From 54fe8bb96fb89edf1ef1fa4afef550a9bc9909b6 Mon Sep 17 00:00:00 2001
From: Aaron Harsh <aaron.harsh@gmail.com>
Date: Sat, 7 Jan 2012 19:15:34 -0800
Subject: [PATCH] libanki support for drag-and-drop changes of deck hierarchy
 in deckbrowser

---
 anki/decks.py       | 37 +++++++++++++++++++++++++++++++++---
 anki/errors.py      |  6 ++++++
 tests/test_decks.py | 46 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/anki/decks.py b/anki/decks.py
index f4948c571..e03ad5fd4 100644
--- a/anki/decks.py
+++ b/anki/decks.py
@@ -6,6 +6,7 @@ import simplejson, copy
 from anki.utils import intTime, ids2str
 from anki.consts import *
 from anki.lang import _
+from anki.errors import DeckRenameError
 
 # fixmes:
 # - make sure users can't set grad interval < 1
@@ -161,7 +162,7 @@ class DeckManager(object):
         "Rename deck prefix to NAME if not exists. Updates children."
         # make sure target node doesn't already exist
         if newName in self.allNames():
-            raise Exception("Deck exists")
+            raise DeckRenameError(_("That deck already exists."))
         # rename children
         for grp in self.all():
             if grp['name'].startswith(g['name'] + "::"):
@@ -174,10 +175,40 @@ class DeckManager(object):
         # finally, ensure we have parents
         self._ensureParents(newName)
 
+    def renameForDragAndDrop(self, draggedDeckDid, ontoDeckDid):
+        draggedDeck = self.get(draggedDeckDid)
+        draggedDeckName = draggedDeck['name']
+        ontoDeckName = self.get(ontoDeckDid)['name']
+
+        if ontoDeckDid == None or ontoDeckDid == '':
+            if len(self._path(draggedDeckName)) > 1:
+                self.rename(draggedDeck, self._basename(draggedDeckName))
+        elif self._canDragAndDrop(draggedDeckName, ontoDeckName):
+            draggedDeck = self.get(draggedDeckDid)
+            draggedDeckName = draggedDeck['name']
+            ontoDeckName = self.get(ontoDeckDid)['name']
+            self.rename(draggedDeck, ontoDeckName + "::" + self._basename(draggedDeckName))
+
+    def _canDragAndDrop(self, draggedDeckName, ontoDeckName):
+        return draggedDeckName <> ontoDeckName \
+                and not self._isParent(ontoDeckName, draggedDeckName) \
+                and not self._isAncestor(draggedDeckName, ontoDeckName)
+
+    def _isParent(self, parentDeckName, childDeckName):
+        return self._path(childDeckName) == self._path(parentDeckName) + [ self._basename(childDeckName) ]
+
+    def _isAncestor(self, ancestorDeckName, descendantDeckName):
+        ancestorPath = self._path(ancestorDeckName)
+        return ancestorPath == self._path(descendantDeckName)[0:len(ancestorPath)]
+
+    def _path(self, name):
+        return name.split("::")
+    def _basename(self, name):
+        return self._path(name)[-1]
+
     def _ensureParents(self, name):
-        path = name.split("::")
         s = ""
-        for p in path[:-1]:
+        for p in self._path(name)[:-1]:
             if not s:
                 s += p
             else:
diff --git a/anki/errors.py b/anki/errors.py
index 9f25339b6..4a683a8b5 100644
--- a/anki/errors.py
+++ b/anki/errors.py
@@ -11,3 +11,9 @@ class AnkiError(Exception):
         if self.data:
             m += ": %s" % repr(self.data)
         return m
+
+class DeckRenameError(Exception):
+    def __init__(self, description):
+        self.description = description
+    def __str__(self):
+        return "Couldn't rename deck: " + description
diff --git a/tests/test_decks.py b/tests/test_decks.py
index 486d9fa16..fcabf57cb 100644
--- a/tests/test_decks.py
+++ b/tests/test_decks.py
@@ -79,3 +79,49 @@ def test_rename():
     d.decks.rename(d.decks.get(id), "yo")
     for n in "yo", "yo::two", "yo::two::three":
         assert n in d.decks.allNames()
+
+def test_renameForDragAndDrop():
+    d = getEmptyDeck()
+
+    def deckNames():
+        return [ name for name in sorted(d.decks.allNames()) if name <> u'Default' ]
+
+    languages_did = d.decks.id('Languages')
+    chinese_did = d.decks.id('Chinese')
+    hsk_did = d.decks.id('Chinese::HSK')
+
+    # Renaming also renames children
+    d.decks.renameForDragAndDrop(chinese_did, languages_did)
+    assert deckNames() == [ 'Languages', 'Languages::Chinese', 'Languages::Chinese::HSK' ]
+
+    # Dragging a deck onto itself is a no-op
+    d.decks.renameForDragAndDrop(languages_did, languages_did)
+    assert deckNames() == [ 'Languages', 'Languages::Chinese', 'Languages::Chinese::HSK' ]
+
+    # Dragging a deck onto its parent is a no-op
+    d.decks.renameForDragAndDrop(hsk_did, chinese_did)
+    assert deckNames() == [ 'Languages', 'Languages::Chinese', 'Languages::Chinese::HSK' ]
+
+    # Dragging a deck onto a descendant is a no-op
+    d.decks.renameForDragAndDrop(languages_did, hsk_did)
+    assert deckNames() == [ 'Languages', 'Languages::Chinese', 'Languages::Chinese::HSK' ]
+
+    # Can drag a grandchild onto its grandparent.  It becomes a child
+    d.decks.renameForDragAndDrop(hsk_did, languages_did)
+    assert deckNames() == [ 'Languages', 'Languages::Chinese', 'Languages::HSK' ]
+
+    # Can drag a deck onto its sibling
+    d.decks.renameForDragAndDrop(hsk_did, chinese_did)
+    assert deckNames() == [ 'Languages', 'Languages::Chinese', 'Languages::Chinese::HSK' ]
+
+    # Can drag a deck back to the top level
+    d.decks.renameForDragAndDrop(chinese_did, None)
+    assert deckNames() == [ 'Chinese', 'Chinese::HSK', 'Languages' ]
+
+    # Dragging a top level deck to the top level is a no-op
+    d.decks.renameForDragAndDrop(chinese_did, None)
+    assert deckNames() == [ 'Chinese', 'Chinese::HSK', 'Languages' ]
+
+    # '' is a convenient alias for the top level DID
+    d.decks.renameForDragAndDrop(hsk_did, '')
+    assert deckNames() == [ 'Chinese', 'HSK', 'Languages' ]