;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
;;; Copyright © 2013 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2014 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 derivations)
  #:use-module (guix packages)
  #:use-module (guix profiles)
  #:use-module (guix monads)
  #:use-module (guix utils)
  #:use-module (guix config)
  #:use-module (guix scripts build)
  #:use-module ((guix build utils)
                #:select (directory-exists? mkdir-p search-path-as-list))
  #:use-module (ice-9 format)
  #:use-module (ice-9 match)
  #:use-module (ice-9 regex)
  #:use-module (ice-9 vlist)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-19)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (srfi srfi-37)
  #:use-module (gnu packages)
  #:use-module (gnu packages base)
  #:use-module (gnu packages guile)
  #:use-module ((gnu packages bootstrap) #:select (%bootstrap-guile))
  #:export (specification->package+output
            switch-to-generation
            switch-to-previous-generation
            roll-back
            delete-generation
            delete-generations
            guix-package))

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

\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 (link-to-empty-profile store generation)
  "Link GENERATION, a string, to the empty profile."
  (let* ((drv  (run-with-store store
                 (profile-derivation (manifest '()))))
         (prof (derivation->output-path drv "out")))
    (when (not (build-derivations store (list drv)))
          (leave (_ "failed to build the empty profile~%")))

    (switch-symlinks generation prof)))

(define (switch-to-generation profile number)
  "Atomically switch PROFILE to the generation NUMBER."
  (let ((current    (generation-number profile))
        (generation (generation-file-name profile number)))
    (cond ((not (file-exists? profile))
           (raise (condition (&profile-not-found-error
                              (profile profile)))))
          ((not (file-exists? generation))
           (raise (condition (&missing-generation-error
                              (profile profile)
                              (generation number)))))
          (else
           (format #t (_ "switching from generation ~a to ~a~%")
                   current number)
           (switch-symlinks profile generation)))))

(define (switch-to-previous-generation profile)
  "Atomically switch PROFILE to the previous generation."
  (switch-to-generation profile
                        (previous-generation-number profile)))

(define (roll-back store profile)
  "Roll back to the previous generation of PROFILE."
  (let* ((number              (generation-number profile))
         (previous-number     (previous-generation-number profile number))
         (previous-generation (generation-file-name profile previous-number)))
    (cond ((not (file-exists? profile))                 ; invalid profile
           (raise (condition (&profile-not-found-error
                              (profile profile)))))
          ((zero? number)                               ; empty profile
           (format (current-error-port)
                   (_ "nothing to do: already at the empty profile~%")))
          ((or (zero? previous-number)                  ; going to emptiness
               (not (file-exists? previous-generation)))
           (link-to-empty-profile store previous-generation)
           (switch-to-previous-generation profile))
          (else
           (switch-to-previous-generation profile)))))  ; anything else

(define (delete-generation store profile number)
  "Delete generation with NUMBER from PROFILE."
  (define (display-and-delete)
    (let ((generation (generation-file-name profile number)))
      (format #t (_ "deleting ~a~%") generation)
      (delete-file generation)))

  (let* ((current-number      (generation-number profile))
         (previous-number     (previous-generation-number profile number))
         (previous-generation (generation-file-name profile previous-number)))
    (cond ((zero? number))              ; do not delete generation 0
          ((and (= number current-number)
                (not (file-exists? previous-generation)))
           (link-to-empty-profile store previous-generation)
           (switch-to-previous-generation profile)
           (display-and-delete))
          ((= number current-number)
           (roll-back store profile)
           (display-and-delete))
          (else
           (display-and-delete)))))

(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* (matching-generations str #:optional (profile %current-profile)
                               #:key (duration-relation <=))
  "Return the list of available generations matching a pattern in STR.  See
'string->generations' and 'string->duration' for the list of valid patterns.
When STR is a duration pattern, return all the generations whose ctime has
DURATION-RELATION with the current time."
  (define (valid-generations lst)
    (define (valid-generation? n)
      (any (cut = n <>) (generation-numbers profile)))

    (fold-right (lambda (x acc)
                  (if (valid-generation? x)
                      (cons x acc)
                      acc))
                '()
                lst))

  (define (filter-generations generations)
    (match generations
      (() '())
      (('>= n)
       (drop-while (cut > n <>)
                   (generation-numbers profile)))
      (('<= n)
       (valid-generations (iota n 1)))
      ((lst ..1)
       (valid-generations lst))
      (_ #f)))

  (define (filter-by-duration duration)
    (define (time-at-midnight time)
      ;; Return TIME at midnight by setting nanoseconds, seconds, minutes, and
      ;; hours to zeros.
      (let ((d (time-utc->date time)))
         (date->time-utc
          (make-date 0 0 0 0
                     (date-day d) (date-month d)
                     (date-year d) (date-zone-offset d)))))

