# journal.py

#

# Copyright 2014-2016 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.

"""track previous positions of bookmarks (EXPERIMENTAL)

This extension adds a new command: `hg journal`, which shows you where

bookmarks were previously located.

"""

from __future__ import absolute_import

import collections

import errno

import os

import weakref

from mercurial.i18n import _

from mercurial import (

    bookmarks,

    cmdutil,

    dispatch,

    error,

    extensions,

    hg,

    localrepo,

    lock,

    node,

    pycompat,

    registrar,

    util,

)

from . import share

cmdtable = {}

command = registrar.command(cmdtable)

# 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'

# storage format version; increment when the format changes

storageversion = 0

# namespaces

bookmarktype = 'bookmark'

wdirparenttype = 'wdirparent'

# In a shared repository, what shared feature name is used

# to indicate this namespace is shared with the source?

sharednamespaces = {

    bookmarktype: hg.sharedbookmarks,

}

# Journal recording, register hooks and storage object

def extsetup(ui):

    extensions.wrapfunction(dispatch, 'runcommand', runcommand)

    extensions.wrapfunction(bookmarks.bmstore, '_write', recordbookmarks)

    extensions.wrapfilecache(

        localrepo.localrepository, 'dirstate', wrapdirstate)

    extensions.wrapfunction(hg, 'postshare', wrappostshare)

    extensions.wrapfunction(hg, 'copystore', unsharejournal)

def reposetup(ui, repo):

    if repo.local():

        repo.journal = journalstorage(repo)

        repo._wlockfreeprefix.add('namejournal')

        dirstate, cached = localrepo.isfilecached(repo, 'dirstate')

        if cached:

            # already instantiated dirstate isn't yet marked as

            # "journal"-ing, even though repo.dirstate() was already

            # wrapped by own wrapdirstate()

            _setupdirstate(repo, dirstate)

def runcommand(orig, lui, repo, cmd, fullargs, *args):

    """Track the command line options for recording in the journal"""

    journalstorage.recordcommand(*fullargs)

    return orig(lui, repo, cmd, fullargs, *args)

def _setupdirstate(repo, dirstate):

    dirstate.journalstorage = repo.journal

    dirstate.addparentchangecallback('journal', recorddirstateparents)

# hooks to record dirstate changes

def wrapdirstate(orig, repo):

    """Make journal storage available to the dirstate object"""

    dirstate = orig(repo)

    if util.safehasattr(repo, 'journal'):

        _setupdirstate(repo, dirstate)

    return dirstate

def recorddirstateparents(dirstate, old, new):

    """Records all dirstate parent changes in the journal."""

    old = list(old)

    new = list(new)

    if util.safehasattr(dirstate, 'journalstorage'):

        # only record two hashes if there was a merge

        oldhashes = old[:1] if old[1] == node.nullid else old

        newhashes = new[:1] if new[1] == node.nullid else new

        dirstate.journalstorage.record(

            wdirparenttype, '.', oldhashes, newhashes)

# hooks to record bookmark changes (both local and remote)

def recordbookmarks(orig, store, fp):

    """Records all bookmark changes in the journal."""

    repo = store._repo

    if util.safehasattr(repo, 'journal'):

        oldmarks = bookmarks.bmstore(repo)

        for mark, value in store.iteritems():

            oldvalue = oldmarks.get(mark, node.nullid)

            if value != oldvalue:

                repo.journal.record(bookmarktype, mark, oldvalue, value)

    return orig(store, fp)

# shared repository support

def _readsharedfeatures(repo):

    """A set of shared features for this repository"""

    try:

        return set(repo.vfs.read('shared').splitlines())

    except IOError as inst:

        if inst.errno != errno.ENOENT:

            raise

        return set()

def _mergeentriesiter(*iterables, **kwargs):

    """Given a set of sorted iterables, yield the next entry in merged order

    Note that by default entries go from most recent to oldest.

