# uncommit - undo the actions of a commit
#
# Copyright 2011 Peter Arrenbrecht <peter.arrenbrecht@gmail.com>
#                Logilab SA        <contact@logilab.fr>
#                Pierre-Yves David <pierre-yves.david@ens-lyon.org>
#                Patrick Mezard <patrick@mezard.eu>
# Copyright 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.

"""uncommit part or all of a local changeset (EXPERIMENTAL)

This command undoes the effect of a local commit, returning the affected
files to their uncommitted state. This means that files modified, added or
removed in the changeset will be left unchanged, and so will remain modified,
added and removed in the working directory.
"""

from __future__ import absolute_import

from mercurial.i18n import _

from mercurial import (
    cmdutil,
    commands,
    context,
    copies as copiesmod,
    error,
    node,
    obsolete,
    obsutil,
    patch,
    pycompat,
    registrar,
    rewriteutil,
    scmutil,
    util,
)

cmdtable = {}
command = registrar.command(cmdtable)

configtable = {}
configitem = registrar.configitem(configtable)

configitem('experimental', 'uncommitondirtywdir',
    default=False,
)

stringio = util.stringio

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'

def _commitfiltered(repo, ctx, match, keepcommit):
    """Recommit ctx with changed files not in match. Return the new
    node identifier, or None if nothing changed.
    """
    base = ctx.p1()
    # ctx
    initialfiles = set(ctx.files())
    exclude = set(f for f in initialfiles if match(f))

    # No files matched commit, so nothing excluded
    if not exclude:
        return None

    files = (initialfiles - exclude)
    # return the p1 so that we don't create an obsmarker later
    if not keepcommit:
        return ctx.p1().node()

    # Filter copies
    copied = copiesmod.pathcopies(base, ctx)
    copied = dict((dst, src) for dst, src in copied.iteritems()
                  if dst in files)
    def filectxfn(repo, memctx, path, contentctx=ctx, redirect=()):
        if path not in contentctx:
            return None
        fctx = contentctx[path]
        mctx = context.memfilectx(repo, memctx, fctx.path(), fctx.data(),
                                  fctx.islink(),
                                  fctx.isexec(),
                                  copied=copied.get(path))
        return mctx

    new = context.memctx(repo,
                         parents=[base.node(), node.nullid],
                         text=ctx.description(),
                         files=files,
                         filectxfn=filectxfn,
                         user=ctx.user(),
                         date=ctx.date(),
                         extra=ctx.extra())
    return repo.commitctx(new)

def _fixdirstate(repo, oldctx, newctx, match=None):
    """ fix the dirstate after switching the working directory from oldctx to
    newctx which can be result of either unamend or uncommit.
    """
    ds = repo.dirstate
    ds.setparents(newctx.node(), node.nullid)
    copies = dict(ds.copies())
    s = newctx.status(oldctx, match=match)
    for f in s.modified:
        if ds[f] == 'r':
            # modified + removed -> removed
            continue
        ds.normallookup(f)

    for f in s.added:
        if ds[f] == 'r':
            # added + removed -> unknown
            ds.drop(f)
        elif ds[f] != 'a':
            ds.add(f)

    for f in s.removed:
        if ds[f] == 'a':
            # removed + added -> normal
            ds.normallookup(f)
        elif ds[f] != 'r':
            ds.remove(f)

    # Merge old parent and old working dir copies
    oldcopies = copiesmod.pathcopies(newctx, oldctx, match)
    oldcopies.update(copies)
    copies = dict((dst, oldcopies.get(src, src))
                  for dst, src in oldcopies.iteritems())
    # Adjust the dirstate copies
    for dst, src in copies.iteritems():
        if (src not in newctx or dst in newctx or ds[dst] != 'a'):
            src = None
        ds.copy(src, dst)


def _uncommitdirstate(repo, oldctx, match, interactive):
    """Fix the dirstate after switching the working directory from
    oldctx to a copy of oldctx not containing changed files matched by
    match.
    """
    ctx = repo['.']
    ds = repo.dirstate
    copies = dict(ds.copies())
    if interactive:
        # In interactive cases, we will find the status between oldctx and ctx
        # and considering only the files which are changed between oldctx and
        # ctx, and the status of what changed between oldctx and ctx will help
        # us in defining the exact behavior
        m, a, r = repo.status(oldctx, ctx, match=match)[:3]
        for f in m:
            # These are files which are modified between oldctx and ctx which
            # contains two cases: 1) Were modified in oldctx and some
            # modifications are uncommitted
            # 2) Were added in oldctx but some part is uncommitted (this cannot
            # contain the case when added files are uncommitted completely as
            # that will result in status as removed not modified.)
            # Also any modifications to a removed file will result the status as
            # added, so we have only two cases. So in either of the cases, the
            # resulting status can be modified or clean.
            if ds[f] == 'r':
                # But the file is removed in the working directory, leaving that
                # as removed
                continue
            ds.normallookup(f)

