"""

bundlerepo.py - repository class for viewing uncompressed bundles

This provides a read-only repository interface to bundles as if

they were part of the actual repository.

Copyright 2006 Benoit Boissinot <benoit.boissinot@ens-lyon.org>

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

demandload(globals(), "util os struct")

import localrepo, changelog, manifest, filelog, revlog

def getchunk(source):

    """get a chunk from a group"""

    d = source.read(4)

    if not d:

        return ""

    l = struct.unpack(">l", d)[0]

    if l <= 4:

        return ""

    d = source.read(l - 4)

    if len(d) < l - 4:

        raise util.Abort(_("premature EOF reading chunk"

                           " (got %d bytes, expected %d)")

                          % (len(d), l - 4))

    return d

class bundlerevlog(revlog.revlog):

    def __init__(self, opener, indexfile, datafile, bundlefile,

                 linkmapper=None):

        # How it works:

        # to retrieve a revision, we need to know the offset of

        # the revision in the bundlefile (an opened file).

        #

        # We store this offset in the index (start), to differentiate a

        # rev in the bundle and from a rev in the revlog, we check

        # len(index[r]). If the tuple is bigger than 7, it is a bundle

        # (it is bigger since we store the node to which the delta is)

        #

        revlog.revlog.__init__(self, opener, indexfile, datafile)

        self.bundlefile = bundlefile

        def genchunk():

            while 1:

                pos = bundlefile.tell()

                chunk = getchunk(bundlefile)

                if not chunk:

                    break

                yield chunk, pos + 4 # XXX struct.calcsize(">l") == 4

        n = self.count()

        prev = None

        for chunk, start in genchunk():

            size = len(chunk)

            if size < 80:

                raise util.Abort("invalid changegroup")

            start += 80

            size -= 80

            node, p1, p2, cs = struct.unpack("20s20s20s20s", chunk[:80])

            if node in self.nodemap:

                prev = node

                continue

            for p in (p1, p2):

                if not p in self.nodemap:

                    raise RevlogError(_("unknown parent %s") % short(p1))

            if linkmapper is None:

                link = n

            else:

                link = linkmapper(cs)

            if not prev:

                prev = p1

            # start, size, base is not used, link, p1, p2, delta ref

            e = (start, size, None, link, p1, p2, node, prev)

            self.index.append(e)

            self.nodemap[node] = n

            prev = node

            n += 1

    def bundle(self, rev):

        """is rev from the bundle"""

        if rev < 0:

            return False

        return len(self.index[rev]) > 7

    def bundlebase(self, rev): return self.index[rev][7]

    def chunk(self, rev):

        # Warning: in case of bundle, the diff is against bundlebase,

        # not against rev - 1

        # XXX: could use some caching

        if not self.bundle(rev):

            return revlog.revlog.chunk(self, rev)

        self.bundlefile.seek(self.start(rev))

        return self.bundlefile.read(self.length(rev))

    def revdiff(self, rev1, rev2):

        """return or calculate a delta between two revisions"""

        if self.bundle(rev1) and self.bundle(rev2):

            # hot path for bundle

            revb = self.rev(self.bundlebase(rev2))

            if revb == rev1:

                return self.chunk(rev2)

        elif not self.bundle(rev1) and not self.bundle(rev2):

            return revlog.revlog.chunk(self, rev1, rev2)

        return self.diff(self.revision(self.node(rev1)),

                         self.revision(self.node(rev2)))

    def revision(self, node):

        """return an uncompressed revision of a given"""

        if node == nullid: return ""

        text = None

        chain = []

        iter_node = node

        rev = self.rev(iter_node)

        # reconstruct the revision if it is from a changegroup

        while self.bundle(rev):

            if self.cache and self.cache[0] == iter_node:

                text = self.cache[2]

                break

            chain.append(rev)

            iter_node = self.bundlebase(rev)

            rev = self.rev(iter_node)

        if text is None:

            text = revlog.revlog.revision(self, iter_node)

        while chain:

            delta = self.chunk(chain.pop())

            text = self.patches(text, [delta])

        p1, p2 = self.parents(node)

        if node != revlog.hash(text, p1, p2):

            raise RevlogError(_("integrity check failed on %s:%d")

                          % (self.datafile, self.rev(node)))

        self.cache = (node, rev, text)

        return text

    def addrevision(self, text, transaction, link, p1=None, p2=None, d=None):

        raise NotImplementedError

    def addgroup(self, revs, linkmapper, transaction, unique=0):

        raise NotImplementedError

    def strip(self, rev, minlink):

        raise NotImplementedError

    def checksize(self):

        raise NotImplementedError

class bundlechangelog(bundlerevlog, changelog.changelog):

    def __init__(self, opener, bundlefile):

        changelog.changelog.__init__(self, opener)

        bundlerevlog.__init__(self, opener, "00changelog.i", "00changelog.d",

                              bundlefile)

class bundlemanifest(bundlerevlog, manifest.manifest):

    def __init__(self, opener, bundlefile, linkmapper):

        manifest.manifest.__init__(self, opener)

        bundlerevlog.__init__(self, opener, self.indexfile, self.datafile,

                              bundlefile, linkmapper)

class bundlefilelog(bundlerevlog, filelog.filelog):

    def __init__(self, opener, path, bundlefile, linkmapper):

        filelog.filelog.__init__(self, opener, path)

        bundlerevlog.__init__(self, opener, self.indexfile, self.datafile,

                              bundlefile, linkmapper)

class bundlerepository(localrepo.localrepository):

    def __init__(self, ui, path, bundlename):

        localrepo.localrepository.__init__(self, ui, path)

        f = open(bundlename, "rb")

        s = os.fstat(f.fileno())

        self.bundlefile = f

        header = self.bundlefile.read(4)

        if header == "HG10":

            raise util.Abort(_("%s: compressed bundle not supported")

                             % bundlename)

        elif header != "HG11":

            raise util.Abort(_("%s: not a Mercurial bundle file") % bundlename)

        self.changelog = bundlechangelog(self.opener, self.bundlefile)

        self.manifest = bundlemanifest(self.opener, self.bundlefile,

                                       self.changelog.rev)

        # dict with the mapping 'filename' -> position in the bundle

        self.bundlefilespos = {}

        while 1:

                f = getchunk(self.bundlefile)

                if not f:

                    break

                self.bundlefilespos[f] = self.bundlefile.tell()

                while getchunk(self.bundlefile):

                    pass

    def dev(self):

        return -1

    def file(self, f):

        if f[0] == '/':

            f = f[1:]

        if f in self.bundlefilespos:

            self.bundlefile.seek(self.bundlefilespos[f])

            return bundlefilelog(self.opener, f, self.bundlefile,

                                 self.changelog.rev)

        else:

            return filelog.filelog(self.opener, f)