# changegroup.py - Mercurial changegroup manipulation functions
#
#  Copyright 2006 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 _
from node import nullrev, nullid, hex
import mdiff, util, dagutil
import struct, os, bz2, zlib, tempfile
import discovery

_BUNDLE10_DELTA_HEADER = "20s20s20s20s"

def readexactly(stream, n):
    '''read n bytes from stream.read and abort if less was available'''
    s = stream.read(n)
    if len(s) < n:
        raise util.Abort(_("stream ended unexpectedly"
                           " (got %d bytes, expected %d)")
                          % (len(s), n))
    return s

def getchunk(stream):
    """return the next chunk from stream as a string"""
    d = readexactly(stream, 4)
    l = struct.unpack(">l", d)[0]
    if l <= 4:
        if l:
            raise util.Abort(_("invalid chunk length %d") % l)
        return ""
    return readexactly(stream, l - 4)

def chunkheader(length):
    """return a changegroup chunk header (string)"""
    return struct.pack(">l", length + 4)

def closechunk():
    """return a changegroup chunk header (string) for a zero-length chunk"""
    return struct.pack(">l", 0)

class nocompress(object):
    def compress(self, x):
        return x
    def flush(self):
        return ""

bundletypes = {
    "": ("", nocompress), # only when using unbundle on ssh and old http servers
                          # since the unification ssh accepts a header but there
                          # is no capability signaling it.
    "HG10UN": ("HG10UN", nocompress),
    "HG10BZ": ("HG10", lambda: bz2.BZ2Compressor()),
    "HG10GZ": ("HG10GZ", lambda: zlib.compressobj()),
}

# hgweb uses this list to communicate its preferred type
bundlepriority = ['HG10GZ', 'HG10BZ', 'HG10UN']

def writebundle(cg, filename, bundletype):
    """Write a bundle file and return its filename.

    Existing files will not be overwritten.
    If no filename is specified, a temporary file is created.
    bz2 compression can be turned off.
    The bundle file will be deleted in case of errors.
    """

    fh = None
    cleanup = None
    try:
        if filename:
            fh = open(filename, "wb")
        else:
            fd, filename = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg")
            fh = os.fdopen(fd, "wb")
        cleanup = filename

        header, compressor = bundletypes[bundletype]
        fh.write(header)
        z = compressor()

        # parse the changegroup data, otherwise we will block
        # in case of sshrepo because we don't know the end of the stream

        # an empty chunkgroup is the end of the changegroup
        # a changegroup has at least 2 chunkgroups (changelog and manifest).
        # after that, an empty chunkgroup is the end of the changegroup
        empty = False
        count = 0
        while not empty or count <= 2:
            empty = True
            count += 1
            while True:
                chunk = getchunk(cg)
                if not chunk:
                    break
                empty = False
                fh.write(z.compress(chunkheader(len(chunk))))
                pos = 0
                while pos < len(chunk):
                    next = pos + 2**20
                    fh.write(z.compress(chunk[pos:next]))
                    pos = next
            fh.write(z.compress(closechunk()))
        fh.write(z.flush())
        cleanup = None
        return filename
    finally:
        if fh is not None:
            fh.close()
        if cleanup is not None:
            os.unlink(cleanup)

def decompressor(fh, alg):
    if alg == 'UN':
        return fh
    elif alg == 'GZ':
        def generator(f):
            zd = zlib.decompressobj()
            for chunk in util.filechunkiter(f):
                yield zd.decompress(chunk)
    elif alg == 'BZ':
        def generator(f):
            zd = bz2.BZ2Decompressor()
            zd.decompress("BZ")
            for chunk in util.filechunkiter(f, 4096):
                yield zd.decompress(chunk)
    else:
        raise util.Abort("unknown bundle compression '%s'" % alg)
    return util.chunkbuffer(generator(fh))

class unbundle10(object):
    deltaheader = _BUNDLE10_DELTA_HEADER
    deltaheadersize = struct.calcsize(deltaheader)
    def __init__(self, fh, alg):
        self._stream = decompressor(fh, alg)
        self._type = alg
        self.callback = None
    def compressed(self):
        return self._type != 'UN'
    def read(self, l):
        return self._stream.read(l)
    def seek(self, pos):
        return self._stream.seek(pos)
    def tell(self):
        return self._stream.tell()
    def close(self):
        return self._stream.close()

