* src/data.c (Flocal_variable_p): Handle variable aliases correctly.

[emacs.git] / lisp / emacs-lisp / package.el

;;; package.el --- Simple package system for Emacs

;; Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

;; Author: Tom Tromey <tromey@redhat.com>
;; Created: 10 Mar 2007
;; Version: 0.9
;; Keywords: tools

;; 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, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Change Log:

;;  2 Apr 2007 - now using ChangeLog file
;; 15 Mar 2007 - updated documentation
;; 14 Mar 2007 - Changed how obsolete packages are handled
;; 13 Mar 2007 - Wrote package-install-from-buffer
;; 12 Mar 2007 - Wrote package-menu mode

;;; Commentary:

;; The idea behind package.el is to be able to download packages and
;; install them.  Packages are versioned and have versioned
;; dependencies.  Furthermore, this supports built-in packages which
;; may or may not be newer than user-specified packages.  This makes
;; it possible to upgrade Emacs and automatically disable packages
;; which have moved from external to core.  (Note though that we don't
;; currently register any of these, so this feature does not actually
;; work.)

;; A package is described by its name and version.  The distribution
;; format is either  a tar file or a single .el file.

;; A tar file should be named "NAME-VERSION.tar".  The tar file must
;; unpack into a directory named after the package and version:
;; "NAME-VERSION".  It must contain a file named "PACKAGE-pkg.el"
;; which consists of a call to define-package.  It may also contain a
;; "dir" file and the info files it references.

;; A .el file is named "NAME-VERSION.el" in the remote archive, but is
;; installed as simply "NAME.el" in a directory named "NAME-VERSION".

;; The downloader downloads all dependent packages.  By default,
;; packages come from the official GNU sources, but others may be
;; added by customizing the `package-archives' alist.  Packages get
;; byte-compiled at install time.

;; At activation time we will set up the load-path and the info path,
;; and we will load the package's autoloads.  If a package's
;; dependencies are not available, we will not activate that package.

;; Conceptually a package has multiple state transitions:
;;
;; * Download.  Fetching the package from ELPA.
;; * Install.  Untar the package, or write the .el file, into
;;   ~/.emacs.d/elpa/ directory.
;; * Byte compile.  Currently this phase is done during install,
;;   but we may change this.
;; * Activate.  Evaluate the autoloads for the package to make it
;;   available to the user.
;; * Load.  Actually load the package and run some code from it.

;; Other external functions you may want to use:
;;
;; M-x package-list-packages
;;    Enters a mode similar to buffer-menu which lets you manage
;;    packages.  You can choose packages for install (mark with "i",
;;    then "x" to execute) or deletion (not implemented yet), and you
;;    can see what packages are available.  This will automatically
;;    fetch the latest list of packages from ELPA.
;;
;; M-x package-list-packages-no-fetch
;;    Like package-list-packages, but does not automatically fetch the
;;    new list of packages.
;;
;; M-x package-install-from-buffer
;;    Install a package consisting of a single .el file that appears
;;    in the current buffer.  This only works for packages which
;;    define a Version header properly; package.el also supports the
;;    extension headers Package-Version (in case Version is an RCS id
;;    or similar), and Package-Requires (if the package requires other
;;    packages).
;;
;; M-x package-install-file
;;    Install a package from the indicated file.  The package can be
;;    either a tar file or a .el file.  A tar file must contain an
;;    appropriately-named "-pkg.el" file; a .el file must be properly
;;    formatted as with package-install-from-buffer.

;;; Thanks:
;;; (sorted by sort-lines):

;; Jim Blandy <jimb@red-bean.com>
;; Karl Fogel <kfogel@red-bean.com>
;; Kevin Ryde <user42@zip.com.au>
;; Lawrence Mitchell
;; Michael Olson <mwolson@member.fsf.org>
;; Sebastian Tennant <sebyte@smolny.plus.com>
;; Stefan Monnier <monnier@iro.umontreal.ca>
;; Vinicius Jose Latorre <viniciusjl@ig.com.br>
;; Phil Hagelberg <phil@hagelb.org>

;;; ToDo:

;; - putting info dirs at the start of the info path means
;;   users see a weird ordering of categories.  OTOH we want to
;;   override later entries.  maybe emacs needs to enforce
;;   the standard layout?
;; - put bytecode in a separate directory tree
;; - perhaps give users a way to recompile their bytecode
;;   or do it automatically when emacs changes
;; - give users a way to know whether a package is installed ok
;; - give users a way to view a package's documentation when it
;;   only appears in the .el
;; - use/extend checkdoc so people can tell if their package will work
;; - "installed" instead of a blank in the status column
;; - tramp needs its files to be compiled in a certain order.
;;   how to handle this?  fix tramp?
;; - on emacs 21 we don't kill the -autoloads.el buffer.  what about 22?
;; - maybe we need separate .elc directories for various emacs versions
;;   and also emacs-vs-xemacs.  That way conditional compilation can
;;   work.  But would this break anything?
;; - should store the package's keywords in archive-contents, then
;;   let the users filter the package-menu by keyword.  See
;;   finder-by-keyword.  (We could also let people view the
;;   Commentary, but it isn't clear how useful this is.)
;; - William Xu suggests being able to open a package file without
;;   installing it
;; - Interface with desktop.el so that restarting after an install
;;   works properly
;; - Implement M-x package-upgrade, to upgrade any/all existing packages
;; - Use hierarchical layout.  PKG/etc PKG/lisp PKG/info
;;   ... except maybe lisp?
;; - It may be nice to have a macro that expands to the package's
;;   private data dir, aka ".../etc".  Or, maybe data-directory
;;   needs to be a list (though this would be less nice)
;;   a few packages want this, eg sokoban
;; - package menu needs:
;;     ability to know which packages are built-in & thus not deletable
;;     it can sometimes print odd results, like 0.3 available but 0.4 active
;;        why is that?
;; - Allow multiple versions on the server...?
;;   [ why bother? ]
;; - Don't install a package which will invalidate dependencies overall
;; - Allow something like (or (>= emacs 21.0) (>= xemacs 21.5))
;;   [ currently thinking, why bother.. KISS ]
;; - Allow optional package dependencies
;;   then if we require 'bbdb', bbdb-specific lisp in lisp/bbdb
;;   and just don't compile to add to load path ...?
;; - Have a list of archive URLs?  [ maybe there's no point ]
;; - David Kastrup pointed out on the xemacs list that for GPL it
;;   is friendlier to ship the source tree.  We could "support" that
;;   by just having a "src" subdir in the package.  This isn't ideal
;;   but it probably is not worth trying to support random source
;;   tree layouts, build schemes, etc.
;; - Our treatment of the info path is somewhat bogus
;; - perhaps have an "unstable" tree in ELPA as well as a stable one

;;; Code:

(defgroup package nil
  "Manager for Emacs Lisp packages."
  :group 'applications
  :version "24.1")

;;;###autoload
(defcustom package-enable-at-startup t
  "Whether to activate installed packages when Emacs starts.
If non-nil, packages are activated after reading the init file
and before `after-init-hook'.  Activation is not done if
`user-init-file' is nil (e.g. Emacs was started with \"-q\").

Even if the value is nil, you can type \\[package-initialize] to
activate the package system at any time."
  :type 'boolean
  :group 'package
  :version "24.1")

(defcustom package-load-list '(all)
  "List of packages for `package-initialize' to load.
Each element in this list should be a list (NAME VERSION), or the
symbol `all'.  The symbol `all' says to load the latest installed
versions of all packages not specified by other elements.

