enforce schema version; allow importing+exporting v2 scheduler

To avoid all sorts of problems, we need to ensure cards scheduled with
the V2 scheduler are not studied in older clients. Unfortunately we
can't just bump the file's schema version, as the existing clients will
freely import files created with newer versions. This patch changes
that, so things should be a bit easier in the future.

In the mean time, we need a way to prevent older clients from importing
files created with the V2 scheduler. To do this, we switch to using a
'collection.anki21' file in the archive, and include a dummy collection
.anki2 file.

The code has been tested with both deck and collection packages, but
exporting deck packages w/ scheduling info will remain disabled until
the V2 scheduler has had more testing.

anki/exporting.py

@@ -4,7 +4,7 @@
 
 import   re, os, zipfile, shutil
 from anki.lang import _
-from anki.utils import  ids2str, splitFields, json
+from anki.utils import ids2str, splitFields, json, namedtmp
 from anki.hooks import runHook
 from anki import Collection
 
@@ -113,6 +113,9 @@ class AnkiExporter(Exporter):
         Exporter.__init__(self, col)
 
     def exportInto(self, path):
+        # sched info+v2 scheduler not compatible w/ older clients
+        self._v2sched = self.col.schedVer() != 1 and self.includeSched
+
         # create a new collection at the target
         try:
             os.unlink(path)
@@ -263,13 +266,19 @@ class AnkiPackageExporter(AnkiExporter):
         z.close()
 
     def doExport(self, z, path):
-        if self.col.schedVer() != 1:
-            raise Exception("Experimental scheduler currently doesn't support deck exports.")
-
         # export into the anki2 file
         colfile = path.replace(".apkg", ".anki2")
         AnkiExporter.exportInto(self, colfile)
+        if not self._v2sched:
             z.write(colfile, "collection.anki2")
+        else:
+            # fixme: remove in the future
+            raise Exception("Please switch to the normal scheduler before exporting a single deck with scheduling information.")
+
+            # prevent older clients from accessing
+            self._addDummyCollection(z)
+            z.write(colfile, "collection.anki21")
+
         # and media
         self.prepareMedia()
         media = self._exportMedia(z, self.mediaFiles, self.mediaDir)
@@ -304,6 +313,20 @@ class AnkiPackageExporter(AnkiExporter):
         # is zipped up
         pass
 
+    # create a dummy collection to ensure older clients don't try to read
+    # data they don't understand
+    def _addDummyCollection(self, zip):
+        path = namedtmp("dummy.anki2")
+        c = Collection(path)
+        n = c.newNote()
+        n['Front'] = "This file requires a newer version of Anki."
+        c.addNote(n)
+        c.save()
+        c.close()
+
+        zip.write(path, "collection.anki2")
+        os.unlink(path)
+
 # Collection package
 ######################################################################
 
@@ -320,8 +343,13 @@ class AnkiCollectionPackageExporter(AnkiPackageExporter):
     def doExport(self, z, path):
         # close our deck & write it into the zip file, and reopen
         self.count = self.col.cardCount()
+        v2 = self.col.schedVer() != 1
         self.col.close()
+        if not v2:
             z.write(self.col.path, "collection.anki2")
+        else:
+            self._addDummyCollection(z)
+            z.write(self.col.path, "collection.anki21")
         self.col.reopen()
         # copy all media
         if not self.includeMedia:

anki/importing/anki2.py

@@ -31,6 +31,9 @@ class Anki2Importer(Importer):
             self.src.close(save=False)
 
     def _prepareFiles(self):
+        if self.file.endswith(".anki21") and self.col.schedVer() == 1:
+            raise Exception("V2 scheduler must be enabled to import this file.")
+
         self.dst = self.col
         self.src = Collection(self.file)
 

anki/importing/apkg.py

@@ -12,8 +12,15 @@ class AnkiPackageImporter(Anki2Importer):
     def run(self):
         # extract the deck from the zip file
         self.zip = z = zipfile.ZipFile(self.file)
-        col = z.read("collection.anki2")
-        colpath = tmpfile(suffix=".anki2")
+        # v2 scheduler?
+        try:
+            z.getinfo("collection.anki21")
+            suffix = ".anki21"
+        except KeyError:
+            suffix = ".anki2"
+
+        col = z.read("collection"+suffix)
+        colpath = tmpfile(suffix=suffix)
         with open(colpath, "wb") as f:
             f.write(col)
         self.file = colpath

anki/storage.py

@@ -40,6 +40,8 @@ def Collection(path, lock=True, server=False, sync=True, log=False):
     col = _Collection(db, server, log)
     if ver < SCHEMA_VERSION:
         _upgrade(col, ver)
+    elif ver > SCHEMA_VERSION:
+        raise Exception("This file requires a newer version of Anki.")
     elif create:
         # add in reverse order so basic is default
         addClozeModel(col)

aqt/importing.py

@@ -388,10 +388,18 @@ def replaceWithApkg(mw, file, backup):
 
 def _replaceWithApkg(mw, file, backup):
     mw.progress.start(immediate=True)
-    # overwrite collection
+
     z = zipfile.ZipFile(file)
+
+    # v2 scheduler?
+    colname = "collection.anki21"
     try:
-        z.extract("collection.anki2", mw.pm.profileFolder())
+        z.getinfo(colname)
+    except KeyError:
+        colname = "collection.anki2"
+
+    try:
+        z.extract(colname, mw.pm.profileFolder())
     except:
         mw.progress.finish()
         showWarning(_("The provided file is not a valid .apkg file."))