# metadata.py -- code related to various metadata computation and access.

#

# Copyright 2019 Google, Inc <martinvonz@google.com>

# Copyright 2020 Pierre-Yves David <pierre-yves.david@octobus.net>

#

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

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

from __future__ import absolute_import, print_function

import multiprocessing

from . import (

    error,

    node,

    pycompat,

    util,

)

from .revlogutils import (

    flagutil as sidedataflag,

    sidedata as sidedatamod,

)

class ChangingFiles(object):

    """A class recording the changes made to a file by a changeset

    Actions performed on files are gathered into 3 sets:

    - added:   files actively added in the changeset.

    - removed: files removed in the revision

    - touched: files affected by the merge

    and copies information is held by 2 mappings

    - copied_from_p1: {"<new-name>": "<source-name-in-p1>"} mapping for copies

    - copied_from_p2: {"<new-name>": "<source-name-in-p2>"} mapping for copies

    See their inline help for details.

    """

    def __init__(

        self, touched=(), added=(), removed=(), p1_copies=(), p2_copies=(),

    ):

        self._added = set(added)

        self._removed = set(removed)

        self._touched = set(touched)

        self._touched.update(self._added)

        self._touched.update(self._removed)

        self._p1_copies = dict(p1_copies)

        self._p2_copies = dict(p2_copies)

    def __eq__(self, other):

        return (

            self.added == other.added

            and self.removed == other.removed

            and self.touched == other.touched

            and self.copied_from_p1 == other.copied_from_p1

            and self.copied_from_p2 == other.copied_from_p2

        )

    @property

    def added(self):

        """files actively added in the changeset

        Any file present in that revision that was absent in all the changeset's

        parents.

        In case of merge, this means a file absent in one of the parents but

        existing in the other will *not* be contained in this set. (They were

        added by an ancestor)

        """

        return frozenset(self._added)

    def mark_added(self, filename):

        self._added.add(filename)

        self._touched.add(filename)

    def update_added(self, filenames):

        for f in filenames:

            self.mark_added(f)

    @property

    def removed(self):

        """files actively removed by the changeset

        In case of merge this will only contain the set of files removing "new"

        content. For any file absent in the current changeset:

        a) If the file exists in both parents, it is clearly "actively" removed

        by this changeset.

        b) If a file exists in only one parent and in none of the common

        ancestors, then the file was newly added in one of the merged branches

        and then got "actively" removed.

        c) If a file exists in only one parent and at least one of the common

        ancestors using the same filenode, then the file was unchanged on one

        side and deleted on the other side. The merge "passively" propagated

        that deletion, but didn't "actively" remove the file. In this case the

        file is *not* included in the `removed` set.

        d) If a file exists in only one parent and at least one of the common

        ancestors using a different filenode, then the file was changed on one

        side and removed on the other side. The merge process "actively"

        decided to drop the new change and delete the file. Unlike in the

        previous case, (c), the file included in the `removed` set.

        Summary table for merge:

        case | exists in parents | exists in gca || removed

         (a) |       both        |     *         ||   yes

         (b) |       one         |     none      ||   yes

         (c) |       one         | same filenode ||   no

         (d) |       one         |  new filenode ||   yes

        """

        return frozenset(self._removed)

    def mark_removed(self, filename):

        self._removed.add(filename)

        self._touched.add(filename)

    def update_removed(self, filenames):

        for f in filenames:

            self.mark_removed(f)

    @property

    def touched(self):

        """files either actively modified, added or removed"""

        return frozenset(self._touched)

    def mark_touched(self, filename):

        self._touched.add(filename)

    def update_touched(self, filenames):

        for f in filenames:

            self.mark_touched(f)

    @property

    def copied_from_p1(self):

        return self._p1_copies.copy()

    def mark_copied_from_p1(self, source, dest):

        self._p1_copies[dest] = source

    def update_copies_from_p1(self, copies):

        for dest, source in copies.items():

            self.mark_copied_from_p1(source, dest)

