;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
;;; Copyright © 2013, 2015 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2014, 2016 Alex Kost <alezost@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix 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 Guix 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 Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (guix scripts package)
  #:use-module (guix ui)
  #:use-module (guix store)
  #:use-module (guix grafts)
  #:use-module (guix derivations)
  #:use-module (guix packages)
  #:use-module (guix profiles)
  #:use-module (guix search-paths)
  #:use-module (guix monads)
  #:use-module (guix utils)
  #:use-module (guix config)
  #:use-module (guix scripts)
  #:use-module (guix scripts build)
  #:use-module ((guix build utils)
                #:select (directory-exists? mkdir-p))
  #:use-module (ice-9 format)
  #:use-module (ice-9 match)
  #:use-module (ice-9 vlist)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (srfi srfi-37)
  #:use-module (gnu packages)
  #:autoload   (gnu packages base) (canonical-package)
  #:autoload   (gnu packages guile) (guile-2.0)
  #:autoload   (gnu packages bootstrap) (%bootstrap-guile)
  #:export (delete-generations
            display-search-paths
            guix-package))

(define %store
  (make-parameter #f))


;;;
;;; Profiles.
;;;

(define %user-profile-directory
  (and=> (getenv "HOME")
         (cut string-append <> "/.guix-profile")))

(define %profile-directory
  (string-append %state-directory "/profiles/"
                 (or (and=> (or (getenv "USER")
                                (getenv "LOGNAME"))
                            (cut string-append "per-user/" <>))
                     "default")))

(define %current-profile
  ;; Call it `guix-profile', not `profile', to allow Guix profiles to
  ;; coexist with Nix profiles.
  (string-append %profile-directory "/guix-profile"))

(define (canonicalize-profile profile)
  "If PROFILE is %USER-PROFILE-DIRECTORY, return %CURRENT-PROFILE.  Otherwise
return PROFILE unchanged.  The goal is to treat '-p ~/.guix-profile' as if
'-p' was omitted."                           ; see <http://bugs.gnu.org/17939>
  (if (and %user-profile-directory
           (string=? (canonicalize-path (dirname profile))
                     (dirname %user-profile-directory))
           (string=? (basename profile) (basename %user-profile-directory)))
      %current-profile
      profile))

(define (user-friendly-profile profile)
  "Return either ~/.guix-profile if that's what PROFILE refers to, directly or
indirectly, or PROFILE."
  (if (and %user-profile-directory
           (false-if-exception
            (string=? (readlink %user-profile-directory) profile)))
      %user-profile-directory
      profile))

(define (ensure-default-profile)
  "Ensure the default profile symlink and directory exist and are writable."

  (define (rtfm)
    (format (current-error-port)
            (_ "Try \"info '(guix) Invoking guix package'\" for \
more information.~%"))
    (exit 1))

  ;; Create ~/.guix-profile if it doesn't exist yet.
  (when (and %user-profile-directory
             %current-profile
             (not (false-if-exception
                   (lstat %user-profile-directory))))
    (symlink %current-profile %user-profile-directory))

  (let ((s (stat %profile-directory #f)))
    ;; Attempt to create /…/profiles/per-user/$USER if needed.
    (unless (and s (eq? 'directory (stat:type s)))
      (catch 'system-error
        (lambda ()
          (mkdir-p %profile-directory))
        (lambda args
          ;; Often, we cannot create %PROFILE-DIRECTORY because its
          ;; parent directory is root-owned and we're running
          ;; unprivileged.
          (format (current-error-port)
                  (_ "error: while creating directory `~a': ~a~%")
                  %profile-directory
                  (strerror (system-error-errno args)))
          (format (current-error-port)
                  (_ "Please create the `~a' directory, with you as the owner.~%")
                  %profile-directory)
          (rtfm))))

