# blobstore.py - local and remote (speaking Git-LFS protocol) blob storages

#

# Copyright 2017 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 errno

import hashlib

import json

import os

import re

import socket

from mercurial.i18n import _

from mercurial import (

    error,

    pathutil,

    pycompat,

    url as urlmod,

    util,

    vfs as vfsmod,

    worker,

)

from ..largefiles import lfutil

# 64 bytes for SHA256

_lfsre = re.compile(br'\A[a-f0-9]{64}\Z')

class lfsvfs(vfsmod.vfs):

    def join(self, path):

        """split the path at first two characters, like: XX/XXXXX..."""

        if not _lfsre.match(path):

            raise error.ProgrammingError('unexpected lfs path: %s' % path)

        return super(lfsvfs, self).join(path[0:2], path[2:])

    def walk(self, path=None, onerror=None):

        """Yield (dirpath, [], oids) tuple for blobs under path

        Oids only exist in the root of this vfs, so dirpath is always ''.

        """

        root = os.path.normpath(self.base)

        # when dirpath == root, dirpath[prefixlen:] becomes empty

        # because len(dirpath) < prefixlen.

        prefixlen = len(pathutil.normasprefix(root))

        oids = []

        for dirpath, dirs, files in os.walk(self.reljoin(self.base, path or ''),

                                            onerror=onerror):

            dirpath = dirpath[prefixlen:]

            # Silently skip unexpected files and directories

            if len(dirpath) == 2:

                oids.extend([dirpath + f for f in files

                             if _lfsre.match(dirpath + f)])

        yield ('', [], oids)

class nullvfs(lfsvfs):

    def __init__(self):

        pass

    def exists(self, oid):

        return False

    def read(self, oid):

        # store.read() calls into here if the blob doesn't exist in its

        # self.vfs.  Raise the same error as a normal vfs when asked to read a

        # file that doesn't exist.  The only difference is the full file path

        # isn't available in the error.

        raise IOError(errno.ENOENT, '%s: No such file or directory' % oid)

    def walk(self, path=None, onerror=None):

        return ('', [], [])

    def write(self, oid, data):

        pass

class filewithprogress(object):

    """a file-like object that supports __len__ and read.

    Useful to provide progress information for how many bytes are read.

    """

    def __init__(self, fp, callback):

        self._fp = fp

        self._callback = callback # func(readsize)

        fp.seek(0, os.SEEK_END)

        self._len = fp.tell()

        fp.seek(0)

    def __len__(self):

        return self._len

    def read(self, size):

        if self._fp is None:

            return b''

        data = self._fp.read(size)

        if data:

            if self._callback:

                self._callback(len(data))

        else:

            self._fp.close()

            self._fp = None

        return data

class local(object):

    """Local blobstore for large file contents.

    This blobstore is used both as a cache and as a staging area for large blobs

    to be uploaded to the remote blobstore.

    """

    def __init__(self, repo):

        fullpath = repo.svfs.join('lfs/objects')

        self.vfs = lfsvfs(fullpath)

        if repo.ui.configbool('experimental', 'lfs.disableusercache'):

            self.cachevfs = nullvfs()

        else:

            usercache = lfutil._usercachedir(repo.ui, 'lfs')

            self.cachevfs = lfsvfs(usercache)

        self.ui = repo.ui

    def open(self, oid):

        """Open a read-only file descriptor to the named blob, in either the

        usercache or the local store."""

        # The usercache is the most likely place to hold the file.  Commit will

        # write to both it and the local store, as will anything that downloads

        # the blobs.  However, things like clone without an update won't

        # populate the local store.  For an init + push of a local clone,

        # the usercache is the only place it _could_ be.  If not present, the

        # missing file msg here will indicate the local repo, not the usercache.

        if self.cachevfs.exists(oid):

            return self.cachevfs(oid, 'rb')

        return self.vfs(oid, 'rb')

    def download(self, oid, src):

        """Read the blob from the remote source in chunks, verify the content,

        and write to this local blobstore."""

        sha256 = hashlib.sha256()

        with self.vfs(oid, 'wb', atomictemp=True) as fp:

            for chunk in util.filechunkiter(src, size=1048576):

                fp.write(chunk)

                sha256.update(chunk)

            realoid = sha256.hexdigest()

            if realoid != oid:

                raise LfsCorruptionError(_('corrupt remote lfs object: %s')

                                         % oid)

        self._linktousercache(oid)

    def write(self, oid, data):

        """Write blob to local blobstore.

        This should only be called from the filelog during a commit or similar.

        As such, there is no need to verify the data.  Imports from a remote

        store must use ``download()`` instead."""

        with self.vfs(oid, 'wb', atomictemp=True) as fp:

            fp.write(data)

        self._linktousercache(oid)

    def linkfromusercache(self, oid):

        """Link blobs found in the user cache into this store.

        The server module needs to do this when it lets the client know not to

        upload the blob, to ensure it is always available in this store.

        Normally this is done implicitly when the client reads or writes the

        blob, but that doesn't happen when the server tells the client that it

        already has the blob.

