From dc9da6b2e8e835cb0cc39e78f637572c441b9390 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 18 Apr 2023 22:31:58 +0530
Subject: [PATCH] Allow adding arbitrary files to a book record stored as
 auxiliary data by right clicking the add books button and choosing "Add data
 files"

---
 manual/gui.rst                  | 14 +++++++++++++-
 src/calibre/db/cache.py         |  6 ++++++
 src/calibre/gui2/actions/add.py | 14 ++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/manual/gui.rst b/manual/gui.rst
index 19b57869a1..0d6960e664 100644
--- a/manual/gui.rst
+++ b/manual/gui.rst
@@ -57,7 +57,9 @@ Add books
 
     6. **Add files to selected book records**: Allows you to add or update the files associated with an existing book in your library.
 
-    7. **Add an empty file to selected book records**: Allows you to add an empty file of the specified format to the selected book records.
+    7. **Add data files to selected book records**: Allows you to add any number of extra files that will be stored in a :file:`data` sub-directory in the book directory
+
+    8. **Add an empty file to selected book records**: Allows you to add an empty file of the specified format to the selected book records.
 
 The :guilabel:`Add books` action can read metadata from a wide variety of e-book formats. In addition, it tries to guess metadata from the filename.
 See the :ref:`config_filename_metadata` section, to learn how to configure this.
@@ -70,6 +72,16 @@ To add an additional format for an existing book you can do any of three things:
 
     3. Click the :guilabel:`Add books` button in the top right area of the :guilabel:`Edit metadata` dialog, accessed by the :ref:`edit_meta_information` action.
 
+.. note::
+   The extra data files added to a book will be managed by calibre, as part of
+   the book. However, they cannot be viewed directly or used as conversion
+   sources. Nor are they indexed by the Full text search engine in calibre. To
+   view them select the book and press the :kbd:`O` key which will open up the
+   book folder in your file manager, from where the extra files can be viewed
+   using any program you like. They are most useful to store any ancilliary
+   data associated with a book such as supplementary reading material, digital
+   resources, etc.
+
 .. _edit_meta_information:
 
 Edit metadata
diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index 51ed62aff4..f7776cd830 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -3049,6 +3049,12 @@ class Cache:
     def reindex_annotations(self):
         self.backend.reindex_annotations()
 
+    @write_api
+    def add_extra_files(self, book_id, map_of_relpath_to_stream_or_path):
+        path = self._field_for('path', book_id).replace('/', os.sep)
+        for relpath, stream_or_path in map_of_relpath_to_stream_or_path.items():
+            self.backend.add_extra_file(relpath, stream_or_path, path)
+
 
 def import_library(library_key, importer, library_path, progress=None, abort=None):
     from calibre.db.backend import DB
diff --git a/src/calibre/gui2/actions/add.py b/src/calibre/gui2/actions/add.py
index fdc1e4ce07..f163785382 100644
--- a/src/calibre/gui2/actions/add.py
+++ b/src/calibre/gui2/actions/add.py
@@ -71,6 +71,8 @@ class AddAction(InterfaceAction):
                 triggered=self.add_formats, shortcut='Shift+A')
         ma('add-formats-clipboard', _('Add files to selected book records from clipboard'),
                 triggered=self.add_formats_from_clipboard, shortcut='Shift+Alt+A', icon='edit-paste.png')
+        ma('add-extra-files-to-books', _(
+            'Add data files to selected book records')).triggered.connect(self.add_extra_files)
         ma('add-empty-format-to-books', _(
             'Add an empty file to selected book records')).triggered.connect(self.add_empty_format_choose)
         self.add_menu.addSeparator()
@@ -145,6 +147,18 @@ class AddAction(InterfaceAction):
         if books:
             self._add_formats(books, ids)
 
+    def add_extra_files(self):
+        ids = self._check_add_formats_ok()
+        if not ids:
+            return
+        books = choose_files_and_remember_all_files(self.gui, 'add extra data files dialog dir',
+                _('Select extra data files'), filters=get_filters())
+        if books:
+            rmap = {'data/' + os.path.basename(x): x for x in books}
+            db = self.gui.current_db.new_api
+            for book_id in ids:
+                db.add_extra_files(book_id, rmap)
+
     def _add_formats(self, paths, ids):
         if len(ids) > 1 and not question_dialog(
                 self.gui,