# repository.py - Interfaces and base classes for repositories and peers.

#

# Copyright 2017 Gregory Szorc <gregory.szorc@gmail.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

from .i18n import _

from . import (

    error,

)

from .utils import (

    interfaceutil,

)

# When narrowing is finalized and no longer subject to format changes,

# we should move this to just "narrow" or similar.

NARROW_REQUIREMENT = 'narrowhg-experimental'

# Local repository feature string.

# Revlogs are being used for file storage.

REPO_FEATURE_REVLOG_FILE_STORAGE = b'revlogfilestorage'

# The storage part of the repository is shared from an external source.

REPO_FEATURE_SHARED_STORAGE = b'sharedstore'

# LFS supported for backing file storage.

REPO_FEATURE_LFS = b'lfs'

# Repository supports being stream cloned.

REPO_FEATURE_STREAM_CLONE = b'streamclone'

REVISION_FLAG_CENSORED = 1 << 15

REVISION_FLAG_ELLIPSIS = 1 << 14

REVISION_FLAG_EXTSTORED = 1 << 13

REVISION_FLAGS_KNOWN = (

    REVISION_FLAG_CENSORED | REVISION_FLAG_ELLIPSIS | REVISION_FLAG_EXTSTORED)

class ipeerconnection(interfaceutil.Interface):

    """Represents a "connection" to a repository.

    This is the base interface for representing a connection to a repository.

    It holds basic properties and methods applicable to all peer types.

    This is not a complete interface definition and should not be used

    outside of this module.

    """

    ui = interfaceutil.Attribute("""ui.ui instance""")

    def url():

        """Returns a URL string representing this peer.

        Currently, implementations expose the raw URL used to construct the

        instance. It may contain credentials as part of the URL. The

        expectations of the value aren't well-defined and this could lead to

        data leakage.

        TODO audit/clean consumers and more clearly define the contents of this

        value.

        """

    def local():

        """Returns a local repository instance.

        If the peer represents a local repository, returns an object that

        can be used to interface with it. Otherwise returns ``None``.

        """

    def peer():

        """Returns an object conforming to this interface.

        Most implementations will ``return self``.

        """

    def canpush():

        """Returns a boolean indicating if this peer can be pushed to."""

    def close():

        """Close the connection to this peer.

        This is called when the peer will no longer be used. Resources

        associated with the peer should be cleaned up.

        """

class ipeercapabilities(interfaceutil.Interface):

    """Peer sub-interface related to capabilities."""

    def capable(name):

        """Determine support for a named capability.

        Returns ``False`` if capability not supported.

        Returns ``True`` if boolean capability is supported. Returns a string

        if capability support is non-boolean.

        Capability strings may or may not map to wire protocol capabilities.

        """

    def requirecap(name, purpose):

        """Require a capability to be present.

        Raises a ``CapabilityError`` if the capability isn't present.

        """

class ipeercommands(interfaceutil.Interface):

    """Client-side interface for communicating over the wire protocol.

    This interface is used as a gateway to the Mercurial wire protocol.

    methods commonly call wire protocol commands of the same name.

    """

    def branchmap():

        """Obtain heads in named branches.

        Returns a dict mapping branch name to an iterable of nodes that are

        heads on that branch.

        """

    def capabilities():

        """Obtain capabilities of the peer.

        Returns a set of string capabilities.

        """

    def clonebundles():

        """Obtains the clone bundles manifest for the repo.

        Returns the manifest as unparsed bytes.

        """

    def debugwireargs(one, two, three=None, four=None, five=None):

        """Used to facilitate debugging of arguments passed over the wire."""

    def getbundle(source, **kwargs):

        """Obtain remote repository data as a bundle.

        This command is how the bulk of repository data is transferred from

        the peer to the local repository

        Returns a generator of bundle data.

        """

    def heads():

        """Determine all known head revisions in the peer.

        Returns an iterable of binary nodes.

        """

    def known(nodes):

        """Determine whether multiple nodes are known.

        Accepts an iterable of nodes whose presence to check for.

        Returns an iterable of booleans indicating of the corresponding node

        at that index is known to the peer.

        """

    def listkeys(namespace):

        """Obtain all keys in a pushkey namespace.

        Returns an iterable of key names.

        """

    def lookup(key):

        """Resolve a value to a known revision.

        Returns a binary node of the resolved revision on success.

        """

    def pushkey(namespace, key, old, new):

        """Set a value using the ``pushkey`` protocol.

        Arguments correspond to the pushkey namespace and key to operate on and

        the old and new values for that key.