For an element (NAME VERSION), NAME is a package name (a symbol).
VERSION should be t, a string, or nil.
If VERSION is t, all versions are loaded, though obsolete ones
 will be put in `package-obsolete-alist' and not activated.
If VERSION is a string, only that version is ever loaded.
 Any other version, even if newer, is silently ignored.
 Hence, the package is \"held\" at that version.
If VERSION is nil, the package is not loaded (it is \"disabled\")."
  :type '(repeat symbol)
  :risky t
  :group 'package
  :version "24.1")

(defvar Info-directory-list)
(declare-function info-initialize "info" ())
(declare-function url-http-parse-response "url-http" ())
(declare-function lm-header "lisp-mnt" (header))
(declare-function lm-commentary "lisp-mnt" (&optional file))
(declare-function dired-delete-file "dired" (file &optional recursive trash))

(defcustom package-archives '(("gnu" . "http://elpa.gnu.org/packages/"))
  "An alist of archives from which to fetch.
The default value points to the GNU Emacs package repository.
Each element has the form (ID . URL), where ID is an identifier
string for an archive and URL is a http: URL (a string)."
  :type '(alist :key-type (string :tag "Archive name")
                :value-type (string :tag "Archive URL"))
  :risky t
  :group 'package
  :version "24.1")

(defconst package-archive-version 1
  "Version number of the package archive understood by this file.
Lower version numbers than this will probably be understood as well.")

(defconst package-el-version "1.0"
  "Version of package.el.")

;; We don't prime the cache since it tends to get out of date.
(defvar package-archive-contents nil
  "Cache of the contents of the Emacs Lisp Package Archive.
This is an alist mapping package names (symbols) to package
descriptor vectors.  These are like the vectors for `package-alist'
but have extra entries: one which is 'tar for tar packages and
'single for single-file packages, and one which is the name of
the archive from which it came.")
(put 'package-archive-contents 'risky-local-variable t)

(defcustom package-user-dir (locate-user-emacs-file "elpa")
  "Directory containing the user's Emacs Lisp packages.
The directory name should be absolute.
Apart from this directory, Emacs also looks for system-wide
packages in `package-directory-list'."
  :type 'directory
  :risky t
  :group 'package
  :version "24.1")

(defcustom package-directory-list
  ;; Defaults are subdirs named "elpa" in the site-lisp dirs.
  (let (result)
    (dolist (f load-path)
      (if (equal (file-name-nondirectory f) "site-lisp")
          (push (expand-file-name "elpa" f) result)))
    (nreverse result))
  "List of additional directories containing Emacs Lisp packages.
Each directory name should be absolute.

These directories contain packages intended for system-wide; in
contrast, `package-user-dir' contains packages for personal use."
  :type '(repeat directory)
  :risky t
  :group 'package
  :version "24.1")

(defun package-version-split (string)
  "Split a package string into a version list."
  (mapcar 'string-to-int (split-string string "[.]")))

(defconst package--builtins-base
  ;; We use package-version split here to make sure to pick up the
  ;; minor version.
  `((emacs . [,(package-version-split emacs-version) nil
              "GNU Emacs"])
    (package . [,(package-version-split package-el-version)
                nil "Simple package system for GNU Emacs"]))
  "Packages which are always built-in.")

(defvar package--builtins
  (delq nil
        (append
         package--builtins-base
         (if (>= emacs-major-version 22)
             ;; FIXME: emacs 22 includes tramp, rcirc, maybe
             ;; other things...
             '((erc . [(5 2) nil "Internet Relay Chat client"])
               ;; The external URL is version 1.15, so make sure the
               ;; built-in one looks newer.
               (url . [(1 16) nil "URL handling libary"])))
         (if (>= emacs-major-version 23)
             '(;; Strangely, nxml-version is missing in Emacs 23.
               ;; We pick the merge date as the version.
               (nxml . [(20071123) nil "Major mode for XML documents"])
               (bubbles . [(0 5) nil "A puzzle game"])))))
  "Alist of all built-in packages.
Maps the package name to a vector [VERSION REQS DOCSTRING].")
(put 'package--builtins 'risky-local-variable t)

(defvar package-alist package--builtins
  "Alist of all packages available for activation.
This maps the package name to a vector [VERSION REQS DOCSTRING].

The value is generated by `package-load-descriptor', usually
called via `package-initialize'.  For user customizations of
which packages to load/activate, see `package-load-list'.")
(put 'package-archive-contents 'risky-local-variable t)

(defvar package-activated-list
  (mapcar #'car package-alist)
  "List of the names of currently activated packages.")
(put 'package-activated-list 'risky-local-variable t)

(defvar package-obsolete-alist nil
  "Representation of obsolete packages.
Like `package-alist', but maps package name to a second alist.
The inner alist is keyed by version.")
(put 'package-obsolete-alist 'risky-local-variable t)

(defconst package-subdirectory-regexp
  "^\\([^.].*\\)-\\([0-9]+\\(?:[.][0-9]+\\)*\\)$"
  "Regular expression matching the name of a package subdirectory.
The first subexpression is the package name.
The second subexpression is the version string.")

(defun package-version-join (l)
  "Turn a list of version numbers into a version string."
  (mapconcat 'int-to-string l "."))

(defun package--version-first-nonzero (l)
  (while (and l (= (car l) 0))
    (setq l (cdr l)))
  (if l (car l) 0))

(defun package-version-compare (v1 v2 fun)
  "Compare two version lists according to FUN.
FUN can be <, <=, =, >, >=, or /=."
  (while (and v1 v2 (= (car v1) (car v2)))
    (setq v1 (cdr v1)
          v2 (cdr v2)))
  (if v1
      (if v2
          ;; Both not null; we know the cars are not =.
          (funcall fun (car v1) (car v2))
        ;; V1 not null, V2 null.
        (funcall fun (package--version-first-nonzero v1) 0))
    (if v2
        ;; V1 null, V2 not null.
        (funcall fun 0 (package--version-first-nonzero v2))
      ;; Both null.
      (funcall fun 0 0))))

(defun package-strip-version (dirname)
  "Strip the version from a combined package name and version.
E.g., if given \"quux-23.0\", will return \"quux\""
  (if (string-match package-subdirectory-regexp dirname)
      (match-string 1 dirname)))

(defun package-load-descriptor (dir package)
  "Load the description file in directory DIR for package PACKAGE."
  (let* ((pkg-dir (expand-file-name package dir))
         (pkg-file (expand-file-name
                    (concat (package-strip-version package) "-pkg")
                    pkg-dir)))
    (when (and (file-directory-p pkg-dir)
               (file-exists-p (concat pkg-file ".el")))
      (load pkg-file nil t))))

(defun package-load-all-descriptors ()
  "Load descriptors for installed Emacs Lisp packages.
This looks for package subdirectories in `package-user-dir' and
`package-directory-list'.  The variable `package-load-list'
controls which package subdirectories may be loaded.

