;;; Buid --- The builder for FG42 -*- lexical-binding: t; -*-
;;
;; Copyright (c) 2010-2022 Sameer Rahmani & Contributors
;;
;; Author: Sameer Rahmani <lxsameer@gnu.org>
;; URL: https://gitlab.com/FG42/FG42
;; Version: 3.0.0
;;
;; 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 thnis program.  If not, see <http://www.gnu.org/licenses/>.
;;
;;; Commentary:
;; Cubes are the building blocks of any `FG42' editor.  Each `cube' is a
;; unit which defines different abilities in a deterministic and idempotent
;; way.  Cubes are composable and a composition of cubes creates an editor.
;;
;;; Code:

(require 'seq)


(defvar fg42/build-project-name "FG42"
  "The name to be uesd with in the output as as the project name")

(defvar fg42/build-project-root nil
  "Root directory of the website source code.")

(defvar fg42/build-debug-mode nil)

(defvar fg42/build-author-name "Sameer Rahmani")
(defvar fg42/build-author-email "lxsameer@gnu.org")

(defvar fg42/build-docs-root "/docs/site"
  "Where to find the docs. It sould be relative to the
project root.")

(defvar fg42/build-dev-base-url "http://localhost:3003"
  "The base url to use with the docs for dev.")

(defvar fg42/build-prod-base-url "https://fg42.org"
  "The base url to use with the docs for production.")

(defvar fg42/build-docs-pages-dir "/pages"
  "Where to find the pages (relative to docs dir)")

(defvar fg42/build-docs-ignore-category-check nil
  "A list of files that should be ignored by category/tag checks")

(defvar fg42/build-docs-actions nil
  "Set of actions to run before building the
main docs.")
(defvar fg42/build-output-dir "/build"
  "The path to the build directory.")

(defvar fg42/build-docs-title "FG42"
  "Title of the generated docs. Like the website title")


(defvar fg42/build-docs-desc "The ultimate editor for true believers"
  "Description of the generated docs. Like the website description")

(defvar fg42/build-usage "./builder.el SUBCOMMAND"
  "Title of the generated docs. Like the website title")


(defmacro defproject (prject-name &rest details)
  "Create a project with the given DETAILS.

The build system will consum these details for various purposes."
  (declare (indent defun))
  (cons 'progn
        (cons `(setq fg42/bulid-project-name
                     ,(symbol-name prject-name))
              (seq-reduce
               (lambda (forms pair)
                 (let* ((varname (intern (format "fg42/build-%s" (car pair))))
                        (val (cadr pair))
                        (form `(setq ,varname ,val)))
                   (cons form forms)))
               (seq-partition details 2)
               nil))))


(defmacro command-> (command-var args-var &rest body)
  (declare (indent defun))
  `(defun main ()
     "The entry point to the build script."
     (message (fg42/version))
     (message "\nFG42 Build tool v%s\n\n" (fg42/version))

     ;; UTF-8 as default encoding
     (prefer-coding-system 'utf-8)
     (set-default-coding-systems 'utf-8)
     (set-terminal-coding-system 'utf-8)
     (set-keyboard-coding-system 'utf-8)

     (let* ((fg42-home   (car command-line-args-left))
            (build-dir   (from-root ,fg42/build-output-dir))
            (parsed-args (read-args (cdr command-line-args-left)))
            (eval-string (plist-get (car parsed-args) :e))
            (,command-var     (caadr parsed-args))
            (,args-var        (cdadr parsed-args)))

       ;; Evaluate the expression provided by :e
       (when eval-string
         (eval (car (read-from-string eval-string))))

       (setq fg42/build-debug-mode (plist-get (car parsed-args) :d))

       (cond
        ,@body
        (t (print-help ,command-var))))))


(defun print-help (_)
  "Print out the usage for the build script"
  (message fg42/build-usage))

(defun from-root (path)
  "Return the full path of the given PATH in the project root."
  (concat fg42/build-project-root path))


(defun from-docs (path)
  "Return the full path of the given PATH in the docs root."
  (concat (from-root fg42/build-docs-root) path))


(defun prod-p ()
  "Return non-nil if debug mode is turned off"
  (not fg42/build-debug-mode))


(defun read-args (args)
  "Parse the give ARGS list and return a list in the following
format:
(FLAGS (COMMAND ARGES))"
  (seq-reduce
   (lambda (acc arg)
     (let ((flags (car acc))
           (commands (cadr acc))
           (i (caddr acc))
           (skip (cadddr acc)))

       (if skip
           (list flags commands (1+ i) ())
         (progn
           (cond
            ((string= arg ":d") (plist-put flags :d t))
            ((string= arg ":e") (progn
                                  (plist-put flags :e (nth (1+ i) args))
                                  (setq skip (1+ i))))
            (t (push arg commands)))
           (list flags commands (1+ i) skip)))))
   args
   '((:d () :e ()) () 0 ())))


(defun replace-in-buffer (str replacement)
  "Replace the given STR with its REPLACEMENT in current buffer."
  (with-current-buffer (current-buffer)
    (goto-char (point-min))
    (while (search-forward str nil t)
      (replace-match replacement))))


(defun copy-template (src dest context)
  "Replace the placeholder in SRC with list of pairs given in CONTEXT
and write it to DEST."
  (make-directory (file-name-directory dest) t)
  (message "Copy template: '%s' -> '%s'" src dest)
  (with-temp-file dest
    (insert-file-contents src)
    (dolist (pair context)
      (replace-in-buffer (format "<<<%s>>>" (car pair)) (cdr pair)))))


(defmacro do-command (&rest body)
  "Run the BODY after loading FG42."
  `(progn
     (require 'fg42)
     (fg42/before-initialize)
     ,@body))


(provide 'fg42/build/core)
;;; core.el ends here