# 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 mercurial.i18n import _

from mercurial import (

    commands,

    copies,

    error,

    extensions,

    pycompat,

    registrar,

    scmutil,

    similar,

)

configtable = {}

configitem = registrar.configitem(configtable)

configitem(

    b'automv',

    b'similarity',

    default=95,

)

def extsetup(ui):

    entry = extensions.wrapcommand(commands.table, b'commit', mvcheck)

    entry[1].append(

        (b'', b'no-automv', None, _(b'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)

    with repo.wlock():

        if not disabled:

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

            if not 0 <= threshold <= 100:

                raise error.Abort(

                    _(b'automv.similarity must be between 0 and 100')

                )

            if threshold > 0:

                match = scmutil.match(

                    repo[None], pats, pycompat.byteskwargs(opts)

                )

                added, removed = _interestingfiles(repo, match)

                uipathfn = scmutil.getuipathfn(repo, legacyrelativevalue=True)

                renames = _findrenames(

                    repo, uipathfn, added, removed, threshold / 100.0

                )

        if renames is not None:

            with repo.dirstate.changing_files(repo):

                # XXX this should be wider and integrated with the commit

                # transaction. At the same time as we do the `addremove` logic

                # for commit.  However we can't really do better with the

                # current extension structure, and this is not worse than what

                # happened before.

                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.added

    removed = stat.removed

    copy = copies.pathcopies(repo[b'.'], 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, uipathfn, 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(

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

                    % (uipathfn(src), uipathfn(dst), score * 100)

                )

            renames[dst] = src

    if renames:

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

    return renames