In each valid package subdirectory, this function loads the
description file containing a call to `define-package', which
updates `package-alist' and `package-obsolete-alist'."
  (let ((all (memq 'all package-load-list))
        name version force)
    (dolist (dir (cons package-user-dir package-directory-list))
      (when (file-directory-p dir)
        (dolist (subdir (directory-files dir))
          (when (and (file-directory-p (expand-file-name subdir dir))
                     (string-match package-subdirectory-regexp subdir))
            (setq name    (intern (match-string 1 subdir))
                  version (match-string 2 subdir)
                  force   (assq name package-load-list))
            (when (cond
                   ((null force)
                    all) ; not in package-load-list
                   ((null (setq force (cadr force)))
                    nil) ; disabled
                   ((eq force t)
                    t)
                   ((stringp force) ; held
                    (package-version-compare (package-version-split version)
                                             (package-version-split force)
                                             '=))
                   (t
                    (error "Invalid element in `package-load-list'")))
              (package-load-descriptor dir subdir))))))))

(defsubst package-desc-vers (desc)
  "Extract version from a package description vector."
  (aref desc 0))

(defsubst package-desc-reqs (desc)
  "Extract requirements from a package description vector."
  (aref desc 1))

(defsubst package-desc-doc (desc)
  "Extract doc string from a package description vector."
  (aref desc 2))

(defsubst package-desc-kind (desc)
  "Extract the kind of download from an archive package description vector."
  (aref desc 3))

(defun package--dir (name version-string)
  (let* ((subdir (concat name "-" version-string))
         (dir-list (cons package-user-dir package-directory-list))
         pkg-dir)
    (while dir-list
      (let ((subdir-full (expand-file-name subdir (car dir-list))))
        (if (file-directory-p subdir-full)
            (setq pkg-dir  subdir-full
                  dir-list nil)
          (setq dir-list (cdr dir-list)))))
    pkg-dir))

(defun package-activate-1 (package pkg-vec)
  (let* ((name (symbol-name package))
         (version-str (package-version-join (package-desc-vers pkg-vec)))
         (pkg-dir (package--dir name version-str)))
    (unless pkg-dir
      (error "Internal error: could not find directory for %s-%s"
             name version-str))
    ;; Add info node.
    (if (file-exists-p (expand-file-name "dir" pkg-dir))
        (progn
          ;; FIXME: not the friendliest, but simple.
          (require 'info)
          (info-initialize)
          (setq Info-directory-list (cons pkg-dir Info-directory-list))))
    ;; Add to load path, add autoloads, and activate the package.
    (setq load-path (cons pkg-dir load-path))
    (load (expand-file-name (concat name "-autoloads") pkg-dir) nil t)
    (setq package-activated-list (cons package package-activated-list))
    ;; Don't return nil.
    t))

(defun package--built-in (package version)
  "Return true if the package is built-in to Emacs."
  (let ((elt (assq package package--builtins)))
    (and elt
         (package-version-compare (package-desc-vers (cdr elt)) version '=))))

;; FIXME: return a reason instead?
(defun package-activate (package version)
  "Activate a package, and recursively activate its dependencies.
Return nil if the package could not be activated."
  ;; Assume the user knows what he is doing -- go ahead and activate a
  ;; newer version of a package if an older one has already been
  ;; activated.  This is not ideal; we'd at least need to check to see
  ;; if the package has actually been loaded, and not merely
  ;; activated.  However, don't try to activate 'emacs', as that makes
  ;; no sense.
  (unless (eq package 'emacs)
    (let* ((pkg-desc (assq package package-alist))
           (this-version (package-desc-vers (cdr pkg-desc)))
           (req-list (package-desc-reqs (cdr pkg-desc)))
           ;; If the package was never activated, do it now.
           (keep-going (or (not (memq package package-activated-list))
                           (package-version-compare this-version version '>))))
      (while (and req-list keep-going)
        (let* ((req (car req-list))
               (req-name (car req))
               (req-version (cadr req)))
          (or (package-activate req-name req-version)
              (setq keep-going nil)))
        (setq req-list (cdr req-list)))
      (if keep-going
          (package-activate-1 package (cdr pkg-desc))
        ;; We get here if a dependency failed to activate -- but we
        ;; can also get here if the requested package was already
        ;; activated.  Return non-nil in the latter case.
        (and (memq package package-activated-list)
             (package-version-compare this-version version '>=))))))

(defun package-mark-obsolete (package pkg-vec)
  "Put package on the obsolete list, if not already there."
  (let ((elt (assq package package-obsolete-alist)))
    (if elt
        ;; If this obsolete version does not exist in the list, update
        ;; it the list.
        (unless (assoc (package-desc-vers pkg-vec) (cdr elt))
          (setcdr elt (cons (cons (package-desc-vers pkg-vec) pkg-vec)
                            (cdr elt))))
      ;; Make a new association.
      (setq package-obsolete-alist
            (cons (cons package (list (cons (package-desc-vers pkg-vec)
                                            pkg-vec)))
                  package-obsolete-alist)))))

;; (define-package "emacs" "21.4.1" "GNU Emacs core package.")
;; (define-package "erc" "5.1" "ERC - irc client" '((emacs "21.0")))
(defun define-package (name-str version-string
                                &optional docstring requirements)
  "Define a new package.
NAME is the name of the package, a string.
VERSION-STRING is the version of the package, a dotted sequence
of integers.
DOCSTRING is the optional description.
REQUIREMENTS is a list of requirements on other packages.
Each requirement is of the form (OTHER-PACKAGE \"VERSION\")."
  (let* ((name (intern name-str))
         (pkg-desc (assq name package-alist))
         (new-version (package-version-split version-string))
         (new-pkg-desc
          (cons name
                (vector new-version
                        (mapcar
                         (lambda (elt)
                           (list (car elt)
                                 (package-version-split (car (cdr elt)))))
                         requirements)
                        docstring))))
    ;; Only redefine a package if the redefinition is newer.
    (if (or (not pkg-desc)
            (package-version-compare new-version
                                     (package-desc-vers (cdr pkg-desc))
                                     '>))
        (progn
          (when pkg-desc
            ;; Remove old package and declare it obsolete.
            (setq package-alist (delq pkg-desc package-alist))
            (package-mark-obsolete (car pkg-desc) (cdr pkg-desc)))
          ;; Add package to the alist.
          (setq package-alist (cons new-pkg-desc package-alist)))
      ;; You can have two packages with the same version, for instance
      ;; one in the system package directory and one in your private
      ;; directory.  We just let the first one win.
      (unless (package-version-compare new-version
                                       (package-desc-vers (cdr pkg-desc))
                                       '=)
        ;; The package is born obsolete.
        (package-mark-obsolete (car new-pkg-desc) (cdr new-pkg-desc))))))

;; From Emacs 22.
(defun package-autoload-ensure-default-file (file)
  "Make sure that the autoload file FILE exists and if not create it."
  (unless (file-exists-p file)
    (write-region
     (concat ";;; " (file-name-nondirectory file)
             " --- automatically extracted autoloads\n"
             ";;\n"
             ";;; Code:\n\n"
             "\f\n;; Local Variables:\n"
             ";; version-control: never\n"
             ";; no-byte-compile: t\n"
             ";; no-update-autoloads: t\n"
             ";; End:\n"
             ";;; " (file-name-nondirectory file)
             " ends here\n")
     nil file))
  file)

(defun package-generate-autoloads (name pkg-dir)
  (let* ((auto-name (concat name "-autoloads.el"))
         (ignore-name (concat name "-pkg.el"))
         (generated-autoload-file (expand-file-name auto-name pkg-dir))
         (version-control 'never))
    (require 'autoload)
    (unless (fboundp 'autoload-ensure-default-file)
      (package-autoload-ensure-default-file generated-autoload-file))
    (update-directory-autoloads pkg-dir)))

