;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019 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/>.


;; This file contains machinery to build HTML and PDF copies of the manual
;; that can be readily published on the web site.  To do that, run:
;;
;;  guix build -f build.scm
;;
;; The result is a directory hierarchy that can be used as the manual/
;; sub-directory of the web site.

(use-modules (guix)
             (guix gexp)
             (guix git)
             (guix git-download)
             (git)
             (gnu packages base)
             (gnu packages gawk)
             (gnu packages gettext)
             (gnu packages guile)
             (gnu packages texinfo)
             (gnu packages tex)
             (srfi srfi-19)
             (srfi srfi-71))

(define file-append*
  (@@ (guix self) file-append*))

(define translated-texi-manuals
  (@@ (guix self) translate-texi-manuals))

(define info-manual
  (@@ (guix self) info-manual))

(define %languages
  '("de" "en" "es" "fr" "ru" "zh_CN"))

(define (texinfo-manual-images source)
  "Return a directory containing all the images used by the user manual, taken
from SOURCE, the root of the source tree."
  (define graphviz
    (module-ref (resolve-interface '(gnu packages graphviz))
                'graphviz))

  (define images
    (file-append* source "doc/images"))

  (define build
    (with-imported-modules '((guix build utils))
      #~(begin
          (use-modules (guix build utils)
                       (srfi srfi-26))

          (define (dot->image dot-file format)
            (invoke #+(file-append graphviz "/bin/dot")
                    "-T" format "-Gratio=.9" "-Gnodesep=.005"
                    "-Granksep=.00005" "-Nfontsize=9"
                    "-Nheight=.1" "-Nwidth=.1"
                    "-o" (string-append #$output "/"
                                        (basename dot-file ".dot")
                                        "." format)
                    dot-file))

          ;; Build graphs.
          (mkdir-p #$output)
          (for-each (lambda (dot-file)
                      (for-each (cut dot->image dot-file <>)
                                '("png" "pdf")))
                    (find-files #$images "\\.dot$"))

          ;; Copy other PNGs.
          (for-each (lambda (png-file)
                      (install-file png-file #$output))
                    (find-files #$images "\\.png$")))))

  (computed-file "texinfo-manual-images" build))

(define* (texinfo-manual-source source #:key
                                (version "0.0")
                                (languages %languages)
                                (date 1))
  "Gather all the source files of the Texinfo manuals from SOURCE--.texi file
as well as images, OS examples, and translations."
  (define documentation
    (file-append* source "doc"))

  (define examples
    (file-append* source "gnu/system/examples"))

  (define build
    (with-imported-modules '((guix build utils))
      #~(begin
          (use-modules (guix build utils)
                       (srfi srfi-19))

          (define (make-version-texi language)
            ;; Create the 'version.texi' file for LANGUAGE.
            (let ((file (if (string=? language "en")
                            "version.texi"
                            (string-append "version-" language ".texi"))))
              (call-with-output-file (string-append #$output "/" file)
                (lambda (port)
                  (let* ((version #$version)
                         (time    (make-time time-utc 0 #$date))
                         (date    (time-utc->date time)))
                    (format port "
@set UPDATED ~a
@set UPDATED-MONTH ~a
@set EDITION ~a
@set VERSION ~a\n"
                            (date->string date "~e ~B ~Y")
                            (date->string date "~B ~Y")
                            version version))))))

          (install-file #$(file-append* documentation "/htmlxref.cnf")
                        #$output)

          (for-each (lambda (texi)
                      (install-file texi #$output))
                    (append (find-files #$documentation "\\.(texi|scm)$")
                            (find-files #$(translated-texi-manuals source)
                                        "\\.texi$")))

          ;; Create 'version.texi'.
          (for-each make-version-texi '#$languages)

          ;; Copy configuration templates that the manual includes.
          (for-each (lambda (template)
                      (copy-file template
                                 (string-append
                                  #$output "/os-config-"
                                  (basename template ".tmpl")
                                  ".texi")))
                    (find-files #$examples "\\.tmpl$"))

          (symlink #$(texinfo-manual-images source)
                   (string-append #$output "/images")))))

  (computed-file "texinfo-manual-source" build))

(define %web-site-url
  ;; URL of the web site home page.
  (or (getenv "GUIX_WEB_SITE_URL")
      "/software/guix/"))

(define %makeinfo-html-options
  ;; Options passed to 'makeinfo --html'.
  '("--css-ref=https://www.gnu.org/software/gnulib/manual.css"))

