;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018 Ludovic Courtès <ludo@gnu.org>
;;;
;;; 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 inferior)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-9 gnu)
  #:use-module ((guix utils)
                #:select (%current-system
                          source-properties->location
                          call-with-temporary-directory
                          version>? version-prefix?
                          cache-directory))
  #:use-module ((guix store)
                #:select (nix-server-socket
                          nix-server-major-version
                          nix-server-minor-version
                          store-lift))
  #:use-module ((guix derivations)
                #:select (read-derivation-from-file))
  #:use-module (guix gexp)
  #:use-module (guix search-paths)
  #:use-module (guix profiles)
  #:use-module (guix channels)
  #:use-module (guix monads)
  #:use-module (guix store)
  #:use-module (guix derivations)
  #:use-module (guix base32)
  #:use-module (gcrypt hash)
  #:autoload   (guix cache) (maybe-remove-expired-cache-entries)
  #:autoload   (guix ui) (show-what-to-build*)
  #:autoload   (guix build utils) (mkdir-p)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:autoload   (ice-9 ftw) (scandir)
  #:use-module (ice-9 match)
  #:use-module (ice-9 popen)
  #:use-module (ice-9 vlist)
  #:use-module (ice-9 binary-ports)
  #:use-module ((rnrs bytevectors) #:select (string->utf8))
  #:export (inferior?
            open-inferior
            close-inferior
            inferior-eval
            inferior-eval-with-store
            inferior-object?

            inferior-packages
            lookup-inferior-packages

            inferior-package?
            inferior-package-name
            inferior-package-version
            inferior-package-synopsis
            inferior-package-description
            inferior-package-home-page
            inferior-package-location
            inferior-package-inputs
            inferior-package-native-inputs
            inferior-package-propagated-inputs
            inferior-package-transitive-propagated-inputs
            inferior-package-native-search-paths
            inferior-package-transitive-native-search-paths
            inferior-package-search-paths
            inferior-package-derivation

            inferior-package->manifest-entry

            %inferior-cache-directory
            inferior-for-channels))

;;; Commentary:
;;;
;;; This module provides a way to spawn Guix "inferior" processes and to talk
;;; to them.  It allows us, from one instance of Guix, to interact with
;;; another instance of Guix coming from a different commit.
;;;
;;; Code:

;; Inferior Guix process.
(define-record-type <inferior>
  (inferior pid socket version packages table)
  inferior?
  (pid      inferior-pid)
  (socket   inferior-socket)
  (version  inferior-version)                    ;REPL protocol version
  (packages inferior-package-promise)            ;promise of inferior packages
  (table    inferior-package-table))             ;promise of vhash

(define (inferior-pipe directory command)
  "Return an input/output pipe on the Guix instance in DIRECTORY.  This runs
'DIRECTORY/COMMAND repl' if it exists, or falls back to some other method if
it's an old Guix."
  (let ((pipe (with-error-to-port (%make-void-port "w")
                (lambda ()
                  (open-pipe* OPEN_BOTH
                              (string-append directory "/" command)
                              "repl" "-t" "machine")))))
    (if (eof-object? (peek-char pipe))
        (begin
          (close-pipe pipe)

          ;; Older versions of Guix didn't have a 'guix repl' command, so
          ;; emulate it.
          (open-pipe* OPEN_BOTH "guile"
                      "-L" (string-append directory "/share/guile/site/"
                                          (effective-version))
                      "-C" (string-append directory "/share/guile/site/"
                                          (effective-version))
                      "-C" (string-append directory "/lib/guile/"
                                          (effective-version) "/site-ccache")
                      "-c"
                      (object->string
                       `(begin
                          (primitive-load ,(search-path %load-path
                                                        "guix/scripts/repl.scm"))
                          ((@ (guix scripts repl) machine-repl))))))
        pipe)))

(define* (open-inferior directory #:key (command "bin/guix"))
  "Open the inferior Guix in DIRECTORY, running 'DIRECTORY/COMMAND repl' or
equivalent.  Return #f if the inferior could not be launched."
  (define pipe
    (inferior-pipe directory command))

  (cond-expand
    ((and guile-2 (not guile-2.2)) #t)
    (else (setvbuf pipe 'line)))

  (match (read pipe)
    (('repl-version 0 rest ...)
     (letrec ((result (inferior 'pipe pipe (cons 0 rest)
                                (delay (%inferior-packages result))
                                (delay (%inferior-package-table result)))))
       (inferior-eval '(use-modules (guix)) result)
       (inferior-eval '(use-modules (gnu)) result)
       (inferior-eval '(use-modules (ice-9 match)) result)
       (inferior-eval '(define %package-table (make-hash-table))
                      result)
       result))
    (_
     #f)))

