# rebase.py - rebasing feature for mercurial

#

# Copyright 2008 Stefano Tortarolo <stefano.tortarolo at gmail dot com>

#

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

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

'''command to move sets of revisions to a different ancestor

This extension lets you rebase changesets in an existing Mercurial

repository.

For more information:

http://mercurial.selenic.com/wiki/RebaseExtension

'''

from mercurial import hg, util, repair, merge, cmdutil, commands, error

from mercurial import extensions, ancestor, copies, patch

from mercurial.commands import templateopts

from mercurial.node import nullrev

from mercurial.lock import release

from mercurial.i18n import _

import os, errno

nullmerge = -2

def rebase(ui, repo, **opts):

    """move changeset (and descendants) to a different branch

    Rebase uses repeated merging to graft changesets from one part of

    history (the source) onto another (the destination). This can be

    useful for linearizing *local* changes relative to a master

    development tree.

    You should not rebase changesets that have already been shared

    with others. Doing so will force everybody else to perform the

    same rebase or they will end up with duplicated changesets after

    pulling in your rebased changesets.

    If you don't specify a destination changeset (``-d/--dest``),

    rebase uses the tipmost head of the current named branch as the

    destination. (The destination changeset is not modified by

    rebasing, but new changesets are added as its descendants.)

    You can specify which changesets to rebase in two ways: as a

    "source" changeset or as a "base" changeset. Both are shorthand

    for a topologically related set of changesets (the "source

    branch"). If you specify source (``-s/--source``), rebase will

    rebase that changeset and all of its descendants onto dest. If you

    specify base (``-b/--base``), rebase will select ancestors of base

    back to but not including the common ancestor with dest. Thus,

    ``-b`` is less precise but more convenient than ``-s``: you can

    specify any changeset in the source branch, and rebase will select

    the whole branch. If you specify neither ``-s`` nor ``-b``, rebase

    uses the parent of the working directory as the base.

    By default, rebase recreates the changesets in the source branch

    as descendants of dest and then destroys the originals. Use

    ``--keep`` to preserve the original source changesets. Some

    changesets in the source branch (e.g. merges from the destination

    branch) may be dropped if they no longer contribute any change.

    One result of the rules for selecting the destination changeset

    and source branch is that, unlike ``merge``, rebase will do

    nothing if you are at the latest (tipmost) head of a named branch

    with two heads. You need to explicitly specify source and/or

    destination (or ``update`` to the other head, if it's the head of

    the intended source branch).

    If a rebase is interrupted to manually resolve a merge, it can be

    continued with --continue/-c or aborted with --abort/-a.

    Returns 0 on success, 1 if nothing to rebase.

    """

    originalwd = target = None

    external = nullrev

    state = {}

    skipped = set()

    targetancestors = set()

    lock = wlock = None

    try:

        lock = repo.lock()

        wlock = repo.wlock()

        # Validate input and define rebasing points

        destf = opts.get('dest', None)

        srcf = opts.get('source', None)

        basef = opts.get('base', None)

        contf = opts.get('continue')

        abortf = opts.get('abort')

        collapsef = opts.get('collapse', False)

        extrafn = opts.get('extrafn')

        keepf = opts.get('keep', False)

        keepbranchesf = opts.get('keepbranches', False)

        detachf = opts.get('detach', False)

        # keepopen is not meant for use on the command line, but by

        # other extensions

        keepopen = opts.get('keepopen', False)

        if contf or abortf:

            if contf and abortf:

                raise util.Abort(_('cannot use both abort and continue'))

            if collapsef:

                raise util.Abort(

                    _('cannot use collapse with continue or abort'))

            if detachf:

                raise util.Abort(_('cannot use detach with continue or abort'))

            if srcf or basef or destf:

                raise util.Abort(

                    _('abort and continue do not allow specifying revisions'))

            (originalwd, target, state, collapsef, keepf,

                                keepbranchesf, external) = restorestatus(repo)

            if abortf:

                return abort(repo, originalwd, target, state)

        else:

            if srcf and basef:

                raise util.Abort(_('cannot specify both a '

                                   'revision and a base'))

            if detachf:

                if not srcf:

                    raise util.Abort(

                        _('detach requires a revision to be specified'))

                if basef:

                    raise util.Abort(_('cannot specify a base with detach'))

            cmdutil.bail_if_changed(repo)

            result = buildstate(repo, destf, srcf, basef, detachf)

            if not result:

                # Empty state built, nothing to rebase

                ui.status(_('nothing to rebase\n'))

                return 1

            else:

                originalwd, target, state = result

                if collapsef:

                    targetancestors = set(repo.changelog.ancestors(target))

                    external = checkexternal(repo, state, targetancestors)

        if keepbranchesf:

            if extrafn:

                raise util.Abort(_('cannot use both keepbranches and extrafn'))

            def extrafn(ctx, extra):

                extra['branch'] = ctx.branch()

        # Rebase

        if not targetancestors:

            targetancestors = set(repo.changelog.ancestors(target))

            targetancestors.add(target)

        for rev in sorted(state):

            if state[rev] == -1:

                ui.debug("rebasing %d:%s\n" % (rev, repo[rev]))

                storestatus(repo, originalwd, target, state, collapsef, keepf,

                                                    keepbranchesf, external)

                p1, p2 = defineparents(repo, rev, target, state,

                                                        targetancestors)

                if len(repo.parents()) == 2:

                    repo.ui.debug('resuming interrupted rebase\n')

                else:

                    stats = rebasenode(repo, rev, p1, p2, state)

                    if stats and stats[3] > 0:

                        raise util.Abort(_('fix unresolved conflicts with hg '

                                    'resolve then run hg rebase --continue'))

                updatedirstate(repo, rev, target, p2)

                if not collapsef:

                    newrev = concludenode(repo, rev, p1, p2, extrafn=extrafn)

                else:

                    # Skip commit if we are collapsing

                    repo.dirstate.setparents(repo[p1].node())

                    newrev = None

                # Update the state

                if newrev is not None:

                    state[rev] = repo[newrev].rev()

                else:

                    if not collapsef:

                        ui.note(_('no changes, revision %d skipped\n') % rev)

                        ui.debug('next revision set to %s\n' % p1)

                        skipped.add(rev)

                    state[rev] = p1

        ui.note(_('rebase merging completed\n'))

        if collapsef and not keepopen:

            p1, p2 = defineparents(repo, min(state), target,

                                                        state, targetancestors)

            commitmsg = 'Collapsed revision'

            for rebased in state:

                if rebased not in skipped and state[rebased] != nullmerge:

                    commitmsg += '\n* %s' % repo[rebased].description()

            commitmsg = ui.edit(commitmsg, repo.ui.username())

            newrev = concludenode(repo, rev, p1, external, commitmsg=commitmsg,

                                  extrafn=extrafn)

        if 'qtip' in repo.tags():

            updatemq(repo, state, skipped, **opts)

        if not keepf:

            # Remove no more useful revisions

            rebased = [rev for rev in state if state[rev] != nullmerge]

            if rebased:

                if set(repo.changelog.descendants(min(rebased))) - set(state):

                    ui.warn(_("warning: new changesets detected "

                              "on source branch, not stripping\n"))

                else:

                    # backup the old csets by default

                    repair.strip(ui, repo, repo[min(rebased)].node(), "all")

        clearstatus(repo)

        ui.note(_("rebase completed\n"))

        if os.path.exists(repo.sjoin('undo')):

            util.unlink(repo.sjoin('undo'))

        if skipped:

            ui.note(_("%d revisions have been skipped\n") % len(skipped))

    finally:

        release(lock, wlock)

def rebasemerge(repo, rev, first=False):

    'return the correct ancestor'

    oldancestor = ancestor.ancestor

    def newancestor(a, b, pfunc):

        if b == rev:

            return repo[rev].parents()[0].rev()

        return oldancestor(a, b, pfunc)

    if not first:

        ancestor.ancestor = newancestor

    else:

        repo.ui.debug("first revision, do not change ancestor\n")

    try:

        stats = merge.update(repo, rev, True, True, False)

        return stats

    finally:

        ancestor.ancestor = oldancestor

def checkexternal(repo, state, targetancestors):

    """Check whether one or more external revisions need to be taken in

    consideration. In the latter case, abort.

