# copies.py - copy detection for Mercurial
#
# Copyright 2008 Matt Mackall <[email protected]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2, incorporated herein by reference.

from i18n import _
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 _findoldnames(fctx, limit):
   "find files that path was copied from, back to linkrev limit"
   old = {}
   seen = set()
   orig = fctx.path()
   visit = [(fctx, 0)]
   while visit:
       fc, depth = visit.pop()
       s = str(fc)
       if s in seen:
           continue
       seen.add(s)
       if fc.path() != orig and fc.path() not in old:
           old[fc.path()] = (depth, fc.path()) # remember depth
       if fc.rev() is not None and fc.rev() < limit:
           continue
       visit += [(p, depth - 1) for p in fc.parents()]

   # return old names sorted by depth
   return [o[1] for o in sorted(old.values())]

def _findlimit(repo, a, b):
   "find the earliest revision that's an ancestor of a or b but not both"
   # 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)
   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 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
       if side[r]:
           limit = r # lowest rev visited
           interesting -= 1
   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())
   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 checkcopies(f, m1, m2):
       '''check possible copies of f from m1 to m2'''
       c1 = ctx(f, m1[f])
       for of in _findoldnames(c1, limit):
           fullcopy[f] = of # remember for dir rename detection
           if of in m2: # original file not in other manifest?
               # if the original file is unchanged on the other branch,
               # no merge needed
               if m2[of] != ma.get(of):
                   c2 = ctx(of, m2[of])
                   ca = c1.ancestor(c2)
                   # related and named changed on only one side?
                   if ca and (ca.path() == f or ca.path() == c2.path()):
                       if c1 != ca or c2 != ca: # merge needed?
                           copy[f] = of
           elif 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:
           del diverge[of] # not actually divergent
       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

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