(defun package-untar-buffer ()
  "Untar the current buffer.
This uses `tar-untar-buffer' if it is available.
Otherwise it uses an external `tar' program.
`default-directory' should be set by the caller."
  (require 'tar-mode)
  (if (fboundp 'tar-untar-buffer)
      (progn
        ;; tar-mode messes with narrowing, so we just let it have the
        ;; whole buffer to play with.
        (delete-region (point-min) (point))
        (tar-mode)
        (tar-untar-buffer))
    ;; FIXME: check the result.
    (call-process-region (point) (point-max) "tar" nil '(nil nil) nil
                         "xf" "-")))

(defun package-unpack (name version)
  (let ((pkg-dir (expand-file-name (concat (symbol-name name) "-" version)
                                   package-user-dir)))
    ;; Be careful!!
    (make-directory package-user-dir t)
    (if (file-directory-p pkg-dir)
        (mapc (lambda (file) nil) ; 'delete-file -- FIXME: when we're
                                  ; more confident
              (directory-files pkg-dir t "^[^.]")))
    (let* ((default-directory (file-name-as-directory package-user-dir)))
      (package-untar-buffer)
      (package-generate-autoloads (symbol-name name) pkg-dir)
      (let ((load-path (cons pkg-dir load-path)))
        (byte-recompile-directory pkg-dir 0 t)))))

(defun package--write-file-no-coding (file-name excl)
  (let ((buffer-file-coding-system 'no-conversion))
    (write-region (point-min) (point-max) file-name nil nil nil excl)))

(defun package-unpack-single (file-name version desc requires)
  "Install the contents of the current buffer as a package."
  ;; Special case "package".
  (if (string= file-name "package")
      (package--write-file-no-coding
       (expand-file-name (concat file-name ".el") package-user-dir)
       nil)
    (let* ((pkg-dir  (expand-file-name (concat file-name "-" version)
                                       package-user-dir))
           (el-file  (expand-file-name (concat file-name ".el") pkg-dir))
           (pkg-file (expand-file-name (concat file-name "-pkg.el") pkg-dir)))
      (make-directory pkg-dir t)
      (package--write-file-no-coding el-file 'excl)
      (let ((print-level nil)
            (print-length nil))
        (write-region
         (concat
          (prin1-to-string
           (list 'define-package
                 file-name
                 version
                 desc
                 (list 'quote
                       ;; Turn version lists into string form.
                       (mapcar
                        (lambda (elt)
                          (list (car elt)
                                (package-version-join (car (cdr elt)))))
                        requires))))
          "\n")
         nil
         pkg-file
         nil nil nil 'excl))
      (package-generate-autoloads file-name pkg-dir)
      (let ((load-path (cons pkg-dir load-path)))
        (byte-recompile-directory pkg-dir 0 t)))))

(defun package-handle-response ()
  "Handle the response from the server.
Parse the HTTP response and throw if an error occurred.
The url package seems to require extra processing for this.
This should be called in a `save-excursion', in the download buffer.
It will move point to somewhere in the headers."
  ;; We assume HTTP here.
  (require 'url-http)
  (let ((response (url-http-parse-response)))
    (when (or (< response 200) (>= response 300))
      (display-buffer (current-buffer))
      (error "Error during download request:%s"
             (buffer-substring-no-properties (point) (progn
                                                       (end-of-line)
                                                       (point)))))))

(defun package-download-single (name version desc requires)
  "Download and install a single-file package."
  (let ((buffer (url-retrieve-synchronously
                 (concat (package-archive-url name)
                         (symbol-name name) "-" version ".el"))))
    (with-current-buffer buffer
      (package-handle-response)
      (re-search-forward "^$" nil 'move)
      (forward-char)
      (delete-region (point-min) (point))
      (package-unpack-single (symbol-name name) version desc requires)
      (kill-buffer buffer))))

(defun package-download-tar (name version)
  "Download and install a tar package."
  (let ((tar-buffer (url-retrieve-synchronously
                     (concat (package-archive-url name)
                             (symbol-name name) "-" version ".tar"))))
    (with-current-buffer tar-buffer
      (package-handle-response)
      (re-search-forward "^$" nil 'move)
      (forward-char)
      (package-unpack name version)
      (kill-buffer tar-buffer))))

(defun package-installed-p (package &optional min-version)
  (let ((pkg-desc (assq package package-alist)))
    (and pkg-desc
         (package-version-compare min-version
                                  (package-desc-vers (cdr pkg-desc))
                                  '<=))))

(defun package-compute-transaction (result requirements)
  (dolist (elt requirements)
    (let* ((next-pkg (car elt))
           (next-version (cadr elt)))
      (unless (package-installed-p next-pkg next-version)
        ;; A package is required, but not installed.  It might also be
        ;; blocked via `package-load-list'.
        (let ((pkg-desc (assq next-pkg package-archive-contents))
              hold)
          (when (setq hold (assq next-pkg package-load-list))
            (setq hold (cadr hold))
            (cond ((eq hold nil)
                   (error "Required package '%s' is disabled"
                          (symbol-name next-pkg)))
                  ((null (stringp hold))
                   (error "Invalid element in `package-load-list'"))
                  ((package-version-compare next-version
                                            (package-version-split hold)
                                            '>)
                   (error "Package '%s' held at version %s, \
but version %s required"
                          (symbol-name next-pkg) hold
                          (package-version-join next-version)))))
          (unless pkg-desc
            (error "Package '%s' is not available for installation"
                   (symbol-name next-pkg)))
          (unless (package-version-compare (package-desc-vers (cdr pkg-desc))
                                           next-version
                                           '>=)
            (error
             "Need package '%s' with version %s, but only %s is available"
             (symbol-name next-pkg) (package-version-join next-version)
             (package-version-join (package-desc-vers (cdr pkg-desc)))))
          ;; Only add to the transaction if we don't already have it.
          (unless (memq next-pkg result)
            (setq result (cons next-pkg result)))
          (setq result
                (package-compute-transaction result
                                             (package-desc-reqs
                                              (cdr pkg-desc))))))))
  result)

(defun package-read-from-string (str)
  "Read a Lisp expression from STR.
Signal an error if the entire string was not used."
  (let* ((read-data (read-from-string str))
          (more-left
             (condition-case nil
                       ;; The call to `ignore' suppresses a compiler warning.
                       (progn (ignore (read-from-string
                                       (substring str (cdr read-data))))
                                   t)
                   (end-of-file nil))))
    (if more-left
        (error "Can't read whole string")
      (car read-data))))

(defun package--read-archive-file (file)
  "Re-read archive file FILE, if it exists.
Will return the data from the file, or nil if the file does not exist.
Will throw an error if the archive version is too new."
  (let ((filename (expand-file-name file package-user-dir)))
    (if (file-exists-p filename)
        (with-temp-buffer
          (insert-file-contents-literally filename)
          (let ((contents (package-read-from-string
                           (buffer-substring-no-properties (point-min)
                                                           (point-max)))))
            (if (> (car contents) package-archive-version)
                (error "Package archive version %d is greater than %d - upgrade package.el"
                       (car contents) package-archive-version))
            (cdr contents))))))

(defun package-read-all-archive-contents ()
  "Re-read `archive-contents' and `builtin-packages', if they exist.
Set `package-archive-contents' and `package--builtins' if successful.
Throw an error if the archive version is too new."
  (dolist (archive package-archives)
    (package-read-archive-contents (car archive)))
  (let ((builtins (package--read-archive-file "builtin-packages")))
    (if builtins
        ;; Version 1 of 'builtin-packages' is a list where the car is
        ;; a split emacs version and the cdr is an alist suitable for
        ;; package--builtins.
        (let ((our-version (package-version-split emacs-version))
              (result package--builtins-base))
          (setq package--builtins
                (dolist (elt builtins result)
                  (if (package-version-compare our-version (car elt) '>=)
                      (setq result (append (cdr elt) result)))))))))

