# ext-sidedata.py - small extension to test the sidedata logic

#

# Copyright 2019 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

import hashlib

import struct

from mercurial import (

    extensions,

    node,

    requirements,

    revlog,

    upgrade,

)

from mercurial.revlogutils import sidedata

def wrapaddrevision(

    orig, self, text, transaction, link, p1, p2, *args, **kwargs

):

    if kwargs.get('sidedata') is None:

        kwargs['sidedata'] = {}

    sd = kwargs['sidedata']

    ## let's store some arbitrary data just for testing

    # text length

    sd[sidedata.SD_TEST1] = struct.pack('>I', len(text))

    # and sha2 hashes

    sha256 = hashlib.sha256(text).digest()

    sd[sidedata.SD_TEST2] = struct.pack('>32s', sha256)

    return orig(self, text, transaction, link, p1, p2, *args, **kwargs)

def wraprevision(orig, self, nodeorrev, *args, **kwargs):

    text = orig(self, nodeorrev, *args, **kwargs)

    if getattr(self, 'sidedatanocheck', False):

        return text

    if nodeorrev != node.nullrev and nodeorrev != node.nullid:

        sd = self.sidedata(nodeorrev)

        if len(text) != struct.unpack('>I', sd[sidedata.SD_TEST1])[0]:

            raise RuntimeError('text size mismatch')

        expected = sd[sidedata.SD_TEST2]

        got = hashlib.sha256(text).digest()

        if got != expected:

            raise RuntimeError('sha256 mismatch')

    return text

def wrapgetsidedatacompanion(orig, srcrepo, dstrepo):

    sidedatacompanion = orig(srcrepo, dstrepo)

    addedreqs = dstrepo.requirements - srcrepo.requirements

    if requirements.SIDEDATA_REQUIREMENT in addedreqs:

        assert sidedatacompanion is None  # deal with composition later

        def sidedatacompanion(revlog, rev):

            update = {}

            revlog.sidedatanocheck = True

            try:

                text = revlog.revision(rev)

            finally:

                del revlog.sidedatanocheck

            ## let's store some arbitrary data just for testing

            # text length

            update[sidedata.SD_TEST1] = struct.pack('>I', len(text))

            # and sha2 hashes

            sha256 = hashlib.sha256(text).digest()

            update[sidedata.SD_TEST2] = struct.pack('>32s', sha256)

    return sidedatacompanion

def extsetup(ui):

    extensions.wrapfunction(revlog.revlog, 'addrevision', wrapaddrevision)

    extensions.wrapfunction(revlog.revlog, 'revision', wraprevision)

    extensions.wrapfunction(

        upgrade, 'getsidedatacompanion', wrapgetsidedatacompanion

    )