# wrapper.py - methods wrapping core mercurial logic

#

# Copyright 2017 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.

from __future__ import absolute_import

import hashlib

from mercurial import (

    error,

    filelog,

    revlog,

    util,

)

from mercurial.i18n import _

from mercurial.node import bin, nullid, short

from . import (

    blobstore,

    pointer,

)

def supportedoutgoingversions(orig, repo):

    versions = orig(repo)

    versions.discard('01')

    versions.discard('02')

    versions.add('03')

    return versions

def allsupportedversions(orig, ui):

    versions = orig(ui)

    versions.add('03')

    return versions

def bypasscheckhash(self, text):

    return False

def readfromstore(self, text):

    """Read filelog content from local blobstore transform for flagprocessor.

    Default tranform for flagprocessor, returning contents from blobstore.

    Returns a 2-typle (text, validatehash) where validatehash is True as the

    contents of the blobstore should be checked using checkhash.

    """

    p = pointer.deserialize(text)

    oid = p.oid()

    store = self.opener.lfslocalblobstore

    if not store.has(oid):

        p.filename = getattr(self, 'indexfile', None)

        self.opener.lfsremoteblobstore.readbatch([p], store)

    text = store.read(oid)

    # pack hg filelog metadata

    hgmeta = {}

    for k in p.keys():

        if k.startswith('x-hg-'):

            name = k[len('x-hg-'):]

            hgmeta[name] = p[k]

    if hgmeta or text.startswith('\1\n'):

        text = filelog.packmeta(hgmeta, text)

    return (text, True)

def writetostore(self, text):

    # hg filelog metadata (includes rename, etc)

    hgmeta, offset = filelog.parsemeta(text)

    if offset and offset > 0:

        # lfs blob does not contain hg filelog metadata

        text = text[offset:]

    # git-lfs only supports sha256

    oid = hashlib.sha256(text).hexdigest()

    self.opener.lfslocalblobstore.write(oid, text)

    # replace contents with metadata

    longoid = 'sha256:%s' % oid

    metadata = pointer.gitlfspointer(oid=longoid, size=str(len(text)))

    # by default, we expect the content to be binary. however, LFS could also

    # be used for non-binary content. add a special entry for non-binary data.

    # this will be used by filectx.isbinary().

    if not util.binary(text):

        # not hg filelog metadata (affecting commit hash), no "x-hg-" prefix

        metadata['x-is-binary'] = '0'

    # translate hg filelog metadata to lfs metadata with "x-hg-" prefix

    if hgmeta is not None:

        for k, v in hgmeta.iteritems():

            metadata['x-hg-%s' % k] = v

    rawtext = metadata.serialize()

    return (rawtext, False)

def _islfs(rlog, node=None, rev=None):

    if rev is None:

        if node is None:

            # both None - likely working copy content where node is not ready

            return False

        rev = rlog.rev(node)

    else:

        node = rlog.node(rev)

    if node == nullid:

        return False

    flags = rlog.flags(rev)

    return bool(flags & revlog.REVIDX_EXTSTORED)

def filelogaddrevision(orig, self, text, transaction, link, p1, p2,

                       cachedelta=None, node=None,

                       flags=revlog.REVIDX_DEFAULT_FLAGS, **kwds):

    threshold = self.opener.options['lfsthreshold']

    textlen = len(text)

    # exclude hg rename meta from file size

    meta, offset = filelog.parsemeta(text)

    if offset:

        textlen -= offset

    if threshold and textlen > threshold:

        flags |= revlog.REVIDX_EXTSTORED

    return orig(self, text, transaction, link, p1, p2, cachedelta=cachedelta,

                node=node, flags=flags, **kwds)

def filelogrenamed(orig, self, node):

    if _islfs(self, node):

        rawtext = self.revision(node, raw=True)

        if not rawtext:

            return False

        metadata = pointer.deserialize(rawtext)

        if 'x-hg-copy' in metadata and 'x-hg-copyrev' in metadata:

            return metadata['x-hg-copy'], bin(metadata['x-hg-copyrev'])

        else:

            return False

    return orig(self, node)

def filelogsize(orig, self, rev):

    if _islfs(self, rev=rev):