(defun package-read-archive-contents (archive)
  "Re-read `archive-contents' and `builtin-packages' for ARCHIVE.
If successful, set `package-archive-contents' and `package--builtins'.
If the archive version is too new, signal an error."
  (let ((archive-contents (package--read-archive-file
                           (concat "archives/" archive
                                   "/archive-contents"))))
    (if archive-contents
        ;; Version 1 of 'archive-contents' is identical to our
        ;; internal representation.
        ;; TODO: merge archive lists
        (dolist (package archive-contents)
          (package--add-to-archive-contents package archive)))))

(defun package--add-to-archive-contents (package archive)
  "Add the PACKAGE from the given ARCHIVE if necessary.
Also, add the originating archive to the end of the package vector."
  (let* ((name    (car package))
         (version (aref (cdr package) 0))
         (entry   (cons (car package)
                        (vconcat (cdr package) (vector archive))))
         (existing-package (cdr (assq name package-archive-contents))))
    (when (or (not existing-package)
              (package-version-compare version
                                       (aref existing-package 0) '>))
      (add-to-list 'package-archive-contents entry))))

(defun package-download-transaction (transaction)
  "Download and install all the packages in the given transaction."
  (dolist (elt transaction)
    (let* ((desc (cdr (assq elt package-archive-contents)))
           ;; As an exception, if package is "held" in
           ;; `package-load-list', download the held version.
           (hold (cadr (assq elt package-load-list)))
           (v-string (or (and (stringp hold) hold)
                         (package-version-join (package-desc-vers desc))))
           (kind (package-desc-kind desc)))
      (cond
       ((eq kind 'tar)
        (package-download-tar elt v-string))
       ((eq kind 'single)
        (package-download-single elt v-string
                                 (package-desc-doc desc)
                                 (package-desc-reqs desc)))
       (t
        (error "Unknown package kind: %s" (symbol-name kind)))))))

;;;###autoload
(defun package-install (name)
  "Install the package named NAME.
Interactively, prompt for the package name.
The package is found on one of the archives in `package-archives'."
  (interactive
   (list (intern (completing-read "Install package: "
                                  (mapcar (lambda (elt)
                                            (cons (symbol-name (car elt))
                                                  nil))
                                          package-archive-contents)
                                  nil t))))
  (let ((pkg-desc (assq name package-archive-contents)))
    (unless pkg-desc
      (error "Package '%s' is not available for installation"
             (symbol-name name)))
    (package-download-transaction
     (package-compute-transaction (list name)
                                  (package-desc-reqs (cdr pkg-desc)))))
  ;; Try to activate it.
  (package-initialize))

(defun package-strip-rcs-id (v-str)
  "Strip RCS version ID from the version string.
If the result looks like a dotted numeric version, return it.
Otherwise return nil."
  (if v-str
      (if (string-match "^[ \t]*[$]Revision:[ \t]\([0-9.]+\)[ \t]*[$]$" v-str)
          (match-string 1 v-str)
        (if (string-match "^[0-9.]*$" v-str)
            v-str))))

(defun package-buffer-info ()
  "Return a vector of information about the package in the current buffer.
The vector looks like [FILENAME REQUIRES DESCRIPTION VERSION COMMENTARY]
FILENAME is the file name, a string.  It does not have the \".el\" extension.
REQUIRES is a requires list, or nil.
DESCRIPTION is the package description (a string).
VERSION is the version, a string.
COMMENTARY is the commentary section, a string, or nil if none.
Throws an exception if the buffer does not contain a conforming package.
If there is a package, narrows the buffer to the file's boundaries.
May narrow buffer or move point even on failure."
  (goto-char (point-min))
  (if (re-search-forward "^;;; \\([^ ]*\\)\\.el --- \\(.*\\)$" nil t)
      (let ((file-name (match-string 1))
            (desc (match-string 2))
            (start (progn (beginning-of-line) (point))))
        (if (search-forward (concat ";;; " file-name ".el ends here"))
            (progn
              ;; Try to include a trailing newline.
              (forward-line)
              (narrow-to-region start (point))
              (require 'lisp-mnt)
              ;; Use some headers we've invented to drive the process.
              (let* ((requires-str (lm-header "package-requires"))
                     (requires (if requires-str
                                   (package-read-from-string requires-str)))
                     ;; Prefer Package-Version, because if it is
                     ;; defined the package author probably wants us
                     ;; to use it.  Otherwise try Version.
                     (pkg-version
                      (or (package-strip-rcs-id (lm-header "package-version"))
                          (package-strip-rcs-id (lm-header "version"))))
                     (commentary (lm-commentary)))
                (unless pkg-version
                  (error
                   "Package does not define a usable \"Version\" or \"Package-Version\" header"))
                ;; Turn string version numbers into list form.
                (setq requires
                      (mapcar
                       (lambda (elt)
                         (list (car elt)
                               (package-version-split (car (cdr elt)))))
                       requires))
                (set-text-properties 0 (length file-name) nil file-name)
                (set-text-properties 0 (length pkg-version) nil pkg-version)
                (set-text-properties 0 (length desc) nil desc)
                (vector file-name requires desc pkg-version commentary)))
          (error "Package missing a terminating comment")))
    (error "No starting comment for package")))

(defun package-tar-file-info (file)
  "Find package information for a tar file.
FILE is the name of the tar file to examine.
The return result is a vector like `package-buffer-info'."
  (unless (string-match "^\\(.+\\)-\\([0-9.]+\\)\\.tar$" file)
    (error "`%s' doesn't have a package-ish name" file))
  (let* ((pkg-name (file-name-nondirectory (match-string-no-properties 1 file)))
         (pkg-version (match-string-no-properties 2 file))
         ;; Extract the package descriptor.
         (pkg-def-contents (shell-command-to-string
                            ;; Requires GNU tar.
                            (concat "tar -xOf " file " "
                                    pkg-name "-" pkg-version "/"
                                    pkg-name "-pkg.el")))
         (pkg-def-parsed (package-read-from-string pkg-def-contents)))
    (unless (eq (car pkg-def-parsed) 'define-package)
      (error "%s-pkg.el doesn't contain `define-package' sexp" pkg-name))
    (let ((name-str (nth 1 pkg-def-parsed))
          (version-string (nth 2 pkg-def-parsed))
          (docstring (nth 3 pkg-def-parsed))
          (requires (nth 4 pkg-def-parsed))

          (readme (shell-command-to-string
                   ;; Requires GNU tar.
                   (concat "tar -xOf " file " "
                           pkg-name "-" pkg-version "/README"))))
      (unless (equal pkg-version version-string)
        (error "Inconsistent versions!"))
      (unless (equal pkg-name name-str)
        (error "Inconsistent names!"))
      ;; Kind of a hack.
      (if (string-match ": Not found in archive" readme)
          (setq readme nil))
      ;; Turn string version numbers into list form.
      (if (eq (car requires) 'quote)
          (setq requires (car (cdr requires))))
      (setq requires
            (mapcar
             (lambda (elt)
               (list (car elt)
                     (package-version-split (car (cdr elt)))))
             requires))
      (vector pkg-name requires docstring version-string readme))))