    (define generation-ctime-alist
      (map (lambda (number)
             (cons number
                   (time-second
                    (time-at-midnight
                     (generation-time profile number)))))
           (generation-numbers profile)))

    (match duration
      (#f #f)
      (res
       (let ((s (time-second
                 (subtract-duration (time-at-midnight (current-time))
                                    duration))))
         (delete #f (map (lambda (x)
                           (and (duration-relation s (cdr x))
                                (first x)))
                         generation-ctime-alist))))))

  (cond ((string->generations str)
         =>
         filter-generations)
        ((string->duration str)
         =>
         filter-by-duration)
        (else #f)))

\f
;;;
;;; Package specifications.
;;;

(define (find-packages-by-description rx)
  "Return the list of packages whose name, synopsis, or description matches
RX."
  (define (same-location? p1 p2)
    ;; Compare locations of two packages.
    (equal? (package-location p1) (package-location p2)))

  (delete-duplicates
   (sort
    (fold-packages (lambda (package result)
                     (define matches?
                       (cut regexp-exec rx <>))

                     (if (or (matches? (package-name package))
                             (and=> (package-synopsis package)
                                    (compose matches? P_))
                             (and=> (package-description package)
                                    (compose matches? P_)))
                         (cons package result)
                         result))
                   '())
    (lambda (p1 p2)
      (string<? (package-name p1)
                (package-name p2))))
   same-location?))

(define-syntax-rule (leave-on-EPIPE exp ...)
  "Run EXP... in a context when EPIPE errors are caught and lead to 'exit'
with successful exit code.  This is useful when writing to the standard output
may lead to EPIPE, because the standard output is piped through 'head' or
similar."
  (catch 'system-error
    (lambda ()
      exp ...)
    (lambda args
      ;; We really have to exit this brutally, otherwise Guile eventually
      ;; attempts to flush all the ports, leading to an uncaught EPIPE down
      ;; the path.
      (if (= EPIPE (system-error-errno args))
          (primitive-_exit 0)
          (apply throw args)))))

(define* (specification->package+output spec #:optional (output "out"))
  "Return the package and output specified by SPEC, or #f and #f; SPEC may
optionally contain a version number and an output name, as in these examples:

  guile
  guile-2.0.9
  guile:debug
  guile-2.0.9:debug

If SPEC does not specify a version number, return the preferred newest
version; if SPEC does not specify an output, return OUTPUT."
  (define (ensure-output p sub-drv)
    (if (member sub-drv (package-outputs p))
        sub-drv
        (leave (_ "package `~a' lacks output `~a'~%")
               (package-full-name p)
               sub-drv)))

  (let-values (((name version sub-drv)
                (package-specification->name+version+output spec output)))
    (match (find-best-packages-by-name name version)
      ((p)
       (values p (ensure-output p sub-drv)))
      ((p p* ...)
       (warning (_ "ambiguous package specification `~a'~%")
                spec)
       (warning (_ "choosing ~a from ~a~%")
                (package-full-name p)
                (location->string (package-location p)))
       (values p (ensure-output p sub-drv)))
      (()
       (leave (_ "~a: package not found~%") spec)))))

(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)))

\f
;;;
;;; Search paths.
;;;

(define-syntax-rule (with-null-error-port exp)
  "Evaluate EXP with the error port pointing to the bit bucket."
  (with-error-to-port (%make-void-port "w")
    (lambda () exp)))

(define* (search-path-environment-variables entries profile
                                            #:optional (getenv getenv))
  "Return environment variable definitions that may be needed for the use of
ENTRIES, a list of manifest entries, in PROFILE.  Use GETENV to determine the
current settings and report only settings not already effective."

  ;; Prefer ~/.guix-profile to the real profile directory name.
  (let ((profile (if (and %user-profile-directory
                          (false-if-exception
                           (string=? (readlink %user-profile-directory)
                                     profile)))
                     %user-profile-directory
                     profile)))

    ;; The search path info is not stored in the manifest.  Thus, we infer the
    ;; search paths from same-named packages found in the distro.

