;;; wid-browse.el --- functions for browsing widgets -*- lexical-binding: t -*-
;;
;; Copyright (C) 1997, 2001-2020 Free Software Foundation, Inc.
;;
;; Author: Per Abrahamsen <abraham@dina.kvl.dk>
;; Keywords: extensions
;; Package: emacs

;; This file is part of GNU Emacs.

;; GNU Emacs 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.

;; GNU Emacs 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:
;;
;; Widget browser.  See `widget.el'.

;;; Code:

(require 'easymenu)
(require 'custom)
(require 'wid-edit)

(defgroup widget-browse nil
  "Customization support for browsing widgets."
  :group 'widgets)

;;; The Mode.

(defvar widget-browse-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map widget-keymap)
    (define-key map "q" 'bury-buffer)
    map)
  "Keymap for `widget-browse-mode'.")

(easy-menu-define widget-browse-mode-customize-menu
    widget-browse-mode-map
  "Menu used in widget browser buffers."
  (customize-menu-create 'widgets))

(easy-menu-define widget-browse-mode-menu
    widget-browse-mode-map
  "Menu used in widget browser buffers."
  '("Widget"
    ["Browse" widget-browse t]
    ["Browse At" widget-browse-at t]))

(defcustom widget-browse-mode-hook nil
  "Hook called when entering widget-browse-mode."
  :type 'hook
  :group 'widget-browse)

(defun widget-browse-mode ()
  "Major mode for widget browser buffers.

The following commands are available:

\\[widget-forward]		Move to next button or editable field.
\\[widget-backward]		Move to previous button or editable field.
\\[widget-button-click]		Activate button under the mouse pointer.
\\[widget-button-press]		Activate button under point.

Entry to this mode calls the value of `widget-browse-mode-hook'
if that value is non-nil."
  (kill-all-local-variables)
  (setq major-mode 'widget-browse-mode
	mode-name "Widget")
  (use-local-map widget-browse-mode-map)
  (easy-menu-add widget-browse-mode-customize-menu)
  (easy-menu-add widget-browse-mode-menu)
  (run-mode-hooks 'widget-browse-mode-hook))

(put 'widget-browse-mode 'mode-class 'special)

;;; Commands.

;;;###autoload
(defun widget-browse-at (pos)
  "Browse the widget under point."
  (interactive "d")
  (let* ((field (or
                 ;; See comments in `widget-specify-field' to know why we
                 ;; need this.
                 (get-char-property pos 'real-field)
                 (get-char-property pos 'field)))
	 (button (get-char-property pos 'button))
	 (doc (get-char-property pos 'widget-doc))
	 (text (cond (field "This is an editable text area.")
		     (button "This is an active area.")
		     (doc "This is documentation text.")
		     (t "This is unidentified text.")))
	 (widget (or field button doc)))
    (when widget
      (widget-browse widget))
    (message text)))

(defvar widget-browse-history nil)

;;;###autoload
(defun widget-browse (widget)
  "Create a widget browser for WIDGET."
  (interactive (list (completing-read "Widget: "
				      obarray
				      (lambda (symbol)
					(get symbol 'widget-type))
				      t nil 'widget-browse-history)))
  (if (stringp widget)
      (setq widget (intern widget)))
  (unless (if (symbolp widget)
	      (get widget 'widget-type)
	    (and (consp widget)
		 (get (widget-type widget) 'widget-type)))
    (error "Not a widget"))
  ;; Create the buffer.
  (if (symbolp widget)
      (let ((buffer (format "*Browse %s Widget*" widget)))
	(kill-buffer (get-buffer-create buffer))
	(switch-to-buffer (get-buffer-create buffer)))
    (kill-buffer (get-buffer-create "*Browse Widget*"))
    (switch-to-buffer (get-buffer-create "*Browse Widget*")))
  (widget-browse-mode)

  ;; Quick way to get out.
;;  (widget-create 'push-button
;;		 :action (lambda (widget &optional event)
;;			   (bury-buffer))
;;		 "Quit")
;;  (widget-insert "\n")

  ;; Top text indicating whether it is a class or object browser.
  (if (listp widget)
      (widget-insert "Widget object browser.\n\nClass: ")
    (widget-insert "Widget class browser.\n\n")
    (widget-create 'widget-browse
		   :format "%[%v%]\n%d"
		   :doc (get widget 'widget-documentation)
		   widget)
    (unless (eq (preceding-char) ?\n)
      (widget-insert "\n"))
    (widget-insert "\nSuper: ")
    (setq widget (get widget 'widget-type)))