        Returns a string with the peer result. The value inside varies by the

        namespace.

        """

    def stream_out():

        """Obtain streaming clone data.

        Successful result should be a generator of data chunks.

        """

    def unbundle(bundle, heads, url):

        """Transfer repository data to the peer.

        This is how the bulk of data during a push is transferred.

        Returns the integer number of heads added to the peer.

        """

class ipeerlegacycommands(interfaceutil.Interface):

    """Interface for implementing support for legacy wire protocol commands.

    Wire protocol commands transition to legacy status when they are no longer

    used by modern clients. To facilitate identifying which commands are

    legacy, the interfaces are split.

    """

    def between(pairs):

        """Obtain nodes between pairs of nodes.

        ``pairs`` is an iterable of node pairs.

        Returns an iterable of iterables of nodes corresponding to each

        requested pair.

        """

    def branches(nodes):

        """Obtain ancestor changesets of specific nodes back to a branch point.

        For each requested node, the peer finds the first ancestor node that is

        a DAG root or is a merge.

        Returns an iterable of iterables with the resolved values for each node.

        """

    def changegroup(nodes, source):

        """Obtain a changegroup with data for descendants of specified nodes."""

    def changegroupsubset(bases, heads, source):

        pass

class ipeercommandexecutor(interfaceutil.Interface):

    """Represents a mechanism to execute remote commands.

    This is the primary interface for requesting that wire protocol commands

    be executed. Instances of this interface are active in a context manager

    and have a well-defined lifetime. When the context manager exits, all

    outstanding requests are waited on.

    """

    def callcommand(name, args):

        """Request that a named command be executed.

        Receives the command name and a dictionary of command arguments.

        Returns a ``concurrent.futures.Future`` that will resolve to the

        result of that command request. That exact value is left up to

        the implementation and possibly varies by command.

        Not all commands can coexist with other commands in an executor

        instance: it depends on the underlying wire protocol transport being

        used and the command itself.

        Implementations MAY call ``sendcommands()`` automatically if the

        requested command can not coexist with other commands in this executor.

        Implementations MAY call ``sendcommands()`` automatically when the

        future's ``result()`` is called. So, consumers using multiple

        commands with an executor MUST ensure that ``result()`` is not called

        until all command requests have been issued.

        """

    def sendcommands():

        """Trigger submission of queued command requests.

        Not all transports submit commands as soon as they are requested to

        run. When called, this method forces queued command requests to be

        issued. It will no-op if all commands have already been sent.

        When called, no more new commands may be issued with this executor.

        """

    def close():

        """Signal that this command request is finished.

        When called, no more new commands may be issued. All outstanding

        commands that have previously been issued are waited on before

        returning. This not only includes waiting for the futures to resolve,

        but also waiting for all response data to arrive. In other words,

        calling this waits for all on-wire state for issued command requests

        to finish.

        When used as a context manager, this method is called when exiting the

        context manager.

        This method may call ``sendcommands()`` if there are buffered commands.

        """

class ipeerrequests(interfaceutil.Interface):

    """Interface for executing commands on a peer."""

    def commandexecutor():

        """A context manager that resolves to an ipeercommandexecutor.

        The object this resolves to can be used to issue command requests

        to the peer.

        Callers should call its ``callcommand`` method to issue command

        requests.

        A new executor should be obtained for each distinct set of commands

        (possibly just a single command) that the consumer wants to execute

        as part of a single operation or round trip. This is because some

        peers are half-duplex and/or don't support persistent connections.

        e.g. in the case of HTTP peers, commands sent to an executor represent

        a single HTTP request. While some peers may support multiple command

        sends over the wire per executor, consumers need to code to the least

        capable peer. So it should be assumed that command executors buffer

        called commands until they are told to send them and that each

        command executor could result in a new connection or wire-level request

        being issued.

        """

class ipeerbase(ipeerconnection, ipeercapabilities, ipeerrequests):

    """Unified interface for peer repositories.

    All peer instances must conform to this interface.

    """

class ipeerv2(ipeerconnection, ipeercapabilities, ipeerrequests):

    """Unified peer interface for wire protocol version 2 peers."""

    apidescriptor = interfaceutil.Attribute(

        """Data structure holding description of server API.""")