    ;; Bail out if it's not owned by the user.
    (unless (or (not s) (= (stat:uid s) (getuid)))
      (format (current-error-port)
              (_ "error: directory `~a' is not owned by you~%")
              %profile-directory)
      (format (current-error-port)
              (_ "Please change the owner of `~a' to user ~s.~%")
              %profile-directory (or (getenv "USER")
                                     (getenv "LOGNAME")
                                     (getuid)))
      (rtfm))))

(define (delete-generations store profile generations)
  "Delete GENERATIONS from PROFILE.
GENERATIONS is a list of generation numbers."
  (for-each (cut delete-generation* store profile <>)
            generations))

(define (delete-matching-generations store profile pattern)
  "Delete from PROFILE all the generations matching PATTERN.  PATTERN must be
a string denoting a set of generations: the empty list means \"all generations
but the current one\", a number designates a generation, and other patterns
denote ranges as interpreted by 'matching-generations'."
  (let ((current (generation-number profile)))
    (cond ((not (file-exists? profile))            ; XXX: race condition
           (raise (condition (&profile-not-found-error
                              (profile profile)))))
          ((string-null? pattern)
           (delete-generations store profile
                               (delv current (profile-generations profile))))
          ;; Do not delete the zeroth generation.
          ((equal? 0 (string->number pattern))
           #t)

          ;; If PATTERN is a duration, match generations that are
          ;; older than the specified duration.
          ((matching-generations pattern profile
                                 #:duration-relation >)
           =>
           (lambda (numbers)
             (when (memv current numbers)
               (warning (_ "not removing generation ~a, which is current~%")
                        current))

             ;; Make sure we don't inadvertently remove the current
             ;; generation.
             (let ((numbers (delv current numbers)))
               (when (null-list? numbers)
                 (leave (_ "no matching generation~%")))
               (delete-generations store profile numbers))))
          (else
           (leave (_ "invalid syntax: ~a~%") pattern)))))

(define* (build-and-use-profile store profile manifest
                                #:key
                                bootstrap? use-substitutes?
                                dry-run?)
  "Build a new generation of PROFILE, a file name, using the packages
specified in MANIFEST, a manifest object."
  (when (equal? profile %current-profile)
    (ensure-default-profile))

  (let* ((prof-drv (run-with-store store
                     (profile-derivation manifest
                                         #:hooks (if bootstrap?
                                                     '()
                                                     %default-profile-hooks))))
         (prof     (derivation->output-path prof-drv)))
    (show-what-to-build store (list prof-drv)
                        #:use-substitutes? use-substitutes?
                        #:dry-run? dry-run?)

    (cond
     (dry-run? #t)
     ((and (file-exists? profile)
           (and=> (readlink* profile) (cut string=? prof <>)))
      (format (current-error-port) (_ "nothing to be done~%")))
     (else
      (let* ((number (generation-number profile))

             ;; Always use NUMBER + 1 for the new profile, possibly
             ;; overwriting a "previous future generation".
             (name   (generation-file-name profile (+ 1 number))))
        (and (build-derivations store (list prof-drv))
             (let* ((entries (manifest-entries manifest))
                    (count   (length entries)))
               (switch-symlinks name prof)
               (switch-symlinks profile name)
               (unless (string=? profile %current-profile)
                 (register-gc-root store name))
               (format #t (N_ "~a package in profile~%"
                              "~a packages in profile~%"
                              count)
                       count)
               (display-search-paths entries (list profile)))))))))


;;;
;;; Package specifications.
;;;

(define (find-packages-by-description regexps)
  "Return the list of packages whose name matches one of REGEXPS, or whose
synopsis or description matches all of REGEXPS."
  (define version<? (negate version>=?))