    (define manifest-entry->package
      (match-lambda
       (($ <manifest-entry> name version)
        ;; Use 'find-best-packages-by-name' and not 'find-packages-by-name';
        ;; the former traverses the module tree only once and then allows for
        ;; efficient access via a vhash.
        (match (find-best-packages-by-name name version)
          ((p _ ...) p)
          (_
           (match (find-best-packages-by-name name #f)
             ((p _ ...) p)
             (_ #f)))))))

    (define search-path-definition
      (match-lambda
       (($ <search-path-specification> variable files separator
                                       type pattern)
        (let* ((values (or (and=> (getenv variable)
                                  (cut string-tokenize* <> separator))
                           '()))
               ;; Add a trailing slash to force symlinks to be treated as
               ;; directories when 'find-files' traverses them.
               (files  (if pattern
                           (map (cut string-append <> "/") files)
                           files))

               ;; XXX: Silence 'find-files' when it stumbles upon non-existent
               ;; directories (see
               ;; <http://lists.gnu.org/archive/html/guix-devel/2015-01/msg00269.html>.)
               (path   (with-null-error-port
                        (search-path-as-list files (list profile)
                                             #:type type
                                             #:pattern pattern))))
          (if (every (cut member <> values) path)
              #f
              (format #f "export ~a=\"~a\""
                      variable
                      (string-join path separator)))))))

    (let* ((packages     (filter-map manifest-entry->package entries))
           (search-paths (delete-duplicates
                          (append-map package-native-search-paths
                                      packages))))
      (filter-map search-path-definition search-paths))))

(define (display-search-paths entries profile)
  "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 ((settings (search-path-environment-variables entries profile)))
    (unless (null? settings)
      (format #t (_ "The following environment variable definitions may be needed:~%"))
      (format #t "~{   ~a~%~}" settings))))

\f
;;;
;;; Command-line options.
;;;

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

(define (show-help)
  (display (_ "Usage: guix package [OPTION]... PACKAGES...
Install, remove, or upgrade PACKAGES in a single transaction.\n"))
  (display (_ "
  -i, --install=PACKAGE  install PACKAGE"))
  (display (_ "
  -e, --install-from-expression=EXP
                         install the package EXP evaluates to"))
  (display (_ "
  -r, --remove=PACKAGE   remove PACKAGE"))
  (display (_ "
  -u, --upgrade[=REGEXP] upgrade all the installed packages matching REGEXP"))
  (display (_ "
      --roll-back        roll back to the previous generation"))
  (display (_ "
      --search-paths     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)
  (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 '(#\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 '("roll-back") #f #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'roll-back? #t result)
                           #f)))
         (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 #f
                 (lambda (opt name arg result arg-handler)
                   (values (cons `(query search-paths) result)
                           #f)))
         (option '(#\p "profile") #t #f
                 (lambda (opt name arg result arg-handler)
                   (values (alist-cons 'profile (canonicalize-profile arg)
                                       (alist-delete 'profile 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)))

         %standard-build-options))

(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 (package->manifest-entry* package output)
    (check-package-freshness package)
    ;; When given a package via `-e', install the first of its
    ;; outputs (XXX).
    (package->manifest-entry package output))

  (define upgrade-regexps
    (filter-map (match-lambda
                 (('upgrade . regexp)
                  (make-regexp (or regexp "")))
                 (_ #f))
                opts))

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

  (define to-upgrade
    (map (match-lambda
          ((package output)
           (package->manifest-entry* package output)))
         packages-to-upgrade))

  (define packages-to-install
    (filter-map (match-lambda
                 (('install . (? package? p))
                  (list p "out"))
                 (('install . (? string? spec))
                  (and (not (store-path? spec))
                       (let-values (((package output)
                                     (specification->package+output spec)))
                         (and package (list package output)))))
                 (_ #f))
                opts))

  (define to-install
    (append (map (match-lambda
                  ((package output)
                   (package->manifest-entry* package output)))
                 packages-to-install)
            (filter-map (match-lambda
                         (('install . (? package?))
                          #f)
                         (('install . (? store-path? path))
                          (let-values (((name version)
                                        (package-name->name+version
                                         (store-path-package-name path))))
                            (manifest-entry
                             (name name)
                             (version version)
                             (output #f)
                             (item path))))
                         (_ #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))

(define (readlink* file)
  "Call 'readlink' until the result is not a symlink."
  (catch 'system-error
    (lambda ()
      (readlink* (readlink file)))
    (lambda args
      (if (= EINVAL (system-error-errno args))
          file
          (apply throw args)))))

\f
;;;
;;; Entry point.
;;;

(define (guix-package . args)
  (define (parse-options)
    ;; Return the alist of option values.
    (append (parse-options-from args)
            (parse-options-from (environment-build-options))))

  (define (parse-options-from args)
    ;; Actual parsing takes place here.
    (args-fold* args %options
                (lambda (opt name arg result arg-handler)
                  (leave (_ "~A: unrecognized option~%") name))
                (lambda (arg result arg-handler)
                  (if arg-handler
                      (arg-handler arg result)
                      (leave (_ "~A: extraneous argument~%") arg)))
                %default-options
                #f))

