frame %d)\n"
		      gds-displayed-client
		      (cadr ind)))))

;; Overlay used to highlight the source expression corresponding to
;; the selected frame.
(defvar gds-selected-frame-source-overlay nil)

;; Buffer containing source for the selected frame.
(defvar gds-selected-frame-source-buffer nil)

(defun gds-show-selected-frame (source)
  ;; Highlight the frame source, if possible.
  (if (and source
	   (file-readable-p (car source)))
      (with-current-buffer (find-file-noselect (car source))
	(if gds-selected-frame-source-overlay
	    nil
	  (setq gds-selected-frame-source-overlay (make-overlay 0 0))
	  (overlay-put gds-selected-frame-source-overlay 'face 'highlight))
	;; Move to source line.  Note that Guile line numbering is
	;; 0-based, while Emacs numbering is 1-based.
	(save-restriction
	  (widen)
	  (goto-line (+ (cadr source) 1))
	  (move-to-column (caddr source))
	  (move-overlay gds-selected-frame-source-overlay
			(point)
			(if (not (looking-at ")"))
			    (save-excursion (forward-sexp 1) (point))
			  ;; It seems that the source coordinates for
			  ;; backquoted expressions are at the end of
			  ;; the sexp rather than the beginning...
			  (save-excursion (forward-char 1)
					  (backward-sexp 1) (point)))
			(current-buffer)))
	(setq gds-selected-frame-source-buffer (current-buffer)))
    (if gds-selected-frame-source-overlay
	(move-overlay gds-selected-frame-source-overlay 0 0))))

(defcustom gds-module-filter '(t (guile nil) (ice-9 nil) (oop nil))
  "Specification of which Guile modules the debugger should display.
This is a list with structure (DEFAULT EXCEPTION EXCEPTION...), where
DEFAULT is `t' or `nil' and each EXCEPTION has the structure (SYMBOL
DEFAULT EXCEPTION EXCEPTION...).

A Guile module name `(x y z)' is matched against this filter as
follows.  If one of the top level EXCEPTIONs has SYMBOL `x', continue
by matching the rest of the module name, in this case `(y z)', against
that SYMBOL's DEFAULT and next level EXCEPTION list.  Otherwise, if
the current DEFAULT is `t' display the module, and if the current
DEFAULT is `nil', don't display it.

This variable is usually set to exclude Guile system modules that are
not of primary interest when debugging application code."
  :type 'sexp
  :group 'gds)

(defun gds-show-module-p (name)
  ;; Determine whether to display the NAMEd module by matching NAME
  ;; against `gds-module-filter'.
  (let ((default (car gds-module-filter))
	(exceptions (cdr gds-module-filter)))
    (let ((exception (assq (car name) exceptions)))
      (if exception
	  (let ((gds-module-filter (cdr exception)))
	    (gds-show-module-p (cdr name)))
	default))))

(defun gds-insert-modules (modules)
  (insert "Modules:\n")
  (while modules
    (let ((minfo (car modules)))
      (if (gds-show-module-p (car minfo))
	  (let ((w (widget-create 'push-button
				  :notify (function gds-module-notify)
				  (if (and (cdr minfo)
					   (cadr minfo))
				      "-" "+"))))
	    (widget-put w :module (cons client (car minfo)))
	    (widget-insert " " (prin1-to-string (car minfo)) "\n")
	    (if (cadr minfo)
		(let ((syms (cddr minfo)))
		  (while syms
		    (widget-insert " > " (car syms) "\n")
		    (setq syms (cdr syms))))))))
    (setq modules (cdr modules))))

(defun gds-module-notify (w &rest ignore)
  (let* ((module (widget-get w :module))
	 (client (car module))
	 (name (cdr module))
	 (modules (assq client gds-modules))
	 (minfo (assoc name modules)))
    (if (cdr minfo)
	;; Just toggle expansion state.
	(progn
	  (setcar (cdr minfo) (not (cadr minfo)))
	  (gds-display-state client))
      ;; Set flag to indicate module expanded.
      (setcdr minfo (list t))
      ;; Get symlist from Guile.
      (gds-send (format "(%S query-module %S)\n" client name)))))


;;;; Guile Debugging keymap.

