;;; cedet-global.el --- GNU Global support for CEDET.  -*- lexical-binding: t; -*-

;; Copyright (C) 2008-2021 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:
;;
;; Basic support for calling GNU Global, and testing version numbers.

(defvar cedet-global-min-version "5.0"
  "Minimum version of GNU Global required.")

(defcustom cedet-global-command "global"
  "Command name for the GNU Global executable."
  :type 'string
  :group 'cedet)

(defcustom cedet-global-gtags-command "gtags"
  "Command name for the GNU Global gtags executable.
GTAGS is used to create the tags table queried by the `global' command."
  :type 'string
  :group 'cedet)

;;; Code:
(defun cedet-gnu-global-search (searchtext texttype type scope)
  "Perform a search with GNU Global, 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 `subdirs'."
  (let ((flgs (cond ((eq type 'file)
		     "-a")
		    (t "-xa")))
	(scopeflgs (cond
		    ((eq scope 'project)
		     ""
		     )
		    ((eq scope 'target)
		     "l")))
	(stflag (cond ((or (eq texttype 'tagname)
			   (eq texttype 'tagregexp))
		       "")
		      ((eq texttype 'tagcompletions)
		       "c")
		      ((eq texttype 'regexp)
		       "g")
		      (t "r"))))
    (cedet-gnu-global-call (list (concat flgs scopeflgs stflag)
				 searchtext))))

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

(defun cedet-gnu-global-gtags-call (flags)
  "Create GNU Global TAGS using gtags with FLAGS."
  (let ((b (get-buffer-create "*CEDET Global gtags*"))
	(cd default-directory)
	)
    (with-current-buffer b
      (setq default-directory cd)
      (erase-buffer))
    (apply #'call-process cedet-global-gtags-command
	   nil b nil
	   flags)

    ;; Check for warnings.
    (with-current-buffer b
      (goto-char (point-min))
      (when (re-search-forward "Error\\|Warning\\|invalid" nil t)
	(error "Output:\n%S" (buffer-string))))

    b))

(defun cedet-gnu-global-expand-filename (filename)
  "Expand the FILENAME with GNU Global.
Return a list of absolute filenames or nil if none found.
Signal an error if GNU global not available."
  (interactive "sFile: ")
  (let ((ans (with-current-buffer (cedet-gnu-global-call (list "-Pa" filename))
	       (goto-char (point-min))
	       (if (looking-at "global: ")
		   (error "GNU Global not available")
		 (split-string (buffer-string) "\n" t)))))
    (when (called-interactively-p 'interactive)
      (if ans
	  (if (= (length ans) 1)
	      (message "%s" (car ans))
	    (message "%s + %d others" (car ans)
		     (length (cdr ans))))
	(error "No file found")))
    ans))

(defun cedet-gnu-global-show-root ()
  "Show the root of a GNU Global area under the current buffer."
  (interactive)
  (message "%s" (cedet-gnu-global-root)))

(defun cedet-gnu-global-root (&optional dir)
  "Return the root of any GNU Global scanned project containing DIR.
Returns nil if no GNU Global project can be found.
DIR defaults to `default-directory'."
  (let ((default-directory (or dir default-directory)))
    (with-current-buffer (cedet-gnu-global-call (list "-pq"))
      (goto-char (point-min))
      (when (not (eobp))
	(file-name-as-directory
	 (buffer-substring (point) (point-at-eol)))))))

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

(defun cedet-gnu-global-scan-hits (buffer)
  "Scan all the hits from the GNU Global output BUFFER."
  (let ((hits nil)
	(r1 "^\\([^ ]+\\) +\\([0-9]+\\) \\([^ ]+\\) "))
    (with-current-buffer buffer
      (goto-char (point-min))
      (while (re-search-forward r1 nil t)
	(setq hits (cons (cons (string-to-number (match-string 2))
			       (match-string 3))
			 hits)))
      ;; Return the results
      (nreverse hits))))

(defun cedet-gnu-global-create/update-database (&optional dir)
  "Create a GNU Global database in DIR.
If a database already exists, then just update it."
  (interactive "DDirectory: ")
  (let ((root (cedet-gnu-global-root dir)))
    (if root (setq dir root))
    (let ((default-directory dir))
      (if root
          ;; Incremental update. This can be either "gtags -i" or
          ;; "global -u"; the gtags manpage says it's better to use
          ;; "global -u".
	  (cedet-gnu-global-call (list "-u"))
	(cedet-gnu-global-gtags-call nil)
	)
      )))

(provide 'cedet-global)

;;; cedet-global.el ends here