(define (close-inferior inferior)
  "Close INFERIOR."
  (close-pipe (inferior-socket inferior)))

;; Non-self-quoting object of the inferior.
(define-record-type <inferior-object>
  (inferior-object address appearance)
  inferior-object?
  (address     inferior-object-address)
  (appearance  inferior-object-appearance))

(define (write-inferior-object object port)
  (match object
    (($ <inferior-object> _ appearance)
     (format port "#<inferior-object ~a>" appearance))))

(set-record-type-printer! <inferior-object> write-inferior-object)

(define (read-inferior-response inferior)
  (define sexp->object
    (match-lambda
      (('value value)
       value)
      (('non-self-quoting address string)
       (inferior-object address string))))

  (match (read (inferior-socket inferior))
    (('values objects ...)
     (apply values (map sexp->object objects)))
    (('exception key objects ...)
     (apply throw key (map sexp->object objects)))))

(define (send-inferior-request exp inferior)
  (write exp (inferior-socket inferior))
  (newline (inferior-socket inferior)))

(define (inferior-eval exp inferior)
  "Evaluate EXP in INFERIOR."
  (send-inferior-request exp inferior)
  (read-inferior-response inferior))


;;;
;;; Inferior packages.
;;;

(define-record-type <inferior-package>
  (inferior-package inferior name version id)
  inferior-package?
  (inferior   inferior-package-inferior)
  (name       inferior-package-name)
  (version    inferior-package-version)
  (id         inferior-package-id))

(define (write-inferior-package package port)
  (match package
    (($ <inferior-package> _ name version)
     (format port "#<inferior-package ~a@~a ~a>"
             name version
             (number->string (object-address package) 16)))))

(set-record-type-printer! <inferior-package> write-inferior-package)

(define (%inferior-packages inferior)
  "Compute the list of inferior packages from INFERIOR."
  (let ((result (inferior-eval
                 '(fold-packages (lambda (package result)
                                   (let ((id (object-address package)))
                                     (hashv-set! %package-table id package)
                                     (cons (list (package-name package)
                                                 (package-version package)
                                                 id)
                                           result)))
                                 '())
                 inferior)))
    (map (match-lambda
           ((name version id)
            (inferior-package inferior name version id)))
         result)))

(define (inferior-packages inferior)
  "Return the list of packages known to INFERIOR."
  (force (inferior-package-promise inferior)))

(define (%inferior-package-table inferior)
  "Compute a package lookup table for INFERIOR."
  (fold (lambda (package table)
          (vhash-cons (inferior-package-name package) package
                      table))
        vlist-null
        (inferior-packages inferior)))

(define* (lookup-inferior-packages inferior name #:optional version)
  "Return the sorted list of inferior packages matching NAME in INFERIOR, with
highest version numbers first.  If VERSION is true, return only packages with
a version number prefixed by VERSION."
  ;; This is the counterpart of 'find-packages-by-name'.
  (sort (filter (lambda (package)
                  (or (not version)
                      (version-prefix? version
                                       (inferior-package-version package))))
                (vhash-fold* cons '() name
                             (force (inferior-package-table inferior))))
        (lambda (p1 p2)
          (version>? (inferior-package-version p1)
                     (inferior-package-version p2)))))

(define (inferior-package-field package getter)
  "Return the field of PACKAGE, an inferior package, accessed with GETTER."
  (let ((inferior (inferior-package-inferior package))
        (id       (inferior-package-id package)))
    (inferior-eval `(,getter (hashv-ref %package-table ,id))
                   inferior)))

(define* (inferior-package-synopsis package #:key (translate? #t))
  "Return the Texinfo synopsis of PACKAGE, an inferior package.  When
TRANSLATE? is true, translate it to the current locale's language."
  (inferior-package-field package
                          (if translate?
                              '(compose (@ (guix ui) P_) package-synopsis)
                              'package-synopsis)))

(define* (inferior-package-description package #:key (translate? #t))
  "Return the Texinfo description of PACKAGE, an inferior package.  When
TRANSLATE? is true, translate it to the current locale's language."
  (inferior-package-field package
                          (if translate?
                              '(compose (@ (guix ui) P_) package-description)
                              'package-description)))

(define (inferior-package-home-page package)
  "Return the home page of PACKAGE."
  (inferior-package-field package 'package-home-page))

