From c20db472ebf972583127dfee1d869e14cfd44b9b Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 23 Oct 2013 20:42:27 +0530
Subject: [PATCH] FB2 Input: Add support for note and cite back references

FB2 Input: Add support for note and cite back references. Link pairs of
type="note" and type="cite" now automatically generate the correct back
reference. Fixes #1243714 [Fb2 return link is lost when converted to mobi or epub](https://bugs.launchpad.net/calibre/+bug/1243714)
---
 resources/templates/fb2.xsl                   |  5 +++++
 .../ebooks/conversion/plugins/fb2_input.py    | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/resources/templates/fb2.xsl b/resources/templates/fb2.xsl
index 474c7c0045..83bb9c7f10 100644
--- a/resources/templates/fb2.xsl
+++ b/resources/templates/fb2.xsl
@@ -269,10 +269,15 @@
             </xsl:attribute>
             <xsl:choose>
                 <xsl:when test="(@type) = 'note'">
+                    <xsl:attribute name="link_note"></xsl:attribute>
                     <sup>
                         <xsl:apply-templates/>
                     </sup>
                 </xsl:when>
+                <xsl:when test="(@type) = 'cite' and @id">
+                    <xsl:attribute name="link_cite"><xsl:value-of select="@id"/></xsl:attribute>
+                    <xsl:apply-templates/>
+                </xsl:when>
                 <xsl:otherwise>
                     <xsl:apply-templates/>
                 </xsl:otherwise>
diff --git a/src/calibre/ebooks/conversion/plugins/fb2_input.py b/src/calibre/ebooks/conversion/plugins/fb2_input.py
index f47a63b15f..784b13cfc8 100644
--- a/src/calibre/ebooks/conversion/plugins/fb2_input.py
+++ b/src/calibre/ebooks/conversion/plugins/fb2_input.py
@@ -87,6 +87,25 @@ class FB2Input(InputFormatPlugin):
 
         transform = etree.XSLT(styledoc)
         result = transform(doc)
+
+        # Handle links of type note and cite
+        notes = {a.get('href')[1:]: a for a in result.xpath('//a[@link_note and @href]') if a.get('href').startswith('#')}
+        cites = {a.get('link_cite'): a for a in result.xpath('//a[@link_cite]') if not a.get('href', '')}
+        all_ids = {x for x in result.xpath('//*/@id')}
+        for cite, a in cites.iteritems():
+            note = notes.get(cite, None)
+            if note:
+                c = 1
+                while 'cite%d' % c in all_ids:
+                    c += 1
+                if not note.get('id', None):
+                    note.set('id', 'cite%d' % c)
+                    all_ids.add(note.get('id'))
+                a.set('href', '#%s' % note.get('id'))
+        for x in result.xpath('//*[@link_note or @link_cite]'):
+            x.attrib.pop('link_note', None)
+            x.attrib.pop('link_cite', None)
+
         for img in result.xpath('//img[@src]'):
             src = img.get('src')
             img.set('src', self.binary_map.get(src, src))