(set-keymap-parent gds-mode-map widget-keymap)
(define-key gds-mode-map "g" (function gds-go))
(define-key gds-mode-map "b" (function gds-set-breakpoint))
(define-key gds-mode-map "q" (function gds-quit))
(define-key gds-mode-map "y" (function gds-yield))
(define-key gds-mode-map " " (function gds-next))
(define-key gds-mode-map "e" (function gds-evaluate))
(define-key gds-mode-map "i" (function gds-step-in))
(define-key gds-mode-map "o" (function gds-step-out))
(define-key gds-mode-map "t" (function gds-trace-finish))

(defun gds-client-waiting ()
  (eq (cdr (assq gds-displayed-client gds-statuses)) 'waiting-for-input))

(defun gds-go ()
  (interactive)
  (gds-send (format "(%S debugger-command continue)\n" gds-displayed-client)))

(defun gds-quit ()
  (interactive)
  (if (gds-client-waiting)
      (if (y-or-n-p "Client is waiting for instruction - tell it to continue? ")
	  (gds-go)))
  (gds-yield))

(defun gds-yield ()
  (interactive)
  (if (gds-client-waiting)
      (gds-focus-yield)
    (gds-focus-done)))

(defun gds-next ()
  (interactive)
  (gds-send (format "(%S debugger-command next 1)\n" gds-displayed-client)))

(defun gds-evaluate (expr)
  (interactive "sEvaluate (in this stack frame): ")
  (gds-send (format "(%S debugger-command evaluate %s)\n"
		    gds-displayed-client
		    (prin1-to-string expr))))

(defun gds-step-in ()
  (interactive)
  (gds-send (format "(%S debugger-command step 1)\n" gds-displayed-client)))

(defun gds-step-out ()
  (interactive)
  (gds-send (format "(%S debugger-command finish)\n" gds-displayed-client)))

(defun gds-trace-finish ()
  (interactive)
  (gds-send (format "(%S debugger-command trace-finish)\n"
		    gds-displayed-client)))

(defun gds-set-breakpoint ()
  (interactive)
  (cond ((gds-in-source-buffer)
	 (gds-set-source-breakpoint))
	((gds-in-stack)
	 (gds-set-stack-breakpoint))
	((gds-in-modules)
	 (gds-set-module-breakpoint))
	(t
	 (error "No way to set a breakpoint from here"))))

(defun gds-in-source-buffer ()
  ;; Not yet worked out what will be available in Scheme source
  ;; buffers.
  nil)

(defun gds-in-stack ()
  (and (eq (current-buffer) gds-client-buffer)
       (save-excursion
	 (and (re-search-backward "^\\(Stack\\|Modules\\):" nil t)
	      (looking-at "Stack")))))

(defun gds-in-modules ()
  (and (eq (current-buffer) gds-client-buffer)
       (save-excursion
	 (and (re-search-backward "^\\(Stack\\|Modules\\):" nil t)
	      (looking-at "Modules")))))

(defun gds-set-module-breakpoint ()
  (let ((sym (save-excursion
	       (beginning-of-line)
	       (and (looking-at " > \\([^ \n\t]+\\)")
		    (match-string 1))))
	(module (save-excursion
		  (and (re-search-backward "^\\[[+---]\\] \\(([^)]+)\\)" nil t)
		       (match-string 1)))))
    (or sym
	(error "Couldn't find procedure name on current line"))
    (or module
	(error "Couldn't find module name for current line"))
    (let ((behaviour
	   (completing-read
	    (format "Behaviour for breakpoint at %s:%s (default debug-here): "
		    module sym)
	    '(("debug-here")
	      ("trace-here")
	      ("trace-subtree"))
	    nil
	    t
	    nil
	    nil
	    "debug-here")))
      (gds-send (format "(%S set-breakpoint %s %s %s)\n"
			gds-displayed-client
			module
			sym
			behaviour)))))


;;;; Evaluating code.

;; The following commands send code for evaluation through the GDS TCP
;; connection, receive the result and any output generated through the
;; same connection, and display the result and output to the user.
;;
;; Where there are multiple Guile applications known to GDS, GDS by
;; default sends code to the one that holds the debugging focus,
;; i.e. `gds-displayed-client'.  Where no application has the focus,
;; or the command is invoked `C-u', GDS asks the user which
;; application is intended.