  (define (matches-all? str)
    (every (cut regexp-exec <> str) regexps))

  (define (matches-one? str)
    (find (cut regexp-exec <> str) regexps))

  (sort
   (fold-packages (lambda (package result)
                    (if (or (matches-one? (package-name package))
                            (and=> (package-synopsis package)
                                   (compose matches-all? P_))
                            (and=> (package-description package)
                                   (compose matches-all? P_)))
                        (cons package result)
                        result))
                  '())
   (lambda (p1 p2)
     (case (string-compare (package-name p1) (package-name p2)
                           (const '<) (const '=) (const '>))
       ((=)  (version<? (package-version p1) (package-version p2)))
       ((<)  #t)
       (else #f)))))

(define (upgradeable? name current-version current-path)
  "Return #t if there's a version of package NAME newer than CURRENT-VERSION,
or if the newest available version is equal to CURRENT-VERSION but would have
an output path different than CURRENT-PATH."
  (match (vhash-assoc name (find-newest-available-packages))
    ((_ candidate-version pkg . rest)
     (case (version-compare candidate-version current-version)
       ((>) #t)
       ((<) #f)
       ((=) (let ((candidate-path (derivation->output-path
                                   (package-derivation (%store) pkg))))
              (not (string=? current-path candidate-path))))))
    (#f #f)))


;;;
;;; Search paths.
;;;

(define* (search-path-environment-variables entries profiles
                                            #:optional (getenv getenv)
                                            #:key (kind 'exact))
  "Return environment variable definitions that may be needed for the use of
ENTRIES, a list of manifest entries, in PROFILES.  Use GETENV to determine the
current settings and report only settings not already effective.  KIND
must be one of 'exact, 'prefix, or 'suffix, depending on the kind of search
path definition to be returned."
  (let ((search-paths (delete-duplicates
                       (cons $PATH
                             (append-map manifest-entry-search-paths
                                         entries)))))
    (filter-map (match-lambda
                  ((spec . value)
                   (let ((variable (search-path-specification-variable spec))
                         (sep      (search-path-specification-separator spec)))
                     (environment-variable-definition variable value
                                                      #:separator sep
                                                      #:kind kind))))
                (evaluate-search-paths search-paths profiles
                                       getenv))))

(define* (display-search-paths entries profiles
                               #:key (kind 'exact))
  "Display the search path environment variables that may need to be set for
ENTRIES, a list of manifest entries, in the context of PROFILE."
  (let* ((profiles (map user-friendly-profile profiles))
         (settings (search-path-environment-variables entries profiles
                                                      #:kind kind)))
    (unless (null? settings)
      (format #t (_ "The following environment variable definitions may be needed:~%"))
      (format #t "~{   ~a~%~}" settings))))


;;;
;;; Command-line options.
;;;

(define %default-options
  ;; Alist of default option values.
  `((max-silent-time . 3600)
    (verbosity . 0)
    (graft? . #t)
    (substitutes? . #t)))

(define (show-help)
  (display (_ "Usage: guix package [OPTION]...
Install, remove, or upgrade packages in a single transaction.\n"))
  (display (_ "
  -i, --install PACKAGE ...
                         install PACKAGEs"))
  (display (_ "
  -e, --install-from-expression=EXP
                         install the package EXP evaluates to"))
  (display (_ "
  -f, --install-from-file=FILE
                         install the package that the code within FILE
                         evaluates to"))
  (display (_ "
  -r, --remove PACKAGE ...
                         remove PACKAGEs"))
  (display (_ "
  -u, --upgrade[=REGEXP] upgrade all the installed packages matching REGEXP"))
  (display (_ "
  -m, --manifest=FILE    create a new profile generation with the manifest
                         from FILE"))
  (display (_ "
      --do-not-upgrade[=REGEXP] do not upgrade any packages matching REGEXP"))
  (display (_ "
      --roll-back        roll back to the previous generation"))
  (display (_ "
      --search-paths[=KIND]
                         display needed environment variable definitions"))
  (display (_ "
  -l, --list-generations[=PATTERN]
                         list generations matching PATTERN"))
  (display (_ "
  -d, --delete-generations[=PATTERN]
                         delete generations matching PATTERN"))
  (display (_ "
  -S, --switch-generation=PATTERN
                         switch to a generation matching PATTERN"))
  (display (_ "
  -p, --profile=PROFILE  use PROFILE instead of the user's default profile"))
  (newline)
  (display (_ "
      --bootstrap        use the bootstrap Guile to build the profile"))
  (display (_ "
      --verbose          produce verbose output"))
  (newline)
  (display (_ "
  -s, --search=REGEXP    search in synopsis and description using REGEXP"))
  (display (_ "
  -I, --list-installed[=REGEXP]
                         list installed packages matching REGEXP"))
  (display (_ "
  -A, --list-available[=REGEXP]
                         list available packages matching REGEXP"))
  (display (_ "
      --show=PACKAGE     show details about PACKAGE"))
  (newline)
  (show-build-options-help)
  (newline)
  (show-transformation-options-help)
  (newline)
  (display (_ "
  -h, --help             display this help and exit"))
  (display (_ "
  -V, --version          display version information and exit"))
  (newline)
  (show-bug-report-information))

