feat: add spine-add-book write function

spine.el

@@ -137,6 +137,71 @@ SELECTED-ID expands the matching book's detail section."
           ("reading_count" reading-count)
           ("groups" (nreverse groups))))))
 
+(defun spine-add-book (&rest args)
+  "Add a new WANT book to `spine-org-file'.
+Keyword arguments: :title :author :category :format :isbn :cover
+                   :rec_by :rec_note :date_added :initial_note
+Signals an error on failure."
+  (let ((title (plist-get args :title))
+        (author (plist-get args :author))
+        (category (plist-get args :category))
+        (format (plist-get args :format))
+        (isbn (plist-get args :isbn))
+        (cover (plist-get args :cover))
+        (rec-by (plist-get args :rec_by))
+        (rec-note (plist-get args :rec_note))
+        (date-added (plist-get args :date_added))
+        (initial-note (plist-get args :initial_note)))
+    (unless title
+      (error "spine-add-book: title is required"))
+    (let ((org-file (expand-file-name spine-org-file)))
+      ;; Create file if it doesn't exist
+      (unless (file-exists-p org-file)
+        (with-temp-file org-file
+          (insert "#+TODO: WANT(w) READING(r) | READ(d) ABANDONED(a)\n\n")))
+      (with-current-buffer (find-file-noselect org-file)
+        (unwind-protect
+            (progn
+              (goto-char (point-max))
+              ;; Insert new headline
+              (org-insert-heading nil t)
+              (insert title)
+              ;; Set TODO state
+              (org-todo "WANT")
+              ;; Set properties (only non-empty)
+              (when (and author (> (length author) 0))
+                (org-set-property "AUTHOR" author))
+              (when (and format (> (length format) 0))
+                (org-set-property "FORMAT" format))
+              (when (and isbn (> (length isbn) 0))
+                (org-set-property "ISBN" isbn))
+              (when (and cover (> (length cover) 0))
+                (org-set-property "COVER" cover))
+              (when (and rec-by (> (length rec-by) 0))
+                (org-set-property "REC_BY" rec-by))
+              (when (and rec-note (> (length rec-note) 0))
+                (org-set-property "REC_NOTE" rec-note))
+              (when (and date-added (> (length date-added) 0))
+                (org-set-property "ADDED" (format "[%s]" date-added)))
+              ;; Set ID
+              (org-set-property "ID"
+                (format "%04x-%s"
+                        (random 65535)
+                        (substring (sha1 (concat title (number-to-string (random)))) 0 4)))
+              ;; Set tags
+              (when (and category (> (length category) 0))
+                (org-set-tags (list category)))
+              ;; Add initial note
+              (when (and initial-note (> (length initial-note) 0))
+                (let ((date (if (and date-added (> (length date-added) 0))
+                                date-added
+                              (format-time-string "%Y-%m-%d"))))
+                  (goto-char (org-entry-end-position))
+                  (insert (format "\n- [%s] %s\n" date initial-note))))
+              (save-buffer)
+              t)
+          (kill-buffer))))))
+
 (defun spine--extract-notes (hl-begin hl-end)
   "Extract reading notes from headline body between HL-BEGIN and HL-END.
 Returns list of (date-string text-string) pairs."