# (Be in -*- python -*- mode.)
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# Copyright (c) 2000-2007 CollabNet.  All rights reserved.
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# This software consists of voluntary contributions made by many
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"""This module contains classes describing the sources of symbol fills."""


from cvs2svn_lib.common import InternalError
from cvs2svn_lib.common import FatalError
from cvs2svn_lib.common import SVN_INVALID_REVNUM
from cvs2svn_lib.svn_revision_range import SVNRevisionRange
from cvs2svn_lib.svn_revision_range import RevisionScores


class FillSource:
  """Representation of a fill source.

  A FillSource keeps track of the paths that have to be filled in a
  particular symbol fill.

  This class holds a SVNRevisionRange instance for each CVSFile that
  has to be filled within the subtree of the repository rooted at
  self.cvs_path.  The SVNRevisionRange objects are stored in a tree
  in which the directory nodes are dictionaries mapping CVSPaths to
  subnodes and the leaf nodes are the SVNRevisionRange objects telling
  for what source_lod and what range of revisions the leaf could serve
  as a source.

  FillSource objects are able to compute the score for arbitrary
  source LODs and source revision numbers.

  These objects are used by the symbol filler in SVNOutputOption."""

  def __init__(self, cvs_path, symbol, node_tree):
    """Create a fill source.

    The best LOD and SVN REVNUM to use as the copy source can be
    determined by calling compute_best_source().

    Members:

      cvs_path -- (CVSPath): the CVSPath described by this FillSource.

      _symbol -- (Symbol) the symbol to be filled.

      _node_tree -- (dict) a tree stored as a map { CVSPath : node },
          where subnodes have the same form.  Leaves are
          SVNRevisionRange instances telling the source_lod and range
          of SVN revision numbers from which the CVSPath can be
          copied.

    """

    self.cvs_path = cvs_path
    self._symbol = symbol
    self._node_tree = node_tree

  def _set_node(self, cvs_file, svn_revision_range):
    parent_node = self._get_node(cvs_file.parent_directory, create=True)
    if cvs_file in parent_node:
      raise InternalError(
          '%s appeared twice in sources for %s' % (cvs_file, self._symbol)
          )
    parent_node[cvs_file] = svn_revision_range

  def _get_node(self, cvs_path, create=False):
    if cvs_path == self.cvs_path:
      return self._node_tree
    else:
      parent_node = self._get_node(cvs_path.parent_directory, create=create)
      try:
        return parent_node[cvs_path]
      except KeyError:
        if create:
          node = {}
          parent_node[cvs_path] = node
          return node
        else:
          raise

  def compute_best_source(self, preferred_source):
    """Determine the best source_lod and subversion revision number to copy.

    Return the best source found, as an SVNRevisionRange instance.  If
    PREFERRED_SOURCE is not None and its opening is among the sources
    with the best scores, return it; otherwise, return the oldest such
    revision on the first such source_lod (ordered by the natural LOD
    sort order).  The return value's source_lod is the best LOD to
    copy from, and its opening_revnum is the best SVN revision."""

    # Aggregate openings and closings from our rev tree
    svn_revision_ranges = self._get_revision_ranges(self._node_tree)

    # Score the lists
    revision_scores = RevisionScores(svn_revision_ranges)

    best_source_lod, best_revnum, best_score = \
        revision_scores.get_best_revnum()

    if (
        preferred_source is not None
        and revision_scores.get_score(preferred_source) == best_score
        ):
      best_source_lod = preferred_source.source_lod
      best_revnum = preferred_source.opening_revnum

    if best_revnum == SVN_INVALID_REVNUM:
      raise FatalError(
          "failed to find a revision to copy from when copying %s"
          % self._symbol.name
          )

    return SVNRevisionRange(best_source_lod, best_revnum)

  def _get_revision_ranges(self, node):
    """Return a list of all the SVNRevisionRanges at and under NODE.

    Include duplicates.  This is a helper method used by
    compute_best_source()."""

    if isinstance(node, SVNRevisionRange):
      # It is a leaf node.
      return [ node ]
    else:
      # It is an intermediate node.
      revision_ranges = []
      for key, subnode in node.items():
        revision_ranges.extend(self._get_revision_ranges(subnode))
      return revision_ranges

  def get_subsources(self):
    """Generate (CVSPath, FillSource) for all direct subsources."""

    if not isinstance(self._node_tree, SVNRevisionRange):
      for cvs_path, node in self._node_tree.items():
        fill_source = FillSource(cvs_path, self._symbol, node)
        yield (cvs_path, fill_source)

  def get_subsource_map(self):
    """Return the map {CVSPath : FillSource} of direct subsources."""

    src_entries = {}

    for (cvs_path, fill_subsource) in self.get_subsources():
      src_entries[cvs_path] = fill_subsource

    return src_entries

  def __str__(self):
    """For convenience only.  The format is subject to change at any time."""

    return '%s(%s:%s)' % (
        self.__class__.__name__, self._symbol, self.cvs_path,
        )

  def __repr__(self):
    """For convenience only.  The format is subject to change at any time."""

    return '%s%r' % (self, self._node_tree,)


def get_source_set(symbol, range_map):
  """Return a FillSource describing the fill sources for RANGE_MAP.

  SYMBOL is either a Branch or a Tag.  RANGE_MAP is a map { CVSSymbol
  : SVNRevisionRange } as returned by
  SymbolingsReader.get_range_map().

  Use the SVNRevisionRanges from RANGE_MAP to create a FillSource
  instance describing the sources for filling SYMBOL."""

  root_cvs_directory = symbol.project.get_root_cvs_directory()
  fill_source = FillSource(root_cvs_directory, symbol, {})

  for cvs_symbol, svn_revision_range in range_map.items():
    fill_source._set_node(cvs_symbol.cvs_file, svn_revision_range)

  return fill_source