(define %options
  ;; Specification of the command-line options.
  (cons* (option '(#\h "help") #f #f
                 (lambda args
                   (show-help)
                   (exit 0)))
         (option '(#\V "version") #f #f
                 (lambda args
                   (show-version-and-exit "guix package")))

         (option '(#\i "install") #f #t
                 (lambda (opt name arg result arg-handler)
                   (let arg-handler ((arg arg) (result result))
                     (values (if arg
                                 (alist-cons 'install arg result)
                                 result)
                             arg-handler))))
         (option '(#\e "install-from-expression") #t #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'install (read/eval-package-expression arg)
                                       result)
                           #f)))
         (option '(#\f "install-from-file") #t #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'install
                                       (load* arg (make-user-module '()))
                                       result)
                           #f)))
         (option '(#\r "remove") #f #t
                 (lambda (opt name arg result arg-handler)
                   (let arg-handler ((arg arg) (result result))
                     (values (if arg
                                 (alist-cons 'remove arg result)
                                 result)
                             arg-handler))))
         (option '(#\u "upgrade") #f #t
                 (lambda (opt name arg result arg-handler)
                   (let arg-handler ((arg arg) (result result))
                     (values (alist-cons 'upgrade arg
                                         ;; Delete any prior "upgrade all"
                                         ;; command, or else "--upgrade gcc"
                                         ;; would upgrade everything.
                                         (delete '(upgrade . #f) result))
                             arg-handler))))
         (option '("do-not-upgrade") #f #t
                 (lambda (opt name arg result arg-handler)
                   (let arg-handler ((arg arg) (result result))
                     (values (if arg
                                 (alist-cons 'do-not-upgrade arg result)
                                 result)
                             arg-handler))))
         (option '("roll-back") #f #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'roll-back? #t result)
                           #f)))
         (option '(#\m "manifest") #t #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'manifest arg result)
                           arg-handler)))
         (option '(#\l "list-generations") #f #t
                 (lambda (opt name arg result arg-handler)
                   (values (cons `(query list-generations ,(or arg ""))
                                 result)
                           #f)))
         (option '(#\d "delete-generations") #f #t
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'delete-generations (or arg "")
                                       result)
                           #f)))
         (option '(#\S "switch-generation") #t #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'switch-generation arg result)
                           #f)))
         (option '("search-paths") #f #t
                 (lambda (opt name arg result arg-handler)
                   (let ((kind (match arg
                                 ((or "exact" "prefix" "suffix")
                                  (string->symbol arg))
                                 (#f
                                  'exact)
                                 (x
                                  (leave (_ "~a: unsupported \
kind of search path~%")
                                         x)))))
                     (values (cons `(query search-paths ,kind)
                                   result)
                             #f))))
         (option '(#\p "profile") #t #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'profile (canonicalize-profile arg)
                                       result)
                           #f)))
         (option '(#\n "dry-run") #f #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'dry-run? #t result)
                           #f)))
         (option '("bootstrap") #f #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'bootstrap? #t result)
                           #f)))
         (option '("verbose") #f #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'verbose? #t result)
                           #f)))
         (option '(#\s "search") #t #f
                 (lambda (opt name arg result arg-handler)
                   (values (cons `(query search ,(or arg ""))
                                 result)
                           #f)))
         (option '(#\I "list-installed") #f #t
                 (lambda (opt name arg result arg-handler)
                   (values (cons `(query list-installed ,(or arg ""))
                                 result)
                           #f)))
         (option '(#\A "list-available") #f #t
                 (lambda (opt name arg result arg-handler)
                   (values (cons `(query list-available ,(or arg ""))
                                 result)
                           #f)))
         (option '("show") #t #t
                 (lambda (opt name arg result arg-handler)
                   (values (cons `(query show ,arg)
                                 result)
                           #f)))

