;;; auto-load-project.el --- Auto load elisp file on project open

;; Copyright © 2019 Yann Esposito <yann@esposito.host>

;;; Commentary:
;;

;;; Code:

(require 'projectile)

(defvar auto-load-project/trusted-gpg-key-fingerprints
  '()
  "The list of GPG fingerprint you trust when decrypting a gpg file.
You can retrieve the fingerprints of your own private keys
with: `gpg --list-secret-keys' (take care of removing the
spaces when copy/pasting here)")

(defun auto-load-project/get-sign-key (file)
  "Return the fingerprint of they key that signed FILE.

To sign a file you should used

`gpg --local-user my@email --output project.el.sig --detach-sign project.el`"
  (string-trim-right
   (shell-command-to-string
    (concat
     (format "gpg --status-fd 1 --verify %s.sig %s 2>/dev/null " file file)
     "|grep VALIDSIG"
     "|awk '{print $3}'"))))

(defun auto-load-project/trusted-gpg-origin-p (file)
  "Return non-nil if the FILE is encrypted with a trusted key."
  (member (auto-load-project/get-sign-key file)
          auto-load-project/trusted-gpg-key-fingerprints))

(defconst auto-load-project/project-file "project.el"
  "Project configuration file name.")

(defvar auto-load-project/loaded-projects (list)
  "Projects that have been loaded by `auto-load-project/load'.")

(defun auto-load-project/load ()
  "Loads the `auto-load-project/project-file' for a project.
This is run once the project is loaded signifying project setup."
  (interactive)
  (when (projectile-project-p)
    (lexical-let* ((current-project-root (projectile-project-root))
                   (project-init-file (expand-file-name auto-load-project/project-file current-project-root))
                   (project-sign-file (concat project-init-file ".sig")))
      (when (and (not (member current-project-root auto-load-project/loaded-projects))
                 (file-exists-p project-init-file)
                 (file-exists-p project-sign-file)
                 (auto-load-project/trusted-gpg-origin-p project-init-file))
        (message "Loading project init file for %s" (projectile-project-name))
        (condition-case ex
            (progn (load project-init-file)
                   (add-to-list 'auto-load-project/loaded-projects current-project-root)
                   (message "%s loaded successfully" project-init-file))
          ('error
           (message
            "There was an error loading %s: %s"
            project-init-file
            (error-message-string ex))))))))

(add-hook 'find-file-hook #'auto-load-project/load t)
(add-hook 'dired-mode-hook #'auto-load-project/load t)

(provide 'auto-load-project)

;;; auto-load-project.el ends here