    """

    order = kwargs.pop(r'order', max)

    iterables = [iter(it) for it in iterables]

    # this tracks still active iterables; iterables are deleted as they are

    # exhausted, which is why this is a dictionary and why each entry also

    # stores the key. Entries are mutable so we can store the next value each

    # time.

    iterable_map = {}

    for key, it in enumerate(iterables):

        try:

            iterable_map[key] = [next(it), key, it]

        except StopIteration:

            # empty entry, can be ignored

            pass

    while iterable_map:

        value, key, it = order(iterable_map.itervalues())

        yield value

        try:

            iterable_map[key][0] = next(it)

        except StopIteration:

            # this iterable is empty, remove it from consideration

            del iterable_map[key]

def wrappostshare(orig, sourcerepo, destrepo, **kwargs):

    """Mark this shared working copy as sharing journal information"""

    with destrepo.wlock():

        orig(sourcerepo, destrepo, **kwargs)

        with destrepo.vfs('shared', 'a') as fp:

            fp.write('journal\n')

def unsharejournal(orig, ui, repo, repopath):

    """Copy shared journal entries into this repo when unsharing"""

    if (repo.path == repopath and repo.shared() and

            util.safehasattr(repo, 'journal')):

        sharedrepo = share._getsrcrepo(repo)

        sharedfeatures = _readsharedfeatures(repo)

        if sharedrepo and sharedfeatures > {'journal'}:

            # there is a shared repository and there are shared journal entries

            # to copy. move shared date over from source to destination but

            # move the local file first

            if repo.vfs.exists('namejournal'):

                journalpath = repo.vfs.join('namejournal')

                util.rename(journalpath, journalpath + '.bak')

            storage = repo.journal

            local = storage._open(

                repo.vfs, filename='namejournal.bak', _newestfirst=False)

            shared = (

                e for e in storage._open(sharedrepo.vfs, _newestfirst=False)

                if sharednamespaces.get(e.namespace) in sharedfeatures)

            for entry in _mergeentriesiter(local, shared, order=min):

                storage._write(repo.vfs, entry)

    return orig(ui, repo, repopath)

class journalentry(collections.namedtuple(

        u'journalentry',

        u'timestamp user command namespace name oldhashes newhashes')):

    """Individual journal entry

    * timestamp: a mercurial (time, timezone) tuple

    * user: the username that ran the command

    * namespace: the entry namespace, an opaque string

    * name: the name of the changed item, opaque string with meaning in the

      namespace

    * command: the hg command that triggered this record

    * oldhashes: a tuple of one or more binary hashes for the old location

    * newhashes: a tuple of one or more binary hashes for the new location

    Handles serialisation from and to the storage format. Fields are

    separated by newlines, hashes are written out in hex separated by commas,

    timestamp and timezone are separated by a space.

    """

    @classmethod

    def fromstorage(cls, line):

        (time, user, command, namespace, name,

         oldhashes, newhashes) = line.split('\n')

        timestamp, tz = time.split()

        timestamp, tz = float(timestamp), int(tz)

        oldhashes = tuple(node.bin(hash) for hash in oldhashes.split(','))

        newhashes = tuple(node.bin(hash) for hash in newhashes.split(','))

        return cls(

            (timestamp, tz), user, command, namespace, name,

            oldhashes, newhashes)

    def __str__(self):

        """String representation for storage"""

        time = ' '.join(map(str, self.timestamp))

        oldhashes = ','.join([node.hex(hash) for hash in self.oldhashes])

        newhashes = ','.join([node.hex(hash) for hash in self.newhashes])

        return '\n'.join((

            time, self.user, self.command, self.namespace, self.name,

            oldhashes, newhashes))

class journalstorage(object):

    """Storage for journal entries

    Entries are divided over two files; one with entries that pertain to the

    local working copy *only*, and one with entries that are shared across

    multiple working copies when shared using the share extension.

    Entries are stored with NUL bytes as separators. See the journalentry

    class for the per-entry structure.

    The file format starts with an integer version, delimited by a NUL.

    This storage uses a dedicated lock; this makes it easier to avoid issues

    with adding entries that added when the regular wlock is unlocked (e.g.

    the dirstate).