         (append %transformation-options
                 %standard-build-options)))

(define (options->upgrade-predicate opts)
  "Return a predicate based on the upgrade/do-not-upgrade regexps in OPTS
that, given a package name, returns true if the package is a candidate for
upgrading, #f otherwise."
  (define upgrade-regexps
    (filter-map (match-lambda
                  (('upgrade . regexp)
                   (make-regexp* (or regexp "")))
                  (_ #f))
                opts))

  (define do-not-upgrade-regexps
    (filter-map (match-lambda
                  (('do-not-upgrade . regexp)
                   (make-regexp* regexp))
                  (_ #f))
                opts))

  (lambda (name)
    (and (any (cut regexp-exec <> name) upgrade-regexps)
         (not (any (cut regexp-exec <> name) do-not-upgrade-regexps)))))

(define (store-item->manifest-entry item)
  "Return a manifest entry for ITEM, a \"/gnu/store/...\" file name."
  (let-values (((name version)
                (package-name->name+version (store-path-package-name item))))
    (manifest-entry
      (name name)
      (version version)
      (output #f)
      (item item))))

(define (options->installable opts manifest)
  "Given MANIFEST, the current manifest, and OPTS, the result of 'args-fold',
return the new list of manifest entries."
  (define upgrade?
    (options->upgrade-predicate opts))

  (define to-upgrade
    (filter-map (match-lambda
                  (($ <manifest-entry> name version output path _)
                   (and (upgrade? name)
                        (upgradeable? name version path)
                        (let ((output (or output "out")))
                          (call-with-values
                              (lambda ()
                                (specification->package+output name output))
                            package->manifest-entry))))
                  (_ #f))
                (manifest-entries manifest)))

  (define to-install
    (filter-map (match-lambda
                  (('install . (? package? p))
                   ;; When given a package via `-e', install the first of its
                   ;; outputs (XXX).
                   (package->manifest-entry p "out"))
                  (('install . (? string? spec))
                   (if (store-path? spec)
                       (store-item->manifest-entry spec)
                       (let-values (((package output)
                                     (specification->package+output spec)))
                         (package->manifest-entry package output))))
                  (_ #f))
                opts))

  (append to-upgrade to-install))

(define (options->removable options manifest)
  "Given options, return the list of manifest patterns of packages to be
removed from MANIFEST."
  (filter-map (match-lambda
               (('remove . spec)
                (call-with-values
                    (lambda ()
                      (package-specification->name+version+output spec))
                  (lambda (name version output)
                    (manifest-pattern
                      (name name)
                      (version version)
                      (output output)))))
               (_ #f))
              options))

(define (register-gc-root store profile)
  "Register PROFILE, a profile generation symlink, as a GC root, unless it
doesn't need it."
  (define absolute
    ;; We must pass the daemon an absolute file name for PROFILE.  However, we
    ;; cannot use (canonicalize-path profile) because that would return us the
    ;; target of PROFILE in the store; using a store item as an indirect root
    ;; would mean that said store item will always remain live, which is not
    ;; what we want here.
    (if (string-prefix? "/" profile)
        profile
        (string-append (getcwd) "/" profile)))

