'''enable experimental obsolescence feature of Mercurial

OBSOLESCENCE IS AN EXPERIMENTAL FEATURE MAKE SURE YOU UNDERSTOOD THE INVOLVED
CONCEPT BEFORE USING IT.

/!\ THIS EXTENSION IS INTENDED FOR SERVER SIDE ONLY USAGE /!\

For client side usages it is recommended to use the evolve extension for
improved user interface.'''

import mercurial.obsolete
mercurial.obsolete._enabled = True

import struct
from mercurial import wireproto
from mercurial import extensions
from mercurial import obsolete
from cStringIO import StringIO
from mercurial import node
from mercurial.hgweb import hgweb_mod
_pack = struct.pack

def srv_pushobsmarkers(repo, proto):
    """wireprotocol command"""
    fp = StringIO()
    proto.redirect()
    proto.getfile(fp)
    data = fp.getvalue()
    fp.close()
    lock = repo.lock()
    try:
        tr = repo.transaction('pushkey: obsolete markers')
        try:
            repo.obsstore.mergemarkers(tr, data)
            tr.close()
        finally:
            tr.release()
    finally:
        lock.release()
    return wireproto.pushres(0)

def _encodemarkersstream(fp, markers):
    fp.write(_pack('>B', 0))
    for mark in markers:
        fp.write(obsolete._encodeonemarker(mark))

def _getobsmarkersstream(repo, heads=None, common=None):
    revset = ''
    args = []
    repo = repo.unfiltered()
    if heads is None:
        revset = 'all()'
    elif heads:
        revset += "(::%ln)"
        args.append(heads)
    else:
        assert False, 'pulling no heads?'
    if common:
        revset += ' - (::%ln)'
        args.append(common)
    nodes = [c.node() for c in repo.set(revset, *args)]
    markers = repo.obsstore.relevantmarkers(nodes)
    obsdata = StringIO()
    _encodemarkersstream(obsdata, markers)
    obsdata.seek(0)
    return obsdata

class pruneobsstore(obsolete.obsstore):

    def __init__(self, *args, **kwargs):
        self.prunedchildren = {}
        return super(pruneobsstore, self).__init__(*args, **kwargs)

    def _load(self, markers):
        markers = self._prunedetectingmarkers(markers)
        return super(pruneobsstore, self)._load(markers)


    def _prunedetectingmarkers(self, markers):
        for m in markers:
            if not m[1]: # no successors
                meta = obsolete.decodemeta(m[3])
                if 'p1' in meta:
                    p1 = node.bin(meta['p1'])
                    self.prunedchildren.setdefault(p1, set()).add(m)
                if 'p2' in meta:
                    p2 = node.bin(meta['p2'])
                    self.prunedchildren.setdefault(p2, set()).add(m)
            yield m

def relevantmarkers(self, nodes):
    """return a set of all obsolescence marker relevant to a set of node.

    "relevant" to a set of node mean:

    - marker that use this changeset as successors
    - prune marker of direct children on this changeset.
    - recursive application of the two rules on precursors of these markers

    It  a set so you cannot rely on order"""
    seennodes = set(nodes)
    seenmarkers = set()
    pendingnodes = set(nodes)
    precursorsmarkers = self.precursors
    prunedchildren = self.prunedchildren
    while pendingnodes:
        direct = set()
        for current in pendingnodes:
            direct.update(precursorsmarkers.get(current, ()))
            direct.update(prunedchildren.get(current, ()))
        direct -= seenmarkers
        pendingnodes = set([m[0] for m in direct])
        seenmarkers |= direct
        pendingnodes -= seennodes
        seennodes |= pendingnodes
    return seenmarkers

def srv_pullobsmarkers(repo, proto, others):
    opts = wireproto.options('', ['heads', 'common'], others)
    for k, v in opts.iteritems():
        if k in ('heads', 'common'):
            opts[k] = wireproto.decodelist(v)
    obsdata = _getobsmarkersstream(repo, **opts)
    length = '%20i' % len(obsdata.getvalue())
    def data():
        yield length
        for c in proto.groupchunks(obsdata):
            yield c
    return wireproto.streamres(data())


def _obsrelsethashtree(repo):
    cache = []
    unfi = repo.unfiltered()
    for i in unfi:
        ctx = unfi[i]
        entry = 0
        sha = util.sha1()
        # add data from p1
        for p in ctx.parents():
            p = p.rev()
            if p < 0:
                p = node.nullid
            else:
                p = cache[p][1]
            if p != node.nullid:
                entry += 1
                sha.update(p)
        tmarkers = repo.obsstore.relevantmarkers([ctx.node()])
        if tmarkers:
            bmarkers = [obsolete._encodeonemarker(m) for m in tmarkers]
            bmarkers.sort()
            for m in bmarkers:
                entry += 1
                sha.update(m)
        if entry:
            cache.append((ctx.node(), sha.digest()))
        else:
            cache.append((ctx.node(), node.nullid))
    return cache

def _obshash(repo, nodes):
    hashs = _obsrelsethashtree(repo)
    nm = repo.changelog.nodemap
    return  [hashs[nm.get(n)][1] for n in nodes]

def srv_obshash(repo, proto, nodes):
    return wireproto.encodelist(_obshash(repo, wireproto.decodelist(nodes)))

def capabilities(orig, repo, proto):
    """wrapper to advertise new capability"""
    caps = orig(repo, proto)
    if obsolete._enabled:
        caps += ' _evoext_pushobsmarkers_0'
        caps += ' _evoext_pullobsmarkers_0'
        caps += ' _evoext_obshash_0'
    return caps

def extsetup(ui):
    obsolete.obsstore = pruneobsstore
    obsolete.obsstore.relevantmarkers = relevantmarkers
    hgweb_mod.perms['evoext_pushobsmarkers_0'] = 'push'
    hgweb_mod.perms['evoext_pullobsmarkers_0'] = 'pull'
    hgweb_mod.perms['evoext_obshash'] = 'pull'
    wireproto.commands['evoext_pushobsmarkers_0'] = (srv_pushobsmarkers, '')
    wireproto.commands['evoext_pullobsmarkers_0'] = (srv_pullobsmarkers, '*')
    extensions.wrapfunction(wireproto, 'capabilities', capabilities)
    wireproto.commands['evoext_obshash'] = (srv_obshash, 'nodes')