    def chunklength(self):
        d = readexactly(self._stream, 4)
        l = struct.unpack(">l", d)[0]
        if l <= 4:
            if l:
                raise util.Abort(_("invalid chunk length %d") % l)
            return 0
        if self.callback:
            self.callback()
        return l - 4

    def changelogheader(self):
        """v10 does not have a changelog header chunk"""
        return {}

    def manifestheader(self):
        """v10 does not have a manifest header chunk"""
        return {}

    def filelogheader(self):
        """return the header of the filelogs chunk, v10 only has the filename"""
        l = self.chunklength()
        if not l:
            return {}
        fname = readexactly(self._stream, l)
        return {'filename': fname}

    def _deltaheader(self, headertuple, prevnode):
        node, p1, p2, cs = headertuple
        if prevnode is None:
            deltabase = p1
        else:
            deltabase = prevnode
        return node, p1, p2, deltabase, cs

    def deltachunk(self, prevnode):
        l = self.chunklength()
        if not l:
            return {}
        headerdata = readexactly(self._stream, self.deltaheadersize)
        header = struct.unpack(self.deltaheader, headerdata)
        delta = readexactly(self._stream, l - self.deltaheadersize)
        node, p1, p2, deltabase, cs = self._deltaheader(header, prevnode)
        return {'node': node, 'p1': p1, 'p2': p2, 'cs': cs,
                'deltabase': deltabase, 'delta': delta}

class headerlessfixup(object):
    def __init__(self, fh, h):
        self._h = h
        self._fh = fh
    def read(self, n):
        if self._h:
            d, self._h = self._h[:n], self._h[n:]
            if len(d) < n:
                d += readexactly(self._fh, n - len(d))
            return d
        return readexactly(self._fh, n)

def readbundle(fh, fname):
    header = readexactly(fh, 6)

    if not fname:
        fname = "stream"
        if not header.startswith('HG') and header.startswith('\0'):
            fh = headerlessfixup(fh, header)
            header = "HG10UN"

    magic, version, alg = header[0:2], header[2:4], header[4:6]

    if magic != 'HG':
        raise util.Abort(_('%s: not a Mercurial bundle') % fname)
    if version != '10':
        raise util.Abort(_('%s: unknown bundle version %s') % (fname, version))
    return unbundle10(fh, alg)

class bundle10(object):
    deltaheader = _BUNDLE10_DELTA_HEADER
    def __init__(self, repo, bundlecaps=None):
        """Given a source repo, construct a bundler.

        bundlecaps is optional and can be used to specify the set of
        capabilities which can be used to build the bundle.
        """
        # Set of capabilities we can use to build the bundle.
        if bundlecaps is None:
            bundlecaps = set()
        self._bundlecaps = bundlecaps
        self._changelog = repo.changelog
        self._manifest = repo.manifest
        reorder = repo.ui.config('bundle', 'reorder', 'auto')
        if reorder == 'auto':
            reorder = None
        else:
            reorder = util.parsebool(reorder)
        self._repo = repo
        self._reorder = reorder
        self._progress = repo.ui.progress
    def close(self):
        return closechunk()

    def fileheader(self, fname):
        return chunkheader(len(fname)) + fname

    def group(self, nodelist, revlog, lookup, units=None, reorder=None):
        """Calculate a delta group, yielding a sequence of changegroup chunks
        (strings).

        Given a list of changeset revs, return a set of deltas and
        metadata corresponding to nodes. The first delta is
        first parent(nodelist[0]) -> nodelist[0], the receiver is
        guaranteed to have this parent as it has all history before
        these changesets. In the case firstparent is nullrev the
        changegroup starts with a full revision.

