# copies.py - copy detection for Mercurial

#

# Copyright 2008 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.

import util

import heapq

def _dirname(f):

    s = f.rfind("/")

    if s == -1:

        return ""

    return f[:s]

def _findlimit(repo, a, b):

    """

    Find the last revision that needs to be checked to ensure that a full

    transitive closure for file copies can be properly calculated.

    Generally, this means finding the earliest revision number that's an

    ancestor of a or b but not both, except when a or b is a direct descendent

    of the other, in which case we can return the minimum revnum of a and b.

    None if no such revision exists.

    """

    # basic idea:

    # - mark a and b with different sides

    # - if a parent's children are all on the same side, the parent is

    #   on that side, otherwise it is on no side

    # - walk the graph in topological order with the help of a heap;

    #   - add unseen parents to side map

    #   - clear side of any parent that has children on different sides

    #   - track number of interesting revs that might still be on a side

    #   - track the lowest interesting rev seen

    #   - quit when interesting revs is zero

    cl = repo.changelog

    working = len(cl) # pseudo rev for the working directory

    if a is None:

        a = working

    if b is None:

        b = working

    side = {a: -1, b: 1}

    visit = [-a, -b]

    heapq.heapify(visit)

    interesting = len(visit)

    hascommonancestor = False

    limit = working

    while interesting:

        r = -heapq.heappop(visit)

        if r == working:

            parents = [cl.rev(p) for p in repo.dirstate.parents()]

        else:

            parents = cl.parentrevs(r)

        for p in parents:

            if p < 0:

                continue

            if p not in side:

                # first time we see p; add it to visit

                side[p] = side[r]

                if side[p]:

                    interesting += 1

                heapq.heappush(visit, -p)

            elif side[p] and side[p] != side[r]:

                # p was interesting but now we know better

                side[p] = 0

                interesting -= 1

                hascommonancestor = True

        if side[r]:

            limit = r # lowest rev visited

            interesting -= 1

    if not hascommonancestor:

        return None

    # Consider the following flow (see test-commit-amend.t under issue4405):

    # 1/ File 'a0' committed

    # 2/ File renamed from 'a0' to 'a1' in a new commit (call it 'a1')

    # 3/ Move back to first commit

    # 4/ Create a new commit via revert to contents of 'a1' (call it 'a1-amend')

    # 5/ Rename file from 'a1' to 'a2' and commit --amend 'a1-msg'

    #

    # During the amend in step five, we will be in this state:

    #

    # @  3 temporary amend commit for a1-amend

    # |

    # o  2 a1-amend

    # |

    # | o  1 a1

    # |/

    # o  0 a0

    #

    # When _findlimit is called, a and b are revs 3 and 0, so limit will be 2,

    # yet the filelog has the copy information in rev 1 and we will not look

    # back far enough unless we also look at the a and b as candidates.

    # This only occurs when a is a descendent of b or visa-versa.

    return min(limit, a, b)

def _chain(src, dst, a, b):

    '''chain two sets of copies a->b'''

    t = a.copy()

    for k, v in b.iteritems():

        if v in t:

            # found a chain

            if t[v] != k:

                # file wasn't renamed back to itself

                t[k] = t[v]

            if v not in dst:

                # chain was a rename, not a copy

                del t[v]

        if v in src:

            # file is a copy of an existing file

            t[k] = v

    # remove criss-crossed copies

    for k, v in t.items():

        if k in src and v in dst:

            del t[k]

    return t

def _tracefile(fctx, am, limit=-1):

    '''return file context that is the ancestor of fctx present in ancestor

    manifest am, stopping after the first ancestor lower than limit'''

    for f in fctx.ancestors():

        if am.get(f.path(), None) == f.filenode():

            return f

        if limit >= 0 and f.linkrev() < limit and f.rev() < limit:

            return None

def _dirstatecopies(d):

    ds = d._repo.dirstate

    c = ds.copies().copy()

    for k in c.keys():

        if ds[k] not in 'anm':

            del c[k]

    return c

def _computeforwardmissing(a, b):

    """Computes which files are in b but not a.

