Fix a bug in renaming notebook

There was a bug in NotebookManager.save_notebook_object.
Here is how to reproduce:

0. Make sure you don't have Untitled0.
1. Open new notebook Untitled0.
2. Rename it to something else.
3. Copy Untitled0.ipynb to the notebook dir from somewhere.
   (Do not use notebook UI.)
4. New copied Untitled0 cannot be opened.
   The renamed notebook is opened when tried.
   Indeed, accessing to http://localhost:XXXX/notebooks shows
   duplicated notebook_id.

The problem was that NotebookManager.rev_mapping keeps old notebook
name after renaming.

IPython/frontend/html/notebook/notebookmanager.py

@@ -1,275 +1,276 b''
 """A notebook manager that uses the local file system for storage.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import datetime
 import io
 import os
 import uuid
 import glob
 
 from tornado import web
 
 from IPython.config.configurable import LoggingConfigurable
 from IPython.nbformat import current
 from IPython.utils.traitlets import Unicode, List, Dict, Bool
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 class NotebookManager(LoggingConfigurable):
 
     notebook_dir = Unicode(os.getcwdu(), config=True, help="""
         The directory to use for notebooks.
     """)
     
     save_script = Bool(False, config=True,
         help="""Automatically create a Python script when saving the notebook.
         
         For easier use of import, %run and %load across notebooks, a
         <notebook-name>.py script will be created next to any
         <notebook-name>.ipynb on each save.  This can also be set with the
         short `--script` flag.
         """
     )
     
     filename_ext = Unicode(u'.ipynb')
     allowed_formats = List([u'json',u'py'])
 
     # Map notebook_ids to notebook names
     mapping = Dict()
     # Map notebook names to notebook_ids
     rev_mapping = Dict()
 
     def list_notebooks(self):
         """List all notebooks in the notebook dir.
 
         This returns a list of dicts of the form::
 
             dict(notebook_id=notebook,name=name)
         """
         names = glob.glob(os.path.join(self.notebook_dir,
                                        '*' + self.filename_ext))
         names = [os.path.splitext(os.path.basename(name))[0]
                  for name in names]
 
         data = []
         for name in names:
             if name not in self.rev_mapping:
                 notebook_id = self.new_notebook_id(name)
             else:
                 notebook_id = self.rev_mapping[name]
             data.append(dict(notebook_id=notebook_id,name=name))
         data = sorted(data, key=lambda item: item['name'])
         return data
 
     def new_notebook_id(self, name):
         """Generate a new notebook_id for a name and store its mappings."""
         # TODO: the following will give stable urls for notebooks, but unless
         # the notebooks are immediately redirected to their new urls when their
         # filemname changes, nasty inconsistencies result.  So for now it's
         # disabled and instead we use a random uuid4() call.  But we leave the
         # logic here so that we can later reactivate it, whhen the necessary
         # url redirection code is written.
         #notebook_id = unicode(uuid.uuid5(uuid.NAMESPACE_URL,
         #                 'file://'+self.get_path_by_name(name).encode('utf-8')))
         
         notebook_id = unicode(uuid.uuid4())
         
         self.mapping[notebook_id] = name
         self.rev_mapping[name] = notebook_id
         return notebook_id
 
     def delete_notebook_id(self, notebook_id):
         """Delete a notebook's id only. This doesn't delete the actual notebook."""
         name = self.mapping[notebook_id]
         del self.mapping[notebook_id]
         del self.rev_mapping[name]
 
     def notebook_exists(self, notebook_id):
         """Does a notebook exist?"""
         if notebook_id not in self.mapping:
             return False
         path = self.get_path_by_name(self.mapping[notebook_id])
         return os.path.isfile(path)
 
     def find_path(self, notebook_id):
         """Return a full path to a notebook given its notebook_id."""
         try:
             name = self.mapping[notebook_id]
         except KeyError:
             raise web.HTTPError(404, u'Notebook does not exist: %s' % notebook_id)
         return self.get_path_by_name(name)
 
     def get_path_by_name(self, name):
         """Return a full path to a notebook given its name."""
         filename = name + self.filename_ext
         path = os.path.join(self.notebook_dir, filename)
         return path       
 
     def get_notebook(self, notebook_id, format=u'json'):
         """Get the representation of a notebook in format by notebook_id."""
         format = unicode(format)
         if format not in self.allowed_formats:
             raise web.HTTPError(415, u'Invalid notebook format: %s' % format)
         last_modified, nb = self.get_notebook_object(notebook_id)
         kwargs = {}
         if format == 'json':
             # don't split lines for sending over the wire, because it
             # should match the Python in-memory format.
             kwargs['split_lines'] = False
         data = current.writes(nb, format, **kwargs)
         name = nb.get('name','notebook')
         return last_modified, name, data
 
