;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2021 Vinicius Monego <monego@posteo.net>
;;;
;;; 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 godot-build-system)
  #:use-module ((guix build gnu-build-system) #:prefix gnu:)
  #:use-module (guix build utils)
  #:use-module (ice-9 match)
  #:use-module (ice-9 format)
  #:use-module (ice-9 ftw)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:export (%standard-phases
            godot-build))

(define* (configure #:key project-directory #:allow-other-keys)

  ;; Projects may have the 'project.godot' file in different directories.  The
  ;; project-directory key contains the path string to the directory where it
  ;; is located.
  
  (chdir project-directory)
  (setenv "HOME" (getcwd))
  
  ;; Not all projects ship with export_presets.cfg because it may contain
  ;; confidential information such as CI keys.  In that case, we check if
  ;; this file exists, and if it doesn't we use this generic template below.
  ;; There is ongoing effort to separate the keys from that file. See:
  ;; https://github.com/godotengine/godot-demo-projects/issues/329 and
  ;; https://github.com/godotengine/godot/pull/35930.  Until that is fixed and
  ;; developers start to provide the file, we have to use our own template.

  (let ((export-presets "export_presets.cfg"))
    (when (not (file-exists? export-presets))
      (with-output-to-file export-presets
        (lambda ()
          (display
           "[preset.0]

name=\"Guix\"
platform=\"Linux/X11\"
runnable=true
custom_features=\"\"
export_filter=\"all_resources\"
include_filter=\"\"
exclude_filter=\"\"
export_path=\"\"
patch_list=PoolStringArray(  )
script_export_mode=1
script_encryption_key=\"\"

[preset.0.options]

texture_format/bptc=false
texture_format/s3tc=true
texture_format/etc=false
texture_format/etc2=false
texture_format/no_bptc_fallbacks=true
binary_format/64_bits=false
binary_format/embed_pck=false
custom_template/release=\"\"
custom_template/debug=\"\""))))))

(define* (build #:key inputs game export-name #:allow-other-keys)
  (let ((godot (assoc-ref inputs "godot-headless")))
    (invoke (string-append godot "/bin/godot_server")
            "--export-pack" export-name (string-append game ".pck")
            "project.godot")))

(define* (install #:key inputs outputs game #:allow-other-keys)
  (let* ((out (assoc-ref outputs "out"))
         (bin (string-append out "/bin"))
         (share (string-append out "/share"))
         (data (string-append share "/" game))
         (icons (string-append share "/icons/hicolor/256x256/apps")))
    (install-file (string-append game ".pck") data)
    (mkdir-p bin)
    (call-with-output-file (string-append bin "/" game)
      (lambda (port)
        (format port
                "#!/bin/sh~@
                 exec ~a/bin/godot --main-pack ~a/~a.pck~%"
                (assoc-ref inputs "godot") data game)
        (chmod port #o755)))
    (mkdir-p icons)
    (copy-file "icon.png" (string-append icons "/" game ".png"))))

(define %standard-phases
  (modify-phases gnu:%standard-phases
    (delete 'bootstrap)
    (replace 'configure configure)
    (replace 'build build)
    (delete 'check)
    (replace 'install install)))

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