# obsolete.py - introduce the obsolete concept in mercurial.
#
# Copyright 2011 Pierre-Yves David <pierre-yves.david@ens-lyon.org>
#                Logilab SA        <contact@logilab.fr>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""Introduce the Obsolete concept to mercurial

General concept
===============

This extension introduces the *obsolete* concept. It adds a new *obsolete*
relation between two changesets. A relation ``<changeset B> obsolete <changeset
A>`` is set to denote that ``<changeset B>`` is new version of ``<changeset
A>``.

The *obsolete* relation act as a **perpendicular history** to the standard
changeset history. Standard changeset history versions files. The *obsolete*
relation versions changesets.

:obsolete:     a changeset that have been replace by another one.
:out of sync:  a non-obsolet changeset based on another one.
:suspended:    an obsolete changeset with out of sync descendant.



Usage and Feature
=================


Display and Exchange
....................

obsolete changesets are hidden. (except if they have non obsolete changeset)

obsolete changesets are currently not exchange. This will probably change later
but it was the simpler solution for now.

New commands
............

a ``debugobsolete`` command has been added.

It add an obsolete relation between too relation.

Context object
..............

Context gain a ``obsolete`` method that return True if a changeset is obsolete
False otherwise.

revset
......

Add an ``obsolete()`` entry.

repo extension
..............

To Do
-----

* refuse to obsolete published changesets

* handle split

* handle conflict

* handle out of sync

"""
import os
try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO


from mercurial import util
from mercurial import context
from mercurial import revset
from mercurial import scmutil
from mercurial import extensions
from mercurial import pushkey
from mercurial import discovery
from mercurial import error
from mercurial.node import hex, bin
from mercurial.lock import release

### Patch changectx
#############################

def obsolete(ctx):
    """is the changeset obsolete by other"""
    if ctx.node()is None:
        return False
    return bool(ctx._repo.obsoletedby(ctx.node()))

context.changectx.obsolete = obsolete

ohidden = context.changectx.hidden
def hidden(ctx):
    # hack to fill hiddenrevs
    # compute hidden (XXX should move elsewhere)
    if not getattr(ctx._repo.changelog, 'hiddeninit', False):
        basicquery = 'obsolete() - (ancestors(not obsolete() or . or bookmark()))'
        for rev in scmutil.revrange(ctx._repo, [basicquery]):
            ctx._repo.changelog.hiddenrevs.add(rev)
        ctx._repo.changelog.hiddeninit = True

    return ohidden(ctx)
context.changectx.hidden = hidden

### revset
#############################

def revsetobsolete(repo, subset, x):
    args = revset.getargs(x, 0, 0, 'publicheads takes no arguments')
    return [r for r in subset if repo[r].obsolete()] # XXX slow

### Other Extension compat
############################

def concludenode(orig, repo, rev, *args, **kwargs):
    newrev = orig(repo, rev, *args, **kwargs)
    oldnode = repo[rev].node()
    newnode = repo[newrev].node()
    repo.addobsolete(newnode, oldnode)
    return newrev


def extsetup(ui):
    revset.symbols["obsolete"] = revsetobsolete

    def filterobsoleteout(orig, repo, remote, *args,**kwargs):
        common, heads = orig(repo, remote, *args, **kwargs)

        # filter obsolete
        heads = set(map(repo.changelog.rev, heads))
        obsoletes = set()
        for obj in repo._obsobjrels:
            try:
                obsoletes.add(repo.changelog.rev(obj))
            except error.LookupError:
                pass # we don't have this node locally

        outgoing = set(repo.changelog.ancestors(*heads))
        outgoing.update(heads)

        selected = outgoing - obsoletes
        heads = sorted(map(repo.changelog.node, selected))

        return common, heads

    extensions.wrapfunction(discovery, 'findcommonoutgoing', filterobsoleteout)
    
    try:
        rebase = extensions.find('rebase')
        if rebase:
            extensions.wrapfunction(rebase, 'concludenode', concludenode)
    except KeyError:
        pass # rebase not found

# Pushkey mechanism for mutable
#########################################

def pushobsolete(repo, key, old, raw):
    assert key == "relations"
    w = repo.wlock()
    try:
        tmp = StringIO()
        tmp.write(raw)
        tmp.seek(0)
        relations = _obsdeserialise(tmp)
        for sub, objs in relations.iteritems():
            for obj in objs:
                try:
                    repo.addobsolete(sub, obj)
                except error.RepoLookupError:
                    pass
        return 0
    finally:
        w.release()

def listobsolete(repo):
    tmp = StringIO()
    _obsserialise(repo._obssubrels, tmp)
    return {'relations': tmp.getvalue()}

pushkey.register('obsolete', pushobsolete, listobsolete)