@interfaceutil.implementer(ipeerbase)

class peer(object):

    """Base class for peer repositories."""

    def capable(self, name):

        caps = self.capabilities()

        if name in caps:

            return True

        name = '%s=' % name

        for cap in caps:

            if cap.startswith(name):

                return cap[len(name):]

        return False

    def requirecap(self, name, purpose):

        if self.capable(name):

            return

        raise error.CapabilityError(

            _('cannot %s; remote repository does not support the %r '

              'capability') % (purpose, name))

class iverifyproblem(interfaceutil.Interface):

    """Represents a problem with the integrity of the repository.

    Instances of this interface are emitted to describe an integrity issue

    with a repository (e.g. corrupt storage, missing data, etc).

    Instances are essentially messages associated with severity.

    """

    warning = interfaceutil.Attribute(

        """Message indicating a non-fatal problem.""")

    error = interfaceutil.Attribute(

        """Message indicating a fatal problem.""")

    node = interfaceutil.Attribute(

        """Revision encountering the problem.

        ``None`` means the problem doesn't apply to a single revision.

        """)

class irevisiondelta(interfaceutil.Interface):

    """Represents a delta between one revision and another.

    Instances convey enough information to allow a revision to be exchanged

    with another repository.

    Instances represent the fulltext revision data or a delta against

    another revision. Therefore the ``revision`` and ``delta`` attributes

    are mutually exclusive.

    Typically used for changegroup generation.

    """

    node = interfaceutil.Attribute(

        """20 byte node of this revision.""")

    p1node = interfaceutil.Attribute(

        """20 byte node of 1st parent of this revision.""")

    p2node = interfaceutil.Attribute(

        """20 byte node of 2nd parent of this revision.""")

    linknode = interfaceutil.Attribute(

        """20 byte node of the changelog revision this node is linked to.""")

    flags = interfaceutil.Attribute(

        """2 bytes of integer flags that apply to this revision.

        This is a bitwise composition of the ``REVISION_FLAG_*`` constants.

        """)

    basenode = interfaceutil.Attribute(

        """20 byte node of the revision this data is a delta against.

        ``nullid`` indicates that the revision is a full revision and not

        a delta.

        """)

    baserevisionsize = interfaceutil.Attribute(

        """Size of base revision this delta is against.

        May be ``None`` if ``basenode`` is ``nullid``.

        """)

    revision = interfaceutil.Attribute(

        """Raw fulltext of revision data for this node.""")

    delta = interfaceutil.Attribute(

        """Delta between ``basenode`` and ``node``.

        Stored in the bdiff delta format.

        """)

class ifilerevisionssequence(interfaceutil.Interface):

    """Contains index data for all revisions of a file.

    Types implementing this behave like lists of tuples. The index

    in the list corresponds to the revision number. The values contain

    index metadata.

    The *null* revision (revision number -1) is always the last item

    in the index.

    """

    def __len__():

        """The total number of revisions."""

    def __getitem__(rev):

        """Returns the object having a specific revision number.

        Returns an 8-tuple with the following fields:

        offset+flags

           Contains the offset and flags for the revision. 64-bit unsigned

           integer where first 6 bytes are the offset and the next 2 bytes

           are flags. The offset can be 0 if it is not used by the store.

        compressed size

            Size of the revision data in the store. It can be 0 if it isn't

            needed by the store.

        uncompressed size

            Fulltext size. It can be 0 if it isn't needed by the store.

        base revision

            Revision number of revision the delta for storage is encoded

            against. -1 indicates not encoded against a base revision.

        link revision

            Revision number of changelog revision this entry is related to.

        p1 revision

            Revision number of 1st parent. -1 if no 1st parent.

        p2 revision

            Revision number of 2nd parent. -1 if no 1st parent.

        node

            Binary node value for this revision number.

        Negative values should index off the end of the sequence. ``-1``

        should return the null revision. ``-2`` should return the most

        recent revision.

        """

    def __contains__(rev):

        """Whether a revision number exists."""

    def insert(self, i, entry):

        """Add an item to the index at specific revision."""

class ifileindex(interfaceutil.Interface):

    """Storage interface for index data of a single file.

    File storage data is divided into index metadata and data storage.

    This interface defines the index portion of the interface.

    The index logically consists of:

    * A mapping between revision numbers and nodes.

    * DAG data (storing and querying the relationship between nodes).

    * Metadata to facilitate storage.

    """

    def __len__():

        """Obtain the number of revisions stored for this file."""

    def __iter__():

        """Iterate over revision numbers for this file."""

    def hasnode(node):

        """Returns a bool indicating if a node is known to this store.

        Implementations must only return True for full, binary node values:

        hex nodes, revision numbers, and partial node matches must be

        rejected.