        If units is not None, progress detail will be generated, units specifies
        the type of revlog that is touched (changelog, manifest, etc.).
        """
        # if we don't have any revisions touched by these changesets, bail
        if len(nodelist) == 0:
            yield self.close()
            return

        # for generaldelta revlogs, we linearize the revs; this will both be
        # much quicker and generate a much smaller bundle
        if (revlog._generaldelta and reorder is not False) or reorder:
            dag = dagutil.revlogdag(revlog)
            revs = set(revlog.rev(n) for n in nodelist)
            revs = dag.linearize(revs)
        else:
            revs = sorted([revlog.rev(n) for n in nodelist])

        # add the parent of the first rev
        p = revlog.parentrevs(revs[0])[0]
        revs.insert(0, p)

        # build deltas
        total = len(revs) - 1
        msgbundling = _('bundling')
        for r in xrange(len(revs) - 1):
            if units is not None:
                self._progress(msgbundling, r + 1, unit=units, total=total)
            prev, curr = revs[r], revs[r + 1]
            linknode = lookup(revlog.node(curr))
            for c in self.revchunk(revlog, curr, prev, linknode):
                yield c

        yield self.close()

    # filter any nodes that claim to be part of the known set
    def prune(self, revlog, missing, commonrevs, source):
        rr, rl = revlog.rev, revlog.linkrev
        return [n for n in missing if rl(rr(n)) not in commonrevs]

    def generate(self, commonrevs, clnodes, fastpathlinkrev, source):
        '''yield a sequence of changegroup chunks (strings)'''
        repo = self._repo
        cl = self._changelog
        mf = self._manifest
        reorder = self._reorder
        progress = self._progress

        # for progress output
        msgbundling = _('bundling')

        mfs = {} # needed manifests
        fnodes = {} # needed file nodes
        changedfiles = set()

        # Callback for the changelog, used to collect changed files and manifest
        # nodes.
        # Returns the linkrev node (identity in the changelog case).
        def lookupcl(x):
            c = cl.read(x)
            changedfiles.update(c[3])
            # record the first changeset introducing this manifest version
            mfs.setdefault(c[0], x)
            return x

        # Callback for the manifest, used to collect linkrevs for filelog
        # revisions.
        # Returns the linkrev node (collected in lookupcl).
        def lookupmf(x):
            clnode = mfs[x]
            if not fastpathlinkrev:
                mdata = mf.readfast(x)
                for f, n in mdata.iteritems():
                    if f in changedfiles:
                        # record the first changeset introducing this filelog
                        # version
                        fnodes[f].setdefault(n, clnode)
            return clnode

        for chunk in self.group(clnodes, cl, lookupcl, units=_('changesets'),
                                reorder=reorder):
            yield chunk
        progress(msgbundling, None)

        for f in changedfiles:
            fnodes[f] = {}
        mfnodes = self.prune(mf, mfs, commonrevs, source)
        for chunk in self.group(mfnodes, mf, lookupmf, units=_('manifests'),
                                reorder=reorder):
            yield chunk
        progress(msgbundling, None)

        mfs.clear()
        needed = set(cl.rev(x) for x in clnodes)

        def linknodes(filerevlog, fname):
            if fastpathlinkrev:
                ln, llr = filerevlog.node, filerevlog.linkrev
                def genfilenodes():
                    for r in filerevlog:
                        linkrev = llr(r)
                        if linkrev in needed:
                            yield filerevlog.node(r), cl.node(linkrev)
                fnodes[fname] = dict(genfilenodes())
            return fnodes.get(fname, {})

        for chunk in self.generatefiles(changedfiles, linknodes, commonrevs,
                                        source):
            yield chunk

        yield self.close()
        progress(msgbundling, None)

        if clnodes:
            repo.hook('outgoing', node=hex(clnodes[0]), source=source)

    def generatefiles(self, changedfiles, linknodes, commonrevs, source):
        repo = self._repo
        progress = self._progress
        reorder = self._reorder
        msgbundling = _('bundling')

        total = len(changedfiles)
        # for progress output
        msgfiles = _('files')
        for i, fname in enumerate(sorted(changedfiles)):
            filerevlog = repo.file(fname)
            if not filerevlog:
                raise util.Abort(_("empty or missing revlog for %s") % fname)

            linkrevnodes = linknodes(filerevlog, fname)
            # Lookup for filenodes, we collected the linkrev nodes above in the
            # fastpath case and with lookupmf in the slowpath case.
            def lookupfilelog(x):
                return linkrevnodes[x]

