Add journal.el

journal.el

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+(defvar journal-base-directory "/Users/adhearn/Dropbox/exobrain/journal"
+  "The directory that holds journal files, without any date information.")
+
+(defun journal-time->year
+    (time)
+  (nth 5 (decode-time time)))
+
+(defun journal-time->month
+    (time)
+  (nth 4 (decode-time time)))
+
+(defun journal-time->day
+    (time)
+  (nth 3 (decode-time time)))
+
+(defun journal-time->dow
+    (time)
+  "Returns the day of the week from the given time"
+  (nth 6 (decode-time time)))
+
+(defun journal-dow-string
+    (time)
+  "Returns the day of the week as a three character string (e.g. 'Mon', 'Tue', etc.)"
+  (let ((dow (journal-time->dow time)))
+    (cond
+     ((= dow 0) "Sun")
+     ((= dow 1) "Mon")
+     ((= dow 2) "Tue")
+     ((= dow 3) "Wed")
+     ((= dow 4) "Thu")
+     ((= dow 5) "Fri")
+     ((= dow 6) "Sat")
+     (t (error "Invalid day of week: %d", dow)))))
+
+(defun journal-month-string
+    (time)
+  "Returns the month of the given date as a string. The full name of the month is used, all in lowercase."
+  (let ((month-num (journal-time->month time)))
+    (cond
+     ((= month-num 1) "january")
+     ((= month-num 2) "februaury")
+     ((= month-num 3) "march")
+     ((= month-num 4) "april")
+     ((= month-num 5) "may")
+     ((= month-num 6) "june")
+     ((= month-num 7) "july")
+     ((= month-num 8) "august")
+     ((= month-num 9) "september")
+     ((= month-num 10) "october")
+     ((= month-num 11) "november")
+     ((= month-num 12) "december")
+     (t (error "Invalid month: %d", month-num)))))
+
+(defun journal-day-string
+    (time)
+  "Returns the day of the month of the given time as a string."
+  (number-to-string (journal-time->day time)))
+
+(defun journal-filename-for-date
+    (date)
+  "Returns the filename corresponding to today's date."
+  (let ((year (journal-time->year date))
+        (month (journal-month-string date))
+        (day (journal-time->day date)))
+    (convert-standard-filename
+     (format "%s/%d/%s/%d.txt" journal-base-directory year month day))))
+
+(defun journal-timestamp-str
+    (time)
+  (let ((year (journal-time->year time))
+        (month (journal-time->month time))
+        (day (journal-time->day time))
+        (dow (journal-dow-string time)))
+    (format "<%4d-%02d-%02d %s>" year month day dow)))
+
+(defun journal-insert-timestamp
+    (time)
+  "Inserts a timestamp into the current buffer, followed by a newline."
+  (insert (journal-timestamp-str time))
+  (insert "\n"))
+
+(defun journal-buffer-empty-p
+    (buf)
+  "Returns true if the given buffer is empty, false otherwise"
+  (= (buffer-size buf) 0))
+
+(defun journal-open-today
+    ()
+  "Opens the file for today into a new buffer and switches to that buffer."
+  (let ((filename (journal-filename-for-date (current-time))))
+    (let ((buffer (find-file filename)))
+      (when (journal-buffer-empty-p buffer)
+        (journal-insert-timestamp (current-time)))
+      (visual-line-mode))))
+
+(defun journal ()
+  "An interactive functiont that wraps journal-open-today"
+  (interactive)
+  (journal-open-today))
+
+(provide 'journal)
+
+