# remotefilelog.py - filelog implementation where filelog history is stored

#                    remotely

#

# Copyright 2013 Facebook, Inc.

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import collections

import os

from mercurial.node import bin, nullid

from mercurial.i18n import _

from mercurial import (

    ancestor,

    error,

    mdiff,

    revlog,

)

from mercurial.utils import storageutil

from . import (

    constants,

    fileserverclient,

    shallowutil,

)

class remotefilelognodemap(object):

    def __init__(self, filename, store):

        self._filename = filename

        self._store = store

    def __contains__(self, node):

        missing = self._store.getmissing([(self._filename, node)])

        return not bool(missing)

    def __get__(self, node):

        if node not in self:

            raise KeyError(node)

        return node

class remotefilelog(object):

    _generaldelta = True

    def __init__(self, opener, path, repo):

        self.opener = opener

        self.filename = path

        self.repo = repo

        self.nodemap = remotefilelognodemap(self.filename, repo.contentstore)

        self.version = 1

    def read(self, node):

        """returns the file contents at this node"""

        t = self.revision(node)

        if not t.startswith('\1\n'):

            return t

        s = t.index('\1\n', 2)

        return t[s + 2:]

    def add(self, text, meta, transaction, linknode, p1=None, p2=None):

        hashtext = text

        # hash with the metadata, like in vanilla filelogs

        hashtext = shallowutil.createrevlogtext(text, meta.get('copy'),

                                                meta.get('copyrev'))

        node = storageutil.hashrevisionsha1(hashtext, p1, p2)

        return self.addrevision(hashtext, transaction, linknode, p1, p2,

                                node=node)

    def _createfileblob(self, text, meta, flags, p1, p2, node, linknode):

        # text passed to "_createfileblob" does not include filelog metadata

        header = shallowutil.buildfileblobheader(len(text), flags)

        data = "%s\0%s" % (header, text)

        realp1 = p1

        copyfrom = ""

        if meta and 'copy' in meta:

            copyfrom = meta['copy']

            realp1 = bin(meta['copyrev'])

        data += "%s%s%s%s%s\0" % (node, realp1, p2, linknode, copyfrom)

        visited = set()

        pancestors = {}

        queue = []

        if realp1 != nullid:

            p1flog = self

            if copyfrom:

                p1flog = remotefilelog(self.opener, copyfrom, self.repo)

            pancestors.update(p1flog.ancestormap(realp1))

            queue.append(realp1)

            visited.add(realp1)

        if p2 != nullid:

            pancestors.update(self.ancestormap(p2))

            queue.append(p2)

            visited.add(p2)

        ancestortext = ""

        # add the ancestors in topological order

        while queue:

            c = queue.pop(0)

            pa1, pa2, ancestorlinknode, pacopyfrom = pancestors[c]

            pacopyfrom = pacopyfrom or ''

            ancestortext += "%s%s%s%s%s\0" % (

                c, pa1, pa2, ancestorlinknode, pacopyfrom)

            if pa1 != nullid and pa1 not in visited:

                queue.append(pa1)

                visited.add(pa1)

            if pa2 != nullid and pa2 not in visited:

                queue.append(pa2)

                visited.add(pa2)

        data += ancestortext

        return data

    def addrevision(self, text, transaction, linknode, p1, p2, cachedelta=None,

                    node=None, flags=revlog.REVIDX_DEFAULT_FLAGS):

        # text passed to "addrevision" includes hg filelog metadata header

        if node is None:

            node = storageutil.hashrevisionsha1(text, p1, p2)

        meta, metaoffset = storageutil.parsemeta(text)

        rawtext, validatehash = self._processflags(text, flags, 'write')

        return self.addrawrevision(rawtext, transaction, linknode, p1, p2,

                                   node, flags, cachedelta,

                                   _metatuple=(meta, metaoffset))

    def addrawrevision(self, rawtext, transaction, linknode, p1, p2, node,

                       flags, cachedelta=None, _metatuple=None):

        if _metatuple:

