;; geiser-autodoc.el -- autodoc mode

;; Copyright (C) 2009 Jose Antonio Ortega Ruiz

;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
;; Start date: Sun Feb 08, 2009 19:44

;; This file 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 3 of the License, 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 this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Comentary:

;; A minor mode that echoes information about procedures and variables
;; near point at the minibuffer.

;;; Code:

(require 'geiser-eval)
(require 'geiser-syntax)
(require 'geiser-custom)
(require 'geiser-base)

(require 'eldoc)


;;; Customization:

(defgroup geiser-autodoc nil
  "Options for displaying autodoc strings in the echo area."
  :group 'geiser)

(geiser-custom--defface autodoc-current-arg
  'bold geiser-autodoc "highlighting current argument in autodoc messages")

(geiser-custom--defface autodoc-procedure-name
  'font-lock-function-name-face
  geiser-autodoc "highlighting procedure name in autodoc messages")

(defcustom geiser-autodoc-delay 0.3
  "Delay before autodoc messages are fetched and displayed, in seconds."
  :type 'number
  :group 'geiser-autodoc)

(defcustom geiser-autodoc-display-module-p t
  "Whether to display procedure module in autodoc strings."
  :type 'boolean
  :group 'geiser-autodoc)

(defcustom geiser-autodoc-procedure-name-format "%s:%s"
  "Format for displaying module and procedure name, in that order,
when `geiser-autodoc-display-module-p' is on."
  :type 'string
  :group 'geiser-autodoc)


;;; Procedure arguments:

(make-variable-buffer-local
 (defvar geiser-autodoc--cached-signatures nil))

(defun geiser-autodoc--get-signatures (funs)
  (when funs
    (let ((missing) (cached))
      (if (not geiser-autodoc--cached-signatures)
          (setq missing funs)
        (dolist (f funs)
          (let ((cf (assq f geiser-autodoc--cached-signatures)))
            (if cf (push cf cached)
              (push f missing)))))
      (unless cached
        (setq geiser-autodoc--cached-signatures nil))
      (if (not missing)
          geiser-autodoc--cached-signatures
        (let ((res (geiser-eval--send/result `(:eval ((:ge autodoc)
                                                      (quote ,missing)))
                                             500)))
          (when res
            (setq geiser-autodoc--cached-signatures (append cached res))))))))

(defun geiser-autodoc--insert-args (args current &optional pos)
  (dolist (a args)
    (let ((p (point)))
      (insert (format "%s" a))
      (when (or (and (numberp pos)
                     (numberp current)
                     (setq current (1+ current))
                     (= (1+ pos) current))
                (and (symbolp current)
                     (listp a)
                     (eq current (car a))))
        (put-text-property p (point) 'face 'geiser-font-lock-autodoc-current-arg)
        (setq pos nil current nil)))
    (insert " "))
  (when args (backward-char))
  current)

(defsubst geiser-autodoc--proc-name (proc module)
  (let ((str (if module
                 (format geiser-autodoc-procedure-name-format module proc)
               proc)))
    (propertize str 'face 'geiser-font-lock-autodoc-procedure-name)))

(defun geiser-autodoc--str (proc desc signature)
  ;;  (message "composing %s with desc %s and signature %s" proc desc signature)
  (let ((cpos 1)
        (pos (second desc))
        (prev (third desc))
        (module (cdr (assoc 'module signature)))
        (reqs (cdr (assoc 'required signature)))
        (opts (cdr (assoc 'optional signature)))
        (keys (cdr (assoc 'key signature))))
    (save-current-buffer
      (set-buffer (geiser-syntax--font-lock-buffer))
      (erase-buffer)
      (insert (format "(%s " (geiser-autodoc--proc-name proc module)))
      (setq cpos
            (geiser-autodoc--insert-args reqs cpos (and (not (zerop pos)) pos)))
      (when opts
        (insert " [")
        (setq cpos (geiser-autodoc--insert-args opts cpos pos))
        (when keys
          (insert " [")
          (geiser-autodoc--insert-args keys prev nil)
          (insert "]"))
        (insert "]"))
      (insert ")")
      (buffer-string))))

(defun geiser-autodoc--autodoc (path)
  (let* ((funs (nreverse (mapcar 'car path)))
         (signs (geiser-autodoc--get-signatures funs)))
    (when signs
      (catch 'signature
        (dolist (f funs)
          (let ((signature (cdr (assq f signs))))
            (when signature
              (throw 'signature (geiser-autodoc--str f (assq f path) signature)))))))))


;;; Autodoc function:

(defun geiser-autodoc--eldoc-function ()
  (condition-case e
      (geiser-autodoc--autodoc (geiser-syntax--scan-sexps))
    (error (format "Autodoc not available (%s)" (error-message-string e)))))


;;; Autodoc mode:

(make-variable-buffer-local
 (defvar geiser-autodoc-mode-string " A"
   "Modeline indicator for geiser-autodoc-mode"))

(define-minor-mode geiser-autodoc-mode
  "Toggle Geiser's Autodoc mode.
With no argument, this command toggles the mode.
Non-null prefix argument turns on the mode.
Null prefix argument turns off the mode.

When Autodoc mode is enabled, a synopsis of the word at point is
displayed in the minibuffer."
  :init-value nil
  :lighter geiser-autodoc-mode-string
  :group 'geiser-autodoc

  (set (make-local-variable 'eldoc-documentation-function)
       (when geiser-autodoc-mode 'geiser-autodoc--eldoc-function))
  (set (make-local-variable 'eldoc-minor-mode-string) nil)
  (set (make-local-variable 'eldoc-idle-delay) geiser-autodoc-delay)
  (eldoc-mode geiser-autodoc-mode)
  (message "Geiser Autodoc %s" (if geiser-autodoc-mode "enabled" "disabled")))


(provide 'geiser-autodoc)
;;; geiser-autodoc.el ends here