  (add-indirect-root store absolute))


;;;
;;; Queries and actions.
;;;

(define (process-query opts)
  "Process any query specified by OPTS.  Return #t when a query was actually
processed, #f otherwise."
  (let* ((profiles (match (filter-map (match-lambda
                                        (('profile . p) p)
                                        (_              #f))
                                      opts)
                     (() (list %current-profile))
                     (lst lst)))
         (profile  (match profiles
                     ((head tail ...) head))))
    (match (assoc-ref opts 'query)
      (('list-generations pattern)
       (define (list-generation number)
         (unless (zero? number)
           (display-generation profile number)
           (display-profile-content profile number)
           (newline)))

       (cond ((not (file-exists? profile))      ; XXX: race condition
              (raise (condition (&profile-not-found-error
                                 (profile profile)))))
             ((string-null? pattern)
              (for-each list-generation (profile-generations profile)))
             ((matching-generations pattern profile)
              =>
              (lambda (numbers)
                (if (null-list? numbers)
                    (exit 1)
                    (leave-on-EPIPE
                     (for-each list-generation numbers)))))
             (else
              (leave (_ "invalid syntax: ~a~%")
                     pattern)))
       #t)

      (('list-installed regexp)
       (let* ((regexp    (and regexp (make-regexp* regexp)))
              (manifest  (profile-manifest profile))
              (installed (manifest-entries manifest)))
         (leave-on-EPIPE
          (for-each (match-lambda
                      (($ <manifest-entry> name version output path _)
                       (when (or (not regexp)
                                 (regexp-exec regexp name))
                         (format #t "~a\t~a\t~a\t~a~%"
                                 name (or version "?") output path))))

                    ;; Show most recently installed packages last.
                    (reverse installed)))
         #t))

      (('list-available regexp)
       (let* ((regexp    (and regexp (make-regexp* regexp)))
              (available (fold-packages
                          (lambda (p r)
                            (let ((n (package-name p)))
                              (if (supported-package? p)
                                  (if regexp
                                      (if (regexp-exec regexp n)
                                          (cons p r)
                                          r)
                                      (cons p r))
                                  r)))
                          '())))
         (leave-on-EPIPE
          (for-each (lambda (p)
                      (format #t "~a\t~a\t~a\t~a~%"
                              (package-name p)
                              (package-version p)
                              (string-join (package-outputs p) ",")
                              (location->string (package-location p))))
                    (sort available
                          (lambda (p1 p2)
                            (string<? (package-name p1)
                                      (package-name p2))))))
         #t))

      (('search _)
       (let* ((patterns (filter-map (match-lambda
                                      (('query 'search rx) rx)
                                      (_                   #f))
                                    opts))
              (regexps  (map (cut make-regexp* <> regexp/icase) patterns)))
         (leave-on-EPIPE
          (for-each (cute package->recutils <> (current-output-port))
                    (find-packages-by-description regexps)))
         #t))

      (('show requested-name)
       (let-values (((name version)
                     (package-name->name+version requested-name)))
         (leave-on-EPIPE
          (for-each (cute package->recutils <> (current-output-port))
                    (find-packages-by-name name version)))
         #t))

      (('search-paths kind)
       (let* ((manifests (map profile-manifest profiles))
              (entries   (append-map manifest-entries manifests))
              (profiles  (map user-friendly-profile profiles))
              (settings  (search-path-environment-variables entries profiles
                                                            (const #f)
                                                            #:kind kind)))
         (format #t "~{~a~%~}" settings)
         #t))

      (_ #f))))


(define* (roll-back-action store profile arg opts
                           #:key dry-run?)
  "Roll back PROFILE to its previous generation."
  (unless dry-run?
    (roll-back* store profile)))

