;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2019 by Amar Singh <nly@disroot.org>
;;;
;;; This file is part of GNU Guix.
;;; 
;;; This program 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.
;;; 
;;; This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.

(define-module (guix import golang))
(use-modules
 (guix import github)  ;; latest-release
 (guix download)       ;; download-to-store
 ((guix import utils) #:prefix utils:)   ;; hash
 (guix packages)       ;; packages
 (guix build-system go)  ;; go-build-system
 (guix store)          ;; with-store
 (gnu packages golang) ;; inherit (simple) go package
 (ice-9 textual-ports) ;; to parse readme.md
 )

(define go-name* "github.com/gohugoio/hugo") ;; for tests

(define (go-name->url go-name)
  (string-append "https://" go-name))

(define (go-name->tarball go-name version)
  (string-append (go-name->url go-name) "/archive/v" version
                 ".tar.gz"))

;;; Possible remove @@ if upstream exports the symbols
(define (go-name->name go-name)
  ((@@ (guix import github) github-repository)
   (go-name->url go-name)))

;;; Slow; accesses the network
(define (latest-release go-name)
  ((@@ (guix import github) latest-released-version)
   (go-name->url go-name)
   (go-name->name go-name)))

;;; Slow; downloads the url from network;
(define (url->store url)
  (with-store store
    (download-to-store store
                       url)))
;;; Slow; download the source tarball from network and returns base32
;;; nix-hash
(define (go-name->sha256 go-name version)
  (utils:guix-hash-url (url->store (go-name->tarball go-name version))))

;;; Towards go-name->synopsis,description
(define (go-name->readme go-name)
  (string-append "https://raw.githubusercontent.com"
                 (substring go-name
                            (string-length "github.com"))
                 "/master/"
                 "README.md"))

;;; Slow; network access
(define (go-name->readme-string go-name)
  "Slow; network access."
  (call-with-input-file (url->store (go-name->readme go-name))
    (lambda (port) (get-string-n port 4096))))

;;; Maybe try to match the first sentence.
(define (go-name->synopsis go-name readme-string)
  (string-append (go-name->name go-name)
                 (substring readme-string 0 100)))

;;; Maybe try to match the the next two sentences.
(define (go-name->description go-name readme-string)
  (string-append (go-name->name go-name)
                 (substring readme-string 100 300)))

(define-public (make-go-package go-name)
  ;; Do the expensive operations only once; query network for latest version
  (let* ((version (latest-release go-name))
         (sha256 (go-name->sha256 go-name version))
         (readme-string (go-name->readme-string go-name)))
    (package (inherit go-github-com-alsm-ioprogress)
      (name (string-append "go-" (go-name->name go-name)))
      (version version)
      (source (origin (method url-fetch)
                      (uri (go-name->tarball go-name version))
                      (sha256 (base32
                               sha256))))
      (home-page (go-name->url go-name))
      (build-system go-build-system)
      (arguments
       `(#:import-path ,go-name))
      ;; TODO: inputs
      (synopsis
       (go-name->synopsis go-name readme-string))
      (description (go-name->description go-name readme-string))
      ;; TODO: license
      )))

;;; STATUS
;;; 1. latest-release  DONE
;;; 1.b latest-commit PENDING/STALLED
;;; 2. go-name->name DONE
;;; 4. go-name->url DONE
;;; 4.b go-name->tarball DONE
;;; 5. go-name->sha256 (go-name version) DONE
;;; 6. go-name->synopsis DONE
;;; 7. go-name->description DONE
;;; 6-7.b try to extract sentences. TODO
;;; 8. go-name->license TODO
;;; 9. go-name->inputs TODO

;;; golang.scm ends here