# automv.py

#

# Copyright 2013-2016 Facebook, Inc.

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

"""Check for unrecorded moves at commit time (EXPERIMENTAL)

This extension checks at commit/amend time if any of the committed files

comes from an unrecorded mv.

The threshold at which a file is considered a move can be set with the

``automv.similarity`` config option. This option takes a percentage between 0

(disabled) and 100 (files must be identical), the default is 95.

"""

# Using 95 as a default similarity is based on an analysis of the mercurial

# repositories of the cpython, mozilla-central & mercurial repositories, as

# well as 2 very large facebook repositories. At 95 50% of all potential

# missed moves would be caught, as well as correspond with 87% of all

# explicitly marked moves.  Together, 80% of moved files are 95% similar or

# more.

#

# See http://markmail.org/thread/5pxnljesvufvom57 for context.

from __future__ import absolute_import

from mercurial import (

    commands,

    copies,

    error,

    extensions,

    scmutil,

    similar

)

def extsetup(ui):

    entry = extensions.wrapcommand(

        commands.table, 'commit', mvcheck)

    entry[1].append(

        ('', 'no-automv', None,

         _('disable automatic file move detection')))

def mvcheck(orig, ui, repo, *pats, **opts):

    """Hook to check for moves at commit time"""

    renames = None

    disabled = opts.pop('no_automv', False)

    if not disabled:

        threshold = ui.configint('automv', 'similarity', 95)

        if not 0 <= threshold <= 100:

            raise error.Abort(_('automv.similarity must be between 0 and 100'))

        if threshold > 0:

            match = scmutil.match(repo[None], pats, opts)

            added, removed = _interestingfiles(repo, match)

            renames = _findrenames(repo, match, added, removed,

                                   threshold / 100.0)

    with repo.wlock():

        if renames is not None:

            scmutil._markchanges(repo, (), (), renames)

        return orig(ui, repo, *pats, **opts)

def _interestingfiles(repo, matcher):

    """Find what files were added or removed in this commit.

    Returns a tuple of two lists: (added, removed). Only files not *already*

    marked as moved are included in the added list.

    """

    stat = repo.status(match=matcher)

    added = stat[1]

    removed = stat[2]

    copy = copies._forwardcopies(repo['.'], repo[None], matcher)

    # remove the copy files for which we already have copy info

    added = [f for f in added if f not in copy]

    return added, removed

def _findrenames(repo, matcher, added, removed, similarity):

    """Find what files in added are really moved files.

    Any file named in removed that is at least similarity% similar to a file

    in added is seen as a rename.

    """

    renames = {}

    if similarity > 0:

        for src, dst, score in similar.findrenames(

                repo, added, removed, similarity):

            if repo.ui.verbose:

                repo.ui.status(

                    _('detected move of %s as %s (%d%% similar)\n') % (

                        matcher.rel(src), matcher.rel(dst), score * 100))

            renames[dst] = src

    if renames:

        repo.ui.status(_('detected move of %d files\n') % len(renames))

    return renames