# 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 _nonoverlap(d1, d2, d3):

    "Return list of elements in d1 not in d2 or d3"

    return sorted([d for d in d1 if d not in d3 and d not in d2])

def _dirname(f):

    s = f.rfind("/")

    if s == -1:

        return ""

    return f[:s]

def _dirs(files):

    d = set()

    for f in files:

        f = _dirname(f)

        while f not in d:

            d.add(f)

            f = _dirname(f)

    return d

def _findlimit(repo, a, b):

    """Find the earliest revision that's an ancestor of a or b but not both,

    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

    return limit

def copies(repo, c1, c2, ca, checkdirs=False):

    """

    Find moves and copies between context c1 and c2

    """

    # 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.parents()[0]:

        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 = {}

    fullcopy = {}

    diverge = {}

    def related(f1, f2, limit):

        # Walk back to common ancestor to see if the two files originate

        # from the same file. Since workingfilectx's rev() is None it messes

        # up the integer comparison logic, hence the pre-step check for

        # None (f1 and f2 can only be workingfilectx's initially).

        if f1 == f2:

            return f1 # a match

        g1, g2 = f1.ancestors(), f2.ancestors()

        try:

            f1r, f2r = f1.rev(), f2.rev()

            if f1r is None:

                f1 = g1.next()

            if f2r is None:

                f2 = g2.next()

            while 1:

                f1r, f2r = f1.rev(), f2.rev()

                if f1r > f2r:

                    f1 = g1.next()

                elif f2r > f1r:

                    f2 = g2.next()

                elif f1 == f2:

                    return f1 # a match

                elif f1r == f2r or f1r < limit or f2r < limit:

                    return False # copy no longer relevant

        except StopIteration:

            return False

    def checkcopies(f, m1, m2):

        '''check possible copies of f from m1 to m2'''

        of = None

        seen = set([f])

        for oc in ctx(f, m1[f]).ancestors():

            ocr = oc.rev()

            of = oc.path()

            if of in seen:

                # check limit late - grab last rename before

                if ocr < limit:

                    break

                continue

            seen.add(of)

            fullcopy[f] = of # remember for dir rename detection

            if of not in m2:

                continue # no match, keep looking

            if m2[of] == ma.get(of):

                break # no merge needed, quit early

            c2 = ctx(of, m2[of])

            cr = related(oc, c2, ca.rev())

            if cr and (of == f or of == c2.path()): # non-divergent

                copy[f] = of

                of = None

                break

        if of in ma:

            diverge.setdefault(of, []).append(f)

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

    u1 = _nonoverlap(m1, m2, ma)

    u2 = _nonoverlap(m2, m1, ma)

    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))

    for f in u1:

        checkcopies(f, m1, m2)

    for f in u2:

        checkcopies(f, m2, m1)

    diverge2 = set()

    for of, fl in diverge.items():

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

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

        else:

            diverge2.update(fl) # reverse map for below

    if fullcopy:

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

        for f in fullcopy:

            note = ""

            if f in copy:

                note += "*"

            if f in diverge2:

                note += "!"

            repo.ui.debug("   %s -> %s %s\n" % (f, fullcopy[f], note))

    del diverge2

    if not fullcopy or not checkdirs:

        return copy, diverge

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

    # generate a directory move map

    d1, d2 = _dirs(m1), _dirs(m2)

    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, diverge

    for d in dirmove:

        repo.ui.debug("  dir %s -> %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):]

                    if df not in copy:

                        copy[f] = df

                        repo.ui.debug("  file %s -> %s\n" % (f, copy[f]))

                    break

    return copy, diverge