# repoview.py - Filtered view of a localrepo object

#

# Copyright 2012 Pierre-Yves David <pierre-yves.david@ens-lyon.org>

#                Logilab SA        <contact@logilab.fr>

#

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

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

import copy

import weakref

from .i18n import _

from .node import (

    hex,

    nullrev,

)

from . import (

    error,

    obsolete,

    phases,

    pycompat,

    tags as tagsmod,

    util,

)

from .utils import repoviewutil

def hideablerevs(repo):

    """Revision candidates to be hidden

    This is a standalone function to allow extensions to wrap it.

    Because we use the set of immutable changesets as a fallback subset in

    branchmap (see mercurial.utils.repoviewutils.subsettable), you cannot set

    "public" changesets as "hideable". Doing so would break multiple code

    assertions and lead to crashes."""

    obsoletes = obsolete.getrevs(repo, b'obsolete')

    internals = repo._phasecache.getrevset(repo, phases.localhiddenphases)

    internals = frozenset(internals)

    return obsoletes | internals

def pinnedrevs(repo):

    """revisions blocking hidden changesets from being filtered"""

    cl = repo.changelog

    pinned = set()

    pinned.update([par.rev() for par in repo[None].parents()])

    pinned.update([cl.rev(bm) for bm in repo._bookmarks.values()])

    tags = {}

    tagsmod.readlocaltags(repo.ui, repo, tags, {})

    if tags:

        rev = cl.index.get_rev

        pinned.update(rev(t[0]) for t in tags.values())

        pinned.discard(None)

    # Avoid cycle: mercurial.filemerge -> mercurial.templater ->

    # mercurial.templatefuncs -> mercurial.revset -> mercurial.repoview ->

    # mercurial.mergestate -> mercurial.filemerge

    from . import mergestate

    ms = mergestate.mergestate.read(repo)

    if ms.active() and ms.unresolvedcount():

        for node in (ms.local, ms.other):

            rev = cl.index.get_rev(node)

            if rev is not None:

                pinned.add(rev)

    return pinned

def _revealancestors(pfunc, hidden, revs):

    """reveals contiguous chains of hidden ancestors of 'revs' by removing them

    from 'hidden'

    - pfunc(r): a funtion returning parent of 'r',

    - hidden: the (preliminary) hidden revisions, to be updated

    - revs: iterable of revnum,

    (Ancestors are revealed exclusively, i.e. the elements in 'revs' are

    *not* revealed)

    """

    stack = list(revs)

    while stack:

        for p in pfunc(stack.pop()):

            if p != nullrev and p in hidden:

                hidden.remove(p)

                stack.append(p)

def computehidden(repo, visibilityexceptions=None):

    """compute the set of hidden revision to filter

    During most operation hidden should be filtered."""

    assert not repo.changelog.filteredrevs

    hidden = hideablerevs(repo)

    if hidden:

        hidden = set(hidden - pinnedrevs(repo))

        if visibilityexceptions:

            hidden -= visibilityexceptions

        pfunc = repo.changelog.parentrevs

        mutable = repo._phasecache.getrevset(repo, phases.mutablephases)

        visible = mutable - hidden

        _revealancestors(pfunc, hidden, visible)

    return frozenset(hidden)

def computesecret(repo, visibilityexceptions=None):

    """compute the set of revision that can never be exposed through hgweb

    Changeset in the secret phase (or above) should stay unaccessible."""

    assert not repo.changelog.filteredrevs

    secrets = repo._phasecache.getrevset(repo, phases.remotehiddenphases)

    return frozenset(secrets)

def computeunserved(repo, visibilityexceptions=None):

    """compute the set of revision that should be filtered when used a server

    Secret and hidden changeset should not pretend to be here."""

    assert not repo.changelog.filteredrevs

    # fast path in simple case to avoid impact of non optimised code

    hiddens = filterrevs(repo, b'visible')

    secrets = filterrevs(repo, b'served.hidden')

    if secrets:

        return frozenset(hiddens | secrets)

    else:

        return hiddens

def computemutable(repo, visibilityexceptions=None):

    assert not repo.changelog.filteredrevs

    # fast check to avoid revset call on huge repo

    if repo._phasecache.hasnonpublicphases(repo):

        return frozenset(repo._phasecache.getrevset(repo, phases.mutablephases))

    return frozenset()

def computeimpactable(repo, visibilityexceptions=None):

    """Everything impactable by mutable revision

    The immutable filter still have some chance to get invalidated. This will

    happen when:

    - you garbage collect hidden changeset,

    - public phase is moved backward,

    - something is changed in the filtering (this could be fixed)

    This filter out any mutable changeset and any public changeset that may be

    impacted by something happening to a mutable revision.