        """

        if (not isinstance(self.cachevfs, nullvfs)

            and not self.vfs.exists(oid)):

            self.ui.note(_('lfs: found %s in the usercache\n') % oid)

            lfutil.link(self.cachevfs.join(oid), self.vfs.join(oid))

    def _linktousercache(self, oid):

        # XXX: should we verify the content of the cache, and hardlink back to

        # the local store on success, but truncate, write and link on failure?

        if (not self.cachevfs.exists(oid)

            and not isinstance(self.cachevfs, nullvfs)):

            self.ui.note(_('lfs: adding %s to the usercache\n') % oid)

            lfutil.link(self.vfs.join(oid), self.cachevfs.join(oid))

    def read(self, oid, verify=True):

        """Read blob from local blobstore."""

        if not self.vfs.exists(oid):

            blob = self._read(self.cachevfs, oid, verify)

            # Even if revlog will verify the content, it needs to be verified

            # now before making the hardlink to avoid propagating corrupt blobs.

            # Don't abort if corruption is detected, because `hg verify` will

            # give more useful info about the corruption- simply don't add the

            # hardlink.

            if verify or hashlib.sha256(blob).hexdigest() == oid:

                self.ui.note(_('lfs: found %s in the usercache\n') % oid)

                lfutil.link(self.cachevfs.join(oid), self.vfs.join(oid))

        else:

            self.ui.note(_('lfs: found %s in the local lfs store\n') % oid)

            blob = self._read(self.vfs, oid, verify)

        return blob

    def _read(self, vfs, oid, verify):

        """Read blob (after verifying) from the given store"""

        blob = vfs.read(oid)

        if verify:

            _verify(oid, blob)

        return blob

    def verify(self, oid):

        """Indicate whether or not the hash of the underlying file matches its

        name."""

        sha256 = hashlib.sha256()

        with self.open(oid) as fp:

            for chunk in util.filechunkiter(fp, size=1048576):

                sha256.update(chunk)

        return oid == sha256.hexdigest()

    def has(self, oid):

        """Returns True if the local blobstore contains the requested blob,

        False otherwise."""

        return self.cachevfs.exists(oid) or self.vfs.exists(oid)

class _gitlfsremote(object):

    def __init__(self, repo, url):

        ui = repo.ui

        self.ui = ui

        baseurl, authinfo = url.authinfo()

        self.baseurl = baseurl.rstrip('/')

        useragent = repo.ui.config('experimental', 'lfs.user-agent')

        if not useragent:

            useragent = 'git-lfs/2.3.4 (Mercurial %s)' % util.version()

        self.urlopener = urlmod.opener(ui, authinfo, useragent)

        self.retry = ui.configint('lfs', 'retry')

    def writebatch(self, pointers, fromstore):

        """Batch upload from local to remote blobstore."""

        self._batch(_deduplicate(pointers), fromstore, 'upload')

    def readbatch(self, pointers, tostore):

        """Batch download from remote to local blostore."""

        self._batch(_deduplicate(pointers), tostore, 'download')

    def _batchrequest(self, pointers, action):

        """Get metadata about objects pointed by pointers for given action

        Return decoded JSON object like {'objects': [{'oid': '', 'size': 1}]}

        See https://github.com/git-lfs/git-lfs/blob/master/docs/api/batch.md

        """

        objects = [{'oid': p.oid(), 'size': p.size()} for p in pointers]

        requestdata = json.dumps({

            'objects': objects,

            'operation': action,

        })

        url = '%s/objects/batch' % self.baseurl

        batchreq = util.urlreq.request(url, data=requestdata)

        batchreq.add_header('Accept', 'application/vnd.git-lfs+json')

        batchreq.add_header('Content-Type', 'application/vnd.git-lfs+json')

        try:

            rsp = self.urlopener.open(batchreq)

            rawjson = rsp.read()

        except util.urlerr.httperror as ex:

            hints = {

                400: _('check that lfs serving is enabled on %s and "%s" is '

                       'supported') % (self.baseurl, action),

                404: _('the "lfs.url" config may be used to override %s')

                       % self.baseurl,

            }

            hint = hints.get(ex.code, _('api=%s, action=%s') % (url, action))

            raise LfsRemoteError(_('LFS HTTP error: %s') % ex, hint=hint)

        try:

            response = json.loads(rawjson)

        except ValueError:

            raise LfsRemoteError(_('LFS server returns invalid JSON: %s')

                                 % rawjson)

        if self.ui.debugflag:

            self.ui.debug('Status: %d\n' % rsp.status)

            # lfs-test-server and hg serve return headers in different order

            self.ui.debug('%s\n'

                          % '\n'.join(sorted(str(rsp.info()).splitlines())))

            if 'objects' in response:

                response['objects'] = sorted(response['objects'],

                                             key=lambda p: p['oid'])

            self.ui.debug('%s\n'

                          % json.dumps(response, indent=2,

                                       separators=('', ': '), sort_keys=True))

        return response

    def _checkforservererror(self, pointers, responses, action):

        """Scans errors from objects

        Raises LfsRemoteError if any objects have an error"""

        for response in responses:

