# Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net>

# 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 __future__ import absolute_import

import contextlib

from .i18n import _

from .node import (

    nullid,

    nullrev,

)

from . import (

    changegroup,

    dagop,

    discovery,

    encoding,

    error,

    pycompat,

    streamclone,

    util,

    wireprotoframing,

    wireprototypes,

)

from .utils import (

    interfaceutil,

)

FRAMINGTYPE = b'application/mercurial-exp-framing-0005'

HTTP_WIREPROTO_V2 = wireprototypes.HTTP_WIREPROTO_V2

COMMANDS = wireprototypes.commanddict()

def handlehttpv2request(rctx, req, res, checkperm, urlparts):

    from .hgweb import common as hgwebcommon

    # URL space looks like: <permissions>/<command>, where <permission> can

    # be ``ro`` or ``rw`` to signal read-only or read-write, respectively.

    # Root URL does nothing meaningful... yet.

    if not urlparts:

        res.status = b'200 OK'

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('HTTP version 2 API handler'))

        return

    if len(urlparts) == 1:

        res.status = b'404 Not Found'

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('do not know how to process %s\n') %

                         req.dispatchpath)

        return

    permission, command = urlparts[0:2]

    if permission not in (b'ro', b'rw'):

        res.status = b'404 Not Found'

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('unknown permission: %s') % permission)

        return

    if req.method != 'POST':

        res.status = b'405 Method Not Allowed'

        res.headers[b'Allow'] = b'POST'

        res.setbodybytes(_('commands require POST requests'))

        return

    # At some point we'll want to use our own API instead of recycling the

    # behavior of version 1 of the wire protocol...

    # TODO return reasonable responses - not responses that overload the

    # HTTP status line message for error reporting.

    try:

        checkperm(rctx, req, 'pull' if permission == b'ro' else 'push')

    except hgwebcommon.ErrorResponse as e:

        res.status = hgwebcommon.statusmessage(e.code, pycompat.bytestr(e))

        for k, v in e.headers:

            res.headers[k] = v

        res.setbodybytes('permission denied')

        return

    # We have a special endpoint to reflect the request back at the client.

    if command == b'debugreflect':

        _processhttpv2reflectrequest(rctx.repo.ui, rctx.repo, req, res)

        return

    # Extra commands that we handle that aren't really wire protocol

    # commands. Think extra hard before making this hackery available to

    # extension.

    extracommands = {'multirequest'}

    if command not in COMMANDS and command not in extracommands:

        res.status = b'404 Not Found'

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('unknown wire protocol command: %s\n') % command)

        return

    repo = rctx.repo

    ui = repo.ui

    proto = httpv2protocolhandler(req, ui)

    if (not COMMANDS.commandavailable(command, proto)

        and command not in extracommands):

        res.status = b'404 Not Found'

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('invalid wire protocol command: %s') % command)

        return

    # TODO consider cases where proxies may add additional Accept headers.

    if req.headers.get(b'Accept') != FRAMINGTYPE:

        res.status = b'406 Not Acceptable'

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('client MUST specify Accept header with value: %s\n')

                           % FRAMINGTYPE)

        return

    if req.headers.get(b'Content-Type') != FRAMINGTYPE:

        res.status = b'415 Unsupported Media Type'

        # TODO we should send a response with appropriate media type,

        # since client does Accept it.

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('client MUST send Content-Type header with '

                           'value: %s\n') % FRAMINGTYPE)

        return

    _processhttpv2request(ui, repo, req, res, permission, command, proto)

def _processhttpv2reflectrequest(ui, repo, req, res):

    """Reads unified frame protocol request and dumps out state to client.

    This special endpoint can be used to help debug the wire protocol.

    Instead of routing the request through the normal dispatch mechanism,

    we instead read all frames, decode them, and feed them into our state

    tracker. We then dump the log of all that activity back out to the

    client.

    """

    import json

    # Reflection APIs have a history of being abused, accidentally disclosing

    # sensitive data, etc. So we have a config knob.

    if not ui.configbool('experimental', 'web.api.debugreflect'):

        res.status = b'404 Not Found'

        res.headers[b'Content-Type'] = b'text/plain'

        res.setbodybytes(_('debugreflect service not available'))

        return

    # We assume we have a unified framing protocol request body.

    reactor = wireprotoframing.serverreactor()

    states = []

    while True:

        frame = wireprotoframing.readframe(req.bodyfh)

        if not frame:

            states.append(b'received: <no frame>')

            break

        states.append(b'received: %d %d %d %s' % (frame.typeid, frame.flags,

                                                  frame.requestid,

                                                  frame.payload))

        action, meta = reactor.onframerecv(frame)

        states.append(json.dumps((action, meta), sort_keys=True,

                                 separators=(', ', ': ')))

    action, meta = reactor.oninputeof()

    meta['action'] = action

    states.append(json.dumps(meta, sort_keys=True, separators=(', ',': ')))

    res.status = b'200 OK'

    res.headers[b'Content-Type'] = b'text/plain'

    res.setbodybytes(b'\n'.join(states))

def _processhttpv2request(ui, repo, req, res, authedperm, reqcommand, proto):

    """Post-validation handler for HTTPv2 requests.