        # fast path: use lfs metadata to answer size

        rawtext = self.revision(rev, raw=True)

        metadata = pointer.deserialize(rawtext)

        return int(metadata['size'])

    return orig(self, rev)

def filectxcmp(orig, self, fctx):

    """returns True if text is different than fctx"""

    # some fctx (ex. hg-git) is not based on basefilectx and do not have islfs

    if self.islfs() and getattr(fctx, 'islfs', lambda: False)():

        # fast path: check LFS oid

        p1 = pointer.deserialize(self.rawdata())

        p2 = pointer.deserialize(fctx.rawdata())

        return p1.oid() != p2.oid()

    return orig(self, fctx)

def filectxisbinary(orig, self):

    if self.islfs():

        # fast path: use lfs metadata to answer isbinary

        metadata = pointer.deserialize(self.rawdata())

        # if lfs metadata says nothing, assume it's binary by default

        return bool(int(metadata.get('x-is-binary', 1)))

    return orig(self)

def filectxislfs(self):

    return _islfs(self.filelog(), self.filenode())

def vfsinit(orig, self, othervfs):

    orig(self, othervfs)

    # copy lfs related options

    for k, v in othervfs.options.items():

        if k.startswith('lfs'):

            self.options[k] = v

    # also copy lfs blobstores. note: this can run before reposetup, so lfs

    # blobstore attributes are not always ready at this time.

    for name in ['lfslocalblobstore', 'lfsremoteblobstore']:

        if util.safehasattr(othervfs, name):

            setattr(self, name, getattr(othervfs, name))

def _canskipupload(repo):

    # if remotestore is a null store, upload is a no-op and can be skipped

    return isinstance(repo.svfs.lfsremoteblobstore, blobstore._nullremote)

def candownload(repo):

    # if remotestore is a null store, downloads will lead to nothing

    return not isinstance(repo.svfs.lfsremoteblobstore, blobstore._nullremote)

def uploadblobsfromrevs(repo, revs):

    '''upload lfs blobs introduced by revs

    Note: also used by other extensions e. g. infinitepush. avoid renaming.

    '''

    if _canskipupload(repo):

        return

    pointers = extractpointers(repo, revs)

    uploadblobs(repo, pointers)

def prepush(pushop):

    """Prepush hook.

    Read through the revisions to push, looking for filelog entries that can be

    deserialized into metadata so that we can block the push on their upload to

    the remote blobstore.

    """

    return uploadblobsfromrevs(pushop.repo, pushop.outgoing.missing)

def writenewbundle(orig, ui, repo, source, filename, bundletype, outgoing,

                   *args, **kwargs):

    """upload LFS blobs added by outgoing revisions on 'hg bundle'"""

    uploadblobsfromrevs(repo, outgoing.missing)

    return orig(ui, repo, source, filename, bundletype, outgoing, *args,

                **kwargs)

def extractpointers(repo, revs):

    """return a list of lfs pointers added by given revs"""

    ui = repo.ui

    if ui.debugflag:

        ui.write(_('lfs: computing set of blobs to upload\n'))

    pointers = {}

    for r in revs:

        ctx = repo[r]

        for p in pointersfromctx(ctx).values():

            pointers[p.oid()] = p

    return pointers.values()

def pointersfromctx(ctx):

    """return a dict {path: pointer} for given single changectx"""

    result = {}

    for f in ctx.files():

        if f not in ctx:

            continue

        fctx = ctx[f]

        if not _islfs(fctx.filelog(), fctx.filenode()):

            continue

        try:

            result[f] = pointer.deserialize(fctx.rawdata())

        except pointer.InvalidPointer as ex:

            raise error.Abort(_('lfs: corrupted pointer (%s@%s): %s\n')

                              % (f, short(ctx.node()), ex))

    return result

def uploadblobs(repo, pointers):

    """upload given pointers from local blobstore"""

    if not pointers:

        return

    remoteblob = repo.svfs.lfsremoteblobstore

    remoteblob.writebatch(pointers, repo.svfs.lfslocalblobstore)