            # The server should return 404 when objects cannot be found. Some

            # server implementation (ex. lfs-test-server)  does not set "error"

            # but just removes "download" from "actions". Treat that case

            # as the same as 404 error.

            if 'error' not in response:

                if (action == 'download'

                    and action not in response.get('actions', [])):

                    code = 404

                else:

                    continue

            else:

                # An error dict without a code doesn't make much sense, so

                # treat as a server error.

                code = response.get('error').get('code', 500)

            ptrmap = {p.oid(): p for p in pointers}

            p = ptrmap.get(response['oid'], None)

            if p:

                filename = getattr(p, 'filename', 'unknown')

                errors = {

                    404: 'The object does not exist',

                    410: 'The object was removed by the owner',

                    422: 'Validation error',

                    500: 'Internal server error',

                }

                msg = errors.get(code, 'status code %d' % code)

                raise LfsRemoteError(_('LFS server error for "%s": %s')

                                     % (filename, msg))

            else:

                raise LfsRemoteError(

                    _('LFS server error. Unsolicited response for oid %s')

                    % response['oid'])

    def _extractobjects(self, response, pointers, action):

        """extract objects from response of the batch API

        response: parsed JSON object returned by batch API

        return response['objects'] filtered by action

        raise if any object has an error

        """

        # Scan errors from objects - fail early

        objects = response.get('objects', [])

        self._checkforservererror(pointers, objects, action)

        # Filter objects with given action. Practically, this skips uploading

        # objects which exist in the server.

        filteredobjects = [o for o in objects if action in o.get('actions', [])]

        return filteredobjects

    def _basictransfer(self, obj, action, localstore):

        """Download or upload a single object using basic transfer protocol

        obj: dict, an object description returned by batch API

        action: string, one of ['upload', 'download']

        localstore: blobstore.local

        See https://github.com/git-lfs/git-lfs/blob/master/docs/api/\

        basic-transfers.md

        """

        oid = pycompat.bytestr(obj['oid'])

        href = pycompat.bytestr(obj['actions'][action].get('href'))

        headers = obj['actions'][action].get('header', {}).items()

        request = util.urlreq.request(href)

        if action == 'upload':

            # If uploading blobs, read data from local blobstore.

            if not localstore.verify(oid):

                raise error.Abort(_('detected corrupt lfs object: %s') % oid,

                                  hint=_('run hg verify'))

            request.data = filewithprogress(localstore.open(oid), None)

            request.get_method = lambda: 'PUT'

            request.add_header('Content-Type', 'application/octet-stream')

        for k, v in headers:

            request.add_header(k, v)

        response = b''

        try:

            req = self.urlopener.open(request)

            if self.ui.debugflag:

                self.ui.debug('Status: %d\n' % req.status)

                # lfs-test-server and hg serve return headers in different order

                self.ui.debug('%s\n'

                              % '\n'.join(sorted(str(req.info()).splitlines())))

            if action == 'download':

                # If downloading blobs, store downloaded data to local blobstore

                localstore.download(oid, req)

            else:

                while True:

                    data = req.read(1048576)

                    if not data:

                        break

                    response += data

                if response:

                    self.ui.debug('lfs %s response: %s' % (action, response))

        except util.urlerr.httperror as ex:

            if self.ui.debugflag:

                self.ui.debug('%s: %s\n' % (oid, ex.read()))

            raise LfsRemoteError(_('HTTP error: %s (oid=%s, action=%s)')

                                 % (ex, oid, action))

    def _batch(self, pointers, localstore, action):

        if action not in ['upload', 'download']:

            raise error.ProgrammingError('invalid Git-LFS action: %s' % action)

        response = self._batchrequest(pointers, action)

        objects = self._extractobjects(response, pointers, action)

        total = sum(x.get('size', 0) for x in objects)

        sizes = {}

        for obj in objects:

            sizes[obj.get('oid')] = obj.get('size', 0)

        topic = {'upload': _('lfs uploading'),

                 'download': _('lfs downloading')}[action]

        if len(objects) > 1:

            self.ui.note(_('lfs: need to transfer %d objects (%s)\n')

                         % (len(objects), util.bytecount(total)))

        def transfer(chunk):

            for obj in chunk:

                objsize = obj.get('size', 0)

                if self.ui.verbose:

                    if action == 'download':

                        msg = _('lfs: downloading %s (%s)\n')

                    elif action == 'upload':

                        msg = _('lfs: uploading %s (%s)\n')

                    self.ui.note(msg % (obj.get('oid'),

                                 util.bytecount(objsize)))

                retry = self.retry

                while True:

                    try:

                        self._basictransfer(obj, action, localstore)

                        yield 1, obj.get('oid')

                        break

                    except socket.error as ex:

                        if retry > 0:

                            self.ui.note(

                                _('lfs: failed: %r (remaining retry %d)\n')

                                % (ex, retry))

                            retry -= 1

                            continue

                        raise

        # Until https multiplexing gets sorted out

        if self.ui.configbool('experimental', 'lfs.worker-enable'):

            oids = worker.worker(self.ui, 0.1, transfer, (),

                                 sorted(objects, key=lambda o: o.get('oid')))

        else:

            oids = transfer(sorted(objects, key=lambda o: o.get('oid')))