    This is achieved by filtered everything with a revision number equal or

    higher than the first mutable changeset is filtered."""

    assert not repo.changelog.filteredrevs

    cl = repo.changelog

    firstmutable = len(cl)

    roots = repo._phasecache.nonpublicphaseroots(repo)

    if roots:

        firstmutable = min(firstmutable, min(roots))

    # protect from nullrev root

    firstmutable = max(0, firstmutable)

    return frozenset(range(firstmutable, len(cl)))

# function to compute filtered set

#

# When adding a new filter you MUST update the table at:

#     mercurial.utils.repoviewutil.subsettable

# Otherwise your filter will have to recompute all its branches cache

# from scratch (very slow).

filtertable = {

    b'visible': computehidden,

    b'visible-hidden': computehidden,

    b'served.hidden': computesecret,

    b'served': computeunserved,

    b'immutable': computemutable,

    b'base': computeimpactable,

}

# set of filter level that will include the working copy parent no matter what.

filter_has_wc = {b'visible', b'visible-hidden'}

_basefiltername = list(filtertable)

def extrafilter(ui):

    """initialize extra filter and return its id

    If extra filtering is configured, we make sure the associated filtered view

    are declared and return the associated id.

    """

    frevs = ui.config(b'experimental', b'extra-filter-revs')

    if frevs is None:

        return None

    fid = pycompat.sysbytes(util.DIGESTS[b'sha1'](frevs).hexdigest())[:12]

    combine = lambda fname: fname + b'%' + fid

    subsettable = repoviewutil.subsettable

    if combine(b'base') not in filtertable:

        for base_name in _basefiltername:

            def extrafilteredrevs(repo, *args, name=base_name, **kwargs):

                baserevs = filtertable[name](repo, *args, **kwargs)

                extrarevs = frozenset(repo.revs(frevs))

                return baserevs | extrarevs

            filtertable[combine(base_name)] = extrafilteredrevs

            if base_name in subsettable:

                subsettable[combine(base_name)] = combine(

                    subsettable[base_name]

                )

    return fid

def filterrevs(repo, filtername, visibilityexceptions=None):

    """returns set of filtered revision for this filter name

    visibilityexceptions is a set of revs which must are exceptions for

    hidden-state and must be visible. They are dynamic and hence we should not

    cache it's result"""

    if filtername not in repo.filteredrevcache:

        if repo.ui.configbool(b'devel', b'debug.repo-filters'):

            msg = b'computing revision filter for "%s"'

            msg %= filtername

            if repo.ui.tracebackflag and repo.ui.debugflag:

                # XXX use ui.write_err

                util.debugstacktrace(

                    msg,

                    f=repo.ui._fout,

                    otherf=repo.ui._ferr,

                    prefix=b'debug.filters: ',

                )

            else:

                repo.ui.debug(b'debug.filters: %s\n' % msg)

        func = filtertable[filtername]

        if visibilityexceptions:

            return func(repo.unfiltered, visibilityexceptions)

        repo.filteredrevcache[filtername] = func(repo.unfiltered())

    return repo.filteredrevcache[filtername]

def wrapchangelog(unfichangelog, filteredrevs):

    cl = copy.copy(unfichangelog)

    cl.filteredrevs = filteredrevs

    class filteredchangelog(filteredchangelogmixin, cl.__class__):

        pass

    cl.__class__ = filteredchangelog

    return cl

class filteredchangelogmixin:

    def tiprev(self):

        """filtered version of revlog.tiprev"""

        for i in range(len(self) - 1, -2, -1):

            if i not in self.filteredrevs:

                return i

    def __contains__(self, rev):

        """filtered version of revlog.__contains__"""

        return 0 <= rev < len(self) and rev not in self.filteredrevs

    def __iter__(self):

        """filtered version of revlog.__iter__"""

        def filterediter():

            for i in range(len(self)):

                if i not in self.filteredrevs:

                    yield i

        return filterediter()

    def revs(self, start=0, stop=None):

        """filtered version of revlog.revs"""

        for i in super(filteredchangelogmixin, self).revs(start, stop):

            if i not in self.filteredrevs:

                yield i

    def _checknofilteredinrevs(self, revs):

        """raise the appropriate error if 'revs' contains a filtered revision

        This returns a version of 'revs' to be used thereafter by the caller.

