;;; multi-emacs-config.el  --- A tool to use multiple emacs configurations  -*- lexical-binding: t; -*-
;;
;; Author: Rongsong Shen<rshen@shenrs.eu>
;;
;;; Commentary:

;;   This package will enable us to use multiple EMACS startup
;;   configuration(startkit in this package) and switch between
;;   these configuration just by change a single environment
;;   variable (EMACS_STARTKIT).
;;
;;   Currently, we have test it with following:
;;   -  doom-emacs
;;   -  spacemacs
;;   -  frontmacs
;;   -  ohai-emacs
;;   -  graphene
;;   -  prelude
;;   -  radian emacs
;;
;;; Code:

(require 'cl-lib)
(require 'comint)

(defvar emacs-start-kit "The name of emacs startkit we will use")
(defvar emacs-config-name "The directory name of emacs startkit")
(defvar emacs-config-directory "The based directory of emacs start configuration")
(defvar emacs-init-file "The full path of emacs start file")
(defvar startkit-info "Information to install emacs startkit")

(setq emacs-start-kit
      (let ((start-kit (getenv "EMACS_STARTKIT")))
        (if start-kit
            start-kit
          "spacemacs")))

(setq emacs-config-name emacs-start-kit)

(setq emacs-config-directory
      (let ((config-dir (getenv "EMACS_CONFIG_DIR")))
        (if config-dir
            (concat config-dir "/"
                    emacs-config-name "/")
          (concat (substitute-in-file-name "~/.config/emacs/")
                  emacs-config-name "/"))))

(unless (file-exists-p emacs-config-directory)
  (make-directory emacs-config-directory t))

(setq user-emacs-directory emacs-config-directory)

(setq emacs-init-file
      (expand-file-name "init.el" user-emacs-directory))

;; setup customization directory for emacs (custom.el)
(unless custom-file
  (setq custom-file (expand-file-name "custom.el" user-emacs-directory)))

;; Setup default directory which package will be installed
(setq package-user-dir
      (concat user-emacs-directory "/elpa"))

;; setup directory of spacemacs customization
(when (string= emacs-start-kit "spacemacs")
  (let ((spacemacs-dir (concat emacs-config-directory "/.local/etc")))
    (progn
      (setenv "SPACEMACSDIR" spacemacs-dir))))

(setq startkit-info
      '((doom-emacs .
                    (lambda (dir)
                      (list
                       (concat "git clone git@github.com:shen390s/doom-emacs.git " dir)
                       (concat "cd " dir)
                       "cp init.example.el init.el"
                       "make install"
                       "y")))
        (frontmacs .
                   (lambda (dir)
                     (list
                      (concat "mkdir -p " dir )
                      (concat "cd " dir)
                      "wget https://raw.githubusercontent.com/shen390s/frontmacs/master/scripts/init-frontmacs.el"
                      "echo \"(load (expand-file-name \\\"init-frontmacs.el\\\" user-emacs-directory))\" >>init.el")))
        (graphene .
                  (lambda (dir)
                    (list
                     (concat "git clone git@github.com:shen390s/dotfiles-emacs.git " dir))))
        (ohai-emacs .
                    (lambda (dir)
                      (list
                       (concat "git clone git@github.com:shen390s/ohai-emacs.git " dir))))
        (prelude .
                 (lambda (dir)
                   (list
                    (concat "git clone git@github.com:shen390s/prelude.git " dir))))
        (spacemacs .
                   (lambda (dir)
                     (list
                      (concat "git clone https://github.com/syl20bnr/spacemacs.git " dir))))
        (radian-emacs .
                      (lambda (dir)
                        (list
                         (concat "git clone -b radian https://github.com/shen390s/straight-emacs.git " dir))))
        (hell-emacs .
                    (lambda (dir)
                      (list
                       (concat "git clone -b doom-emacs https://github.com/shen390s/straight-emacs.git " dir))))))

(defun install-emacs-startkit (name location)
  "Function to install EMACS startkit. NAME is the name of EMACS startkit.
LOCATION is the target directory which startkit will be installed."
  (progn (let* ((shell-buffer (make-comint-in-buffer "installer" nil "/bin/sh"))
                (shell-process (get-buffer-process shell-buffer)))
           (progn
             (defun on-installer-finished (process event)
               "Callback function when uinstaller process has finished.
We use this function to load startkit initialization file"
               (cond
                ((string= event "finished\n") (load-file emacs-init-file))
                (t (message "Event %s has been ignored" event))))

             (set-process-sentinel shell-process 'on-installer-finished)
             (display-buffer shell-buffer)
             (cl-loop for cmd in (funcall (cdr (assoc (intern name) startkit-info))
                                          location)
                      do (comint-simple-send shell-process
                                             (concat cmd "\n")))
             (comint-simple-send shell-process
                                 "exit\n")))))

(if (not (file-exists-p emacs-init-file))
    (progn
      (install-emacs-startkit emacs-start-kit
                              emacs-config-directory))
  (load-file emacs-init-file))

(provide 'multi-emacs-config)
;;; multi-emacs-config.el ends here