    Called when the HTTP request contains unified frame-based protocol

    frames for evaluation.

    """

    # TODO Some HTTP clients are full duplex and can receive data before

    # the entire request is transmitted. Figure out a way to indicate support

    # for that so we can opt into full duplex mode.

    reactor = wireprotoframing.serverreactor(deferoutput=True)

    seencommand = False

    outstream = reactor.makeoutputstream()

    while True:

        frame = wireprotoframing.readframe(req.bodyfh)

        if not frame:

            break

        action, meta = reactor.onframerecv(frame)

        if action == 'wantframe':

            # Need more data before we can do anything.

            continue

        elif action == 'runcommand':

            sentoutput = _httpv2runcommand(ui, repo, req, res, authedperm,

                                           reqcommand, reactor, outstream,

                                           meta, issubsequent=seencommand)

            if sentoutput:

                return

            seencommand = True

        elif action == 'error':

            # TODO define proper error mechanism.

            res.status = b'200 OK'

            res.headers[b'Content-Type'] = b'text/plain'

            res.setbodybytes(meta['message'] + b'\n')

            return

        else:

            raise error.ProgrammingError(

                'unhandled action from frame processor: %s' % action)

    action, meta = reactor.oninputeof()

    if action == 'sendframes':

        # We assume we haven't started sending the response yet. If we're

        # wrong, the response type will raise an exception.

        res.status = b'200 OK'

        res.headers[b'Content-Type'] = FRAMINGTYPE

        res.setbodygen(meta['framegen'])

    elif action == 'noop':

        pass

    else:

        raise error.ProgrammingError('unhandled action from frame processor: %s'

                                     % action)

def _httpv2runcommand(ui, repo, req, res, authedperm, reqcommand, reactor,

                      outstream, command, issubsequent):

    """Dispatch a wire protocol command made from HTTPv2 requests.

    The authenticated permission (``authedperm``) along with the original

    command from the URL (``reqcommand``) are passed in.

    """

    # We already validated that the session has permissions to perform the

    # actions in ``authedperm``. In the unified frame protocol, the canonical

    # command to run is expressed in a frame. However, the URL also requested

    # to run a specific command. We need to be careful that the command we

    # run doesn't have permissions requirements greater than what was granted

    # by ``authedperm``.

    #

    # Our rule for this is we only allow one command per HTTP request and

    # that command must match the command in the URL. However, we make

    # an exception for the ``multirequest`` URL. This URL is allowed to

    # execute multiple commands. We double check permissions of each command

    # as it is invoked to ensure there is no privilege escalation.

    # TODO consider allowing multiple commands to regular command URLs

    # iff each command is the same.

    proto = httpv2protocolhandler(req, ui, args=command['args'])

    if reqcommand == b'multirequest':

        if not COMMANDS.commandavailable(command['command'], proto):

            # TODO proper error mechanism

            res.status = b'200 OK'

            res.headers[b'Content-Type'] = b'text/plain'

            res.setbodybytes(_('wire protocol command not available: %s') %

                             command['command'])

            return True

        # TODO don't use assert here, since it may be elided by -O.

        assert authedperm in (b'ro', b'rw')

        wirecommand = COMMANDS[command['command']]

        assert wirecommand.permission in ('push', 'pull')

        if authedperm == b'ro' and wirecommand.permission != 'pull':

            # TODO proper error mechanism

            res.status = b'403 Forbidden'

            res.headers[b'Content-Type'] = b'text/plain'

            res.setbodybytes(_('insufficient permissions to execute '

                               'command: %s') % command['command'])

            return True

        # TODO should we also call checkperm() here? Maybe not if we're going

        # to overhaul that API. The granted scope from the URL check should

        # be good enough.

    else:

        # Don't allow multiple commands outside of ``multirequest`` URL.

        if issubsequent:

            # TODO proper error mechanism

            res.status = b'200 OK'

            res.headers[b'Content-Type'] = b'text/plain'

            res.setbodybytes(_('multiple commands cannot be issued to this '

                               'URL'))

            return True

        if reqcommand != command['command']:

            # TODO define proper error mechanism

            res.status = b'200 OK'

            res.headers[b'Content-Type'] = b'text/plain'

            res.setbodybytes(_('command in frame must match command in URL'))

            return True

    res.status = b'200 OK'

    res.headers[b'Content-Type'] = FRAMINGTYPE

    try:

        objs = dispatch(repo, proto, command['command'])

        action, meta = reactor.oncommandresponsereadyobjects(

            outstream, command['requestid'], objs)

    except Exception as e:

        action, meta = reactor.onservererror(

            outstream, command['requestid'],

            _('exception when invoking command: %s') % e)

    if action == 'sendframes':

        res.setbodygen(meta['framegen'])

        return True

    elif action == 'noop':

        return False

    else:

        raise error.ProgrammingError('unhandled event from reactor: %s' %

                                     action)

def getdispatchrepo(repo, proto, command):

    return repo.filtered('served')

def dispatch(repo, proto, command):

    repo = getdispatchrepo(repo, proto, command)

    func, spec = COMMANDS[command]

    args = proto.getargs(spec)

    return func(repo, proto, **args)

@interfaceutil.implementer(wireprototypes.baseprotocolhandler)

class httpv2protocolhandler(object):

    def __init__(self, req, ui, args=None):

        self._req = req

        self._ui = ui

        self._args = args

    @property

    def name(self):

        return HTTP_WIREPROTO_V2

    def getargs(self, args):

        data = {}

        for k, typ in args.items():

            if k == '*':

                raise NotImplementedError('do not support * args')

            elif k in self._args:

                # TODO consider validating value types.

                data[k] = self._args[k]

        return data

    def getprotocaps(self):

        # Protocol capabilities are currently not implemented for HTTP V2.

        return set()

    def getpayload(self):

        raise NotImplementedError

    @contextlib.contextmanager

    def mayberedirectstdio(self):

        raise NotImplementedError

    def client(self):

        raise NotImplementedError

    def addcapabilities(self, repo, caps):

        return caps

    def checkperm(self, perm):

        raise NotImplementedError

def httpv2apidescriptor(req, repo):

    proto = httpv2protocolhandler(req, repo.ui)

    return _capabilitiesv2(repo, proto)

def _capabilitiesv2(repo, proto):

    """Obtain the set of capabilities for version 2 transports.

    These capabilities are distinct from the capabilities for version 1

    transports.

    """

    compression = []

    for engine in wireprototypes.supportedcompengines(repo.ui, util.SERVERROLE):

        compression.append({

            b'name': engine.wireprotosupport().name,

        })

    caps = {

        'commands': {},

        'compression': compression,

        'framingmediatypes': [FRAMINGTYPE],

    }

    # TODO expose available changesetdata fields.

    for command, entry in COMMANDS.items():

        caps['commands'][command] = {

            'args': entry.args,

            'permissions': [entry.permission],

        }

    if streamclone.allowservergeneration(repo):

        caps['rawrepoformats'] = sorted(repo.requirements &

                                        repo.supportedformats)

    return proto.addcapabilities(repo, caps)

def builddeltarequests(store, nodes):

    """Build a series of revision delta requests against a backend store.

    Returns a list of revision numbers in the order they should be sent

    and a list of ``irevisiondeltarequest`` instances to be made against

    the backend store.

    """

    # We sort and send nodes in DAG order because this is optimal for

    # storage emission.

    # TODO we may want a better storage API here - one where we can throw

    # a list of nodes and delta preconditions over a figurative wall and

    # have the storage backend figure it out for us.

    revs = dagop.linearize({store.rev(n) for n in nodes}, store.parentrevs)

    requests = []

    for rev in revs:

        node = store.node(rev)

        parents = store.parents(node)

        deltaparent = store.node(store.deltaparent(rev))

        # There is a delta in storage. That means we can send the delta

        # efficiently.

        #

        # But, the delta may be against a revision the receiver doesn't

        # have (e.g. shallow clone or when the delta isn't against a parent

        # revision). For now, we ignore the problem of shallow clone. As

        # long as a delta exists against a parent, we send it.

        # TODO allow arguments to control this behavior, as the receiver

        # may not have the base revision in some scenarios.

        if deltaparent != nullid and deltaparent in parents:

            basenode = deltaparent

        # Else there is no delta parent in storage or the delta that is

        # # there isn't suitable. Let's use a delta against a parent

        # revision, if possible.

        #

        # There is room to check if the delta parent is in the ancestry of

        # this node. But there isn't an API on the manifest storage object

        # for that. So ignore this case for now.

        elif parents[0] != nullid:

            basenode = parents[0]

        elif parents[1] != nullid:

            basenode = parents[1]

        # No potential bases to delta against. Send a full revision.

        else:

            basenode = nullid

        requests.append(changegroup.revisiondeltarequest(

            node=node,

            p1node=parents[0],

            p2node=parents[1],

            # Receiver deals with linknode resolution.

            linknode=nullid,

            basenode=basenode,

        ))

    return revs, requests

def wireprotocommand(name, args=None, permission='push'):

    """Decorator to declare a wire protocol command.

    ``name`` is the name of the wire protocol command being provided.

    ``args`` is a dict of argument names to example values.

    ``permission`` defines the permission type needed to run this command.

    Can be ``push`` or ``pull``. These roughly map to read-write and read-only,