(defun gds-read-client ()
  (let* ((def (if gds-displayed-client
		  (cdr (assq gds-displayed-client gds-names))))
	 (prompt (if def
		     (concat "Application for eval (default "
			     def
			     "): ")
		   "Application for eval: "))
	 (name
	  (completing-read prompt
			   (mapcar (function cdr) gds-names)
			   nil t nil nil
			   def)))
    (let (client (names gds-names))
      (while (and names (not client))
	(if (string-equal (cadar names) name)
	    (setq client (caar names)))
	(setq names (cdr names))))))

(defun gds-choose-client (client)
  (or ;; If client is an integer, it is the port number of the
      ;; intended client.
      (if (integerp client) client)
      ;; Any other non-nil value indicates invocation with a prefix
      ;; arg, which forces asking the user which application is
      ;; intended.
      (if client (gds-read-client))
      ;; If ask not forced, and there is a client with the focus,
      ;; default to that one.
      gds-displayed-client
      ;; Last resort - ask the user.
      (gds-read-client)
      ;; Signal an error.
      (error "No application chosen.")))

(defcustom gds-default-module-name '(guile-user)
  "Name of the default module for GDS code evaluation, as list of symbols.
This module is used when there is no `define-module' form in the
buffer preceding the code to be evaluated."
  :type 'sexp
  :group 'gds)

(defun gds-module-name (start end)
  "Determine and return the name of the module that governs the
specified region.  The module name is returned as a list of symbols."
  (interactive "r")			; why not?
  (save-excursion
    (goto-char start)
    (let (module-name)
      (while (and (not module-name)
		  (beginning-of-defun-raw 1))
	(if (looking-at "(define-module ")
	    (setq module-name
		  (progn
		    (goto-char (match-end 0))
		    (read (current-buffer))))))
      module-name)))

(defun gds-port-name (start end)
  "Return port name for the specified region of the current buffer.
The name will be used by Guile as the port name when evaluating that
region's code."
  (or (buffer-file-name)
      (concat "Emacs buffer: " (buffer-name))))

(defun gds-eval-region (start end &optional client)
  "Evaluate the current region."
  (interactive "r\nP")
  (setq client (gds-choose-client client))
  (let ((module (gds-module-name start end))
	(port-name (gds-port-name start end))
	line column)
    (save-excursion
      (goto-char start)
      (setq column (current-column))	; 0-based
      (beginning-of-line)
      (setq line (count-lines (point-min) (point)))) ; 0-based
    (gds-send (format "(%S eval %s %S %d %d %S)\n"
		      client
		      (if module (prin1-to-string module) "#f")
		      port-name line column
		      (buffer-substring-no-properties start end)))))

(defun gds-eval-expression (expr &optional client)
  "Evaluate the supplied EXPR (a string)."
  (interactive "sEvaluate expression: \nP")
  (setq client (gds-choose-client client))
  (gds-send (format "(%S eval #f \"Emacs expression\" 0 0 %S)\n"
		    client expr)))

(defun gds-eval-defun (&optional client)
  "Evaluate the defun (top-level form) at point."
  (interactive "P")
  (save-excursion
   (end-of-defun)
   (let ((end (point)))
     (beginning-of-defun)
     (gds-eval-region (point) end client))))

(defun gds-eval-last-sexp (&optional client)
  "Evaluate the sexp before point."
  (interactive "P")
  (gds-eval-region (save-excursion (backward-sexp) (point)) (point) client))

(defcustom gds-source-modes '(scheme-mode)
  "*Used to determine if a buffer contains Scheme source code.
If it's loaded into a buffer that is in one of these major modes, it's
considered a scheme source file by `gds-load-file'."
  :type '(repeat function)
  :group 'gds)

(defvar gds-prev-load-dir/file nil
  "Holds the last (directory . file) pair passed to `gds-load-file'.
Used for determining the default for the next `gds-load-file'.")

(defun gds-load-file (file-name &optional client)
  "Load a Scheme file into the inferior Scheme process."
  (interactive (list (car (comint-get-source "Load Scheme file: "
					     gds-prev-load-dir/file
					     gds-source-modes t))
					; T because LOAD needs an
					; exact name
		     current-prefix-arg))
  (comint-check-source file-name) ; Check to see if buffer needs saved.
  (setq gds-prev-load-dir/file (cons (file-name-directory    file-name)
				     (file-name-nondirectory file-name)))
  (setq client (gds-choose-client client))
  (gds-send (format "(%S load %S)\n" client file-name)))

;; Install the process communication commands in the scheme-mode keymap.
(define-key scheme-mode-map "\M-\C-x" 'gds-eval-defun);gnu convention
(define-key scheme-mode-map "\C-x\C-e" 'gds-eval-last-sexp);gnu convention
(define-key scheme-mode-map "\C-c\C-e" 'gds-eval-defun)
(define-key scheme-mode-map "\C-c\C-r" 'gds-eval-region)
(define-key scheme-mode-map "\C-c\C-l" 'gds-load-file)


;;;; Menu bar entries.