### New commands
#############################


def cmddebugobsolete(ui, repo, subject, object):
    """Add an obsolete relation between a too node
    
    The subject is expected to be a newer version of the object"""
    sub = repo[subject]
    obj = repo[object]
    repo.addobsolete(sub.node(), obj.node())
    return 0

cmdtable = {'debugobsolete': (cmddebugobsolete, [], '<subject> <object>')}

### serialisation
#############################

def _obsserialise(obssubrels, flike):
    for sub, objs in obssubrels.iteritems():
        for obj in objs:
            flike.write('%s %s\n' % (hex(sub), hex(obj)))

def _obsdeserialise(flike):
    rels = {}
    for line in flike:
        subhex, objhex = line.split()
        rels.setdefault(bin(subhex), set()).add(bin(objhex))
    return rels

def reposetup(ui, repo):

    if not repo.local():
        return

    opull = repo.pull
    opush = repo.push
    orollback = repo.rollback
    o_writejournal = repo._writejournal

    class obsoletingrepo(repo.__class__):

        ### Public method
        def obsoletedby(self, node):
            """return the set of node that make <node> obsolete (obj)"""
            return self._obsobjrels.get(node, set())

        def obsolete(self, node):
            """return the set of node that <node> make obsolete (sub)"""
            return self._obssubrels.get(node, set())

        def addobsolete(self, sub, obj):
            """Add a relation marking that node <sub> is a new version of <obj>"""
            self._obssubrels.setdefault(sub, set()).add(obj)
            self._obsobjrels.setdefault(obj, set()).add(sub)
            try:
                self.changelog.hiddenrevs.add(repo[obj].rev())
            except error.RepoLookupError:
                pass #unknow revision (but keep propagating the data
            self._writeobsrels()

        ### obsolete storage
        @util.propertycache
        def _obsobjrels(self):
            """{<old-node> -> set(<new-node>)}

            also compute hidden revision"""
            #reverse sub -> objs mapping
            objrels = {}
            for sub, objs in self._obssubrels.iteritems():
                for obj in objs:
                    objrels.setdefault(obj, set()).add(sub)
            return objrels

        @util.propertycache
        def _obssubrels(self):
            """{<new-node> -> set(<old-node>)}"""
            return self._readobsrels()




        ### Disk IO
        def _readobsrels(self):
            """Write obsolete relation on disk"""
            # XXX handle lock
            try:
                f = self.opener('obsolete-relations')
                try:
                    return _obsdeserialise(f)
                finally:
                    f.close()
            except IOError:
                return {}

        def _writeobsrels(self):
            """Write obsolete relation on disk"""
            # XXX handle lock
            f = self.opener('obsolete-relations', 'w', atomictemp=True)
            try:
                _obsserialise(self._obssubrels, f)
                f.rename()
            finally:
                f.close()

        ### local clone support

        def cancopy(self):
            return not bool(self._obsobjrels) # you can't copy if there is obsolete

        ### pull // push support

        def pull(self, remote, *args, **kwargs):
            result = opull(remote, *args, **kwargs)
            if 'obsolete' in remote.listkeys('namespaces'):
                tmp = StringIO()
                tmp.write(remote.listkeys('obsolete')['relations'])
                tmp.seek(0)
                obsrels = _obsdeserialise(tmp)
                for sub, objs in obsrels.iteritems():
                    for obj in objs:
                        self.addobsolete(sub, obj)
            return result

        def push(self, remote, *args, **opts):
            result = opush(remote, *args, **opts)
            if 'obsolete' in remote.listkeys('namespaces'):
                tmp = StringIO()
                _obsserialise(self._obssubrels, tmp)
                remote.pushkey('obsolete', 'relations', '', tmp.getvalue())

            return result



        ### rollback support

        def _writejournal(self, desc):
            entries = list(o_writejournal(desc))
            filename = 'obsolete-relations'
            filepath = self.join(filename)
            if  os.path.exists(filepath):
                journalname = 'journal.' + filename
                journalpath = self.join(journalname)
                util.copyfile(filepath, journalpath)
                entries.append(journalpath)
            return tuple(entries)

        def rollback(self, dryrun=False):
            wlock = lock = None
            try:
                wlock = self.wlock()
                lock = self.lock()
                ret = orollback(dryrun)
                if not (ret or dryrun): #rollback did not failed
                    src = self.join('undo.obsolete-relations')
                    dst = self.join('obsolete-relations')
                    if os.path.exists(src):
                        util.rename(src, dst)
                    elif os.path.exists(dst): #unlink in any case
                        os.unlink(dst)
                    # invalidate cache
                    self.__dict__.pop('_obssubrels', None)
                    self.__dict__.pop('_obsobjrels', None)
                return ret
            finally:
                release(lock, wlock)

    repo.__class__ = obsoletingrepo