;;; cedet-cscope.el --- CScope support for CEDET  -*- lexical-binding: t; -*-

;; Copyright (C) 2009-2021  Free Software Foundation, Inc.

;; Author: Eric M. Ludlam <zappo@gnu.org>
;; Package: cedet

;; 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:
;;
;; Support using CScope for symbol lookups.

;;; Code:

(defvar cedet-cscope-min-version "15.7"
  "Minimum version of CScope required.")

(defcustom cedet-cscope-command "cscope"
  "Command name for the CScope executable."
  :type 'string
  :group 'cedet)

(defun cedet-cscope-search (searchtext texttype type _scope)
  "Perform a search with CScope, return the created buffer.
SEARCHTEXT is text to find.
TEXTTYPE is the type of text, such as `regexp', `string', `tagname',
`tagregexp', or `tagcompletions'.
TYPE is the type of search, meaning that SEARCHTEXT is compared to
filename, tagname (tags table), references (uses of a tag) , or
symbol (uses of something not in the tag table.)
SCOPE is the scope of the search, such as `project' or `subdir'."
  ;; CScope is an interactive program.  It uses number flags
  ;; in order to perform command line searches.  Useful for this
  ;; tool are:
  ;;
  ;; -0 = Find C symbol
  ;; -1 = Find global definition
  ;; -3 = Find references
  ;; -6 = Find grep -E pattern
  ;; -7 = Find file
  (let ((idx (cond ((eq type 'file)
		    "-7")
		   ;; Non files are symbols and such
		   ((eq texttype 'tagname)
		    "-1")
		   ((eq texttype 'tagregexp)
		    "-0")
		   ((eq texttype 'tagcompletions)
		    (setq searchtext (concat "^" searchtext ".*"))
		    "-1")
		   ((eq texttype 'regexp)
		    "-5")
		   (t
		    "-3")
		   )
	     )
	)
    (cedet-cscope-call (list "-d" "-L" idx searchtext))))

(defun cedet-cscope-create (flags)
  "Create a CScope database at the current directory.
FLAGS are additional flags to pass to cscope beyond the
options -cR."
  (cedet-cscope-call (append (list "-cR") flags)))

(defun cedet-cscope-call (flags)
  "Call CScope with the list of FLAGS."
  (let ((b (get-buffer-create "*CEDET CScope*"))
	(cd default-directory)
	)
    (with-current-buffer b
      (setq default-directory cd)
      (erase-buffer))
    (apply #'call-process cedet-cscope-command
	   nil b nil
	   flags)
    b))

(defun cedet-cscope-expand-filename (filename)
  "Expand the FILENAME with CScope.
Return a fully qualified filename."
  (interactive "sFile: ")
  (let* ((ans1 (with-current-buffer
                   (cedet-cscope-call (list "-d" "-L" "-7" filename))
		 (goto-char (point-min))
		 (if (looking-at "[^ \n]*cscope: ")
		     (error "CScope not available")
		   (split-string (buffer-string) "\n" t))))
	 (ans2 (mapcar (lambda (hit)
			 (expand-file-name (car (split-string hit " "))))
		       ans1)))
    (when (called-interactively-p 'interactive)
      (if ans2
	  (if (= (length ans2) 1)
	      (message "%s" (car ans2))
	    (message "%s + %d others" (car ans2)
		     (length (cdr ans2))))
	(error "No file found")))
    ans2))

(defun cedet-cscope-support-for-directory (&optional dir)
  "Return non-nil if CScope has a support file for DIR.
If DIR is not supplied, use the current default directory.
This works by running cscope on a bogus symbol, and looking for
the error code."
  (interactive "DDirectory: ")
  (save-excursion
    (let ((default-directory (or dir default-directory)))
      (set-buffer (cedet-cscope-call (list "-d" "-L" "-7" "moose")))
      (goto-char (point-min))
      (let ((ans (looking-at "[^ \n]*cscope: ")))
	(if (called-interactively-p 'interactive)
	    (if ans
		(message "No support for CScope in %s" default-directory)
	      (message "CScope is supported in %s" default-directory))
	  (if ans
	      nil
	    t))))))

(defun cedet-cscope-version-check (&optional noerror)
  "Check the version of the installed CScope command.
If optional programmatic argument NOERROR is non-nil,
then instead of throwing an error if CScope isn't available,
return nil."
  (interactive)
  (let ((b (condition-case nil
	       (cedet-cscope-call (list "-V"))
	     (error nil)))
	(rev nil))
    (if (not b)
	(progn
	  (when (called-interactively-p 'interactive)
	    (message "CScope not found."))
	  nil)
      (with-current-buffer b
	(goto-char (point-min))
	(re-search-forward "cscope: version \\([0-9.]+\\)" nil t)
	(setq rev (match-string 1))
        (if (version< rev cedet-cscope-min-version)
	    (if noerror
		nil
	      (error "Version of CScope is %s.  Need at least %s"
		     rev cedet-cscope-min-version))
	  ;; Else, return TRUE, as in good enough.
	  (when (called-interactively-p 'interactive)
	    (message "CScope %s  - Good enough for CEDET." rev))
	  t)))))

(defun cedet-cscope-create/update-database (&optional dir)
  "Create a CScope database in DIR.
CScope will automatically choose incremental rebuild if
there is already a database in DIR."
  (interactive "DDirectory: ")
  (let ((default-directory dir))
    (cedet-cscope-create nil)))

(provide 'cedet-cscope)

;;; cedet-cscope.el ends here