;;; find-paths.el --- setup various XEmacs paths

;; Copyright (C) 1985-1986, 1990, 1992-1997 Free Software Foundation, Inc.
;; Copyright (c) 1993, 1994 Sun Microsystems, Inc.
;; Copyright (C) 1995 Board of Trustees, University of Illinois

;; Author: Mike Sperber <sperber@informatik.uni-tuebingen.de>
;; Maintainer: XEmacs Development Team
;; Keywords: internal, dumped

;; This file is part of XEmacs.

;; XEmacs 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 2, or (at your option)
;; any later version.

;; XEmacs 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 XEmacs; see the file COPYING.  If not, write to the 
;; Free Software Foundation, 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Synched up with: Not in FSF.

;;; Commentary:

;; This file is dumped with XEmacs.

;; This file contains basic library functionality for manipulating paths
;; and path lists and finding paths in the XEmacs hierarchy.


;;; Code:

(defvar paths-version-control-filename-regexp
  "^\\(RCS\\|CVS\\|SCCS\\)$"
  "File bases associated with version control.")

(defvar paths-lisp-filename-regexp
  "^\\(.*\\.elc?\\)$"
  "File bases that contain Lisp file.")

(defvar paths-no-lisp-directory-regexp
  (concat "\\(" paths-version-control-filename-regexp "\\)"
	  "\\|"
	  "\\(" paths-lisp-filename-regexp "\\)")
  "File bases that may not be directories containing Lisp code.")

(defun paths-find-recursive-path (directories &optional max-depth exclude-regexp)
  "Return a list of the directory hierarchy underneath DIRECTORIES.
The returned list is sorted by pre-order and lexicographically.
MAX-DEPTH limits the depth of the search to MAX-DEPTH level,
if it is a number.  If MAX-DEPTH is NIL, the search depth is unlimited.
EXCLUDE-REGEXP is a regexp that matches directory names to exclude
from the search."
  (let ((path '()))
    (while directories
      (let ((directory (file-name-as-directory
			(expand-file-name
			 (car directories)))))
	(if (paths-file-readable-directory-p directory)
	    (let ((raw-entries
		   (if (equal 0 max-depth)
		       '()
		     (directory-files directory nil "^[^.-]")))
		  (reverse-dirs '()))
	      (while raw-entries
		(if (not (and exclude-regexp
			      (string-match exclude-regexp (car raw-entries))))
		    (setq reverse-dirs
			  (cons (expand-file-name (car raw-entries) directory)
				reverse-dirs)))
		(setq raw-entries (cdr raw-entries)))

	      (let ((sub-path
		     (paths-find-recursive-path (reverse reverse-dirs)
						(if (numberp max-depth)
						    (- max-depth 1)
						  max-depth)
						exclude-regexp)))
		(setq path (nconc path
				  (list directory)
				  sub-path))))))
      (setq directories (cdr directories)))
    path))

(defun paths-file-readable-directory-p (filename)
  "Check if filename is a readable directory."
  (and (file-directory-p filename)
       (file-readable-p filename)))

(defun paths-find-recursive-load-path (directories &optional max-depth)
  "Construct a recursive load path underneath DIRECTORIES."
  (paths-find-recursive-path directories
			     max-depth paths-no-lisp-directory-regexp))

(defun paths-emacs-root-p (directory)
  "Check if DIRECTORY is a plausible installation root for XEmacs."
  (or
   ;; installed
   (paths-file-readable-directory-p (paths-construct-path (list directory
								"lib"
								(construct-emacs-version-name))))
   ;; in-place or windows-nt
   (and
    (paths-file-readable-directory-p (paths-construct-path (list directory "lisp")))
    (paths-file-readable-directory-p (paths-construct-path (list directory "etc"))))))

(defun paths-root-in-place-p (root)
  "Check if ROOT is an in-place installation root for XEmacs."
  (paths-file-readable-directory-p (paths-construct-path (list root "lisp"))))

(defun paths-chase-symlink (file-name)
  "Chase a symlink until the bitter end."
      (let ((maybe-symlink (file-symlink-p file-name)))
	(if maybe-symlink
	    (let* ((directory (file-name-directory file-name))
		   (destination (expand-file-name maybe-symlink directory)))
	      (paths-chase-symlink destination))
	  file-name)))

(defun paths-find-emacs-root
  (invocation-directory invocation-name)
  "Find the run-time root of XEmacs."
  (let* ((executable-file-name (paths-chase-symlink
				(concat invocation-directory
					invocation-name)))
	 (executable-directory (file-name-directory executable-file-name))
	 (maybe-root-1 (file-name-as-directory
			(paths-construct-path '("..") executable-directory)))
	 (maybe-root-2 (file-name-as-directory
			(paths-construct-path '(".." "..") executable-directory))))
    (or (and (paths-emacs-root-p maybe-root-1)
	     maybe-root-1)
	(and (paths-emacs-root-p maybe-root-2)
	     maybe-root-2))))

(defun paths-construct-path (components &optional expand-directory)
  "Convert list of path components COMPONENTS into a path.
If EXPAND-DIRECTORY is non-NIL, use it as a directory to feed
to EXPAND-FILE-NAME."
  (let* ((reverse-components (reverse components))
	 (last-component (car reverse-components))
	 (first-components (reverse (cdr reverse-components)))
	 (path
	  (apply #'concat
		 (append (mapcar #'file-name-as-directory first-components)
			 (list last-component)))))
    (if expand-directory
	(expand-file-name path expand-directory)
      path)))

