;;; h.el --- Project navigation and remote checkout -*- lexical-binding: t -*-

;;; Copyright (C) 2022 Félix Baylac Jacqué
;;; Author: Félix Baylac Jacqué <felix at alternativebit.fr>
;;; Maintainer: Félix Baylac Jacqué <felix at alternativebit.fr>
;;; Version: 1.14.0
;;; Homepage: https://alternativebit.fr/TODO
;;; Package-Requires: ((emacs "25.1"))

;;; License:

;;; 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/>

;;;; Commentary:

;;; TODO before publish

;;; Code:

(eval-when-compile (require 'subr-x))

(defgroup h-group nil
  "Variables used to setup the h.el code folder manager."
  :group 'Communication)


(defcustom h-code-root nil
  "Root directory containing all your projects.
h.el organise the git repos you'll checkout in a tree fashion.

All the code fetched using h.el will end up in this root directory. A
tree of subdirectories will be created mirroring the remote URI.

For instance, after checking out
https://git.savannah.gnu.org/git/emacs/org-mode.git, the source code
will live in the h-code-root/git.savannah.gnu.org/git/emacs/org-mode/
local directory"
  :type 'directory
  :group 'h-group)

(defun h--safe-get-code-root ()
    "Ensure ‘h-code-root’ is correctly set, then canonalize the path.
Errors out if ‘h-code-root’ has not been set yet."
    (progn (when (not h-code-root)
             (error "h-code-root has not been set. Please point it to your code root"))
           (file-name-as-directory h-code-root)))

(defcustom h-git-bin "git"
  "Path pointing to the git binary.
By default, it'll look for git in the current $PATH."
  :type 'file
  :group 'h-group)

(defun h--git-path ()
  "Find the git binary path using ‘h-git-bin’.

Errors out if we can't find it."
  (if (file-executable-p h-git-bin)
      h-git-bin
    (let ((git-from-bin-path (locate-file h-git-bin exec-path)))
      (if (file-executable-p git-from-bin-path)
          git-from-bin-path
          (error "Can't find git. Is h-git-bin correctly set?")))))

(defun h--call-git-in-dir (dir args)
  "Call the git binary as pointed by ‘h-git-bin’ in DIR with ARGS."
  (let ((default-directory dir))
    (process-file (h--git-path) nil nil nil args)))

(defun h--is-git-repo (dir)
  "Check if DIR is a git repo using a pretty weak heuristic."
    (file-directory-p (concat (file-name-as-directory dir) ".git")))

(defun h--get-code-root-projects (code-root)
  "Retrieve the projects contained in the CODE-ROOT directory.
We're going to make some hard assumptions about how the ‘h-code-root’
directory should look like. First of all, if a directory seem to be a
git repository, it'll automatically be considered as a project root.

It means that after encountering a git repository, we won't recurse
any further.

If the directory pointed by h-code-root does not exists yet, returns
an empty list."
  (if (not (file-directory-p code-root))
      '()
    (let*
        ((is-not-git-repo (lambda (dir) (not (h--is-git-repo dir))))
         (remove-code-root-prefix
          (lambda (path) (string-remove-prefix (concat (file-name-as-directory code-root)) path)))
         ;; PERF: Using directory-files-recursively is pretty
         ;; inneficient. We have to list the dir content twice:
         ;; 1. when directory-files-recursively checks.
         ;; 2. when we filter the intermediate dirs from this list.
         (recursively-found-dirs
          (directory-files-recursively code-root "" t is-not-git-repo))
         (projects-absolute-path (seq-filter (lambda (e) (h--is-git-repo e)) recursively-found-dirs))
         (projects-relative-to-code-root
          (mapcar remove-code-root-prefix projects-absolute-path)))
      projects-relative-to-code-root)))

(defun h-jump-to-project ()
  "Open a project contained in the ‘h-code-root’ directory.
If the project is not here yet, check it out from the available sources."
  (interactive)
  (let* ((selected-project-from-coderoot
          (completing-read
           "Available projects: "
           (h--get-code-root-projects (h--safe-get-code-root))
           nil t ""))
         (selected-project-absolute-path (concat (h--safe-get-code-root) selected-project-from-coderoot)))
    (if (file-directory-p selected-project-absolute-path)
        (find-file selected-project-absolute-path)
      (error "NOT IMPLEMENTED: cannot checkout a new project for now"))))

(provide 'h)
;;; h.el ends here