Code to get db info for book given its absolute path

src/calibre/gui2/viewer/integration.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python2
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2020, Kovid Goyal <kovid at kovidgoyal.net>
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import os
+import re
+
+from polyglot.functools import lru_cache
+
+
+@lru_cache(maxsize=2)
+def get_book_library_details(absolute_path_to_ebook):
+    absolute_path_to_ebook = os.path.abspath(os.path.expanduser(absolute_path_to_ebook))
+    base = os.path.dirname(absolute_path_to_ebook)
+    m = re.search(r' \((\d+)\)$', os.path.basename(base))
+    if m is None:
+        return
+    book_id = int(m.group(1))
+    library_dir = os.path.dirname(os.path.dirname(base))
+    dbpath = os.path.join(library_dir, 'metadata.db')
+    dbpath = os.environ.get('CALIBRE_OVERRIDE_DATABASE_PATH') or dbpath
+    if not os.path.exists(dbpath):
+        return None
+    return {'dbpath': dbpath, 'book_id': book_id, 'fmt': absolute_path_to_ebook.rpartition('.')[-1].upper()}