            filenodes = self.prune(filerevlog, linkrevnodes, commonrevs, source)
            if filenodes:
                progress(msgbundling, i + 1, item=fname, unit=msgfiles,
                         total=total)
                yield self.fileheader(fname)
                for chunk in self.group(filenodes, filerevlog, lookupfilelog,
                                        reorder=reorder):
                    yield chunk

    def revchunk(self, revlog, rev, prev, linknode):
        node = revlog.node(rev)
        p1, p2 = revlog.parentrevs(rev)
        base = prev

        prefix = ''
        if base == nullrev:
            delta = revlog.revision(node)
            prefix = mdiff.trivialdiffheader(len(delta))
        else:
            delta = revlog.revdiff(base, rev)
        p1n, p2n = revlog.parents(node)
        basenode = revlog.node(base)
        meta = self.builddeltaheader(node, p1n, p2n, basenode, linknode)
        meta += prefix
        l = len(meta) + len(delta)
        yield chunkheader(l)
        yield meta
        yield delta
    def builddeltaheader(self, node, p1n, p2n, basenode, linknode):
        # do nothing with basenode, it is implicitly the previous one in HG10
        return struct.pack(self.deltaheader, node, p1n, p2n, linknode)

def _changegroupinfo(repo, nodes, source):
    if repo.ui.verbose or source == 'bundle':
        repo.ui.status(_("%d changesets found\n") % len(nodes))
    if repo.ui.debugflag:
        repo.ui.debug("list of changesets:\n")
        for node in nodes:
            repo.ui.debug("%s\n" % hex(node))

def getsubset(repo, outgoing, bundler, source, fastpath=False):
    repo = repo.unfiltered()
    commonrevs = outgoing.common
    csets = outgoing.missing
    heads = outgoing.missingheads
    # We go through the fast path if we get told to, or if all (unfiltered
    # heads have been requested (since we then know there all linkrevs will
    # be pulled by the client).
    heads.sort()
    fastpathlinkrev = fastpath or (
            repo.filtername is None and heads == sorted(repo.heads()))

    repo.hook('preoutgoing', throw=True, source=source)
    _changegroupinfo(repo, csets, source)
    gengroup = bundler.generate(commonrevs, csets, fastpathlinkrev, source)
    return unbundle10(util.chunkbuffer(gengroup), 'UN')

def changegroupsubset(repo, roots, heads, source):
    """Compute a changegroup consisting of all the nodes that are
    descendants of any of the roots and ancestors of any of the heads.
    Return a chunkbuffer object whose read() method will return
    successive changegroup chunks.

    It is fairly complex as determining which filenodes and which
    manifest nodes need to be included for the changeset to be complete
    is non-trivial.

    Another wrinkle is doing the reverse, figuring out which changeset in
    the changegroup a particular filenode or manifestnode belongs to.
    """
    cl = repo.changelog
    if not roots:
        roots = [nullid]
    # TODO: remove call to nodesbetween.
    csets, roots, heads = cl.nodesbetween(roots, heads)
    discbases = []
    for n in roots:
        discbases.extend([p for p in cl.parents(n) if p != nullid])
    outgoing = discovery.outgoing(cl, discbases, heads)
    bundler = bundle10(repo)
    return getsubset(repo, outgoing, bundler, source)

def getlocalbundle(repo, source, outgoing, bundlecaps=None):
    """Like getbundle, but taking a discovery.outgoing as an argument.

    This is only implemented for local repos and reuses potentially
    precomputed sets in outgoing."""
    if not outgoing.missing:
        return None
    bundler = bundle10(repo, bundlecaps)
    return getsubset(repo, outgoing, bundler, source)

def getbundle(repo, source, heads=None, common=None, bundlecaps=None):
    """Like changegroupsubset, but returns the set difference between the
    ancestors of heads and the ancestors common.

    If heads is None, use the local heads. If common is None, use [nullid].

    The nodes in common might not all be known locally due to the way the
    current discovery protocol works.
    """
    cl = repo.changelog
    if common:
        hasnode = cl.hasnode
        common = [n for n in common if hasnode(n)]
    else:
        common = [nullid]
    if not heads:
        heads = cl.heads()
    outgoing = discovery.outgoing(cl, common, heads)
    return getlocalbundle(repo, source, outgoing, bundlecaps=bundlecaps)