""" Mercurial phases support code

    ---

    Copyright 2011 Pierre-Yves David <pierre-yves.david@ens-lyon.org>

                   Logilab SA        <contact@logilab.fr>

                   Augie Fackler     <durin42@gmail.com>

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

    GNU General Public License version 2 or any later version.

    ---

This module implements most phase logic in mercurial.

Basic Concept

=============

A 'changeset phases' is an indicator that tells us how a changeset is

manipulated and communicated. The details of each phase is described below,

here we describe the properties they have in common.

Like bookmarks, phases are not stored in history and thus are not permanent and

leave no audit trail.

First, no changeset can be in two phases at once. Phases are ordered, so they

can be considered from lowest to highest. The default, lowest phase is 'public'

- this is the normal phase of existing changesets. A child changeset can not be

in a lower phase than its parents.

These phases share a hierarchy of traits:

            immutable shared

    public:     X        X

    draft:               X

local commits are draft by default

Phase movement and exchange

============================

Phase data are exchanged by pushkey on pull and push. Some server have a

publish option set, we call them publishing server. Pushing to such server make

draft changeset publish.

A small list of fact/rules define the exchange of phase:

* old client never changes server states

* pull never changes server states

* publish and old server csets are seen as public by client

Here is the final table summing up the 49 possible usecase of phase exchange:

                           server

                  old     publish      non-publish

                 N   X    N   D   P    N   D   P

    old client

    pull

     N           -   X/X  -   X/D X/P  -   X/D X/P

     X           -   X/X  -   X/D X/P  -   X/D X/P

    push

     X           X/X X/X  X/P X/P X/P  X/D X/D X/P

    new client

    pull

     N           -   P/X  -   P/D P/P  -   D/D P/P

     D           -   P/X  -   P/D P/P  -   D/D P/P

     P           -   P/X  -   P/D P/P  -   P/D P/P

    push

     D           P/X P/X  P/P P/P P/P  D/D D/D P/P

     P           P/X P/X  P/P P/P P/P  P/P P/P P/P

Legend:

    A/B = final state on client / state on server

    * N = new/not present,

    * P = public,

    * D = draft,

    * X = not tracked (ie: the old client or server has no internal way of

          recording the phase.)

    passive = only pushes

    A cell here can be read like this:

    "When a new client pushes a draft changeset (D) to a publishing server

    where it's not present (N), it's marked public on both sides (P/P)."

Note: old client behave as publish server with Draft only content

- other people see it as public

- content is pushed as draft

"""

import errno

from node import nullid, bin, hex, short

from i18n import _

allphases = range(3)

trackedphases = allphases[1:]

def readroots(repo):

    """Read phase roots from disk"""

    roots = [set() for i in allphases]

    roots[0].add(nullid)

    try:

        f = repo.sopener('phaseroots')

        try:

            for line in f:

                phase, nh = line.strip().split()

                roots[int(phase)].add(bin(nh))

        finally:

            f.close()

    except IOError, inst:

        if inst.errno != errno.ENOENT:

            raise

    return roots

def writeroots(repo):

    """Write phase roots from disk"""

    f = repo.sopener('phaseroots', 'w', atomictemp=True)

    try:

        for phase, roots in enumerate(repo._phaseroots):

            for h in roots:

                f.write('%i %s\n' % (phase, hex(h)))

        repo._dirtyphases = False

    finally:

        f.close()

def filterunknown(repo, phaseroots=None):

    """remove unknown nodes from the phase boundary

    no data is lost as unknown node only old data for their descentants

    """

    if phaseroots is None:

        phaseroots = repo._phaseroots

    for phase, nodes in enumerate(phaseroots):

        missing = [node for node in nodes if node not in repo]

        if missing:

            for mnode in missing:

                msg = _('Removing unknown node %(n)s from %(p)i-phase boundary')

                repo.ui.debug(msg, {'n': short(mnode), 'p': phase})

            nodes.symmetric_difference_update(missing)

            repo._dirtyphases = True

def advanceboundary(repo, targetphase, nodes):

    """Add nodes to a phase changing other nodes phases if necessary.

