# merge.py - directory-level update/merge handling for Mercurial
#
# Copyright 2006 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

from node import *
from i18n import gettext as _
from demandload import *
demandload(globals(), "errno util os tempfile")

def fmerge(f, local, other, ancestor):
    """merge executable flags"""
    a, b, c = ancestor.execf(f), local.execf(f), other.execf(f)
    return ((a^b) | (a^c)) ^ a

def merge3(repo, fn, my, other, p1, p2):
    """perform a 3-way merge in the working directory"""

    def temp(prefix, node):
        pre = "%s~%s." % (os.path.basename(fn), prefix)
        (fd, name) = tempfile.mkstemp(prefix=pre)
        f = os.fdopen(fd, "wb")
        repo.wwrite(fn, fl.read(node), f)
        f.close()
        return name

    fl = repo.file(fn)
    base = fl.ancestor(my, other)
    a = repo.wjoin(fn)
    b = temp("base", base)
    c = temp("other", other)

    repo.ui.note(_("resolving %s\n") % fn)
    repo.ui.debug(_("file %s: my %s other %s ancestor %s\n") %
                          (fn, short(my), short(other), short(base)))

    cmd = (os.environ.get("HGMERGE") or repo.ui.config("ui", "merge")
           or "hgmerge")
    r = util.system('%s "%s" "%s" "%s"' % (cmd, a, b, c), cwd=repo.root,
                    environ={'HG_FILE': fn,
                             'HG_MY_NODE': p1,
                             'HG_OTHER_NODE': p2,
                             'HG_FILE_MY_NODE': hex(my),
                             'HG_FILE_OTHER_NODE': hex(other),
                             'HG_FILE_BASE_NODE': hex(base)})
    if r:
        repo.ui.warn(_("merging %s failed!\n") % fn)

    os.unlink(b)
    os.unlink(c)
    return r

def checkunknown(repo, m2, status):
    """
    check for collisions between unknown files and files in m2
    """
    modified, added, removed, deleted, unknown = status[:5]
    for f in unknown:
        if f in m2:
            if repo.file(f).cmp(m2[f], repo.wread(f)):
                raise util.Abort(_("'%s' already exists in the working"
                                   " dir and differs from remote") % f)

def workingmanifest(repo, man, status):
    """
    Update manifest to correspond to the working directory
    """

    modified, added, removed, deleted, unknown = status[:5]
    for i,l in (("a", added), ("m", modified), ("u", unknown)):
        for f in l:
            man[f] = man.get(f, nullid) + i
            man.set(f, util.is_exec(repo.wjoin(f), man.execf(f)))

    for f in deleted + removed:
        del man[f]

    return man

def forgetremoved(m2, status):
    """
    Forget removed files

    If we're jumping between revisions (as opposed to merging), and if
    neither the working directory nor the target rev has the file,
    then we need to remove it from the dirstate, to prevent the
    dirstate from listing the file when it is no longer in the
    manifest.
    """

    modified, added, removed, deleted, unknown = status[:5]
    action = []

    for f in deleted + removed:
        if f not in m2:
            action.append((f, "f"))

    return action

def manifestmerge(ui, m1, m2, ma, overwrite, backwards, partial):
    """
    Merge manifest m1 with m2 using ancestor ma and generate merge action list
    """

    action = []

    # Filter manifests
    if partial:
        for f in m1.keys():
            if not partial(f): del m1[f]
        for f in m2.keys():
            if not partial(f): del m2[f]

    # Compare manifests
    for f, n in m1.iteritems():
        if f in m2:
            queued = 0

            # are files different?
            if n != m2[f]:
                a = ma.get(f, nullid)
                # are both different from the ancestor?
                if not overwrite and n != a and m2[f] != a:
                    ui.debug(_(" %s versions differ, resolve\n") % f)
                    action.append((f, "m", fmerge(f, m1, m2, ma), n[:20], m2[f]))
                    queued = 1
                # are we clobbering?
                # is remote's version newer?
                # or are we going back in time and clean?
                elif overwrite or m2[f] != a or (backwards and not n[20:]):
                    ui.debug(_(" remote %s is newer, get\n") % f)
                    action.append((f, "g", m2.execf(f), m2[f]))
                    queued = 1
            elif n[20:] in ("u","a"):
                # this unknown file is the same as the checkout
                # we need to reset the dirstate if the file was added
                action.append((f, "g", m2.execf(f), m2[f]))