(defun package-install-buffer-internal (pkg-info type)
  (save-excursion
    (save-restriction
      (let* ((file-name (aref pkg-info 0))
             (requires (aref pkg-info 1))
             (desc (if (string= (aref pkg-info 2) "")
                       "No description available."
                     (aref pkg-info 2)))
             (pkg-version (aref pkg-info 3)))
        ;; Download and install the dependencies.
        (let ((transaction (package-compute-transaction nil requires)))
          (package-download-transaction transaction))
        ;; Install the package itself.
        (cond
         ((eq type 'single)
          (package-unpack-single file-name pkg-version desc requires))
         ((eq type 'tar)
          (package-unpack (intern file-name) pkg-version))
         (t
          (error "Unknown type: %s" (symbol-name type))))
        ;; Try to activate it.
        (package-initialize)))))

;;;###autoload
(defun package-install-from-buffer ()
  "Install a package from the current buffer.
The package is assumed to be a single .el file which
follows the elisp comment guidelines; see
info node `(elisp)Library Headers'."
  (interactive)
  (package-install-buffer-internal (package-buffer-info) 'single))

;;;###autoload
(defun package-install-file (file)
  "Install a package from a file.
The file can either be a tar file or an Emacs Lisp file."
  (interactive "fPackage file name: ")
  (with-temp-buffer
    (insert-file-contents-literally file)
    (cond
     ((string-match "\\.el$" file) (package-install-from-buffer))
     ((string-match "\\.tar$" file)
      (package-install-buffer-internal (package-tar-file-info file) 'tar))
     (t (error "Unrecognized extension `%s'" (file-name-extension file))))))

(defun package-delete (name version)
  (require 'dired)                      ; for dired-delete-file
  (dired-delete-file (expand-file-name (concat name "-" version)
                                       package-user-dir)
                     ;; FIXME: query user?
                     'always))

(defun package-archive-url (name)
  "Return the archive containing the package NAME."
  (let ((desc (cdr (assq (intern-soft name) package-archive-contents))))
    (cdr (assoc (aref desc (- (length desc) 1)) package-archives))))

(defun package--download-one-archive (archive file)
  "Download an archive file FILE from ARCHIVE, and cache it locally."
  (let* ((archive-name (car archive))
         (archive-url  (cdr archive))
         (dir (expand-file-name "archives" package-user-dir))
         (dir (expand-file-name archive-name dir))
         (buffer (url-retrieve-synchronously (concat archive-url file))))
    (with-current-buffer buffer
      (package-handle-response)
      (re-search-forward "^$" nil 'move)
      (forward-char)
      (delete-region (point-min) (point))
      (make-directory dir t)
      (setq buffer-file-name (expand-file-name file dir))
      (let ((version-control 'never))
        (save-buffer)))
    (kill-buffer buffer)))

(defun package-refresh-contents ()
  "Download the ELPA archive description if needed.
Invoking this will ensure that Emacs knows about the latest versions
of all packages.  This will let Emacs make them available for
download."
  (interactive)
  (unless (file-exists-p package-user-dir)
    (make-directory package-user-dir t))
  (dolist (archive package-archives)
    (package--download-one-archive archive "archive-contents"))
  (package-read-all-archive-contents))

;;;###autoload
(defun package-initialize ()
  "Load Emacs Lisp packages, and activate them.
The variable `package-load-list' controls which packages to load."
  (interactive)
  (setq package-obsolete-alist nil)
  (package-load-all-descriptors)
  (package-read-all-archive-contents)
  ;; Try to activate all our packages.
  (mapc (lambda (elt)
          (package-activate (car elt) (package-desc-vers (cdr elt))))
        package-alist))

\f
;;;; Package description buffer.

;;;###autoload
(defun describe-package (package)
  "Display the full documentation of PACKAGE (a symbol)."
  (interactive
   (let* ((packages (append (mapcar 'car package-alist)
                            (mapcar 'car package-archive-contents)))
          (guess (function-called-at-point))
          val)
     (unless (memq guess packages)
       (setq guess nil))
     (setq packages (mapcar 'symbol-name packages))
     (setq val
           (completing-read (if guess
                                (format "Describe package (default %s): "
                                        guess)
                              "Describe package: ")
                            packages nil t nil nil guess))
     (list (if (equal val "")
               guess
             (intern val)))))
  (if (or (null package) (null (symbolp package)))
      (message "You did not specify a package")
    (help-setup-xref (list #'describe-package package)
                     (called-interactively-p 'interactive))
    (with-help-window (help-buffer)
      (with-current-buffer standard-output
        (describe-package-1 package)))))

(defun describe-package-1 (package)
  (let ((desc (cdr (assq package package-alist)))
        reqs version installable)
    (prin1 package)
    (princ " is ")
    (cond
     (desc
      ;; This package is loaded (i.e. in `package-alist').
      (let (pkg-dir)
        (setq version (package-version-join (package-desc-vers desc)))
        (if (assq package package--builtins)
            (princ "a built-in package.\n\n")
          (setq pkg-dir (package--dir (symbol-name package) version))
          (if pkg-dir
              (progn
                (insert "a package installed in `")
                (help-insert-xref-button (file-name-as-directory pkg-dir)
                                         'help-package-def pkg-dir)
                (insert "'.\n\n"))
            ;; This normally does not happen.
            (insert "a deleted package.\n\n")
            (setq version nil)))))
     (t
      ;; An uninstalled package.
      (setq desc (cdr (assq package package-archive-contents))
            version (package-version-join (package-desc-vers desc))
            installable t)
      (insert "an installable package.\n\n")))
    (if version
        (insert "      Version: " version "\n"))
    (setq reqs (package-desc-reqs desc))
    (when reqs
      (insert "     Requires: ")
      (let ((first t)
            name vers text)
        (dolist (req reqs)
          (setq name (car req)
                vers (cadr req)
                text (format "%s-%s" (symbol-name name)
                             (package-version-join vers)))
          (cond (first (setq first nil))
                ((>= (+ 2 (current-column) (length text))
                     (window-width))
                 (insert ",\n               "))
                (t (insert ", ")))
          (help-insert-xref-button text 'help-package name))
        (insert "\n")))
    (insert "  Description: " (package-desc-doc desc) "\n")
    ;; Todo: button for uninstalling a package.
    (when installable
      (let ((button-text (if (display-graphic-p)
                             "Install"
                           "[Install]"))
            (button-face (if (display-graphic-p)
                             '(:box (:line-width 2 :color "dark grey")
                                    :background "light grey"
                                    :foreground "black")
                           'link)))
        (insert "\n")
        (insert-text-button button-text
                            'face button-face
                            'follow-link t
                            'package-symbol package
                            'action (lambda (button)
                                      (package-install
                                       (button-get button 'package-symbol))
                                      (revert-buffer nil t)
                                      (goto-char (point-min))))
        (insert "\n")))))

\f
;;;; Package menu mode.