    @property

    def copied_from_p2(self):

        return self._p2_copies.copy()

    def mark_copied_from_p2(self, source, dest):

        self._p2_copies[dest] = source

    def update_copies_from_p2(self, copies):

        for dest, source in copies.items():

            self.mark_copied_from_p2(source, dest)

def computechangesetfilesadded(ctx):

    """return the list of files added in a changeset

    """

    added = []

    for f in ctx.files():

        if not any(f in p for p in ctx.parents()):

            added.append(f)

    return added

def get_removal_filter(ctx, x=None):

    """return a function to detect files "wrongly" detected as `removed`

    When a file is removed relative to p1 in a merge, this

    function determines whether the absence is due to a

    deletion from a parent, or whether the merge commit

    itself deletes the file. We decide this by doing a

    simplified three way merge of the manifest entry for

    the file. There are two ways we decide the merge

    itself didn't delete a file:

    - neither parent (nor the merge) contain the file

    - exactly one parent contains the file, and that

      parent has the same filelog entry as the merge

      ancestor (or all of them if there two). In other

      words, that parent left the file unchanged while the

      other one deleted it.

    One way to think about this is that deleting a file is

    similar to emptying it, so the list of changed files

    should be similar either way. The computation

    described above is not done directly in _filecommit

    when creating the list of changed files, however

    it does something very similar by comparing filelog

    nodes.

    """

    if x is not None:

        p1, p2, m1, m2 = x

    else:

        p1 = ctx.p1()

        p2 = ctx.p2()

        m1 = p1.manifest()

        m2 = p2.manifest()

    @util.cachefunc

    def mas():

        p1n = p1.node()

        p2n = p2.node()

        cahs = ctx.repo().changelog.commonancestorsheads(p1n, p2n)

        if not cahs:

            cahs = [node.nullrev]

        return [ctx.repo()[r].manifest() for r in cahs]

    def deletionfromparent(f):

        if f in m1:

            return f not in m2 and all(

                f in ma and ma.find(f) == m1.find(f) for ma in mas()

            )

        elif f in m2:

            return all(f in ma and ma.find(f) == m2.find(f) for ma in mas())

        else:

            return True

    return deletionfromparent

def computechangesetfilesremoved(ctx):

    """return the list of files removed in a changeset

    """

    removed = []

    for f in ctx.files():

        if f not in ctx:

            removed.append(f)

    if removed:

        rf = get_removal_filter(ctx)

        removed = [r for r in removed if not rf(r)]

    return removed

def computechangesetcopies(ctx):

    """return the copies data for a changeset

    The copies data are returned as a pair of dictionnary (p1copies, p2copies).

    Each dictionnary are in the form: `{newname: oldname}`

    """

    p1copies = {}

    p2copies = {}

    p1 = ctx.p1()

    p2 = ctx.p2()

    narrowmatch = ctx._repo.narrowmatch()

    for dst in ctx.files():

        if not narrowmatch(dst) or dst not in ctx:

            continue

        copied = ctx[dst].renamed()

        if not copied:

            continue

        src, srcnode = copied

        if src in p1 and p1[src].filenode() == srcnode:

            p1copies[dst] = src

        elif src in p2 and p2[src].filenode() == srcnode:

            p2copies[dst] = src

    return p1copies, p2copies

def encodecopies(files, copies):

    items = []

    for i, dst in enumerate(files):

        if dst in copies:

            items.append(b'%d\0%s' % (i, copies[dst]))

    if len(items) != len(copies):

        raise error.ProgrammingError(

            b'some copy targets missing from file list'

        )

    return b"\n".join(items)

def decodecopies(files, data):

    try:

        copies = {}

        if not data:

            return copies

        for l in data.split(b'\n'):

            strindex, src = l.split(b'\0')

            i = int(strindex)

            dst = files[i]

            copies[dst] = src

        return copies

    except (ValueError, IndexError):