            # _metatuple: used by "addrevision" internally by remotefilelog

            # meta was parsed confidently

            meta, metaoffset = _metatuple

        else:

            # not from self.addrevision, but something else (repo._filecommit)

            # calls addrawrevision directly. remotefilelog needs to get and

            # strip filelog metadata.

            # we don't have confidence about whether rawtext contains filelog

            # metadata or not (flag processor could replace it), so we just

            # parse it as best-effort.

            # in LFS (flags != 0)'s case, the best way is to call LFS code to

            # get the meta information, instead of storageutil.parsemeta.

            meta, metaoffset = storageutil.parsemeta(rawtext)

        if flags != 0:

            # when flags != 0, be conservative and do not mangle rawtext, since

            # a read flag processor expects the text not being mangled at all.

            metaoffset = 0

        if metaoffset:

            # remotefilelog fileblob stores copy metadata in its ancestortext,

            # not its main blob. so we need to remove filelog metadata

            # (containing copy information) from text.

            blobtext = rawtext[metaoffset:]

        else:

            blobtext = rawtext

        data = self._createfileblob(blobtext, meta, flags, p1, p2, node,

                                    linknode)

        self.repo.contentstore.addremotefilelognode(self.filename, node, data)

        return node

    def renamed(self, node):

        ancestors = self.repo.metadatastore.getancestors(self.filename, node)

        p1, p2, linknode, copyfrom = ancestors[node]

        if copyfrom:

            return (copyfrom, p1)

        return False

    def size(self, node):

        """return the size of a given revision"""

        return len(self.read(node))

    rawsize = size

    def cmp(self, node, text):

        """compare text with a given file revision

        returns True if text is different than what is stored.

        """

        if node == nullid:

            return True

        nodetext = self.read(node)

        return nodetext != text

    def __nonzero__(self):

        return True

    def __len__(self):

        if self.filename == '.hgtags':

            # The length of .hgtags is used to fast path tag checking.

            # remotefilelog doesn't support .hgtags since the entire .hgtags

            # history is needed.  Use the excludepattern setting to make

            # .hgtags a normal filelog.

            return 0

        raise RuntimeError("len not supported")

    def empty(self):

        return False

    def flags(self, node):

        if isinstance(node, int):

            raise error.ProgrammingError(

                'remotefilelog does not accept integer rev for flags')

        store = self.repo.contentstore

        return store.getmeta(self.filename, node).get(constants.METAKEYFLAG, 0)

    def parents(self, node):

        if node == nullid:

            return nullid, nullid

        ancestormap = self.repo.metadatastore.getancestors(self.filename, node)

        p1, p2, linknode, copyfrom = ancestormap[node]

        if copyfrom:

            p1 = nullid

        return p1, p2

    def parentrevs(self, rev):

        # TODO(augie): this is a node and should be a rev, but for now

        # nothing in core seems to actually break.

        return self.parents(rev)

    def linknode(self, node):

        ancestormap = self.repo.metadatastore.getancestors(self.filename, node)

        p1, p2, linknode, copyfrom = ancestormap[node]

        return linknode

    def linkrev(self, node):

        return self.repo.unfiltered().changelog.rev(self.linknode(node))

    def emitrevisions(self, nodes, nodesorder=None, revisiondata=False,

                      assumehaveparentrevisions=False, deltaprevious=False,

                      deltamode=None):

