class AttrDict(dict):
  def __init__(self, *args, **kwargs):
    super(AttrDict, self).__init__(*args, **kwargs)
    self.__dict__ = self

  @classmethod
  def deep_copy(cls, attr_dict):
    copy = AttrDict(attr_dict)
    for key, value in copy.items():
      if isinstance(value, AttrDict):
        copy[key] = cls.deep_copy(value)
    return copy


class FastIndexList(object):
  """ List which keeps track of the indicies of its items in a fast manner, and allows for
      quick removal of items.
  """
  def __init__(self):
    self._list = []
    self._index_map = {}
    self._index_offset = 0
    self._counter = 0

  def add(self, item):
    """ Adds an item to the index list. """
    self._list.append(item)
    self._index_map[item] = self._counter
    self._counter = self._counter + 1

  def values(self):
    """ Returns an iterable stream of all the values in the list. """
    return list(self._list)

  def index(self, value):
    """ Returns the index of the given item in the list or None if none. """
    found = self._index_map.get(value, None)
    if found is None:
      return None

    return found - self._index_offset

  def pop_until(self, index_inclusive):
    """ Pops off any items in the list until the given index, inclusive, and returns them. """
    values = self._list[0:index_inclusive+1]
    for value in values:
      self._index_map.pop(value, None)

    self._index_offset = self._index_offset + index_inclusive + 1
    self._list = self._list[index_inclusive+1:]
    return values


class IndexedStreamingDiffTracker(object):
  """ Helper class which tracks the difference between two streams of strings,
      calling the `added` callback for strings when they are successfully verified
      as being present in the first stream and not present in the second stream.
      Unlike StreamingDiffTracker, this class expects each string value to have an
      associated `index` value, which must be the same for equal values in both
      streams and *must* be in order. This allows us to be a bit more efficient
      in clearing up items that we know won't be present. The `index` is *not*
      assumed to start at 0 or be contiguous, merely increasing.
  """
  def __init__(self, reporter, result_per_stream):
    self._reporter = reporter
    self._reports_per_stream = result_per_stream
    self._new_stream_finished = False
    self._old_stream_finished = False

    self._new_stream = []
    self._old_stream = []

    self._new_stream_map = {}
    self._old_stream_map = {}

  def push_new(self, stream_tuples):
    """ Pushes a list of values for the `New` stream.
    """
    stream_tuples_list = list(stream_tuples)
    assert len(stream_tuples_list) <= self._reports_per_stream

    if len(stream_tuples_list) < self._reports_per_stream:
      self._new_stream_finished = True

    for (item, index) in stream_tuples_list:
      if self._new_stream:
        assert index > self._new_stream[-1].index

      self._new_stream_map[index] = item
      self._new_stream.append(AttrDict(item=item, index=index))

    self._process()

  def push_old(self, stream_tuples):
    """ Pushes a list of values for the `Old` stream.
    """
    if self._new_stream_finished and not self._new_stream:
      # Nothing more to do.
      return

    stream_tuples_list = list(stream_tuples)
    assert len(stream_tuples_list) <= self._reports_per_stream

    if len(stream_tuples_list) < self._reports_per_stream:
      self._old_stream_finished = True

    for (item, index) in stream_tuples:
      if self._old_stream:
        assert index > self._old_stream[-1].index

      self._old_stream_map[index] = item
      self._old_stream.append(AttrDict(item=item, index=index))

    self._process()

  def done(self):
    self._old_stream_finished = True
    self._process()

  def _process(self):
    # Process any new items that can be reported.
    old_lower_bound = self._old_stream[0].index if self._old_stream else -1
    for item_info in self._new_stream:
      # If the new item's index <= the old_lower_bound, then we know
      # we can check the old item map for it.
      if item_info.index <= old_lower_bound or self._old_stream_finished:
        if self._old_stream_map.get(item_info.index, None) is None:
          self._reporter(item_info.item)

        # Remove the item from the map.
        self._new_stream_map.pop(item_info.index, None)

    # Rebuild the new stream list (faster than just removing).
    self._new_stream = [item_info for item_info in self._new_stream
                        if self._new_stream_map.get(item_info.index)]

    # Process any old items that can be removed.
    new_lower_bound = self._new_stream[0].index if self._new_stream else -1
    for item_info in list(self._old_stream):
      # Any items with indexes below the new lower bound can be removed,
      # as any comparison from the new stream was done above.
      if item_info.index < new_lower_bound:
        self._old_stream_map.pop(item_info.index, None)

    # Rebuild the old stream list (faster than just removing).
    self._old_stream = [item_info for item_info in self._old_stream
                        if self._old_stream_map.get(item_info.index)]



class StreamingDiffTracker(object):
  """ Helper class which tracks the difference between two streams of strings, calling the
      `added` callback for strings when they are successfully verified as being present in
      the first stream and not present in the second stream. This class requires that the
      streams of strings be consistently ordered *in some way common to both* (but the
      strings themselves do not need to be sorted).
  """
  def __init__(self, reporter, result_per_stream):
    self._reporter = reporter
    self._reports_per_stream = result_per_stream
    self._old_stream_finished = False

    self._old_stream = FastIndexList()
    self._new_stream = FastIndexList()

  def done(self):
    self._old_stream_finished = True
    self.push_new([])

  def push_new(self, stream_values):
    """ Pushes a list of values for the `New` stream.
    """

    # Add all the new values to the list.
    counter = 0
    for value in stream_values:
      self._new_stream.add(value)
      counter = counter + 1

    assert counter <= self._reports_per_stream

    # Process them all to see if anything has changed.
    for value in self._new_stream.values():
      old_index = self._old_stream.index(value)
      if old_index is not None:
        # The item is present, so we cannot report it. However, since we've reached this point,
        # all items *before* this item in the `Old` stream are no longer necessary, so we can
        # throw them out, along with this item.
        self._old_stream.pop_until(old_index)
      else:
        # If the old stream has completely finished, then we can report, knowing no more old
        # information will be present.
        if self._old_stream_finished:
          self._reporter(value)
          self._new_stream.pop_until(self._new_stream.index(value))

  def push_old(self, stream_values):
    """ Pushes a stream of values for the `Old` stream.
    """

    if self._old_stream_finished:
      return

    value_list = list(stream_values)
    assert len(value_list) <= self._reports_per_stream

    for value in value_list:
      # If the value exists in the new stream somewhere, then we know that all items *before*
      # that index in the new stream will not be in the old stream, so we can report them. We can
      # also remove the matching `New` item, as it is clearly in both streams.
      new_index = self._new_stream.index(value)
      if new_index is not None:
        # Report all items up to the current item.
        for item in self._new_stream.pop_until(new_index - 1):
          self._reporter(item)

        # Remove the current item from the new stream.
        self._new_stream.pop_until(0)
      else:
        # This item may be seen later. Add it to the old stream set.
        self._old_stream.add(value)

    # Check to see if the `Old` stream has finished.
    if len(value_list) < self._reports_per_stream:
      self._old_stream_finished = True