(define (inferior-package-location package)
  "Return the source code location of PACKAGE, either #f or a <location>
record."
  (source-properties->location
   (inferior-package-field package
                           '(compose (lambda (loc)
                                       (and loc
                                            (location->source-properties
                                             loc)))
                                     package-location))))

(define (inferior-package-input-field package field)
  "Return the input field FIELD (e.g., 'native-inputs') of PACKAGE, an
inferior package."
  (define field*
    `(compose (lambda (inputs)
                (map (match-lambda
                       ;; XXX: Origins are not handled.
                       ((label (? package? package) rest ...)
                        (let ((id (object-address package)))
                          (hashv-set! %package-table id package)
                          `(,label (package ,id
                                            ,(package-name package)
                                            ,(package-version package))
                                   ,@rest)))
                       (x
                        x))
                     inputs))
              ,field))

  (define inputs
    (inferior-package-field package field*))

  (define inferior
    (inferior-package-inferior package))

  (map (match-lambda
         ((label ('package id name version) . rest)
          ;; XXX: eq?-ness of inferior packages is not preserved here.
          `(,label ,(inferior-package inferior name version id)
                   ,@rest))
         (x x))
       inputs))

(define inferior-package-inputs
  (cut inferior-package-input-field <> 'package-inputs))

(define inferior-package-native-inputs
  (cut inferior-package-input-field <> 'package-native-inputs))

(define inferior-package-propagated-inputs
  (cut inferior-package-input-field <> 'package-propagated-inputs))

(define inferior-package-transitive-propagated-inputs
  (cut inferior-package-input-field <> 'package-transitive-propagated-inputs))

(define (%inferior-package-search-paths package field)
  "Return the list of search path specificiations of PACKAGE, an inferior
package."
  (define paths
    (inferior-package-field package
                            `(compose (lambda (paths)
                                        (map (@ (guix search-paths)
                                                search-path-specification->sexp)
                                             paths))
                                      ,field)))

  (map sexp->search-path-specification paths))

(define inferior-package-native-search-paths
  (cut %inferior-package-search-paths <> 'package-native-search-paths))

(define inferior-package-search-paths
  (cut %inferior-package-search-paths <> 'package-search-paths))

(define inferior-package-transitive-native-search-paths
  (cut %inferior-package-search-paths <> 'package-transitive-native-search-paths))

(define (proxy client backend)                    ;adapted from (guix ssh)
  "Proxy communication between CLIENT and BACKEND until CLIENT closes the
connection, at which point CLIENT is closed (both CLIENT and BACKEND must be
input/output ports.)"
  (define (select* read write except)
    ;; This is a workaround for <https://bugs.gnu.org/30365> in Guile < 2.2.4:
    ;; since 'select' sometimes returns non-empty sets for no good reason,
    ;; call 'select' a second time with a zero timeout to filter out incorrect
    ;; replies.
    (match (select read write except)
      ((read write except)
       (select read write except 0))))

  ;; Use buffered ports so that 'get-bytevector-some' returns up to the
  ;; whole buffer like read(2) would--see <https://bugs.gnu.org/30066>.
  (setvbuf client _IOFBF 65536)
  (setvbuf backend _IOFBF 65536)

  (let loop ()
    (match (select* (list client backend) '() '())
      ((reads () ())
       (when (memq client reads)
         (match (get-bytevector-some client)
           ((? eof-object?)
            (close-port client))
           (bv
            (put-bytevector backend bv)
            (force-output backend))))
       (when (memq backend reads)
         (match (get-bytevector-some backend)
           (bv
            (put-bytevector client bv)
            (force-output client))))
       (unless (port-closed? client)
         (loop))))))

(define (inferior-eval-with-store inferior store code)
  "Evaluate CODE in INFERIOR, passing it STORE as its argument.  CODE must
thus be the code of a one-argument procedure that accepts a store."
  ;; Create a named socket in /tmp and let INFERIOR connect to it and use it
  ;; as its store.  This ensures the inferior uses the same store, with the
  ;; same options, the same per-session GC roots, etc.
  (call-with-temporary-directory
   (lambda (directory)
     (chmod directory #o700)
     (let* ((name     (string-append directory "/inferior"))
            (socket   (socket AF_UNIX SOCK_STREAM 0))
            (major    (nix-server-major-version store))
            (minor    (nix-server-minor-version store))
            (proto    (logior major minor)))
       (bind socket AF_UNIX name)
       (listen socket 1024)
       (send-inferior-request
        `(let ((proc   ,code)
               (socket (socket AF_UNIX SOCK_STREAM 0)))
           (connect socket AF_UNIX ,name)