        # we don't use any of these parameters here

        del nodesorder, revisiondata, assumehaveparentrevisions, deltaprevious

        del deltamode

        prevnode = None

        for node in nodes:

            p1, p2 = self.parents(node)

            if prevnode is None:

                basenode = prevnode = p1

            if basenode == node:

                basenode = nullid

            if basenode != nullid:

                revision = None

                delta = self.revdiff(basenode, node)

            else:

                revision = self.revision(node, raw=True)

                delta = None

            yield revlog.revlogrevisiondelta(

                node=node,

                p1node=p1,

                p2node=p2,

                linknode=self.linknode(node),

                basenode=basenode,

                flags=self.flags(node),

                baserevisionsize=None,

                revision=revision,

                delta=delta,

                )

    def emitrevisiondeltas(self, requests):

        prevnode = None

        for request in requests:

            node = request.node

            p1, p2 = self.parents(node)

            if prevnode is None:

                prevnode = p1

            if request.basenode is not None:

                basenode = request.basenode

            else:

                basenode = p1

            if basenode == nullid:

                revision = self.revision(node, raw=True)

                delta = None

            else:

                revision = None

                delta = self.revdiff(basenode, node)

            yield revlog.revlogrevisiondelta(

                node=node,

                p1node=p1,

                p2node=p2,

                linknode=self.linknode(node),

                basenode=basenode,

                flags=self.flags(node),

                baserevisionsize=None,

                revision=revision,

                delta=delta,

                )

    def revdiff(self, node1, node2):

        return mdiff.textdiff(self.revision(node1, raw=True),

                              self.revision(node2, raw=True))

    def lookup(self, node):

        if len(node) == 40:

            node = bin(node)

        if len(node) != 20:

            raise error.LookupError(node, self.filename,

                                    _('invalid lookup input'))

        return node

    def rev(self, node):

        # This is a hack to make TortoiseHG work.

        return node

    def node(self, rev):

        # This is a hack.

        if isinstance(rev, int):

            raise error.ProgrammingError(

                'remotefilelog does not convert integer rev to node')

        return rev

    def revision(self, node, raw=False):

        """returns the revlog contents at this node.

        this includes the meta data traditionally included in file revlogs.

        this is generally only used for bundling and communicating with vanilla

        hg clients.

        """

        if node == nullid:

            return ""

        if len(node) != 20:

            raise error.LookupError(node, self.filename,

                                    _('invalid revision input'))

        store = self.repo.contentstore

        rawtext = store.get(self.filename, node)

        if raw:

            return rawtext

        flags = store.getmeta(self.filename, node).get(constants.METAKEYFLAG, 0)

        if flags == 0:

            return rawtext

        text, verifyhash = self._processflags(rawtext, flags, 'read')

        return text

    def _processflags(self, text, flags, operation, raw=False):

        # mostly copied from hg/mercurial/revlog.py

        validatehash = True

        orderedflags = revlog.REVIDX_FLAGS_ORDER

        if operation == 'write':

            orderedflags = reversed(orderedflags)

        for flag in orderedflags:

            if flag & flags:

                vhash = True

                if flag not in revlog._flagprocessors:

                    message = _("missing processor for flag '%#x'") % (flag)

                    raise revlog.RevlogError(message)

                readfunc, writefunc, rawfunc = revlog._flagprocessors[flag]

                if raw:

                    vhash = rawfunc(self, text)

                elif operation == 'read':

                    text, vhash = readfunc(self, text)

                elif operation == 'write':

                    text, vhash = writefunc(self, text)

                validatehash = validatehash and vhash

        return text, validatehash

    def _read(self, id):

        """reads the raw file blob from disk, cache, or server"""

        fileservice = self.repo.fileservice

        localcache = fileservice.localcache

        cachekey = fileserverclient.getcachekey(self.repo.name, self.filename,

                                                id)

        try:

            return localcache.read(cachekey)

        except KeyError:

            pass

        localkey = fileserverclient.getlocalkey(self.filename, id)

        localpath = os.path.join(self.localpath, localkey)

        try:

            return shallowutil.readfile(localpath)

        except IOError:

            pass

        fileservice.prefetch([(self.filename, id)])

        try:

            return localcache.read(cachekey)

        except KeyError:

            pass

        raise error.LookupError(id, self.filename, _('no node'))

    def ancestormap(self, node):

        return self.repo.metadatastore.getancestors(self.filename, node)

    def ancestor(self, a, b):