        for f in a:
            # These are the files which are added between oldctx and ctx(new
            # one), which means the files which were removed in oldctx
            # but uncommitted completely while making the ctx
            # This file should be marked as removed if the working directory
            # does not adds it back. If it's adds it back, we do a normallookup.
            # The file can't be removed in working directory, because it was
            # removed in oldctx
            if ds[f] == 'a':
                ds.normallookup(f)
                continue
            ds.remove(f)

        for f in r:
            # These are files which are removed between oldctx and ctx, which
            # means the files which were added in oldctx and were completely
            # uncommitted in ctx. If a added file is partially uncommitted, that
            # would have resulted in modified status, not removed.
            # So a file added in a commit, and uncommitting that addition must
            # result in file being stated as unknown.
            if ds[f] == 'r':
                # The working directory say it's removed, so lets make the file
                # unknown
                ds.drop(f)
                continue
            ds.add(f)
    else:
        m, a, r = repo.status(oldctx.p1(), oldctx, match=match)[:3]
        for f in m:
            if ds[f] == 'r':
                # modified + removed -> removed
                continue
            ds.normallookup(f)

        for f in a:
            if ds[f] == 'r':
                # added + removed -> unknown
                ds.drop(f)
            elif ds[f] != 'a':
                ds.add(f)

        for f in r:
            if ds[f] == 'a':
                # removed + added -> normal
                ds.normallookup(f)
            elif ds[f] != 'r':
                ds.remove(f)

    # Merge old parent and old working dir copies
    oldcopies = {}
    if interactive:
        # Interactive had different meaning of the variables so restoring the
        # original meaning to use them
        m, a, r = repo.status(oldctx.p1(), oldctx, match=match)[:3]
    for f in (m + a):
        src = oldctx[f].renamed()
        if src:
            oldcopies[f] = src[0]
    oldcopies.update(copies)
    copies = dict((dst, oldcopies.get(src, src))
                  for dst, src in oldcopies.iteritems())
    # Adjust the dirstate copies
    for dst, src in copies.iteritems():
        if (src not in ctx or dst in ctx or ds[dst] != 'a'):
            src = None
        ds.copy(src, dst)

@command('uncommit',
    [('i', 'interactive', False, _('interactive mode to uncommit')),
    ('', 'keep', False, _('allow an empty commit after uncommiting')),
    ] + commands.walkopts,
    _('[OPTION]... [FILE]...'),
    helpcategory=command.CATEGORY_CHANGE_MANAGEMENT)
def uncommit(ui, repo, *pats, **opts):
    """uncommit part or all of a local changeset

    This command undoes the effect of a local commit, returning the affected
    files to their uncommitted state. This means that files modified or
    deleted in the changeset will be left unchanged, and so will remain
    modified in the working directory.

    If no files are specified, the commit will be pruned, unless --keep is
    given.
    """
    opts = pycompat.byteskwargs(opts)
    interactive = opts.get('interactive')

    with repo.wlock(), repo.lock():

        if not pats and not repo.ui.configbool('experimental',
                                               'uncommitondirtywdir'):
            cmdutil.bailifchanged(repo)
        old = repo['.']
        rewriteutil.precheck(repo, [old.rev()], 'uncommit')
        if len(old.parents()) > 1:
            raise error.Abort(_("cannot uncommit merge changeset"))

        with repo.transaction('uncommit'):
            match = scmutil.match(old, pats, opts)
            keepcommit = opts.get('keep') or pats
            newid = _commitfiltered(repo, old, match, keepcommit)
            if interactive:
                match = scmutil.match(old, pats, opts)
                newid = _interactiveuncommit(ui, repo, old, match)

            if newid is None:
                ui.status(_("nothing to uncommit\n"))
                return 1

            mapping = {}
            if newid != old.p1().node():
                # Move local changes on filtered changeset
                mapping[old.node()] = (newid,)
            else:
                # Fully removed the old commit
                mapping[old.node()] = ()

            scmutil.cleanupnodes(repo, mapping, 'uncommit', fixphase=True)

            with repo.dirstate.parentchange():
                repo.dirstate.setparents(newid, node.nullid)
                _uncommitdirstate(repo, old, match, interactive)

def _interactiveuncommit(ui, repo, old, match):
    """ The function which contains all the logic for interactively uncommiting
    a commit. This function makes a temporary commit with the chunks which user
    selected to uncommit. After that the diff of the parent and that commit is
    applied to the working directory and committed again which results in the
    new commit which should be one after uncommitted.
    """