(define* (html-manual source #:key (languages %languages)
                      (version "0.0")
                      (manual "guix")
                      (date 1)
                      (options %makeinfo-html-options))
  "Return the HTML manuals built from SOURCE for all LANGUAGES, with the given
makeinfo OPTIONS."
  (define manual-source
    (texinfo-manual-source source
                           #:version version
                           #:languages languages
                           #:date date))

  (define build
    (with-imported-modules '((guix build utils))
      #~(begin
          (use-modules (guix build utils)
                       (ice-9 match))

          (define (normalize language)
            ;; Normalize LANGUAGE.  For instance, "zh_CN" become "zh-cn".
            (string-map (match-lambda
                          (#\_ #\-)
                          (chr chr))
                        (string-downcase language)))

          ;; Install a UTF-8 locale so that 'makeinfo' is at ease.
          (setenv "GUIX_LOCPATH"
                  #+(file-append glibc-utf8-locales "/lib/locale"))
          (setenv "LC_ALL" "en_US.utf8")

          (setvbuf (current-output-port) 'line)
          (setvbuf (current-error-port) 'line)

          (for-each (lambda (language)
                      (let ((opts `("--html"
                                    "-c" ,(string-append "TOP_NODE_UP_URL=/manual/"
                                                         language)
                                    #$@options
                                    ,(if (string=? language "en")
                                         (string-append #$manual-source "/"
                                                        #$manual ".texi")
                                         (string-append #$manual-source "/"
                                                        #$manual "." language ".texi")))))
                        (format #t "building HTML manual for language '~a'...~%"
                                language)
                        (mkdir-p (string-append #$output "/"
                                                (normalize language)))
                        (setenv "LANGUAGE" language)
                        (apply invoke #$(file-append texinfo "/bin/makeinfo")
                               "-o" (string-append #$output "/"
                                                   (normalize language)
                                                   "/html_node")
                               opts)
                        (apply invoke #$(file-append texinfo "/bin/makeinfo")
                               "--no-split"
                               "-o"
                               (string-append #$output "/"
                                              (normalize language)
                                              "/" #$manual
                                              (if (string=? language "en")
                                                  ""
                                                  (string-append "." language))
                                              ".html")
                               opts)))
                    '#$languages))))

  (computed-file (string-append manual "-html-manual") build))

(define* (pdf-manual source #:key (languages %languages)
                     (version "0.0")
                     (manual "guix")
                     (date 1)
                     (options '()))
  "Return the HTML manuals built from SOURCE for all LANGUAGES, with the given
makeinfo OPTIONS."
  (define manual-source
    (texinfo-manual-source source
                           #:version version
                           #:languages languages
                           #:date date))

  ;; FIXME: This union works, except for the table of contents of non-English
  ;; manuals, which contains escape sequences like "^^ca^^fe" instead of
  ;; accented letters.
  ;;
  ;; (define texlive
  ;;   (texlive-union (list texlive-tex-texinfo
  ;;                        texlive-generic-epsf
  ;;                        texlive-fonts-ec)))

  (define build
    (with-imported-modules '((guix build utils))
      #~(begin
          (use-modules (guix build utils)
                       (srfi srfi-34)
                       (ice-9 match))

          (define (normalize language)            ;XXX: deduplicate
            ;; Normalize LANGUAGE.  For instance, "zh_CN" becomes "zh-cn".
            (string-map (match-lambda
                          (#\_ #\-)
                          (chr chr))
                        (string-downcase language)))

          ;; Install a UTF-8 locale so that 'makeinfo' is at ease.
          (setenv "GUIX_LOCPATH"
                  #+(file-append glibc-utf8-locales "/lib/locale"))
          (setenv "LC_ALL" "en_US.utf8")
          (setenv "PATH"
                  (string-append #+(file-append texlive "/bin") ":"
                                 #+(file-append texinfo "/bin") ":"

                                 ;; Below are command-line tools needed by
                                 ;; 'texi2dvi' and friends.
                                 #+(file-append sed "/bin") ":"
                                 #+(file-append grep "/bin") ":"
                                 #+(file-append coreutils "/bin") ":"
                                 #+(file-append gawk "/bin") ":"
                                 #+(file-append tar "/bin") ":"
                                 #+(file-append diffutils "/bin")))

          (setvbuf (current-output-port) 'line)
          (setvbuf (current-error-port) 'line)