        In particular, if revs is an iterator, it is converted into a set.

        """

        if hasattr(revs, '__next__'):

            # Note that inspect.isgenerator() is not true for iterators,

            revs = set(revs)

        filteredrevs = self.filteredrevs

        if hasattr(revs, 'first'):  # smartset

            offenders = revs & filteredrevs

        else:

            offenders = filteredrevs.intersection(revs)

        for rev in offenders:

            raise error.FilteredIndexError(rev)

        return revs

    def _head_node_ids(self):

        # no Rust fast path implemented yet, so just loop in Python

        return [self.node(r) for r in self.headrevs()]

    def headrevs(self, revs=None):

        if revs is None:

            try:

                return self.index.headrevsfiltered(self.filteredrevs)

            # AttributeError covers non-c-extension environments and

            # old c extensions without filter handling.

            except AttributeError:

                return self._headrevs()

        revs = self._checknofilteredinrevs(revs)

        return super(filteredchangelogmixin, self).headrevs(revs)

    def strip(self, *args, **kwargs):

        # XXX make something better than assert

        # We can't expect proper strip behavior if we are filtered.

        assert not self.filteredrevs

        super(filteredchangelogmixin, self).strip(*args, **kwargs)

    def rev(self, node):

        """filtered version of revlog.rev"""

        r = super(filteredchangelogmixin, self).rev(node)

        if r in self.filteredrevs:

            raise error.FilteredLookupError(

                hex(node), self.display_id, _(b'filtered node')

            )

        return r

    def node(self, rev):

        """filtered version of revlog.node"""

        if rev in self.filteredrevs:

            raise error.FilteredIndexError(rev)

        return super(filteredchangelogmixin, self).node(rev)

    def linkrev(self, rev):

        """filtered version of revlog.linkrev"""

        if rev in self.filteredrevs:

            raise error.FilteredIndexError(rev)

        return super(filteredchangelogmixin, self).linkrev(rev)

    def parentrevs(self, rev):

        """filtered version of revlog.parentrevs"""

        if rev in self.filteredrevs:

            raise error.FilteredIndexError(rev)

        return super(filteredchangelogmixin, self).parentrevs(rev)

    def flags(self, rev):

        """filtered version of revlog.flags"""

        if rev in self.filteredrevs:

            raise error.FilteredIndexError(rev)

        return super(filteredchangelogmixin, self).flags(rev)

class repoview:

    """Provide a read/write view of a repo through a filtered changelog

    This object is used to access a filtered version of a repository without

    altering the original repository object itself. We can not alter the

    original object for two main reasons:

    - It prevents the use of a repo with multiple filters at the same time. In

      particular when multiple threads are involved.

    - It makes scope of the filtering harder to control.

    This object behaves very closely to the original repository. All attribute

    operations are done on the original repository:

    - An access to `repoview.someattr` actually returns `repo.someattr`,

    - A write to `repoview.someattr` actually sets value of `repo.someattr`,

    - A deletion of `repoview.someattr` actually drops `someattr`

      from `repo.__dict__`.

    The only exception is the `changelog` property. It is overridden to return

    a (surface) copy of `repo.changelog` with some revisions filtered. The

    `filtername` attribute of the view control the revisions that need to be

    filtered.  (the fact the changelog is copied is an implementation detail).

    Unlike attributes, this object intercepts all method calls. This means that

    all methods are run on the `repoview` object with the filtered `changelog`

    property. For this purpose the simple `repoview` class must be mixed with

    the actual class of the repository. This ensures that the resulting

    `repoview` object have the very same methods than the repo object. This

    leads to the property below.

        repoview.method() --> repo.__class__.method(repoview)