    """

    _currentcommand = ()

    _lockref = None

    def __init__(self, repo):

        self.user = util.getuser()

        self.ui = repo.ui

        self.vfs = repo.vfs

        # is this working copy using a shared storage?

        self.sharedfeatures = self.sharedvfs = None

        if repo.shared():

            features = _readsharedfeatures(repo)

            sharedrepo = share._getsrcrepo(repo)

            if sharedrepo is not None and 'journal' in features:

                self.sharedvfs = sharedrepo.vfs

                self.sharedfeatures = features

    # track the current command for recording in journal entries

    @property

    def command(self):

        commandstr = ' '.join(

            map(util.shellquote, journalstorage._currentcommand))

        if '\n' in commandstr:

            # truncate multi-line commands

            commandstr = commandstr.partition('\n')[0] + ' ...'

        return commandstr

    @classmethod

    def recordcommand(cls, *fullargs):

        """Set the current hg arguments, stored with recorded entries"""

        # Set the current command on the class because we may have started

        # with a non-local repo (cloning for example).

        cls._currentcommand = fullargs

    def _currentlock(self, lockref):

        """Returns the lock if it's held, or None if it's not.

        (This is copied from the localrepo class)

        """

        if lockref is None:

            return None

        l = lockref()

        if l is None or not l.held:

            return None

        return l

    def jlock(self, vfs):

        """Create a lock for the journal file"""

        if self._currentlock(self._lockref) is not None:

            raise error.Abort(_('journal lock does not support nesting'))

        desc = _('journal of %s') % vfs.base

        try:

            l = lock.lock(vfs, 'namejournal.lock', 0, desc=desc)

        except error.LockHeld as inst:

            self.ui.warn(

                _("waiting for lock on %s held by %r\n") % (desc, inst.locker))

            # default to 600 seconds timeout

            l = lock.lock(

                vfs, 'namejournal.lock',

            self.ui.warn(_("got lock after %s seconds\n") % l.delay)

        self._lockref = weakref.ref(l)

        return l

    def record(self, namespace, name, oldhashes, newhashes):

        """Record a new journal entry

        * namespace: an opaque string; this can be used to filter on the type

          of recorded entries.

        * name: the name defining this entry; for bookmarks, this is the

          bookmark name. Can be filtered on when retrieving entries.

        * oldhashes and newhashes: each a single binary hash, or a list of

          binary hashes. These represent the old and new position of the named

          item.

        """

        if not isinstance(oldhashes, list):

            oldhashes = [oldhashes]

        if not isinstance(newhashes, list):

            newhashes = [newhashes]

        entry = journalentry(

            util.makedate(), self.user, self.command, namespace, name,

            oldhashes, newhashes)

        vfs = self.vfs

        if self.sharedvfs is not None:

            # write to the shared repository if this feature is being

            # shared between working copies.

            if sharednamespaces.get(namespace) in self.sharedfeatures:

                vfs = self.sharedvfs

        self._write(vfs, entry)

    def _write(self, vfs, entry):

        with self.jlock(vfs):

            version = None

            # open file in amend mode to ensure it is created if missing

            with vfs('namejournal', mode='a+b') as f:

                f.seek(0, os.SEEK_SET)

                # Read just enough bytes to get a version number (up to 2

                # digits plus separator)

                version = f.read(3).partition('\0')[0]

                if version and version != str(storageversion):

                    # different version of the storage. Exit early (and not

                    # write anything) if this is not a version we can handle or

                    # the file is corrupt. In future, perhaps rotate the file

                    # instead?

                    self.ui.warn(

                        _("unsupported journal file version '%s'\n") % version)

                    return

                if not version:

                    # empty file, write version first

                    f.write(str(storageversion) + '\0')

                f.seek(0, os.SEEK_END)

                f.write(str(entry) + '\0')

    def filtered(self, namespace=None, name=None):

        """Yield all journal entries with the given namespace or name

        Both the namespace and the name are optional; if neither is given all

        entries in the journal are produced.

        Matching supports regular expressions by using the `re:` prefix

        (use `literal:` to match names or namespaces that start with `re:`)

        """

        if namespace is not None:

            namespace = util.stringmatcher(namespace)[-1]

        if name is not None:

            name = util.stringmatcher(name)[-1]

        for entry in self:

            if namespace is not None and not namespace(entry.namespace):

                continue

            if name is not None and not name(entry.name):

                continue

            yield entry

    def __iter__(self):

        """Iterate over the storage

        Yields journalentry instances for each contained journal record.

        """

        local = self._open(self.vfs)