org-journal-list.el

(defcustom org-journal-list-default-dir
  "~/org/"
  "Default location for org files"
  :type 'directory)

(defcustom org-journal-list-display-alist
  '((side . left)
    (window-width . 40)
    (slot . -1))
  "Alist used to display notes buffer.
See `display-buffer-in-side-window' for example options."
  :type 'alist)

(defcustom org-journal-list-preview-size
  5
  "Number of lines visible in the preview of every org file."
  :type 'integer)


(defun org-journal-list--read-journal (path)
  (with-temp-buffer
    (insert-file-contents (concat org-journal-list-default-dir path))
    (split-string (buffer-string) "\n" t)))

(defun org-journal-list--read-first-n-lines (list n)
  (cond ((>= (length list) (+ n 1)) (subseq list 1 n))
        ((>= (length list) 1) (nthcdr 1 list))
        (t list)))

(defun org-journal-list--read-journal-heads (path)
  (mapconcat (function (lambda (line) (format "  %s" line)))
             (org-journal-list--read-first-n-lines (org-journal-list--read-journal path)
                                                   org-journal-list-preview-size) "\n"))

(defun open-journal-mode ()
  (interactive)
  (setq journal-list-buffer (get-buffer-create (generate-new-buffer-name "journal-list.org")))
  (with-current-buffer journal-list-buffer
    (org-mode)
    (setq journal-file-list (directory-files org-journal-list-default-dir nil "\\.org$"))
    (setq journal-file-list (mapcar (lambda (item)
                                      (format "* [[file:%s/%s][%s]]\n\n  #+BEGIN_SRC\n%s\n  #+END_SRC\n"
                                              item
                                              org-journal-list-default-dir
                                              item
                                              (org-journal-list--read-journal-heads item)))
                                    journal-file-list))
    (insert (mapconcat 'identity journal-file-list "\n"))
    (toggle-read-only t)
    (goto-char 1))
  (display-buffer-in-side-window journal-list-buffer org-journal-list-display-alist))