    # create a temporary commit with hunks user selected
    tempnode = _createtempcommit(ui, repo, old, match)

    diffopts = patch.difffeatureopts(repo.ui, whitespace=True)
    diffopts.nodates = True
    diffopts.git = True
    fp = stringio()
    for chunk, label in patch.diffui(repo, tempnode, old.node(), None,
                                     opts=diffopts):
            fp.write(chunk)

    fp.seek(0)
    newnode = _patchtocommit(ui, repo, old, fp)
    # creating obs marker temp -> ()
    obsolete.createmarkers(repo, [(repo[tempnode], ())], operation="uncommit")
    return newnode

def _createtempcommit(ui, repo, old, match):
    """ Creates a temporary commit for `uncommit --interative` which contains
    the hunks which were selected by the user to uncommit.
    """

    pold = old.p1()
    # The logic to interactively selecting something copied from
    # cmdutil.revert()
    diffopts = patch.difffeatureopts(repo.ui, whitespace=True)
    diffopts.nodates = True
    diffopts.git = True
    diff = patch.diff(repo, pold.node(), old.node(), match, opts=diffopts)
    originalchunks = patch.parsepatch(diff)
    # XXX: The interactive selection is buggy and does not let you
    # uncommit a removed file partially.
    # TODO: wrap the operations in mercurial/patch.py and mercurial/crecord.py
    # to add uncommit as an operation taking care of BC.
    chunks, opts = cmdutil.recordfilter(repo.ui, originalchunks,
                                        operation='discard')
    if not chunks:
        raise error.Abort(_("nothing selected to uncommit"))
    fp = stringio()
    for c in chunks:
            c.write(fp)

    fp.seek(0)
    oldnode = node.hex(old.node())[:12]
    message = 'temporary commit for uncommiting %s' % oldnode
    tempnode = _patchtocommit(ui, repo, old, fp, message, oldnode)
    return tempnode

def _patchtocommit(ui, repo, old, fp, message=None, extras=None):
    """ A function which will apply the patch to the working directory and
    make a commit whose parents are same as that of old argument. The message
    argument tells us whether to use the message of the old commit or a
    different message which is passed. Returns the node of new commit made.
    """
    pold = old.p1()
    parents = (old.p1().node(), old.p2().node())
    date = old.date()
    branch = old.branch()
    user = old.user()
    extra = old.extra()
    if extras:
        extra['uncommit_source'] = extras
    if not message:
        message = old.description()
    store = patch.filestore()
    try:
        files = set()
        try:
            patch.patchrepo(ui, repo, pold, store, fp, 1, '',
                            files=files, eolmode=None)
        except patch.PatchError as err:
            raise error.Abort(str(err))

        finally:
            del fp

        memctx = context.memctx(repo, parents, message, files=files,
                                filectxfn=store,
                                user=user,
                                date=date,
                                branch=branch,
                                extra=extra)
        newcm = memctx.commit()
    finally:
        store.close()
    return newcm

def predecessormarkers(ctx):
    """yields the obsolete markers marking the given changeset as a successor"""
    for data in ctx.repo().obsstore.predecessors.get(ctx.node(), ()):
        yield obsutil.marker(ctx.repo(), data)

@command('unamend', [], helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
         helpbasic=True)
def unamend(ui, repo, **opts):
    """undo the most recent amend operation on a current changeset

    This command will roll back to the previous version of a changeset,
    leaving working directory in state in which it was before running
    `hg amend` (e.g. files modified as part of an amend will be
    marked as modified `hg status`)
    """

    unfi = repo.unfiltered()
    with repo.wlock(), repo.lock(), repo.transaction('unamend'):

        # identify the commit from which to unamend
        curctx = repo['.']

        rewriteutil.precheck(repo, [curctx.rev()], 'unamend')

        # identify the commit to which to unamend
        markers = list(predecessormarkers(curctx))
        if len(markers) != 1:
            e = _("changeset must have one predecessor, found %i predecessors")
            raise error.Abort(e % len(markers))

        prednode = markers[0].prednode()
        predctx = unfi[prednode]

        # add an extra so that we get a new hash
        # note: allowing unamend to undo an unamend is an intentional feature
        extras = predctx.extra()
        extras['unamend_source'] = curctx.hex()

        def filectxfn(repo, ctx_, path):
            try:
                return predctx.filectx(path)
            except KeyError:
                return None

        # Make a new commit same as predctx
        newctx = context.memctx(repo,
                                parents=(predctx.p1(), predctx.p2()),
                                text=predctx.description(),
                                files=predctx.files(),
                                filectxfn=filectxfn,
                                user=predctx.user(),
                                date=predctx.date(),
                                extra=extras)
        newprednode = repo.commitctx(newctx)
        newpredctx = repo[newprednode]
        dirstate = repo.dirstate

        with dirstate.parentchange():
            _fixdirstate(repo, curctx, newpredctx)

        mapping = {curctx.node(): (newprednode,)}
        scmutil.cleanupnodes(repo, mapping, 'unamend', fixphase=True)