(defvar package-menu-mode-map
  (let ((map (make-keymap))
        (menu-map (make-sparse-keymap "Package")))
    (suppress-keymap map)
    (define-key map "\C-m" 'package-menu-describe-package)
    (define-key map "q" 'quit-window)
    (define-key map "n" 'next-line)
    (define-key map "p" 'previous-line)
    (define-key map "u" 'package-menu-mark-unmark)
    (define-key map "\177" 'package-menu-backup-unmark)
    (define-key map "d" 'package-menu-mark-delete)
    (define-key map "i" 'package-menu-mark-install)
    (define-key map "g" 'package-menu-revert)
    (define-key map "r" 'package-menu-refresh)
    (define-key map "~" 'package-menu-mark-obsolete-for-deletion)
    (define-key map "x" 'package-menu-execute)
    (define-key map "h" 'package-menu-quick-help)
    (define-key map "?" 'package-menu-view-commentary)
    (define-key map [menu-bar package-menu] (cons "Package" menu-map))
    (define-key menu-map [mq]
      '(menu-item "Quit" quit-window
                  :help "Quit package selection"))
    (define-key menu-map [s1] '("--"))
    (define-key menu-map [mn]
      '(menu-item "Next" next-line
                  :help "Next Line"))
    (define-key menu-map [mp]
      '(menu-item "Previous" previous-line
                  :help "Previous Line"))
    (define-key menu-map [s2] '("--"))
    (define-key menu-map [mu]
      '(menu-item "Unmark" package-menu-mark-unmark
                  :help "Clear any marks on a package and move to the next line"))
    (define-key menu-map [munm]
      '(menu-item "Unmark backwards" package-menu-backup-unmark
                  :help "Back up one line and clear any marks on that package"))
    (define-key menu-map [md]
      '(menu-item "Mark for deletion" package-menu-mark-delete
                  :help "Mark a package for deletion and move to the next line"))
    (define-key menu-map [mi]
      '(menu-item "Mark for install" package-menu-mark-install
                  :help "Mark a package for installation and move to the next line"))
    (define-key menu-map [s3] '("--"))
    (define-key menu-map [mg]
      '(menu-item "Update package list" package-menu-revert
                  :help "Update the list of packages"))
    (define-key menu-map [mr]
      '(menu-item "Refresh package list" package-menu-refresh
                  :help "Download the ELPA archive"))
    (define-key menu-map [s4] '("--"))
    (define-key menu-map [mt]
      '(menu-item "Mark obsolete packages" package-menu-mark-obsolete-for-deletion
                  :help "Mark all obsolete packages for deletion"))
    (define-key menu-map [mx]
      '(menu-item "Execute actions" package-menu-execute
                  :help "Perform all the marked actions"))
    (define-key menu-map [s5] '("--"))
    (define-key menu-map [mh]
      '(menu-item "Help" package-menu-quick-help
                  :help "Show short key binding help for package-menu-mode"))
    (define-key menu-map [mc]
      '(menu-item "View Commentary" package-menu-view-commentary
                  :help "Display information about this package"))
    map)
  "Local keymap for `package-menu-mode' buffers.")

(defvar package-menu-sort-button-map
  (let ((map (make-sparse-keymap)))
    (define-key map [header-line mouse-1] 'package-menu-sort-by-column)
    (define-key map [follow-link] 'mouse-face)
    map)
  "Local keymap for package menu sort buttons.")

(put 'package-menu-mode 'mode-class 'special)

(defun package-menu-mode ()
  "Major mode for browsing a list of packages.
Letters do not insert themselves; instead, they are commands.
\\<package-menu-mode-map>
\\{package-menu-mode-map}"
  (kill-all-local-variables)
  (use-local-map package-menu-mode-map)
  (setq major-mode 'package-menu-mode)
  (setq mode-name "Package Menu")
  (setq truncate-lines t)
  (setq buffer-read-only t)
  ;; Support Emacs 21.
  (if (fboundp 'run-mode-hooks)
      (run-mode-hooks 'package-menu-mode-hook)
    (run-hooks 'package-menu-mode-hook)))

(defun package-menu-refresh ()
  "Download the ELPA archive.
This fetches the file describing the current contents of
the Emacs Lisp Package Archive, and then refreshes the
package menu.  This lets you see what new packages are
available for download."
  (interactive)
  (package-refresh-contents)
  (package-list-packages-internal))

(defun package-menu-revert ()
  "Update the list of packages."
  (interactive)
  (package-list-packages-internal))

(defun package-menu-describe-package ()
  "Describe the package in the current line."
  (interactive)
  (let ((name (package-menu-get-package)))
    (if name
        (describe-package (intern name))
      (message "No package on this line"))))

(defun package-menu-mark-internal (what)
  (unless (eobp)
    (let ((buffer-read-only nil))
      (beginning-of-line)
      (delete-char 1)
      (insert what)
      (forward-line))))

;; fixme numeric argument
(defun package-menu-mark-delete (num)
  "Mark a package for deletion and move to the next line."
  (interactive "p")
  (package-menu-mark-internal "D"))

(defun package-menu-mark-install (num)
  "Mark a package for installation and move to the next line."
  (interactive "p")
  (package-menu-mark-internal "I"))

(defun package-menu-mark-unmark (num)
  "Clear any marks on a package and move to the next line."
  (interactive "p")
  (package-menu-mark-internal " "))

(defun package-menu-backup-unmark ()
  "Back up one line and clear any marks on that package."
  (interactive)
  (forward-line -1)
  (package-menu-mark-internal " ")
  (forward-line -1))

(defun package-menu-mark-obsolete-for-deletion ()
  "Mark all obsolete packages for deletion."
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (forward-line 2)
    (while (not (eobp))
      (if (looking-at ".*\\s obsolete\\s ")
          (package-menu-mark-internal "D")
        (forward-line 1)))))

(defun package-menu-quick-help ()
  "Show short key binding help for package-menu-mode."
  (interactive)
  (message "n-ext, i-nstall, d-elete, u-nmark, x-ecute, r-efresh, h-elp"))

(defun package-menu-view-commentary ()
  "Display information about this package.
For single-file packages, shows the commentary section from the header.
For larger packages, shows the README file."
  (interactive)
  (let* ((pkg-name (package-menu-get-package))
         (buffer (url-retrieve-synchronously
                  (concat (package-archive-url pkg-name)
                          pkg-name
                          "-readme.txt")))
         start-point ok)
    (with-current-buffer buffer
      ;; FIXME: it would be nice to work with any URL type.
      (setq start-point url-http-end-of-headers)
      (setq ok (eq (url-http-parse-response) 200)))
    (let ((new-buffer (get-buffer-create "*Package Info*")))
      (with-current-buffer new-buffer
        (let ((buffer-read-only nil))
          (erase-buffer)
          (insert "Package information for " pkg-name "\n\n")
          (if ok
              (insert-buffer-substring buffer start-point)
            (insert "This package lacks a README file or commentary.\n"))
          (goto-char (point-min))
          (view-mode)))
      (display-buffer new-buffer t))))

;; Return the name of the package on the current line.
(defun package-menu-get-package ()
  (save-excursion
    (beginning-of-line)
    (if (looking-at ". \\([^ \t]*\\)")
        (match-string-no-properties 1))))

;; Return the version of the package on the current line.
(defun package-menu-get-version ()
  (save-excursion
    (beginning-of-line)
    (if (looking-at ". [^ \t]*[ \t]*\\([0-9.]*\\)")
        (match-string 1))))

(defun package-menu-get-status ()
  (save-excursion
    (if (looking-at ". [^ \t]*[ \t]*[^ \t]*[ \t]*\\([^ \t]*\\)")
        (match-string 1)
      "")))