          (setenv "HOME" (getcwd))                ;for kpathsea/mktextfm

          ;; 'SOURCE_DATE_EPOCH' is honored by pdftex.
          (setenv "SOURCE_DATE_EPOCH" "1")

          (for-each (lambda (language)
                      (let ((opts `("--pdf"
                                    "-I" "."
                                    #$@options
                                    ,(if (string=? language "en")
                                         (string-append #$manual-source "/"
                                                        #$manual ".texi")
                                         (string-append #$manual-source "/"
                                                        #$manual "." language ".texi")))))
                        (format #t "building PDF manual for language '~a'...~%"
                                language)
                        (mkdir-p (string-append #$output "/"
                                                (normalize language)))
                        (setenv "LANGUAGE" language)


                        ;; FIXME: Unfortunately building PDFs for non-Latin
                        ;; alphabets doesn't work:
                        ;; <https://lists.gnu.org/archive/html/help-texinfo/2012-01/msg00014.html>.
                        (guard (c ((invoke-error? c)
                                   (format (current-error-port)
                                           "~%~%Failed to produce \
PDF for language '~a'!~%~%"
                                           language)))
                         (apply invoke #$(file-append texinfo "/bin/makeinfo")
                                "--pdf" "-o"
                                (string-append #$output "/"
                                               (normalize language)
                                               "/" #$manual
                                               (if (string=? language "en")
                                                   ""
                                                   (string-append "."
                                                                  language))
                                               ".pdf")
                                opts))))
                    '#$languages))))

  (computed-file (string-append manual "-pdf-manual") build))

(define (guix-manual-text-domain source languages)
  "Return the PO files for LANGUAGES of the 'guix-manual' text domain taken
from SOURCE."
  (define po-directory
    (file-append* source "/po/doc"))

  (define build
    (with-imported-modules '((guix build utils))
      #~(begin
          (use-modules (guix build utils))

          (mkdir-p #$output)
          (for-each (lambda (language)
                      (define directory
                        (string-append #$output "/" language
                                       "/LC_MESSAGES"))

                      (mkdir-p directory)
                      (invoke #+(file-append gnu-gettext "/bin/msgfmt")
                              "-c" "-o"
                              (string-append directory "/guix-manual.mo")
                              (string-append #$po-directory "/guix-manual."
                                             language ".po")))
                    '#$(delete "en" languages)))))

  (computed-file "guix-manual-po" build))

(define* (html-manual-indexes source
                              #:key (languages %languages)
                              (version "0.0")
                              (manual "guix")
                              (date 1))
  (define build
    (with-imported-modules '((guix build utils))
      #~(begin
          (use-modules (guix build utils)
                       (ice-9 match)
                       (ice-9 popen)
                       (sxml simple)
                       (srfi srfi-19))

          (define (normalize language)            ;XXX: deduplicate
            ;; Normalize LANGUAGE.  For instance, "zh_CN" become "zh-cn".
            (string-map (match-lambda
                          (#\_ #\-)
                          (chr chr))
                        (string-downcase language)))

          (define-syntax-rule (with-language language exp ...)
            (let ((lang (getenv "LANGUAGE")))
              (dynamic-wind
                (lambda ()
                  (setenv "LANGUAGE" language)
                  (setlocale LC_MESSAGES))
                (lambda () exp ...)
                (lambda ()
                  (if lang
                      (setenv "LANGUAGE" lang)
                      (unsetenv "LANGUAGE"))
                  (setlocale LC_MESSAGES)))))

          ;; (put 'with-language 'scheme-indent-function 1)
          (define* (translate str language
                              #:key (domain "guix-manual"))
            (define exp
              `(begin
                 (bindtextdomain "guix-manual"
                                 #+(guix-manual-text-domain
                                    source
                                    languages))
                 (write (gettext ,str "guix-manual"))))

            (with-language language
              ;; Since the 'gettext' function caches msgid translations,
              ;; regardless of $LANGUAGE, we have to spawn a new process each
              ;; time we want to translate to a different language.  Bah!
              (let* ((pipe (open-pipe* OPEN_READ
                                       #+(file-append guile-2.2
                                                      "/bin/guile")
                                       "-c" (object->string exp)))
                     (str  (read pipe)))
                (close-pipe pipe)
                str)))

          (define (seconds->string seconds language)
            (let* ((time (make-time time-utc 0 seconds))
                   (date (time-utc->date time)))
              (with-language language (date->string date "~e ~B ~Y"))))

          (define (guix-url path)
            (string-append #$%web-site-url path))