            # do we still need to look at mode bits?
            if not queued and m1.execf(f) != m2.execf(f):
                if overwrite:
                    ui.debug(_(" updating permissions for %s\n") % f)
                    action.append((f, "e", m2.execf(f)))
                else:
                    mode = fmerge(f, m1, m2, ma)
                    if mode != m1.execf(f):
                        ui.debug(_(" updating permissions for %s\n")
                                      % f)
                        action.append((f, "e", m2.execf(f)))
            del m2[f]
        elif f in ma:
            if n != ma[f]:
                r = _("d")
                if not overwrite:
                    r = ui.prompt(
                        (_(" local changed %s which remote deleted\n") % f) +
                         _("(k)eep or (d)elete?"), _("[kd]"), _("k"))
                if r == _("d"):
                    action.append((f, "r"))
            else:
                ui.debug(_("other deleted %s\n") % f)
                action.append((f, "r"))
        else:
            # file is created on branch or in working directory
            if overwrite and n[20:] != "u":
                ui.debug(_("remote deleted %s, clobbering\n") % f)
                action.append((f, "r"))
            elif not n[20:]: # same as parent
                if backwards:
                    ui.debug(_("remote deleted %s\n") % f)
                    action.append((f, "r"))
                else:
                    ui.debug(_("local modified %s, keeping\n") % f)
            else:
                ui.debug(_("working dir created %s, keeping\n") % f)

    for f, n in m2.iteritems():
        if f[0] == "/":
            continue
        if f in ma and n != ma[f]:
            r = _("k")
            if not overwrite:
                r = ui.prompt(
                    (_("remote changed %s which local deleted\n") % f) +
                     _("(k)eep or (d)elete?"), _("[kd]"), _("k"))
            if r == _("k"):
                action.append((f, "g", m2.execf(f), n))
        elif f not in ma:
            ui.debug(_("remote created %s\n") % f)
            action.append((f, "g", m2.execf(f), n))
        else:
            if overwrite or backwards:
                ui.debug(_("local deleted %s, recreating\n") % f)
                action.append((f, "g", m2.execf(f), n))
            else:
                ui.debug(_("local deleted %s\n") % f)

    return action

def update(repo, node, branchmerge=False, force=False, partial=None,
           wlock=None, show_stats=True, remind=True):

    overwrite = force and not branchmerge
    forcemerge = force and branchmerge

    if not wlock:
        wlock = repo.wlock()

    ### check phase

    pl = repo.dirstate.parents()
    if not overwrite and pl[1] != nullid:
        raise util.Abort(_("outstanding uncommitted merges"))

    p1, p2 = pl[0], node
    pa = repo.changelog.ancestor(p1, p2)

    # are we going backwards?
    backwards = (pa == p2)

    # is there a linear path from p1 to p2?
    linear = (pa == p1 or pa == p2)
    if branchmerge and linear:
        raise util.Abort(_("there is nothing to merge, just use "
                           "'hg update' or look at 'hg heads'"))

    if not linear and not (overwrite or branchmerge):
        raise util.Abort(_("update spans branches, use 'hg merge' "
                           "or 'hg update -C' to lose changes"))

    status = repo.status()
    modified, added, removed, deleted, unknown = status[:5]
    if branchmerge and not forcemerge:
        if modified or added or removed:
            raise util.Abort(_("outstanding uncommitted changes"))

    m1 = repo.changectx(p1).manifest().copy()
    m2 = repo.changectx(p2).manifest().copy()
    ma = repo.changectx(pa).manifest()