(defun package-menu-execute ()
  "Perform all the marked actions.
Packages marked for installation will be downloaded and
installed.  Packages marked for deletion will be removed.
Note that after installing packages you will want to restart
Emacs."
  (interactive)
  (goto-char (point-min))
  (while (not (eobp))
    (let ((cmd (char-after))
          (pkg-name (package-menu-get-package))
          (pkg-vers (package-menu-get-version))
          (pkg-status (package-menu-get-status)))
      (cond
       ((eq cmd ?D)
        (when (and (string= pkg-status "installed")
                   (string= pkg-name "package"))
          ;; FIXME: actually, we could be tricky and remove all info.
          ;; But that is drastic and the user can do that instead.
          (error "Can't delete most recent version of `package'"))
        ;; Ask for confirmation here?  Maybe if package status is ""?
        ;; Or if any lisp from package is actually loaded?
        (message "Deleting %s-%s..." pkg-name pkg-vers)
        (package-delete pkg-name pkg-vers)
        (message "Deleting %s-%s... done" pkg-name pkg-vers))
       ((eq cmd ?I)
        (package-install (intern pkg-name)))))
    (forward-line))
  (package-menu-revert))

(defun package-print-package (package version key desc)
  (let ((face
         (cond ((string= key "built-in") 'font-lock-builtin-face)
               ((string= key "available") 'default)
               ((string= key "held") 'font-lock-constant-face)
               ((string= key "disabled") 'font-lock-warning-face)
               ((string= key "installed") 'font-lock-comment-face)
               (t ; obsolete, but also the default.
                'font-lock-warning-face))))
    (insert (propertize "  " 'font-lock-face face))
    (insert-text-button (symbol-name package)
                        'face 'link
                        'follow-link t
                        'package-symbol package
                        'action (lambda (button)
                                  (describe-package
                                   (button-get button 'package-symbol))))
    (indent-to 20 1)
    (insert (propertize (package-version-join version) 'font-lock-face face))
    (indent-to 32 1)
    (insert (propertize key 'font-lock-face face))
    ;; FIXME: this 'when' is bogus...
    (when desc
      (indent-to 43 1)
      (let ((opoint (point)))
        (insert (propertize desc 'font-lock-face face))
        (upcase-region opoint (min (point) (1+ opoint)))))
    (insert "\n")))

(defun package-list-maybe-add (package version status description result)
  (unless (assoc (cons package version) result)
    (setq result (cons (list (cons package version) status description)
                       result)))
  result)

;; This decides how we should sort; nil means by package name.
(defvar package-menu-sort-key nil)

(defun package-list-packages-internal ()
  (package-initialize)                  ; FIXME: do this here?
  (with-current-buffer (get-buffer-create "*Packages*")
    (setq buffer-read-only nil)
    (erase-buffer)
    (let ((info-list)
          name desc hold
          builtin)
      ;; List installed packages
      (dolist (elt package-alist)
        ;; Ignore the Emacs package.
        (setq name (car elt)
              desc (cdr elt)
              hold (assq name package-load-list))
        (unless (eq name 'emacs)
          (setq info-list
                (package-list-maybe-add
                 name (package-desc-vers desc)
                 ;; FIXME: it turns out to be tricky to see if this
                 ;; package is presently activated.
                 (cond ((stringp (cadr hold))
                        "held")
                       ((and (setq builtin (assq name package--builtins))
                             (package-version-compare
                              (package-desc-vers (cdr builtin))
                              (package-desc-vers desc)
                              '=))
                        "built-in")
                       (t "installed"))
                 (package-desc-doc desc)
                 info-list))))
      ;; List available packages
      (dolist (elt package-archive-contents)
        (setq name (car elt)
              desc (cdr elt)
              hold (assq name package-load-list))
        (unless (and hold (stringp (cadr hold))
                     (package-installed-p
                      name (package-version-split (cadr hold))))
          (setq info-list
                (package-list-maybe-add name
                                        (package-desc-vers desc)
                                        (if (and hold (null (cadr hold)))
                                            "disabled"
                                          "available")
                                        (package-desc-doc (cdr elt))
                                        info-list))))
      ;; List obsolete packages
      (mapc (lambda (elt)
              (mapc (lambda (inner-elt)
                      (setq info-list
                            (package-list-maybe-add (car elt)
                                                    (package-desc-vers
                                                     (cdr inner-elt))
                                                    "obsolete"
                                                    (package-desc-doc
                                                     (cdr inner-elt))
                                                    info-list)))
                    (cdr elt)))
            package-obsolete-alist)
      (let ((selector (cond
                       ((string= package-menu-sort-key "Version")
                        ;; FIXME this doesn't work.
                        #'(lambda (e) (cdr (car e))))
                       ((string= package-menu-sort-key "Status")
                        #'(lambda (e) (car (cdr e))))
                       ((string= package-menu-sort-key "Description")
                        #'(lambda (e) (car (cdr (cdr e)))))
                       (t ; "Package" is default.
                        #'(lambda (e) (symbol-name (car (car e))))))))
        (setq info-list
              (sort info-list
                    (lambda (left right)
                      (let ((vleft (funcall selector left))
                            (vright (funcall selector right)))
                        (string< vleft vright))))))
      (mapc (lambda (elt)
              (package-print-package (car (car elt))
                                     (cdr (car elt))
                                     (car (cdr elt))
                                     (car (cdr (cdr elt)))))
            info-list))
    (goto-char (point-min))
    (current-buffer)))

(defun package-menu-sort-by-column (&optional e)
  "Sort the package menu by the last column clicked on."
  (interactive (list last-input-event))
  (if e (mouse-select-window e))
  (let* ((pos (event-start e))
         (obj (posn-object pos))
         (col (if obj
                  (get-text-property (cdr obj) 'column-name (car obj))
                (get-text-property (posn-point pos) 'column-name))))
    (setq package-menu-sort-key col))
  (package-list-packages-internal))

(defun package--list-packages ()
  "Display a list of packages.
Helper function that does all the work for the user-facing functions."
  (with-current-buffer (package-list-packages-internal)
    (package-menu-mode)
    ;; Set up the header line.
    (setq header-line-format
          (mapconcat
           (lambda (pair)
             (let ((column (car pair))
                   (name (cdr pair)))
               (concat
                ;; Insert a space that aligns the button properly.
                (propertize " " 'display (list 'space :align-to column)
                            'face 'fixed-pitch)
                ;; Set up the column button.
                (if (string= name "Version")
                    name
                  (propertize name
                              'column-name name
                              'help-echo "mouse-1: sort by column"
                              'mouse-face 'highlight
                              'keymap package-menu-sort-button-map)))))
           ;; We take a trick from buff-menu and have a dummy leading
           ;; space to align the header line with the beginning of the
           ;; text.  This doesn't really work properly on Emacs 21,
           ;; but it is close enough.
           '((0 . "")
             (2 . "Package")
             (20 . "Version")
             (32 . "Status")
             (43 . "Description"))
           ""))

    ;; It's okay to use pop-to-buffer here.  The package menu buffer
    ;; has keybindings, and the user just typed 'M-x
    ;; package-list-packages', suggesting that they might want to use
    ;; them.
    (pop-to-buffer (current-buffer))))

;;;###autoload
(defun package-list-packages ()
  "Display a list of packages.
Fetches the updated list of packages before displaying.
The list is displayed in a buffer named `*Packages*'."
  (interactive)
  (package-refresh-contents)
  (package--list-packages))

(defun package-list-packages-no-fetch ()
  "Display a list of packages.
Does not fetch the updated list of packages before displaying.
The list is displayed in a buffer named `*Packages*'."
  (interactive)
  (package--list-packages))

(provide 'package)

;;; package.el ends here