# manifest.py - manifest revision class for mercurial

#

# Copyright 2005-2007 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.

from i18n import _

import mdiff, parsers, error, revlog, util, dicthelpers

import array, struct

class manifestdict(dict):

    def __init__(self, mapping=None, flags=None):

        if mapping is None:

            mapping = {}

        if flags is None:

            flags = {}

        dict.__init__(self, mapping)

        self._flags = flags

    def flags(self, f):

        return self._flags.get(f, "")

    def withflags(self):

        return set(self._flags.keys())

    def setflag(self, f, flags):

        """Set the flags (symlink, executable) for path f."""

        self._flags[f] = flags

    def copy(self):

        return manifestdict(self, dict.copy(self._flags))

    def intersectfiles(self, files):

        '''make a new manifestdict with the intersection of self with files

        The algorithm assumes that files is much smaller than self.'''

        ret = manifestdict()

        for fn in files:

            if fn in self:

                ret[fn] = self[fn]

                flags = self._flags.get(fn, None)

                if flags:

                    ret._flags[fn] = flags

        return ret

    def text(self):

        """Get the full data of this manifest as a bytestring."""

        fl = sorted(self)

        _checkforbidden(fl)

        hex, flags = revlog.hex, self.flags

        # if this is changed to support newlines in filenames,

        # be sure to check the templates/ dir again (especially *-raw.tmpl)

        return ''.join("%s\0%s%s\n" % (f, hex(self[f]), flags(f)) for f in fl)

    def fastdelta(self, base, changes):

        """Given a base manifest text as an array.array and a list of changes

        relative to that text, compute a delta that can be used by revlog.

        """

        delta = []

        dstart = None

        dend = None

        dline = [""]

        start = 0

        # zero copy representation of base as a buffer

        addbuf = util.buffer(base)

        # start with a readonly loop that finds the offset of

        # each line and creates the deltas

        for f, todelete in changes:

            # bs will either be the index of the item or the insert point

            start, end = _msearch(addbuf, f, start)

            if not todelete:

                l = "%s\0%s%s\n" % (f, revlog.hex(self[f]), self.flags(f))

            else:

                if start == end:

                    # item we want to delete was not found, error out

                    raise AssertionError(

                            _("failed to remove %s from manifest") % f)

                l = ""

            if dstart is not None and dstart <= start and dend >= start:

                if dend < end:

                    dend = end

                if l:

                    dline.append(l)

            else:

                if dstart is not None:

                    delta.append([dstart, dend, "".join(dline)])

                dstart = start

                dend = end

                dline = [l]

        if dstart is not None:

            delta.append([dstart, dend, "".join(dline)])

        # apply the delta to the base, and get a delta for addrevision

        deltatext, arraytext = _addlistdelta(base, delta)

        return arraytext, deltatext

def _msearch(m, s, lo=0, hi=None):

    '''return a tuple (start, end) that says where to find s within m.

    If the string is found m[start:end] are the line containing

    that string.  If start == end the string was not found and

    they indicate the proper sorted insertion point.

    m should be a buffer or a string

    s is a string'''

    def advance(i, c):

        while i < lenm and m[i] != c:

            i += 1

        return i

    if not s:

        return (lo, lo)

    lenm = len(m)

    if not hi:

        hi = lenm

    while lo < hi:

        mid = (lo + hi) // 2

        start = mid

        while start > 0 and m[start - 1] != '\n':

            start -= 1

        end = advance(start, '\0')

        if m[start:end] < s:

            # we know that after the null there are 40 bytes of sha1

            # this translates to the bisect lo = mid + 1

            lo = advance(end + 40, '\n') + 1

        else:

            # this translates to the bisect hi = mid

            hi = start

    end = advance(lo, '\0')

    found = m[lo:end]

    if s == found:

        # we know that after the null there are 40 bytes of sha1

        end = advance(end + 40, '\n')

        return (lo, end + 1)

    else:

        return (lo, lo)

def _checkforbidden(l):

    """Check filenames for illegal characters."""

    for f in l:

        if '\n' in f or '\r' in f:

            raise error.RevlogError(

                _("'\\n' and '\\r' disallowed in filenames: %r") % f)

# apply the changes collected during the bisect loop to our addlist

# return a delta suitable for addrevision

def _addlistdelta(addlist, x):

    # for large addlist arrays, building a new array is cheaper

    # than repeatedly modifying the existing one

    currentposition = 0

    newaddlist = array.array('c')

    for start, end, content in x:

        newaddlist += addlist[currentposition:start]

        if content:

            newaddlist += array.array('c', content)

        currentposition = end

    newaddlist += addlist[currentposition:]

    deltatext = "".join(struct.pack(">lll", start, end, len(content))

                   + content for start, end, content in x)

    return deltatext, newaddlist

def _parse(lines):

    mfdict = manifestdict()

    parsers.parse_manifest(mfdict, mfdict._flags, lines)

    return mfdict

class manifest(revlog.revlog):

    def __init__(self, opener):

        # we expect to deal with not more than four revs at a time,

        # during a commit --amend

        self._mancache = util.lrucachedict(4)

        revlog.revlog.__init__(self, opener, "00manifest.i")

    def readdelta(self, node):

        r = self.rev(node)

        return _parse(mdiff.patchtext(self.revdiff(self.deltaparent(r), r)))

    def readfast(self, node):

        '''use the faster of readdelta or read'''

        r = self.rev(node)

        deltaparent = self.deltaparent(r)

        if deltaparent != revlog.nullrev and deltaparent in self.parentrevs(r):

            return self.readdelta(node)

        return self.read(node)

    def read(self, node):

        if node == revlog.nullid:

            return manifestdict() # don't upset local cache

        if node in self._mancache:

            return self._mancache[node][0]

        text = self.revision(node)

        arraytext = array.array('c', text)

        mapping = _parse(text)

        self._mancache[node] = (mapping, arraytext)

        return mapping

    def find(self, node, f):

        '''look up entry for a single file efficiently.

        return (node, flags) pair if found, (None, None) if not.'''

        if node in self._mancache:

            mapping = self._mancache[node][0]

            return mapping.get(f), mapping.flags(f)

        text = self.revision(node)

        start, end = _msearch(text, f)

        if start == end:

            return None, None

        l = text[start:end]

        f, n = l.split('\0')

        return revlog.bin(n[:40]), n[40:-1]

    def add(self, map, transaction, link, p1, p2, added, removed):

        if p1 in self._mancache:

            # If our first parent is in the manifest cache, we can

            # compute a delta here using properties we know about the

            # manifest up-front, which may save time later for the

            # revlog layer.

            _checkforbidden(added)

            # combine the changed lists into one list for sorting

            work = [(x, False) for x in added]

            work.extend((x, True) for x in removed)

            # this could use heapq.merge() (from Python 2.6+) or equivalent

            # since the lists are already sorted

            work.sort()

            arraytext, deltatext = map.fastdelta(self._mancache[p1][1], work)

            cachedelta = self.rev(p1), deltatext

            text = util.buffer(arraytext)

        else:

            # The first parent manifest isn't already loaded, so we'll

            # just encode a fulltext of the manifest and pass that

            # through to the revlog layer, and let it handle the delta

            # process.

            text = map.text()

            arraytext = array.array('c', text)

            cachedelta = None

        n = self.addrevision(text, transaction, link, p1, p2, cachedelta)

        self._mancache[n] = (map, arraytext)

        return n