    This is its own function so extensions can easily wrap this call to see what

    files _forwardcopies is about to process.

    """

    return b.manifest().filesnotin(a.manifest())

def _forwardcopies(a, b):

    '''find {dst@b: src@a} copy mapping where a is an ancestor of b'''

    # check for working copy

    w = None

    if b.rev() is None:

        w = b

        b = w.p1()

        if a == b:

            # short-circuit to avoid issues with merge states

            return _dirstatecopies(w)

    # files might have to be traced back to the fctx parent of the last

    # one-side-only changeset, but not further back than that

    limit = _findlimit(a._repo, a.rev(), b.rev())

    if limit is None:

        limit = -1

    am = a.manifest()

    # find where new files came from

    # we currently don't try to find where old files went, too expensive

    # this means we can miss a case like 'hg rm b; hg cp a b'

    cm = {}

    missing = _computeforwardmissing(a, b)

    ancestrycontext = a._repo.changelog.ancestors([b.rev()], inclusive=True)

    for f in missing:

        fctx = b[f]

        fctx._ancestrycontext = ancestrycontext

        ofctx = _tracefile(fctx, am, limit)

        if ofctx:

            cm[f] = ofctx.path()

    # combine copies from dirstate if necessary

    if w is not None:

        cm = _chain(a, w, cm, _dirstatecopies(w))

    return cm

def _backwardrenames(a, b):

    # Even though we're not taking copies into account, 1:n rename situations

    # can still exist (e.g. hg cp a b; hg mv a c). In those cases we

    # arbitrarily pick one of the renames.

    f = _forwardcopies(b, a)

    r = {}

    for k, v in sorted(f.iteritems()):

        # remove copies

        if v in a:

            continue

        r[v] = k

    return r

def pathcopies(x, y):

    '''find {dst@y: src@x} copy mapping for directed compare'''

    if x == y or not x or not y:

        return {}

    a = y.ancestor(x)

    if a == x:

        return _forwardcopies(x, y)

    if a == y:

        return _backwardrenames(x, y)

    return _chain(x, y, _backwardrenames(x, a), _forwardcopies(a, y))

def _computenonoverlap(repo, m1, m2, ma):

    """Computes the files exclusive to m1 and m2.

    This is its own function so extensions can easily wrap this call to see what

    files mergecopies is about to process.

    """

    addedinm1 = m1.filesnotin(ma)

    addedinm2 = m2.filesnotin(ma)

    u1 = sorted(addedinm1 - addedinm2)

    u2 = sorted(addedinm2 - addedinm1)

    if u1:

        repo.ui.debug("  unmatched files in local:\n   %s\n"

                      % "\n   ".join(u1))

    if u2:

        repo.ui.debug("  unmatched files in other:\n   %s\n"

                      % "\n   ".join(u2))

    return u1, u2

def mergecopies(repo, c1, c2, ca):

    """

    Find moves and copies between context c1 and c2 that are relevant

    for merging.

    Returns four dicts: "copy", "movewithdir", "diverge", and

    "renamedelete".

    "copy" is a mapping from destination name -> source name,

    where source is in c1 and destination is in c2 or vice-versa.

    "movewithdir" is a mapping from source name -> destination name,

    where the file at source present in one context but not the other

    needs to be moved to destination by the merge process, because the

    other context moved the directory it is in.

    "diverge" is a mapping of source name -> list of destination names

    for divergent renames.

    "renamedelete" is a mapping of source name -> list of destination

    names for files deleted in c1 that were renamed in c2 or vice-versa.