    """

    external = nullrev

    source = min(state)

    for rev in state:

        if rev == source:

            continue

        # Check externals and fail if there are more than one

        for p in repo[rev].parents():

            if (p.rev() not in state

                        and p.rev() not in targetancestors):

                if external != nullrev:

                    raise util.Abort(_('unable to collapse, there is more '

                            'than one external parent'))

                external = p.rev()

    return external

def updatedirstate(repo, rev, p1, p2):

    """Keep track of renamed files in the revision that is going to be rebased

    """

    # Here we simulate the copies and renames in the source changeset

    cop, diver = copies.copies(repo, repo[rev], repo[p1], repo[p2], True)

    m1 = repo[rev].manifest()

    m2 = repo[p1].manifest()

    for k, v in cop.iteritems():

        if k in m1:

            if v in m1 or v in m2:

                repo.dirstate.copy(v, k)

                if v in m2 and v not in m1:

                    repo.dirstate.remove(v)

def concludenode(repo, rev, p1, p2, commitmsg=None, extrafn=None):

    'Commit the changes and store useful information in extra'

    try:

        repo.dirstate.setparents(repo[p1].node(), repo[p2].node())

        if commitmsg is None:

            commitmsg = repo[rev].description()

        ctx = repo[rev]

        extra = {'rebase_source': ctx.hex()}

        if extrafn:

            extrafn(ctx, extra)

        # Commit might fail if unresolved files exist

        newrev = repo.commit(text=commitmsg, user=ctx.user(),

                             date=ctx.date(), extra=extra)

        repo.dirstate.setbranch(repo[newrev].branch())

        return newrev

    except util.Abort:

        # Invalidate the previous setparents

        repo.dirstate.invalidate()

        raise

def rebasenode(repo, rev, p1, p2, state):

    'Rebase a single revision'

    # Merge phase

    # Update to target and merge it with local

    if repo['.'].rev() != repo[p1].rev():

        repo.ui.debug(" update to %d:%s\n" % (repo[p1].rev(), repo[p1]))

        merge.update(repo, p1, False, True, False)

    else:

        repo.ui.debug(" already in target\n")

    repo.dirstate.write()

    repo.ui.debug(" merge against %d:%s\n" % (repo[rev].rev(), repo[rev]))

    first = repo[rev].rev() == repo[min(state)].rev()

    stats = rebasemerge(repo, rev, first)

    return stats

def defineparents(repo, rev, target, state, targetancestors):

    'Return the new parent relationship of the revision that will be rebased'

    parents = repo[rev].parents()

    p1 = p2 = nullrev

    P1n = parents[0].rev()

    if P1n in targetancestors:

        p1 = target

    elif P1n in state:

        if state[P1n] == nullmerge:

            p1 = target

        else:

            p1 = state[P1n]

    else: # P1n external

        p1 = target

        p2 = P1n

    if len(parents) == 2 and parents[1].rev() not in targetancestors:

        P2n = parents[1].rev()

        # interesting second parent

        if P2n in state:

            if p1 == target: # P1n in targetancestors or external

                p1 = state[P2n]

            else:

                p2 = state[P2n]

        else: # P2n external

            if p2 != nullrev: # P1n external too => rev is a merged revision

                raise util.Abort(_('cannot use revision %d as base, result '

                        'would have 3 parents') % rev)

            p2 = P2n

    repo.ui.debug(" future parents are %d and %d\n" %

                            (repo[p1].rev(), repo[p2].rev()))

    return p1, p2

def isagitpatch(repo, patchname):

    'Return true if the given patch is in git format'

    mqpatch = os.path.join(repo.mq.path, patchname)

    for line in patch.linereader(file(mqpatch, 'rb')):

        if line.startswith('diff --git'):

            return True

    return False

def updatemq(repo, state, skipped, **opts):

    'Update rebased mq patches - finalize and then import them'

    mqrebase = {}

    for p in repo.mq.applied:

        if repo[p.node].rev() in state:

            repo.ui.debug('revision %d is an mq patch (%s), finalize it.\n' %

                                        (repo[p.node].rev(), p.name))

            mqrebase[repo[p.node].rev()] = (p.name, isagitpatch(repo, p.name))

    if mqrebase:

        repo.mq.finish(repo, mqrebase.keys())

        # We must start import from the newest revision

        for rev in sorted(mqrebase, reverse=True):

            if rev not in skipped:

                repo.ui.debug('import mq patch %d (%s)\n'

                              % (state[rev], mqrebase[rev][0]))

                repo.mq.qimport(repo, (), patchname=mqrebase[rev][0],

                            git=mqrebase[rev][1],rev=[str(state[rev])])

        repo.mq.save_dirty()