  ;; Now show the attributes.
  (let ((name (car widget))
	(items (cdr widget))
	key value printer)
    (widget-create 'widget-browse
		   :format "%[%v%]"
		   name)
    (widget-insert "\n")
    (while items
      (setq key (nth 0 items)
	    value (nth 1 items)
	    printer (or (get key 'widget-keyword-printer)
			'widget-browse-sexp)
	    items (cdr (cdr items)))
      (widget-insert "\n" (symbol-name key) "\n\t")
      (funcall printer widget key value)
      (widget-insert "\n")))
  (widget-setup)
  (goto-char (point-min)))

;;;###autoload
(defun widget-browse-other-window (&optional widget)
  "Show widget browser for WIDGET in other window."
  (interactive)
  (let ((window (selected-window)))
    (switch-to-buffer-other-window "*Browse Widget*")
    (if widget
	(widget-browse widget)
      (call-interactively 'widget-browse))
    (select-window window)))


;;; The `widget-browse' Widget.

(define-widget 'widget-browse 'push-button
  "Button for creating a widget browser.
The :value of the widget should be the widget to be browsed."
  :format "%[[%v]%]"
  :value-create 'widget-browse-value-create
  :action 'widget-browse-action)

(defun widget-browse-action (widget &optional _event)
  ;; Create widget browser for WIDGET's :value.
  (widget-browse (widget-get widget :value)))

(defun widget-browse-value-create (widget)
  ;; Insert type name.
  (let ((value (widget-get widget :value)))
    (cond ((symbolp value)
	   (insert (symbol-name value)))
	  ((consp value)
	   (insert (symbol-name (widget-type value))))
	  (t
	   (insert "strange")))))

;;; Keyword Printer Functions.

(defun widget-browse-widget (_widget _key value)
  "Insert description of WIDGET's KEY VALUE.
VALUE is assumed to be a widget."
  (widget-create 'widget-browse value))

(defun widget-browse-widgets (_widget _key value)
  "Insert description of WIDGET's KEY VALUE.
VALUE is assumed to be a list of widgets."
  (while value
    (widget-create 'widget-browse
		   (car value))
    (setq value (cdr value))
    (when value
      (widget-insert " "))))

(defun widget-browse-sexp (_widget _key value)
  "Insert description of WIDGET's KEY VALUE.
Nothing is assumed about value."
  (let ((pp (condition-case signal
		(pp-to-string value)
	      (error (prin1-to-string signal)))))
    (when (string-match "\n\\'" pp)
      (setq pp (substring pp 0 (1- (length pp)))))
    (if (cond ((string-match "\n" pp)
	       nil)
	      ((> (length pp) (- (window-width) (current-column)))
	       nil)
	      (t t))
	(widget-insert pp)
      (widget-create 'push-button
		     :tag "show"
		     :action (lambda (widget &optional _event)
			       (with-output-to-temp-buffer
				   "*Pp Eval Output*"
				 (princ (widget-get widget :value))))
		     pp))))

(defun widget-browse-sexps (widget key value)
  "Insert description of WIDGET's KEY VALUE.
VALUE is assumed to be a list of widgets."
  (let ((target (current-column)))
    (while value
      (widget-browse-sexp widget key (car value))
      (setq value (cdr value))
      (when value
	(widget-insert "\n" (make-string target ?\ ))))))

;;; Keyword Printers.

(put :parent 'widget-keyword-printer 'widget-browse-widget)
(put :children 'widget-keyword-printer 'widget-browse-widgets)
(put :buttons 'widget-keyword-printer 'widget-browse-widgets)
(put :button 'widget-keyword-printer 'widget-browse-widget)
(put :args 'widget-keyword-printer 'widget-browse-sexps)

;;; Widget Minor Mode.

(defvar widget-minor-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map widget-keymap)
    map)
  "Keymap used in Widget Minor Mode.")

;;;###autoload
(define-minor-mode widget-minor-mode
  "Minor mode for traversing widgets."
  :lighter " Widget")

;;; The End:

(provide 'wid-browse)

;;; wid-browse.el ends here