From a49b518cde782a8efc43c39aed998d1d5f6fafde Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 16 Jul 2013 17:58:22 +0530
Subject: [PATCH] cover_last_modified()

---
 src/calibre/db/backend.py | 7 +++++++
 src/calibre/db/cache.py   | 8 ++++++++
 src/calibre/db/legacy.py  | 4 ++++
 3 files changed, 19 insertions(+)

diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index 2c4dfb8395..1f561980bd 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -963,6 +963,13 @@ class DB(object):
                 import traceback
                 traceback.print_exc()
 
+    def cover_last_modified(self, path):
+        path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
+        try:
+            return utcfromtimestamp(os.stat(path).st_mtime)
+        except EnvironmentError:
+            pass  # Cover doesn't exist
+
     def copy_cover_to(self, path, dest, windows_atomic_move=None, use_hardlink=False):
         path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
         if windows_atomic_move is not None:
diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index 6564a9a9a2..e7c3114f0d 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -526,6 +526,14 @@ class Cache(object):
                 ret = i
         return ret
 
+    @read_api
+    def cover_last_modified(self, book_id):
+        try:
+            path = self._field_for('path', book_id).replace('/', os.sep)
+        except AttributeError:
+            return
+        return self.backend.cover_last_modified(path)
+
     @read_api
     def copy_cover_to(self, book_id, dest, use_hardlink=False):
         '''
diff --git a/src/calibre/db/legacy.py b/src/calibre/db/legacy.py
index f13e8107df..a6d7f22989 100644
--- a/src/calibre/db/legacy.py
+++ b/src/calibre/db/legacy.py
@@ -290,6 +290,10 @@ class LibraryDatabase(object):
         mi = self.new_api.get_metadata(book_id, get_cover=key == 'cover')
         return mi.get(key, default)
 
+    def cover_last_modified(self, index, index_is_id=False):
+        book_id = index if index_is_id else self.id(index)
+        return self.new_api.cover_last_modified(book_id) or self.last_modified()
+
     def authors_sort_strings(self, index, index_is_id=False):
         book_id = index if index_is_id else self.id(index)
         return list(self.new_api.author_sort_strings_for_books((book_id,))[book_id])