# discovery.py - protocol changeset discovery functions

#

# Copyright 2010 Matt Mackall <mpm@selenic.com>

#

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

# GNU General Public License version 2 or any later version.

from node import nullid, short

from i18n import _

import util, setdiscovery, treediscovery

def findcommonincoming(repo, remote, heads=None, force=False):

    """Return a tuple (common, anyincoming, heads) used to identify the common

    subset of nodes between repo and remote.

    "common" is a list of (at least) the heads of the common subset.

    "anyincoming" is testable as a boolean indicating if any nodes are missing

      locally. If remote does not support getbundle, this actually is a list of

      roots of the nodes that would be incoming, to be supplied to

      changegroupsubset. No code except for pull should be relying on this fact

      any longer.

    "heads" is either the supplied heads, or else the remote's heads.

    If you pass heads and they are all known locally, the reponse lists justs

    these heads in "common" and in "heads".

    Please use findcommonoutgoing to compute the set of outgoing nodes to give

    extensions a good hook into outgoing.

    """

    if not remote.capable('getbundle'):

        return treediscovery.findcommonincoming(repo, remote, heads, force)

    if heads:

        allknown = True

        nm = repo.changelog.nodemap

        for h in heads:

            if nm.get(h) is None:

                allknown = False

                break

        if allknown:

            return (heads, False, heads)

    res = setdiscovery.findcommonheads(repo.ui, repo, remote,

                                       abortwhenunrelated=not force)

    common, anyinc, srvheads = res

    return (list(common), anyinc, heads or list(srvheads))

def findcommonoutgoing(repo, other, onlyheads=None, force=False, commoninc=None):

    '''Return a tuple (common, anyoutgoing, heads) used to identify the set

    of nodes present in repo but not in other.

    If onlyheads is given, only nodes ancestral to nodes in onlyheads (inclusive)

    are included. If you already know the local repo's heads, passing them in

    onlyheads is faster than letting them be recomputed here.

    If commoninc is given, it must the the result of a prior call to

    findcommonincoming(repo, other, force) to avoid recomputing it here.

    The returned tuple is meant to be passed to changelog.findmissing.'''

    common, _any, _hds = commoninc or findcommonincoming(repo, other, force=force)

    return (common, onlyheads or repo.heads())

def prepush(repo, remote, force, revs, newbranch):

    '''Analyze the local and remote repositories and determine which

    changesets need to be pushed to the remote. Return value depends

    on circumstances:

    If we are not going to push anything, return a tuple (None,

    outgoing) where outgoing is 0 if there are no outgoing

    changesets and 1 if there are, but we refuse to push them

    (e.g. would create new remote heads).

    Otherwise, return a tuple (changegroup, remoteheads), where

    changegroup is a readable file-like object whose read() returns

    successive changegroup chunks ready to be sent over the wire and

    remoteheads is the list of remote heads.'''

    commoninc = findcommonincoming(repo, remote, force=force)

    common, revs = findcommonoutgoing(repo, remote, onlyheads=revs,

                                      commoninc=commoninc, force=force)

    _common, inc, remoteheads = commoninc

    cl = repo.changelog

    outg = cl.findmissing(common, revs)

    if not outg:

        repo.ui.status(_("no changes found\n"))

        return None, 1

    if not force and remoteheads != [nullid]:

        if remote.capable('branchmap'):

            # Check for each named branch if we're creating new remote heads.

            # To be a remote head after push, node must be either:

            # - unknown locally

            # - a local outgoing head descended from update

            # - a remote head that's known locally and not

            #   ancestral to an outgoing head

            # 1. Create set of branches involved in the push.

            branches = set(repo[n].branch() for n in outg)

            # 2. Check for new branches on the remote.

            remotemap = remote.branchmap()

            newbranches = branches - set(remotemap)

            if newbranches and not newbranch: # new branch requires --new-branch

                branchnames = ', '.join(sorted(newbranches))

                raise util.Abort(_("push creates new remote branches: %s!")

                                   % branchnames,

                                 hint=_("use 'hg push --new-branch' to create"

                                        " new remote branches"))

            branches.difference_update(newbranches)

            # 3. Construct the initial oldmap and newmap dicts.

            # They contain information about the remote heads before and

            # after the push, respectively.

            # Heads not found locally are not included in either dict,

            # since they won't be affected by the push.

            # unsynced contains all branches with incoming changesets.

            oldmap = {}

            newmap = {}

            unsynced = set()

            for branch in branches:

                remotebrheads = remotemap[branch]

                prunedbrheads = [h for h in remotebrheads if h in cl.nodemap]

                oldmap[branch] = prunedbrheads

                newmap[branch] = list(prunedbrheads)

                if len(remotebrheads) > len(prunedbrheads):

                    unsynced.add(branch)

            # 4. Update newmap with outgoing changes.

            # This will possibly add new heads and remove existing ones.

            ctxgen = (repo[n] for n in outg)

            repo._updatebranchcache(newmap, ctxgen)

        else:

            # 1-4b. old servers: Check for new topological heads.

            # Construct {old,new}map with branch = None (topological branch).

            # (code based on _updatebranchcache)

            oldheads = set(h for h in remoteheads if h in cl.nodemap)

            newheads = oldheads.union(outg)

            if len(newheads) > 1:

                for latest in reversed(outg):

                    if latest not in newheads:

                        continue

                    minhrev = min(cl.rev(h) for h in newheads)

                    reachable = cl.reachable(latest, cl.node(minhrev))

                    reachable.remove(latest)

                    newheads.difference_update(reachable)

            branches = set([None])

            newmap = {None: newheads}

            oldmap = {None: oldheads}

            unsynced = inc and branches or set()

        # 5. Check for new heads.

        # If there are more heads after the push than before, a suitable

        # error message, depending on unsynced status, is displayed.

        error = None

        for branch in branches:

            newhs = set(newmap[branch])

            oldhs = set(oldmap[branch])

            if len(newhs) > len(oldhs):

                dhs = list(newhs - oldhs)

                if error is None:

                    if branch != 'default':

                        error = _("push creates new remote head %s "

                                  "on branch '%s'!") % (short(dhs[0]), branch)

                    else:

                        error = _("push creates new remote head %s!"

                                  ) % short(dhs[0])

                    if branch in unsynced:

                        hint = _("you should pull and merge or "

                                 "use push -f to force")

                    else:

                        hint = _("did you forget to merge? "

                                 "use push -f to force")

                repo.ui.note("new remote heads on branch '%s'\n" % branch)

                for h in dhs:

                    repo.ui.note("new remote head %s\n" % short(h))

        if error:

            raise util.Abort(error, hint=hint)

        # 6. Check for unsynced changes on involved branches.

        if unsynced:

            repo.ui.warn(_("note: unsynced remote changes!\n"))

    if revs is None:

        # use the fast path, no race possible on push

        cg = repo._changegroup(outg, 'push')

    else:

        cg = repo.getbundle('push', heads=revs, common=common)

    return cg, remoteheads