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

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

"""server side extension to advertise pre-generated bundles to seed clones.

The extension essentially serves the content of a .hg/clonebundles.manifest

file to clients that request it.

The clonebundles.manifest file contains a list of URLs and attributes. URLs

hold pre-generated bundles that a client fetches and applies. After applying

the pre-generated bundle, the client will connect back to the original server

and pull data not in the pre-generated bundle.

Manifest File Format:

The manifest file contains a newline (\n) delimited list of entries.

Each line in this file defines an available bundle. Lines have the format:

    <URL> [<key>=<value]

That is, a URL followed by extra metadata describing it. Metadata keys and

values should be URL encoded.

This metadata is optional. It is up to server operators to populate this

metadata.

Keys in UPPERCASE are reserved for use by Mercurial. All non-uppercase keys

can be used by site installations.

The server operator is responsible for generating the bundle manifest file.

Metadata Attributes:

"""

from mercurial import (

    extensions,

    wireproto,

)

testedwith = 'internal'

def capabilities(orig, repo, proto):

    caps = orig(repo, proto)

    # Only advertise if a manifest exists. This does add some I/O to requests.

    # But this should be cheaper than a wasted network round trip due to

    # missing file.

    if repo.opener.exists('clonebundles.manifest'):

        caps.append('clonebundles')

    return caps

@wireproto.wireprotocommand('clonebundles', '')

def bundles(repo, proto):

    """Server command for returning info for available bundles to seed clones.

    Clients will parse this response and determine what bundle to fetch.

    Other extensions may wrap this command to filter or dynamically emit

    data depending on the request. e.g. you could advertise URLs for

    the closest data center given the client's IP address.

    """

    return repo.opener.tryread('clonebundles.manifest')

def extsetup(ui):

    extensions.wrapfunction(wireproto, '_capabilities', capabilities)