    """

    # avoid silly behavior for update from empty dir

    if not c1 or not c2 or c1 == c2:

        return {}, {}, {}, {}

    # avoid silly behavior for parent -> working dir

    if c2.node() is None and c1.node() == repo.dirstate.p1():

        return repo.dirstate.copies(), {}, {}, {}

    limit = _findlimit(repo, c1.rev(), c2.rev())

    if limit is None:

        # no common ancestor, no copies

        return {}, {}, {}, {}

    m1 = c1.manifest()

    m2 = c2.manifest()

    ma = ca.manifest()

    def makectx(f, n):

        if len(n) != 20: # in a working context?

            if c1.rev() is None:

                return c1.filectx(f)

            return c2.filectx(f)

        return repo.filectx(f, fileid=n)

    ctx = util.lrucachefunc(makectx)

    copy = {}

    movewithdir = {}

    fullcopy = {}

    diverge = {}

    repo.ui.debug("  searching for copies back to rev %d\n" % limit)

    u1, u2 = _computenonoverlap(repo, m1, m2, ma)

    for f in u1:

        checkcopies(ctx, f, m1, m2, ca, limit, diverge, copy, fullcopy)

    for f in u2:

        checkcopies(ctx, f, m2, m1, ca, limit, diverge, copy, fullcopy)

    renamedelete = {}

    renamedelete2 = set()

    diverge2 = set()

    for of, fl in diverge.items():

        if len(fl) == 1 or of in c1 or of in c2:

            del diverge[of] # not actually divergent, or not a rename

            if of not in c1 and of not in c2:

                # renamed on one side, deleted on the other side, but filter

                # out files that have been renamed and then deleted

                renamedelete[of] = [f for f in fl if f in c1 or f in c2]

                renamedelete2.update(fl) # reverse map for below

        else:

            diverge2.update(fl) # reverse map for below

    if bothnew:

        repo.ui.debug("  unmatched files new in both:\n   %s\n"

                      % "\n   ".join(bothnew))

    bothdiverge, _copy, _fullcopy = {}, {}, {}

    for f in bothnew:

        checkcopies(ctx, f, m1, m2, ca, limit, bothdiverge, _copy, _fullcopy)

        checkcopies(ctx, f, m2, m1, ca, limit, bothdiverge, _copy, _fullcopy)

    for of, fl in bothdiverge.items():

        if len(fl) == 2 and fl[0] == fl[1]:

            copy[fl[0]] = of # not actually divergent, just matching renames

    if fullcopy and repo.ui.debugflag:

        repo.ui.debug("  all copies found (* = to merge, ! = divergent, "

                      "% = renamed and deleted):\n")

        for f in sorted(fullcopy):

            note = ""

            if f in copy:

                note += "*"

            if f in diverge2:

                note += "!"

            if f in renamedelete2:

                note += "%"

            repo.ui.debug("   src: '%s' -> dst: '%s' %s\n" % (fullcopy[f], f,

                                                              note))

    del diverge2

    if not fullcopy:

        return copy, movewithdir, diverge, renamedelete

    repo.ui.debug("  checking for directory renames\n")

    # generate a directory move map

    d1, d2 = c1.dirs(), c2.dirs()

    d1.addpath('/')

    d2.addpath('/')

    invalid = set()

    dirmove = {}

    # examine each file copy for a potential directory move, which is

    # when all the files in a directory are moved to a new directory

    for dst, src in fullcopy.iteritems():

        dsrc, ddst = _dirname(src), _dirname(dst)

        if dsrc in invalid:

            # already seen to be uninteresting

            continue

        elif dsrc in d1 and ddst in d1:

            # directory wasn't entirely moved locally

            invalid.add(dsrc)

        elif dsrc in d2 and ddst in d2:

            # directory wasn't entirely moved remotely

            invalid.add(dsrc)

        elif dsrc in dirmove and dirmove[dsrc] != ddst:

            # files from the same directory moved to two different places

            invalid.add(dsrc)

        else:

            # looks good so far

            dirmove[dsrc + "/"] = ddst + "/"

    for i in invalid:

        if i in dirmove:

            del dirmove[i]

    del d1, d2, invalid

    if not dirmove:

        return copy, movewithdir, diverge, renamedelete

    for d in dirmove:

        repo.ui.debug("   discovered dir src: '%s' -> dst: '%s'\n" %

                      (d, dirmove[d]))

    # check unaccounted nonoverlapping files against directory moves

    for f in u1 + u2:

        if f not in fullcopy:

            for d in dirmove:

                if f.startswith(d):

                    # new file added in a directory that was moved, move it

                    df = dirmove[d] + f[len(d):]