(defun paths-construct-emacs-directory (root suffix base)
  "Construct a directory name within the XEmacs hierarchy."
  (file-name-as-directory
   (expand-file-name
    (concat
     (file-name-as-directory root)
     suffix
     base))))

(defun paths-find-emacs-directory (roots suffix base
				   &optional envvar default keep-suffix
				   	     in-place-external)
  "Find a directory in the XEmacs hierarchy.
ROOTS must be a list of installation roots.
SUFFIX is the subdirectory from there.
BASE is the base to look for.
ENVVAR is the name of the environment variable that might also
specify the directory.
DEFAULT is the preferred value.
If KEEP-SUFFIX is non-nil, the suffix must be respected in searching
the directory.
If IN-PLACE-EXTERNAL is non-nil, the directory might be found outside
an in-place root-hierarchy."
  (let ((preferred-value (or (and envvar (getenv envvar))
			     default)))
    (if (and preferred-value
	     (paths-file-readable-directory-p preferred-value))
	(file-name-as-directory preferred-value)
      (catch 'gotcha
	(while roots
	  (let ((root (car roots)))
	    ;; installed
	    (let ((path (paths-construct-emacs-directory root suffix base)))
	      (if (paths-file-readable-directory-p path)
		  (throw 'gotcha path)))
	    ;; in-place
	    (if (null keep-suffix)
		(let ((path (paths-construct-emacs-directory root "" base)))
		  (if (paths-file-readable-directory-p path)
		      (throw 'gotcha path))))
	    (if (and in-place-external
		     (paths-root-in-place-p root))
		(let ((path (paths-construct-emacs-directory
			     (paths-construct-path '("..") root)
			     "" base)))
		  (if (paths-file-readable-directory-p path)
		      (throw 'gotcha path)))))
	  (setq roots (cdr roots)))
	nil))))

(defun paths-find-site-directory (roots base &optional envvar default in-place-external)
  "Find a site-specific directory in the XEmacs hierarchy.
If IN-PLACE-EXTERNAL is non-nil, the directory might be found outside
an in-place root-hierarchy."
  (paths-find-emacs-directory roots
			      (file-name-as-directory
			       (paths-construct-path (list
						      "lib"
						      emacs-program-name)))
			      base
			      envvar default
			      nil
			      in-place-external))

(defun paths-find-version-directory (roots base
				     &optional envvar default enforce-version)
  "Find a version-specific directory in the XEmacs hierarchy.
If ENFORCE-VERSION is non-nil, the directory must contain the XEmacs version."
  (paths-find-emacs-directory roots
			      (file-name-as-directory
			       (paths-construct-path
				(list "lib"
				      (construct-emacs-version-name))))
			      base
			      envvar default
			      enforce-version))

(defun paths-find-architecture-directory (roots base &optional envvar default)
  "Find an architecture-specific directory in the XEmacs hierarchy."
  (or
   ;; from more to less specific
   (paths-find-version-directory roots
				 (concat base system-configuration)
				 envvar default)
   (paths-find-version-directory roots
				 base
				 envvar)
   (paths-find-version-directory roots
				 system-configuration
				 envvar)))

(defun construct-emacs-version-name ()
  "Construct the raw XEmacs version number."
  (concat emacs-program-name "-" emacs-program-version))

(defun paths-directories-which-exist (directories)
  "Return the directories among DIRECTORIES."
  (let ((reverse-directories '()))
    (while directories
      (if (paths-file-readable-directory-p (car directories))
	  (setq reverse-directories
		(cons (car directories)
		      reverse-directories)))
      (setq directories (cdr directories)))
    (reverse reverse-directories)))

(defun paths-uniq-append (list-1 list-2)
  "Append LIST-1 and LIST-2, omitting duplicates."
  (let ((reverse-survivors '()))
    (while list-2
      (if (null (member (car list-2) list-1))
	  (setq reverse-survivors (cons (car list-2) reverse-survivors)))
      (setq list-2 (cdr list-2)))
    (append list-1
	    (reverse reverse-survivors))))

(defun paths-filter (predicate list)
  "Delete all matches of PREDICATE from LIST."
  (let ((reverse-result '()))
    (while list
      (if (funcall predicate (car list))
	  (setq reverse-result (cons (car list) reverse-result)))
      (setq list (cdr list)))
    (nreverse reverse-result)))

(defun paths-decode-directory-path (string &optional drop-empties)
  "Split STRING at path separators into a directory list.
Non-\"\" components are converted into directory form.
If DROP-EMPTIES is non-NIL, \"\" components are dropped from the output.
Otherwise, they are left alone."
  (let* ((components (split-path string))
	 (directories
	  (mapcar #'(lambda (component)
		      (if (string-equal "" component)
			  component
			(file-name-as-directory component)))
		  components)))
    (if drop-empties
	(paths-filter #'(lambda (component)
			  (null (string-equal "" component)))
		      directories)
      directories)))

(defun paths-find-emacs-roots (invocation-directory
			       invocation-name)
  "Find all plausible installation roots for XEmacs."
  (let* ((potential-invocation-root
	  (paths-find-emacs-root invocation-directory invocation-name))
	 (invocation-roots
	  (and potential-invocation-root
	       (list potential-invocation-root)))
	 (potential-installation-roots
	  (paths-uniq-append
	   (and configure-exec-prefix-directory
		(list (file-name-as-directory
		       configure-exec-prefix-directory)))
	   (and configure-prefix-directory
		(list (file-name-as-directory
		       configure-prefix-directory)))))
	 (installation-roots
	  (paths-filter #'paths-emacs-root-p potential-installation-roots)))
    (paths-uniq-append invocation-roots
		       installation-roots)))

;;; find-paths.el ends here