          (define (sxml-index language)
            (define title
              (translate "GNU Guix Reference Manual" language))

            ;; FIXME: Avoid duplicating styling info from guix-artwork.git.
            `(html (@ (lang ,language))
                   (head
                    (title ,(string-append title " — GNU Guix"))
                    (meta (@ (charset "UTF-8")))
                    (meta (@ (name "viewport") (content "width=device-width, initial-scale=1.0")))
                    ;; Menu prefetch.
                    (link (@ (rel "prefetch") (href ,(guix-url "menu/index.html"))))
                    ;; Base CSS.
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/elements.css"))))
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/common.css"))))
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/messages.css"))))
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/navbar.css"))))
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/breadcrumbs.css"))))
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/buttons.css"))))
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/footer.css"))))

                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/page.css"))))
                    (link (@ (rel "stylesheet") (href ,(guix-url "static/base/css/post.css")))))
                   (body
                    (header (@ (class "navbar"))
                            (h1 (a (@ (class "branding")
                                      (href #$%web-site-url)))
                                (span (@ (class "a11y-offset"))
                                      "Guix"))
                            (nav (@ (class "menu"))))
                    (nav (@ (class "breadcrumbs"))
                         (a (@ (class "crumb")
                               (href #$%web-site-url))
                            "Home"))
                    (main
                     (article
                      (@ (class "page centered-block limit-width"))
                      (h2 ,title)
                      (p (@ (class "post-metadata centered-text"))
                         #$version " — "
                         ,(seconds->string #$date language))

                      (div
                       (ul
                        (li (a (@ (href "html_node"))
                               "HTML, with one page per node"))
                        (li (a (@ (href
                                   ,(string-append
                                     #$manual
                                     (if (string=? language
                                                   "en")
                                         ""
                                         (string-append "."
                                                        language))
                                     ".html")))
                               "HTML, entirely on one page"))
                        ,@(if (member language '("ru" "zh_CN"))
                              '()
                              `((li (a (@ (href ,(string-append
                                                  #$manual
                                                  (if (string=? language "en")
                                                      ""
                                                      (string-append "."
                                                                     language))
                                                  ".pdf"))))
                                    "PDF")))))))
                    (footer))))

          (define (write-index language file)
            (call-with-output-file file
              (lambda (port)
                (display "<!DOCTYPE html>\n" port)
                (sxml->xml (sxml-index language) port))))

          (setenv "GUIX_LOCPATH"
                  #+(file-append glibc-utf8-locales "/lib/locale"))
          (setenv "LC_ALL" "en_US.utf8")
          (setlocale LC_ALL "en_US.utf8")

          (bindtextdomain "guix-manual"
                          #+(guix-manual-text-domain source languages))

          (for-each (lambda (language)
                      (define directory
                        (string-append #$output "/"
                                       (normalize language)))

                      (mkdir-p directory)
                      (write-index language
                                   (string-append directory
                                                  "/index.html")))
                    '#$languages))))

  (computed-file "html-indexes" build))

(define* (pdf+html-manual source
                          #:key (languages %languages)
                          (version "0.0")
                          (date (time-second (current-time time-utc)))
                          (manual "guix"))
  "Return the union of the HTML and PDF manuals, as well as the indexes."
  (directory-union (string-append manual "-manual")
                   (map (lambda (proc)
                          (proc source
                                #:date date
                                #:languages languages
                                #:version version
                                #:manual manual))
                        (list html-manual-indexes
                              html-manual pdf-manual))
                   #:copy? #t))

(define (latest-commit+date directory)
  "Return two values: the last commit ID (a hex string) for DIRECTORY, and its
commit date (an integer)."
  (let* ((repository (repository-open directory))
         (head       (repository-head repository))
         (oid        (reference-target head))
         (commit     (commit-lookup repository oid)))
    ;; TODO: Use (git describe) when it's widely available.
    (values (oid->string oid) (commit-time commit))))


(let* ((root (canonicalize-path
              (string-append (current-source-directory) "/..")))
       (commit date (latest-commit+date root)))
  (format (current-error-port)
          "building manual from work tree around commit ~a, ~a~%"
          commit
          (let* ((time (make-time time-utc 0 date))
                 (date (time-utc->date time)))
            (date->string date "~e ~B ~Y")))
  (pdf+html-manual (local-file root "guix" #:recursive? #t
                               #:select? (git-predicate root))
                   #:version (or (getenv "GUIX_MANUAL_VERSION")
                                 (string-take commit 7))
                   #:date date))