From 044f84632ecf8518184f45802a97a9fa91f9a6d6 Mon Sep 17 00:00:00 2001
From: Aaron Ecay <aaronecay@gmail.com>
Date: Thu, 7 Mar 2013 00:22:07 -0500
Subject: [PATCH] Support export of bibliography links (WIP)

---
 lisp/ox-bib.el   | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lisp/ox-latex.el |   8 +++++
 lisp/ox.el       |   1 +
 3 files changed, 117 insertions(+)
 create mode 100644 lisp/ox-bib.el

diff --git a/lisp/ox-bib.el b/lisp/ox-bib.el
new file mode 100644
index 0000000..d726e31
--- /dev/null
+++ b/lisp/ox-bib.el
@@ -0,0 +1,108 @@
+(require 'bibtex)
+(require 'ox)
+
+(defvar ox-bib-find-entries-in-org-file nil
+  "Whether to look for bibliogrpahy entries in an org mode file
+or a bibtex file.")
+
+(defun ox-bib-get-bibliography ()
+  (mapcar (lambda (s)
+            (org-no-properties s))
+	  ;; Don't explode if before the first headline
+          (or
+           (condition-case nil
+               (plist-get (org-export-get-environment nil t) :bibliography)
+             (error nil))
+           (save-excursion
+             (widen)
+             (goto-char (point-min))
+             (plist-get (org-export-get-environment) :bibliography)))))
+
+(defun ox-bib-get-key (path &optional desc)
+  "Extract cite key from a link path and desc.
+
+Currently expects links in the format:
+\[[type:key;pre;post;][desc]]"
+  (nth 0 (split-string path ";")))
+
+(defun ox-bib-get-pre (path &optional desc)
+  "Extract pre-citation arg from a link path and desc.
+
+Currently expects links in the format:
+\[[type:key;pre;post;][desc]]"
+  (or (nth 1 (split-string path ";")) ""))
+
+(defun ox-bib-get-post (path &optional desc)
+  "Extract post-citation arg from a link path and desc.
+
+Currently expects links in the format:
+\[[type:key;pre;post;][desc]]"
+  (or (nth 2 (split-string path ";")) ""))
+
+;; Adapted from org-find-entry-with-custom-id; there might be a better
+;; way to do this
+(defun org-find-entry-with-custom-id (ident)
+  (let ((id ident)
+        (case-fold-search nil))
+    (save-excursion
+      (save-restriction
+        (widen)
+        (goto-char (point-min))
+        (when (re-search-forward
+               (concat "^[ \t]*:CUSTOM_ID:[ \t]+" (regexp-quote id) "[ \t]*$")
+               nil t)
+          (org-back-to-heading t)
+          (point))))))
+
+(defun ox-bib-cite-follow (path)
+  (let* ((files (ox-bib-get-bibliography))
+	 (key (ox-bib-get-key path))
+	 file done)
+    (when ox-bib-find-entries-in-org-file
+      (setq files
+	    (mapcar (lambda (s)
+		      (replace-regexp-in-string "\\.bib\\'" ".org" s))
+		    files)))
+    (while (and (car-safe files) (not done))
+      (setq file (car-safe files))
+      (when (file-exists-p file)
+        (let* ((buf (find-file-noselect file))
+
+	       (pos (with-current-buffer buf
+		      (cond
+		       (ox-bib-find-entries-in-org-file
+			(org-find-entry-with-custom-id key))
+		       (t (bibtex-search-entry key))))))
+	  (when pos
+	    (setq done (cons buf pos)))))
+      (setq files (cdr files)))
+    (if done
+	(progn
+          (pop-to-buffer (car done))
+	  (goto-char (cdr done))
+          (when ox-bib-find-entries-in-org-file
+            (org-show-context)))
+      (message "Citation not found: %s" key))))
+
+(defun ox-bib-textcite-export (path desc format)
+  (cond
+   ((org-export-derived-backend-p format 'latex)
+    (let ((key (ox-bib-get-key path desc))
+	  (pre (ox-bib-get-pre path desc))
+	  (post (ox-bib-get-post path desc)))
+      (format "\\textcite[%s][%s]{%s}" pre post key)))
+   (t
+    (format "<textcite to: %s>" path))))
+
+(defun ox-bib-parencite-export (path desc format)
+  (cond
+   ((org-export-derived-backend-p format 'latex)
+    (let ((key (ox-bib-get-key path desc))
+          (pre (ox-bib-get-pre path desc))
+          (post (ox-bib-get-post path desc)))
+      (format "\\parencite[%s][%s]{%s}" pre post key)))
+   (t
+    (format "<parencite to: %s>" path))))
+
+(org-add-link-type "textcite" #'ox-bib-cite-follow #'ox-bib-textcite-export)
+(org-add-link-type "parencite" #'ox-bib-cite-follow #'ox-bib-parencite-export)
diff --git a/lisp/ox-latex.el b/lisp/ox-latex.el
index 8a5b6a6..ed5dcad 100644
--- a/lisp/ox-latex.el
+++ b/lisp/ox-latex.el
@@ -1153,6 +1153,14 @@ holding export options."
 	       (or (plist-get info :description) "")
 	       (if (not (plist-get info :with-creator)) ""
 		 (plist-get info :creator))))
+     ;; Bibliography
+     (let* ((bibs (plist-get info :bibliography))
+            (bib-cmds (mapconcat (lambda (s)
+                                   (format "\\addbibresource{%s}" s))
+                                 bibs "\n")))
+       (if bibs
+	   (concat bib-cmds "\n")
+	 ""))
      ;; Document start.
      "\\begin{document}\n\n"
      ;; Title command.
diff --git a/lisp/ox.el b/lisp/ox.el
index 3a0764d..bdff5ee 100644
--- a/lisp/ox.el
+++ b/lisp/ox.el
@@ -118,6 +118,7 @@
     (:select-tags "SELECT_TAGS" nil org-export-select-tags split)
     (:time-stamp-file nil "timestamp" org-export-time-stamp-file)
     (:title "TITLE" nil nil space)
+    (:bibliography "BIBLIOGRAPHY" nil nil split)
     (:with-archived-trees nil "arch" org-export-with-archived-trees)
     (:with-author nil "author" org-export-with-author)
     (:with-clocks nil "c" org-export-with-clocks)
-- 
1.8.1.5