BibTeX convertor

I've been thinking about using my LibraryThing account with BibTeX. The problem is, LibraryThing doesn't export to BibTeX format. So I wrote a kludgy convertor: this takes a CSV export file from LibraryThing and generates BibTeX entries from it. I'm sure it could be a zillion times better, but it seems to work pretty well under SBCL. It requires CL-PPCRE.

I apologize for the formatting, I'll fix it if I can figure it out.

;;; Attempt to actually process LibraryThing export CSV file
;;;
;;; Mark Peever
;;; 2009-02-16

;;; Requires:
;;; cl-ppcre

(defparameter library-thing-encoding :ISO-8859-1)

;; The CSV fields may contain commas
(defparameter line-pattern (concatenate 'STRING 
                    "^\"(.+?)\"," ; title
                    "\"(.+?)\","  ; author-simple
                    "\"(.+?)\","  ; author
                    "([^,]*),"    ; date
                    "([^,]*),"    ; lcc
                    "([^,]*),"    ; ddc
                    "([^,]*),"    ; isbn
                    "\"(.+?)\","  ; publication
                    "([^,]*),"    ; rating
                    "([^,]*),"    ; review
                    "\"(.+?)\","  ; entry-date
                    "([^,]*),"    ; copies
                    ))

;; Structure to hold a book entry
(defstruct book
  title
  author-simple
  author
  date
  lcc
  ddc
  isbn
  publication-data
  rating
  review
  entry-date
  copies)

(defun create-bibtex-file (export-file bibtex-file)
  "Create a BibTex file from a LibraryThing export file."
  (write-data bibtex-file 
          (mapcar #'bibtex-entry (parse-export-file export-file))))

(defun load-data (export-file)
  "Load a LibraryThing export file into a list of CSV lines. This is almost entirely a wrapper for 'fare-csv:read-csv-file."
  (read-text-file export-file :format library-thing-encoding))

(defun write-data (bibtex-file entries)
  "Write a list of BibTeX entries to a file."
  (with-open-file (out-stream bibtex-file 
                  :direction :output
                  :if-exists :append
                  :if-does-not-exist :create
                  :external-format :utf-8)
    (loop for entry in entries
    do (write-line entry out-stream)
     finally (probe-file bibtex-file))))

(defun read-text-file (filename &key (format :utf-8))
  "Read a text file into a list of lines. The EXTERNAL-FORMAT is passed as a keyword argument."
  (with-open-file (istream filename 
               :direction :input
               :external-format format)
    (loop for line = (read-line istream nil)
     while (not (null line))
     collect line)))

(defun line->book (csv-line)
  "Generate a BOOK object from a CSV line from the export file." 
  (cl-ppcre:register-groups-bind (title 
                  author-simple 
                  author 
                  date 
                  lcc 
                  ddc
                  isbn
                  publication-data
                  rating
                  review
                  entry-date
                  copies) 
      (line-pattern csv-line)
    (make-book :title title 
           :author-simple author-simple 
           :author author 
           :date date 
           :lcc lcc 
           :ddc ddc
           :isbn isbn
           :publication-data publication-data
           :rating rating
           :review review
           :entry-date (remove-if-not #'safe-char? entry-date)
           :copies copies)))

(defun parse-export-file (filename)
  "Return a list of BOOKS parsed from the output file."
  (remove-if-not #'book-p
         (mapcar #'line->book (load-data filename))))

(defun safe-char? (char)
  "Check whether CHAR is safe for use in a BibTex cite key"
  (not 
   (find
    char
    '(#\. #\, #\; #\% #\" #\' #\) #\( #\# #\Space #\Tab #\NewLine))))

(defun cite-key (book)
  "Create a cite-key for a book."
  (concatenate 'string
           (remove-if-not #'safe-char? (book-author book))
           ":"
           (remove-if-not #'safe-char? (book-title book))
           ":"
           (remove-if-not #'safe-char? (book-date book))))

(defun bibtex-entry (book)
  "Generate a BIBTEX entry from a BOOK object."
  (if (not (book-p book))
      nil
      (concatenate 'STRING 
           (format nil "@book {~A,~%" (cite-key book))
           (format nil "title={~A},~%" (book-title book))
           (format nil "author=~S,~%" (book-author book))
           (format nil "publisher=~S,~%" 
               (book-publication-data book))
           (format nil "date={~A} ~%" (book-date book))
           "}")))