        # Perhaps someone had chosen the same key name (e.g. "p1copies") and

        # used different syntax for the value.

        return None

def encodefileindices(files, subset):

    subset = set(subset)

    indices = []

    for i, f in enumerate(files):

        if f in subset:

            indices.append(b'%d' % i)

    return b'\n'.join(indices)

def decodefileindices(files, data):

    try:

        subset = []

        if not data:

            return subset

        for strindex in data.split(b'\n'):

            i = int(strindex)

            if i < 0 or i >= len(files):

                return None

            subset.append(files[i])

        return subset

    except (ValueError, IndexError):

        # Perhaps someone had chosen the same key name (e.g. "added") and

        # used different syntax for the value.

        return None

    sortedfiles = sorted(files.touched)

    sidedata = {}

    p1copies = files.copied_from_p1

    if p1copies:

        p1copies = encodecopies(sortedfiles, p1copies)

        sidedata[sidedatamod.SD_P1COPIES] = p1copies

    p2copies = files.copied_from_p2

    if p2copies:

        p2copies = encodecopies(sortedfiles, p2copies)

        sidedata[sidedatamod.SD_P2COPIES] = p2copies

    filesadded = files.added

    if filesadded:

        filesadded = encodefileindices(sortedfiles, filesadded)

        sidedata[sidedatamod.SD_FILESADDED] = filesadded

    filesremoved = files.removed

    if filesremoved:

        filesremoved = encodefileindices(sortedfiles, filesremoved)

        sidedata[sidedatamod.SD_FILESREMOVED] = filesremoved

    if not sidedata:

        sidedata = None

    return sidedata

def _getsidedata(srcrepo, rev):

    ctx = srcrepo[rev]

    filescopies = computechangesetcopies(ctx)

    filesadded = computechangesetfilesadded(ctx)

    filesremoved = computechangesetfilesremoved(ctx)

    sidedata = {}

    if any([filescopies, filesadded, filesremoved]):

        sortedfiles = sorted(ctx.files())

        p1copies, p2copies = filescopies

        p1copies = encodecopies(sortedfiles, p1copies)

        p2copies = encodecopies(sortedfiles, p2copies)

        filesadded = encodefileindices(sortedfiles, filesadded)

        filesremoved = encodefileindices(sortedfiles, filesremoved)

        if p1copies:

            sidedata[sidedatamod.SD_P1COPIES] = p1copies

        if p2copies:

            sidedata[sidedatamod.SD_P2COPIES] = p2copies

        if filesadded:

            sidedata[sidedatamod.SD_FILESADDED] = filesadded

        if filesremoved:

            sidedata[sidedatamod.SD_FILESREMOVED] = filesremoved

    return sidedata

def getsidedataadder(srcrepo, destrepo):

    use_w = srcrepo.ui.configbool(b'experimental', b'worker.repository-upgrade')

    if pycompat.iswindows or not use_w:

        return _get_simple_sidedata_adder(srcrepo, destrepo)

    else:

        return _get_worker_sidedata_adder(srcrepo, destrepo)

def _sidedata_worker(srcrepo, revs_queue, sidedata_queue, tokens):

    """The function used by worker precomputing sidedata

    It read an input queue containing revision numbers

    It write in an output queue containing (rev, <sidedata-map>)

    The `None` input value is used as a stop signal.

    The `tokens` semaphore is user to avoid having too many unprocessed

    entries. The workers needs to acquire one token before fetching a task.

    They will be released by the consumer of the produced data.

    """

    tokens.acquire()

    rev = revs_queue.get()

    while rev is not None:

        data = _getsidedata(srcrepo, rev)

        sidedata_queue.put((rev, data))

        tokens.acquire()

        rev = revs_queue.get()

    # processing of `None` is completed, release the token.

    tokens.release()

BUFF_PER_WORKER = 50

def _get_worker_sidedata_adder(srcrepo, destrepo):

    """The parallel version of the sidedata computation

    This code spawn a pool of worker that precompute a buffer of sidedata

    before we actually need them"""

    # avoid circular import copies -> scmutil -> worker -> copies

    from . import worker