     def get_notebook_object(self, notebook_id):
         """Get the NotebookNode representation of a notebook by notebook_id."""
         path = self.find_path(notebook_id)
         if not os.path.isfile(path):
             raise web.HTTPError(404, u'Notebook does not exist: %s' % notebook_id)
         info = os.stat(path)
         last_modified = datetime.datetime.utcfromtimestamp(info.st_mtime)
         with open(path,'r') as f:
             s = f.read()
             try:
                 # v1 and v2 and json in the .ipynb files.
                 nb = current.reads(s, u'json')
             except:
                 raise web.HTTPError(500, u'Unreadable JSON notebook.')
         # Always use the filename as the notebook name.
         nb.metadata.name = os.path.split(path)[-1].split(u'.')[0]
         return last_modified, nb
 
     def save_new_notebook(self, data, name=None, format=u'json'):
         """Save a new notebook and return its notebook_id.
 
         If a name is passed in, it overrides any values in the notebook data
         and the value in the data is updated to use that value.
         """
         if format not in self.allowed_formats:
             raise web.HTTPError(415, u'Invalid notebook format: %s' % format)
 
         try:
             nb = current.reads(data.decode('utf-8'), format)
         except:
             raise web.HTTPError(400, u'Invalid JSON data')
 
         if name is None:
             try:
                 name = nb.metadata.name
             except AttributeError:
                 raise web.HTTPError(400, u'Missing notebook name')
         nb.metadata.name = name
 
         notebook_id = self.new_notebook_id(name)
         self.save_notebook_object(notebook_id, nb)
         return notebook_id
 
     def save_notebook(self, notebook_id, data, name=None, format=u'json'):
         """Save an existing notebook by notebook_id."""
         if format not in self.allowed_formats:
             raise web.HTTPError(415, u'Invalid notebook format: %s' % format)
 
         try:
             nb = current.reads(data.decode('utf-8'), format)
         except:
             raise web.HTTPError(400, u'Invalid JSON data')
 
         if name is not None:
             nb.metadata.name = name
         self.save_notebook_object(notebook_id, nb)
 
     def save_notebook_object(self, notebook_id, nb):
         """Save an existing notebook object by notebook_id."""
         if notebook_id not in self.mapping:
             raise web.HTTPError(404, u'Notebook does not exist: %s' % notebook_id)
         old_name = self.mapping[notebook_id]
         try:
             new_name = nb.metadata.name
         except AttributeError:
             raise web.HTTPError(400, u'Missing notebook name')
         path = self.get_path_by_name(new_name)
         try:
             with open(path,'w') as f:
                 current.write(nb, f, u'json')
         except Exception as e:
             raise web.HTTPError(400, u'Unexpected error while saving notebook: %s' % e)
         # save .py script as well
         if self.save_script:
             pypath = os.path.splitext(path)[0] + '.py'
             try:
                 with io.open(pypath,'w', encoding='utf-8') as f:
                     current.write(nb, f, u'py')
             except Exception as e:
                 raise web.HTTPError(400, u'Unexpected error while saving notebook as script: %s' % e)
         
         if old_name != new_name:
             old_path = self.get_path_by_name(old_name)
             if os.path.isfile(old_path):
                 os.unlink(old_path)
             if self.save_script:
                 old_pypath = os.path.splitext(old_path)[0] + '.py'
                 if os.path.isfile(old_pypath):
                     os.unlink(old_pypath)
             self.mapping[notebook_id] = new_name
             self.rev_mapping[new_name] = notebook_id
+            del self.rev_mapping[old_name]
 
     def delete_notebook(self, notebook_id):
         """Delete notebook by notebook_id."""
         path = self.find_path(notebook_id)
         if not os.path.isfile(path):
             raise web.HTTPError(404, u'Notebook does not exist: %s' % notebook_id)
         os.unlink(path)
         self.delete_notebook_id(notebook_id)
 
     def increment_filename(self, basename):
         """Return a non-used filename of the form basename<int>.
         
         This searches through the filenames (basename0, basename1, ...)
         until is find one that is not already being used. It is used to
         create Untitled and Copy names that are unique.
         """
         i = 0
         while True:
             name = u'%s%i' % (basename,i)
             path = self.get_path_by_name(name)
             if not os.path.isfile(path):
                 break
             else:
                 i = i+1
         return path, name
 
     def new_notebook(self):
         """Create a new notebook and return its notebook_id."""
         path, name = self.increment_filename('Untitled')
         notebook_id = self.new_notebook_id(name)
         metadata = current.new_metadata(name=name)
         nb = current.new_notebook(metadata=metadata)
         with open(path,'w') as f:
             current.write(nb, f, u'json')
         return notebook_id
 
     def copy_notebook(self, notebook_id):
         """Copy an existing notebook and return its notebook_id."""
         last_mod, nb = self.get_notebook_object(notebook_id)
         name = nb.metadata.name + '-Copy'
         path, name = self.increment_filename(name)
         nb.metadata.name = name
         notebook_id = self.new_notebook_id(name)
         self.save_notebook_object(notebook_id, nb)
         return notebook_id