(define* (switch-generation-action store profile spec opts
                                   #:key dry-run?)
  "Switch PROFILE to the generation specified by SPEC."
  (unless dry-run?
    (let* ((number (string->number spec))
           (number (and number
                        (case (string-ref spec 0)
                          ((#\+ #\-)
                           (relative-generation profile number))
                          (else number)))))
      (if number
          (switch-to-generation* profile number)
          (leave (_ "cannot switch to generation '~a'~%") spec)))))

(define* (delete-generations-action store profile pattern opts
                                    #:key dry-run?)
  "Delete PROFILE's generations that match PATTERN."
  (unless dry-run?
    (delete-matching-generations store profile pattern)))

(define* (manifest-action store profile file opts
                          #:key dry-run?)
  "Change PROFILE to contain the packages specified in FILE."
  (let* ((user-module  (make-user-module '((guix profiles) (gnu))))
         (manifest     (load* file user-module))
         (bootstrap?   (assoc-ref opts 'bootstrap?))
         (substitutes? (assoc-ref opts 'substitutes?)))
    (if dry-run?
        (format #t (_ "would install new manifest from '~a' with ~d entries~%")
                file (length (manifest-entries manifest)))
        (format #t (_ "installing new manifest from '~a' with ~d entries~%")
                file (length (manifest-entries manifest))))
    (build-and-use-profile store profile manifest
                           #:bootstrap? bootstrap?
                           #:use-substitutes? substitutes?
                           #:dry-run? dry-run?)))

(define %actions
  ;; List of actions that may be processed.  The car of each pair is the
  ;; action's symbol in the option list; the cdr is the action's procedure.
  `((roll-back? . ,roll-back-action)
    (switch-generation . ,switch-generation-action)
    (delete-generations . ,delete-generations-action)
    (manifest . ,manifest-action)))

(define (process-actions store opts)
  "Process any install/remove/upgrade action from OPTS."

  (define dry-run? (assoc-ref opts 'dry-run?))
  (define bootstrap? (assoc-ref opts 'bootstrap?))
  (define substitutes? (assoc-ref opts 'substitutes?))
  (define profile  (or (assoc-ref opts 'profile) %current-profile))
  (define transform (options->transformation opts))

  (define (transform-entry entry)
    (manifest-entry
      (inherit entry)
      (item (transform store (manifest-entry-item entry)))))

  ;; First, process roll-backs, generation removals, etc.
  (for-each (match-lambda
              ((key . arg)
               (and=> (assoc-ref %actions key)
                      (lambda (proc)
                        (proc store profile arg opts
                              #:dry-run? dry-run?)))))
            opts)

  ;; Then, process normal package installation/removal/upgrade.
  (let* ((manifest    (profile-manifest profile))
         (install     (options->installable opts manifest))
         (remove      (options->removable opts manifest))
         (transaction (manifest-transaction
                       (install (map transform-entry install))
                       (remove remove)))
         (new         (manifest-perform-transaction manifest transaction)))

    (unless (and (null? install) (null? remove))
      (show-manifest-transaction store manifest transaction
                                 #:dry-run? dry-run?)
      (build-and-use-profile store profile new
                             #:bootstrap? bootstrap?
                             #:use-substitutes? substitutes?
                             #:dry-run? dry-run?))))


;;;
;;; Entry point.
;;;

(define (guix-package . args)
  (define (handle-argument arg result arg-handler)
    ;; Process non-option argument ARG by calling back ARG-HANDLER.
    (if arg-handler
        (arg-handler arg result)
        (leave (_ "~A: extraneous argument~%") arg)))

  (let ((opts (parse-command-line args %options (list %default-options #f)
                                  #:argument-handler handle-argument)))
    (with-error-handling
      (or (process-query opts)
          (parameterize ((%store  (open-connection))
                         (%graft? (assoc-ref opts 'graft?)))
            (set-build-options-from-command-line (%store) opts)

            (parameterize ((%guile-for-build
                            (package-derivation
                             (%store)
                             (if (assoc-ref opts 'bootstrap?)
                                 %bootstrap-guile
                                 (canonical-package guile-2.0)))))
              (process-actions (%store) opts)))))))