           ;; 'port->connection' appeared in June 2018 and we can hardly
           ;; emulate it on older versions.  Thus fall back to
           ;; 'open-connection', at the risk of talking to the wrong daemon or
           ;; having our build result reclaimed (XXX).
           (let ((store (if (defined? 'port->connection)
                            (port->connection socket #:version ,proto)
                            (open-connection))))
             (dynamic-wind
               (const #t)
               (lambda ()
                 (proc store))
               (lambda ()
                 (close-connection store)
                 (close-port socket)))))
        inferior)
       (match (accept socket)
         ((client . address)
          (proxy client (nix-server-socket store))))
       (close-port socket)
       (read-inferior-response inferior)))))

(define* (inferior-package-derivation store package
                                      #:optional
                                      (system (%current-system))
                                      #:key target)
  "Return the derivation for PACKAGE, an inferior package, built for SYSTEM
and cross-built for TARGET if TARGET is true.  The inferior corresponding to
PACKAGE must be live."
  (define proc
    `(lambda (store)
       (let* ((package (hashv-ref %package-table
                                  ,(inferior-package-id package)))
              (drv     ,(if target
                            `(package-cross-derivation store package
                                                       ,target
                                                       ,system)
                            `(package-derivation store package
                                                 ,system))))
         (derivation-file-name drv))))

  (and=> (inferior-eval-with-store (inferior-package-inferior package) store
                                   proc)
         read-derivation-from-file))

(define inferior-package->derivation
  (store-lift inferior-package-derivation))

(define-gexp-compiler (package-compiler (package <inferior-package>) system
                                        target)
  ;; Compile PACKAGE for SYSTEM, optionally cross-building for TARGET.
  (inferior-package->derivation package system #:target target))


;;;
;;; Manifest entries.
;;;

(define* (inferior-package->manifest-entry package
                                           #:optional (output "out")
                                           #:key (parent (delay #f))
                                           (properties '()))
  "Return a manifest entry for the OUTPUT of package PACKAGE."
  ;; For each dependency, keep a promise pointing to its "parent" entry.
  (letrec* ((deps  (map (match-lambda
                          ((label package)
                           (inferior-package->manifest-entry package
                                                             #:parent (delay entry)))
                          ((label package output)
                           (inferior-package->manifest-entry package output
                                                             #:parent (delay entry))))
                        (inferior-package-propagated-inputs package)))
            (entry (manifest-entry
                     (name (inferior-package-name package))
                     (version (inferior-package-version package))
                     (output output)
                     (item package)
                     (dependencies (delete-duplicates deps))
                     (search-paths
                      (inferior-package-transitive-native-search-paths package))
                     (parent parent)
                     (properties properties))))
    entry))


;;;
;;; Cached inferiors.
;;;

(define %inferior-cache-directory
  ;; Directory for cached inferiors (GC roots).
  (make-parameter (string-append (cache-directory #:ensure? #f)
                                 "/inferiors")))

(define* (inferior-for-channels channels
                                #:key
                                (cache-directory (%inferior-cache-directory))
                                (ttl (* 3600 24 30)))
  "Return an inferior for CHANNELS, a list of channels.  Use the cache at
CACHE-DIRECTORY, where entries can be reclaimed after TTL seconds.  This
procedure opens a new connection to the build daemon.

This is a convenience procedure that people may use in manifests passed to
'guix package -m', for instance."
  (with-store store
    (let ()
      (define instances
        (latest-channel-instances store channels))

      (define key
        (bytevector->base32-string
         (sha256
          (string->utf8
           (string-concatenate (map channel-instance-commit instances))))))

      (define cached
        (string-append cache-directory "/" key))

      (define (base32-encoded-sha256? str)
        (= (string-length str) 52))

      (define (cache-entries directory)
        (map (lambda (file)
               (string-append directory "/" file))
             (scandir directory base32-encoded-sha256?)))

      (define symlink*
        (lift2 symlink %store-monad))

      (define add-indirect-root*
        (store-lift add-indirect-root))

      (mkdir-p cache-directory)
      (maybe-remove-expired-cache-entries cache-directory
                                          cache-entries
                                          #:entry-expiration
                                          (file-expiration-time ttl))

      (if (file-exists? cached)
          (open-inferior cached)
          (run-with-store store
            (mlet %store-monad ((profile
                                 (channel-instances->derivation instances)))
              (mbegin %store-monad
                (show-what-to-build* (list profile))
                (built-derivations (list profile))
                (symlink* (derivation->output-path profile) cached)
                (add-indirect-root* cached)
                (return (open-inferior cached)))))))))
