;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019, 2020 Nicolò Balzarotti <nicolo@nixo.xyz>
;;; Copyright © 2021 Jean-Baptiste Volatier <jbv@pm.me>
;;;
;;; 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 build julia-build-system)
  #:use-module ((guix build gnu-build-system) #:prefix gnu:)
  #:use-module (guix build utils)
  #:use-module (rnrs io ports)
  #:use-module (ice-9 match)
  #:use-module (ice-9 regex)
  #:use-module (ice-9 rdelim)
  #:use-module (ice-9 popen)
  #:export (%standard-phases
            julia-create-package-toml
            julia-build))

;; Commentary:
;;
;; Builder-side code of the standard build procedure for Julia packages.
;;
;; Code:

(define (invoke-julia code)
  (invoke "julia" "-e" code))

;; subpath where we store the package content
(define %package-path "/share/julia/loadpath/")

(define (project.toml->name file)
  "Look for Julia package name in the TOML file FILE (usually named
Project.toml)."
  (call-with-input-file file
    (lambda (in)
      (let loop ((line (read-line in 'concat)))
        (if (eof-object? line)
            #f
            (let ((m (string-match "name\\s*=\\s*\"(.*)\"" line)))
              (if m (match:substring m 1)
                  (loop (read-line in 'concat)))))))))

(define (project.toml->uuid file)
  "Look for Julia package uuid in the TOML file FILE (usually named
Project.toml)."
  (call-with-input-file file
    (lambda (in)
      (let loop ((line (read-line in 'concat)))
        (if (eof-object? line)
            #f
            (let ((m (string-match "uuid\\s*=\\s*\"(.*)\"" line)))
              (if m (match:substring m 1)
                  (loop (read-line in 'concat)))))))))

(define* (install #:key source inputs outputs julia-package-name
                  #:allow-other-keys)
  (let* ((out (assoc-ref outputs "out"))
         (package-dir (string-append out %package-path
                                     (or
                                      julia-package-name
                                      (project.toml->name "Project.toml")))))
    (mkdir-p package-dir)
    (copy-recursively (getcwd) package-dir))
  #t)

(define* (precompile #:key source inputs outputs julia-package-name
                     #:allow-other-keys)
  (let* ((out (assoc-ref outputs "out"))
         (builddir (string-append out "/share/julia/"))
         (package (or julia-package-name (project.toml->name "Project.toml"))))
    (mkdir-p builddir)
    ;; With a patch, SOURCE_DATE_EPOCH is honored
    (setenv "SOURCE_DATE_EPOCH" "1")
    (setenv "JULIA_DEPOT_PATH" builddir)
    ;; Add new package dir to the load path.
    (setenv "JULIA_LOAD_PATH"
            (string-append builddir "loadpath/" ":"
                           (or (getenv "JULIA_LOAD_PATH")
                               "")))
    ;; Actual precompilation:
    (invoke-julia
     ;; When using Julia as a user, Julia writes precompile cache to the first
     ;; entry of the DEPOT_PATH list (by default, the home dir).  We want to
     ;; write it to the store, so let's push the store path as the first
     ;; element of DEPOT_PATH.  Once the cache file exists, this hack is not
     ;; needed anymore (like in the check phase).  If the user install new
     ;; packages, those will be installed and precompiled in the home dir.
     (string-append "pushfirst!(DEPOT_PATH, pop!(DEPOT_PATH)); using " package)))
  #t)

(define* (check #:key tests? source inputs outputs julia-package-name
                #:allow-other-keys)
  (when tests?
    (let* ((out (assoc-ref outputs "out"))
           (package (or julia-package-name (project.toml->name "Project.toml")))
           (builddir (string-append out "/share/julia/")))
      ;; With a patch, SOURCE_DATE_EPOCH is honored
      (setenv "SOURCE_DATE_EPOCH" "1")
      (setenv "JULIA_DEPOT_PATH" builddir)
      (setenv "JULIA_LOAD_PATH"
              (string-append builddir "loadpath/" ":"
                             (or (getenv "JULIA_LOAD_PATH")
                                 "")))
      (setenv "HOME" "/tmp")
      (invoke "julia" "--depwarn=yes"
              (string-append builddir "loadpath/"
                             package "/test/runtests.jl"))))
  #t)

(define* (link-depot #:key source inputs outputs julia-package-name julia-package-uuid
                     #:allow-other-keys)
  (let* ((out (assoc-ref outputs "out"))
         (package-name (or
                        julia-package-name
                        (project.toml->name "Project.toml")))
         (package-dir (string-append out %package-path package-name))
         (uuid (or julia-package-uuid (project.toml->uuid "Project.toml")))
         (pipe (open-pipe* OPEN_READ "julia" "-e"
                           (format #f "using Pkg;
println(Base.version_slug(Base.UUID(\"~a\"),
                          Base.SHA1(Pkg.GitTools.tree_hash(\".\"))))" uuid)))
         (slug (string-trim-right (get-string-all pipe))))
    ;; When installing a package, julia looks first at in the JULIA_DEPOT_PATH
    ;; for a path like packages/PACKAGE/XXXX
    ;; Where XXXX is a slug encoding the package UUID and SHA1 of the files
    ;; Here we create a link with the correct path to enable julia to find the package
    (mkdir-p (string-append out "/share/julia/packages/" package-name))
    (symlink package-dir (string-append out "/share/julia/packages/" package-name "/" slug)))
  #t)

(define (julia-create-package-toml outputs source
                                   name uuid version
                                   deps)
  "Some packages are not using the new Package.toml dependency specifications.
Write this file manually, so that Julia can find its dependencies."
  (let ((f (open-file
            (string-append
             (assoc-ref outputs "out")
             %package-path
             (string-append
              name "/Project.toml"))
            "w")))
    (display (string-append
              "
name = \"" name "\"
uuid = \"" uuid "\"
version = \"" version "\"
") f)
    (when (not (null? deps))
      (display "[deps]\n" f)
      (for-each (lambda dep
                  (display (string-append (car (car dep)) " = \"" (cdr (car dep)) "\"\n")
                           f))
                deps))
    (close-port f))
  #t)

(define %standard-phases
  (modify-phases gnu:%standard-phases
    (delete 'check) ; tests must be run after installation
    (replace 'install install)
    (add-after 'install 'precompile precompile)
    (add-after 'unpack 'link-depot link-depot)
    (add-after 'install 'check check)
    ;; TODO: In the future we could add a "system-image-generation" phase
    ;; where we use PackageCompiler.jl to speed up package loading times
    (delete 'configure)
    (delete 'bootstrap)
    (delete 'patch-usr-bin-file)
    (delete 'build)))

(define* (julia-build #:key inputs julia-package-name julia-package-uuid
                      (phases %standard-phases)
                      #:allow-other-keys #:rest args)
  "Build the given Julia package, applying all of PHASES in order."
  (apply gnu:gnu-build
         #:inputs inputs #:phases phases
         #:julia-package-name julia-package-name
         #:julia-package-uuid julia-package-uuid
         args))