    This function move boundary *forward* this means that all nodes are set

    in the target phase or kept in a *lower* phase.

    Simplify boundary to contains phase roots only."""

    delroots = [] # set of root deleted by this path

    for phase in xrange(targetphase + 1, len(allphases)):

        # filter nodes that are not in a compatible phase already

        # XXX rev phase cache might have been invalidated by a previous loop

        # XXX we need to be smarter here

        nodes = [n for n in nodes if repo[n].phase() >= phase]

        if not nodes:

            break # no roots to move anymore

        roots = repo._phaseroots[phase]

        olds = roots.copy()

        ctxs = list(repo.set('roots((%ln::) - (%ln::%ln))', olds, olds, nodes))

        roots.clear()

        roots.update(ctx.node() for ctx in ctxs)

        if olds != roots:

            # invalidate cache (we probably could be smarter here

            if '_phaserev' in vars(repo):

                del repo._phaserev

            repo._dirtyphases = True

            # some roots may need to be declared for lower phases

            delroots.extend(olds - roots)

        # declare deleted root in the target phase

        if targetphase != 0:

            retractboundary(repo, targetphase, delroots)

def retractboundary(repo, targetphase, nodes):

    """Set nodes back to a phase changing other nodes phases if necessary.

    This function move boundary *backward* this means that all nodes are set

    in the target phase or kept in a *higher* phase.

    Simplify boundary to contains phase roots only."""

    currentroots = repo._phaseroots[targetphase]

    newroots = [n for n in nodes if repo[n].phase() < targetphase]

    if newroots:

        currentroots.update(newroots)

        ctxs = repo.set('roots(%ln::)', currentroots)

        currentroots.intersection_update(ctx.node() for ctx in ctxs)

        if '_phaserev' in vars(repo):

            del repo._phaserev

        repo._dirtyphases = True

def listphases(repo):

    """List phases root for serialisation over pushkey"""

    keys = {}

    for phase in trackedphases:

        for root in repo._phaseroots[phase]:

            keys[hex(root)] = '%i' % phase

    if repo.ui.configbool('phases', 'publish', True):

        # Add an extra data to let remote know we are a publishing repo.

        # Publishing repo can't just pretend they are old repo. When pushing to

        # a publishing repo, the client still need to push phase boundary

        #

        # Push do not only push changeset. It also push phase data. New

        # phase data may apply to common changeset which won't be push (as they

        # are common).  Here is a very simple example:

        #

        # 1) repo A push changeset X as draft to repo B

        # 2) repo B make changeset X public

        # 3) repo B push to repo A. X is not pushed but the data that X as now

        #    public should

        #

        # The server can't handle it on it's own as it has no idea of client

        # phase data.

        keys['publishing'] = 'True'

    return keys

def pushphase(repo, nhex, oldphasestr, newphasestr):

    """List phases root for serialisation over pushkey"""

    lock = repo.lock()

    try:

        currentphase = repo[nhex].phase()

        newphase = abs(int(newphasestr)) # let's avoid negative index surprise

        oldphase = abs(int(oldphasestr)) # let's avoid negative index surprise

        if currentphase == oldphase and newphase < oldphase:

            advanceboundary(repo, newphase, [bin(nhex)])

            return 1

        else:

            return 0

    finally:

        lock.release()

def analyzeremotephases(repo, subset, roots):

    """Compute phases heads and root in a subset of node from root dict

    * subset is heads of the subset

    * roots is {<nodeid> => phase} mapping. key and value are string.

    Accept unknown element input

    """

    # build list from dictionary

    phaseroots = [[] for p in allphases]

    for nhex, phase in roots.iteritems():

        if nhex == 'publishing': # ignore data related to publish option

            continue

        node = bin(nhex)

        phase = int(phase)

        if node in repo:

            phaseroots[phase].append(node)

    # compute heads

    phaseheads = [[] for p in allphases]

    for phase in allphases[:-1]:

        toproof = phaseroots[phase + 1]

        revset = repo.set('heads((%ln + parents(%ln)) - (%ln::%ln))',

                          subset, toproof, toproof, subset)

        phaseheads[phase].extend(c.node() for c in revset)

    return phaseheads, phaseroots