;;; isbn.el --- utilities for generating bibtex entries from an ISBN  -*- lexical-binding: t; -*-

;; Copyright (C) 2015  John Kitchin

;; Author: John Kitchin <jkitchin@andrew.cmu.edu>
;; Keywords: convenience

;; 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 <http://www.gnu.org/licenses/>.

;;; Commentary:

;;

;;; Code:

;; * ISBN utility

;; I found this on the web. It can be handy, but the bibtex entry has a lot of stuff in it.

(defun isbn-to-bibtex-lead (isbn)
 "Search lead.to for ISBN bibtex entry.
You have to copy the entry if it is on the page to your bibtex
file."
 (interactive "sISBN: ")
 (browse-url
  (format
   "http://lead.to/amazon/en/?key=%s+&si=all&op=bt&bn=&so=sa&ht=us"
   isbn)))

;; Here we get isbn metadata and build a bibtex entry.
;; http://xisbn.worldcat.org/xisbnadmin/doc/api.htm#getmetadata

(defun isbn-to-bibtex (isbn bibfile)
  "Get bibtex entry for ISBN and insert it into BIBFILE unless an
entry with the generated key already exists in the file."
  (interactive
   (list
    (read-string
     "ISBN: "
     ;; now set initial input
     (cond
      ;; If region is active and it starts with a number, we use it
      ((and  (region-active-p)
	     (s-match "^[0-9]" (buffer-substring (region-beginning) (region-end))))
       (buffer-substring (region-beginning) (region-end)))
      ;; if first entry in kill ring starts with a number assume it is an isbn
      ;; and use it as the guess
      ((if (s-match "^[0-9]" (car kill-ring))
	   (car kill-ring)))
      ;; type or paste it in
      (t
       nil)))
    (ido-completing-read
     "Bibfile: "
     (append (f-entries "." (lambda (f) (f-ext? f "bib")))
	     org-ref-default-bibliography))))

  (let* ((results (with-current-buffer
		      (url-retrieve-synchronously
		       (format
			"http://xisbn.worldcat.org/webservices/xid/isbn/%s?method=getMetadata&format=json&fl=*"
			isbn))
		    (json-read-from-string
		     (buffer-substring url-http-end-of-headers (point-max)))))
	 (status (cdr (nth 1 results)))
	 (metadata (aref (cdar results) 0))
	 (new-entry)
	 (new-key))

    ;; check if we got something
    (unless (string= "ok" status)
      (error "Status is %s" status))

    ;; construct an alphabetically sorted bibtex entry. I assume ISBN numbers go
    ;; with book entries.
    (setq new-entry
	  (concat "\n@book{,\n"
		  (mapconcat
		   'identity
		   (cl-loop for field in (-sort 'string-lessp (mapcar 'car metadata))
			    collect
			    (format "  %s={%s}," field (cdr (assoc field metadata))))
		   "\n")
		  "\n}\n"))

    ;; build entry in temp buffer to get the key so we can check for duplicates
    (setq new-entry (with-temp-buffer
		      (insert new-entry)
		      (org-ref-clean-bibtex-entry)
		      (setq new-key (bibtex-key-in-head))
		      (buffer-string)))
    (find-file bibfile)
    (goto-char (point-min))
    (when (search-forward new-key nil t)
      (beep)
      (setq new-key (read-string
		     (format  "%s already exists. Enter new key (C-g to cancel): " new-key)
		     new-key)))
    (goto-char (point-max))
    (insert new-entry)
    ;; set key. It is simplest to just replace it, even if it is the same.
    (bibtex-beginning-of-entry)
    (re-search-forward bibtex-entry-maybe-empty-head)
    (if (match-beginning bibtex-key-in-head)
	(delete-region (match-beginning bibtex-key-in-head)
		       (match-end bibtex-key-in-head)))
    (insert new-key)
    (bibtex-fill-entry)
    (save-buffer)))

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