    # resolve the manifest to determine which files
    # we care about merging
    repo.ui.note(_("resolving manifests\n"))
    repo.ui.debug(_(" overwrite %s branchmerge %s partial %s linear %s\n") %
                  (overwrite, branchmerge, bool(partial), linear))
    repo.ui.debug(_(" ancestor %s local %s remote %s\n") %
                  (short(p1), short(p2), short(pa)))

    action = []
    m1 = workingmanifest(repo, m1, status)

    if not force:
        checkunknown(repo, m2, status)
    if linear:
        action += forgetremoved(m2, status)
    action += manifestmerge(repo.ui, m1, m2, ma, overwrite, backwards, partial)
    del m1, m2, ma

    ### apply phase

    if linear or overwrite:
        # we don't need to do any magic, just jump to the new rev
        p1, p2 = p2, nullid

    xp1 = hex(p1)
    xp2 = hex(p2)
    if p2 == nullid: xxp2 = ''
    else: xxp2 = xp2

    repo.hook('preupdate', throw=True, parent1=xp1, parent2=xxp2)

    # update files
    updated, merged, removed, unresolved = 0, 0, 0, 0
    action.sort()
    for a in action:
        f, m = a[:2]
        if f[0] == "/":
            continue
        if m == "r": # remove
            repo.ui.note(_("removing %s\n") % f)
            util.audit_path(f)
            try:
                util.unlink(repo.wjoin(f))
            except OSError, inst:
                if inst.errno != errno.ENOENT:
                    repo.ui.warn(_("update failed to remove %s: %s!\n") %
                                 (f, inst.strerror))
            removed +=1
        elif m == "m": # merge
            flag, my, other = a[2:]
            repo.ui.status(_("merging %s\n") % f)
            if merge3(repo, f, my, other, xp1, xp2):
                unresolved += 1
            util.set_exec(repo.wjoin(f), flag)
            merged += 1
        elif m == "g": # get
            flag, node = a[2:]
            repo.ui.note(_("getting %s\n") % f)
            t = repo.file(f).read(node)
            repo.wwrite(f, t)
            util.set_exec(repo.wjoin(f), flag)
            updated += 1
        elif m == "e": # exec
            flag = a[2:]
            util.set_exec(repo.wjoin(f), flag)

    # update dirstate
    if not partial:
        repo.dirstate.setparents(p1, p2)
        for a in action:
            f, m = a[:2]
            if m == "r": # remove
                if branchmerge:
                    repo.dirstate.update([f], 'r')
                else:
                    repo.dirstate.forget([f])
            elif m == "f": # forget
                repo.dirstate.forget([f])
            elif m == "g": # get
                if branchmerge:
                    repo.dirstate.update([f], 'n', st_mtime=-1)
                else:
                    repo.dirstate.update([f], 'n')
            elif m == "m": # merge
                flag, my, other = a[2:]
                if branchmerge:
                    # We've done a branch merge, mark this file as merged
                    # so that we properly record the merger later
                    repo.dirstate.update([f], 'm')
                else:
                    # We've update-merged a locally modified file, so
                    # we set the dirstate to emulate a normal checkout
                    # of that file some time in the past. Thus our
                    # merge will appear as a normal local file
                    # modification.
                    fl = repo.file(f)
                    f_len = fl.size(fl.rev(other))
                    repo.dirstate.update([f], 'n', st_size=f_len, st_mtime=-1)

    if show_stats:
        stats = ((updated, _("updated")),
                 (merged - unresolved, _("merged")),
                 (removed, _("removed")),
                 (unresolved, _("unresolved")))
        note = ", ".join([_("%d files %s") % s for s in stats])
        repo.ui.status("%s\n" % note)
    if not partial:
        if branchmerge:
            if unresolved:
                repo.ui.status(_("There are unresolved merges,"
                                " you can redo the full merge using:\n"
                                "  hg update -C %s\n"
                                "  hg merge %s\n"
                                % (repo.changelog.rev(p1),
                                    repo.changelog.rev(p2))))
            elif remind:
                repo.ui.status(_("(branch merge, don't forget to commit)\n"))
        elif unresolved:
            repo.ui.status(_("There are unresolved merges with"
                             " locally modified files.\n"))

    repo.hook('update', parent1=xp1, parent2=xxp2, error=unresolved)
    return unresolved