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

    (define dry-run? (assoc-ref opts 'dry-run?))
    (define profile  (assoc-ref opts 'profile))

    (define current-generation-number
      (generation-number profile))

    ;; First roll back if asked to.
    (cond ((and (assoc-ref opts 'roll-back?)
                (not dry-run?))
           (roll-back (%store) profile)
           (process-actions (alist-delete 'roll-back? opts)))
          ((and (assoc-ref opts 'switch-generation)
                (not dry-run?))
           (for-each
            (match-lambda
              (('switch-generation . pattern)
               (let* ((number (string->number pattern))
                      (number (and number
                                   (case (string-ref pattern 0)
                                     ((#\+ #\-)
                                      (relative-generation profile number))
                                     (else number)))))
                 (if number
                     (switch-to-generation profile number)
                     (leave (_ "cannot switch to generation '~a'~%")
                            pattern)))
               (process-actions (alist-delete 'switch-generation opts)))
              (_ #f))
            opts))
          ((and (assoc-ref opts 'delete-generations)
                (not dry-run?))
           (for-each
            (match-lambda
             (('delete-generations . pattern)
              (cond ((not (file-exists? profile)) ; XXX: race condition
                     (raise (condition (&profile-not-found-error
                                        (profile profile)))))
                    ((string-null? pattern)
                     (delete-generations
                      (%store) profile
                      (delete current-generation-number
                              (profile-generations profile))))
                    ;; Do not delete the zeroth generation.
                    ((equal? 0 (string->number pattern))
                     (exit 0))

                    ;; If PATTERN is a duration, match generations that are
                    ;; older than the specified duration.
                    ((matching-generations pattern profile
                                           #:duration-relation >)
                     =>
                     (lambda (numbers)
                       (if (null-list? numbers)
                           (exit 1)
                           (delete-generations (%store) profile numbers))))
                    (else
                     (leave (_ "invalid syntax: ~a~%")
                            pattern)))

              (process-actions
               (alist-delete 'delete-generations opts)))
             (_ #f))
            opts))
          (else
           (let* ((manifest    (profile-manifest profile))
                  (install     (options->installable opts manifest))
                  (remove      (options->removable opts manifest))
                  (bootstrap?  (assoc-ref opts 'bootstrap?))
                  (transaction (manifest-transaction (install install)
                                                     (remove remove)))
                  (new         (manifest-perform-transaction
                                manifest transaction)))

             (when (equal? profile %current-profile)
               (ensure-default-profile))

             (unless (and (null? install) (null? remove))
               (let* ((prof-drv (run-with-store (%store)
                                  (profile-derivation
                                   new
                                   #:info-dir? (not bootstrap?))))
                      (prof     (derivation->output-path prof-drv)))
                 (show-manifest-transaction (%store) manifest transaction
                                            #:dry-run? dry-run?)
                 (show-what-to-build (%store) (list prof-drv)
                                     #:use-substitutes?
                                     (assoc-ref opts '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 new))
                                 (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
                                                  profile))))))))))))

  (define (process-query opts)
    ;; Process any query specified by OPTS.  Return #t when a query was
    ;; actually processed, #f otherwise.
    (let ((profile  (assoc-ref opts 'profile)))
      (match (assoc-ref opts 'query)
        (('list-generations pattern)
         (define (list-generation number)
           (unless (zero? number)
             (let ((header (format #f (_ "Generation ~a\t~a") number
                                   (date->string
                                    (time-utc->date
                                     (generation-time profile number))
                                    "~b ~d ~Y ~T")))
                   (current (generation-number profile)))
               (if (= number current)
                   (format #t (_ "~a\t(current)~%") header)
                   (format #t "~a~%" header)))
             (for-each (match-lambda
                        (($ <manifest-entry> name version output location _)
                         (format #t "  ~a\t~a\t~a\t~a~%"
                                 name version output location)))

                       ;; Show most recently installed packages last.
                       (reverse
                        (manifest-entries
                         (profile-manifest
                          (generation-file-name 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 regexp
                                    (if (regexp-exec regexp n)
                                        (cons p r)
                                        r)
                                    (cons p 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 regexp)
         (let ((regexp (make-regexp regexp regexp/icase)))
           (leave-on-EPIPE
            (for-each (cute package->recutils <> (current-output-port))
                      (find-packages-by-description regexp)))
           #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)
         (let* ((manifest (profile-manifest profile))
                (entries  (manifest-entries manifest))
                (settings (search-path-environment-variables entries profile
                                                             (const #f))))
           (format #t "~{~a~%~}" settings)
           #t))

        (_ #f))))

  (let ((opts (parse-options)))
    (with-error-handling
      (or (process-query opts)
          (parameterize ((%store (open-connection)))
            (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 opts)))))))