(defvar gds-debug-menu nil
  "GDS debugging menu.")
(if gds-debug-menu
    nil
  (setq gds-debug-menu (make-sparse-keymap "Debug"))
  (define-key gds-debug-menu [go]
    '(menu-item "Go" gds-go))
  (define-key gds-debug-menu [trace-finish]
    '(menu-item "Trace This Frame" gds-trace-finish))
  (define-key gds-debug-menu [step-out]
    '(menu-item "Finish This Frame" gds-step-out))
  (define-key gds-debug-menu [next]
    '(menu-item "Next" gds-next))
  (define-key gds-debug-menu [step-in]
    '(menu-item "Single Step" gds-step-in))
  (define-key gds-debug-menu [eval]
    '(menu-item "Eval In This Frame..." gds-evaluate)))

(defvar gds-eval-menu nil
  "GDS evaluation menu.")
(if gds-eval-menu
    nil
  (setq gds-eval-menu (make-sparse-keymap "Evaluate"))
  (define-key gds-eval-menu [load-file]
    '(menu-item "Load Scheme File" gds-load-file))
  (define-key gds-eval-menu [defun]
    '(menu-item "Defun At Point" gds-eval-defun))
  (define-key gds-eval-menu [region]
    '(menu-item "Region" gds-eval-region))
  (define-key gds-eval-menu [last-sexp]
    '(menu-item "Sexp Before Point" gds-eval-last-sexp))
  (define-key gds-eval-menu [expr]
    '(menu-item "Expression..." gds-eval-expression)))

(defvar gds-help-menu nil
  "GDS help menu.")
(if gds-help-menu
    nil
  (setq gds-help-menu (make-sparse-keymap "Help"))
  (define-key gds-help-menu [apropos]
    '(menu-item "Apropos..." gds-apropos))
  (define-key gds-help-menu [sym-here]
    '(menu-item "Symbol At Point" gds-help-symbol-here))
  (define-key gds-help-menu [sym]
    '(menu-item "Symbol..." gds-help-symbol)))

(defvar gds-advanced-menu nil
  "Menu of rarely needed GDS operations.")
(if gds-advanced-menu
    nil
  (setq gds-advanced-menu (make-sparse-keymap "Advanced"))
  (define-key gds-advanced-menu [restart-gds]
    '(menu-item "Restart IDE" gds-start :enable gds-process))
  (define-key gds-advanced-menu [kill-gds]
    '(menu-item "Shutdown IDE" gds-shutdown :enable gds-process))
  (define-key gds-advanced-menu [start-gds]
    '(menu-item "Start IDE" gds-start :enable (not gds-process))))

(defvar gds-menu nil
  "Global menu for GDS commands.")
(if gds-menu
    nil
  (setq gds-menu (make-sparse-keymap "Guile"))
  (define-key gds-menu [advanced]
    (cons "Advanced" gds-advanced-menu))
  (define-key gds-menu [separator-1]
    '("--"))
  (define-key gds-menu [help]
    `(menu-item "Help" ,gds-help-menu :enable gds-names))
  (define-key gds-menu [eval]
    `(menu-item "Evaluate" ,gds-eval-menu :enable gds-names))
  (define-key gds-menu [debug]
    `(menu-item "Debug" ,gds-debug-menu :enable (and gds-displayed-client
						     (gds-client-waiting))))
  (setq menu-bar-final-items
	(cons 'guile menu-bar-final-items))
  (define-key global-map [menu-bar guile]
    (cons "Guile" gds-menu)))

;;;; Autostarting the GDS server.

(defcustom gds-autostart-server t
  "Whether to automatically start the GDS server when `gds.el' is loaded."
  :type 'boolean
  :group 'gds)

(if (and gds-autostart-server
	 (not gds-process))
    (gds-start))

(provide 'gds)

;;; gds.el ends here.