# dirstatedocket.py - docket file for dirstate-v2

#

# Copyright Mercurial Contributors

#

# 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 struct

from ..revlogutils import docket as docket_mod

from . import v2

V2_FORMAT_MARKER = b"dirstate-v2\n"

# * 12 bytes: format marker

# * 32 bytes: node ID of the working directory's first parent

# * 32 bytes: node ID of the working directory's second parent

# * {TREE_METADATA_SIZE} bytes: tree metadata, parsed separately

# * 4 bytes: big-endian used size of the data file

# * 1 byte: length of the data file's UUID

# * variable: data file's UUID

#

# Node IDs are null-padded if shorter than 32 bytes.

# A data file shorter than the specified used size is corrupted (truncated)

HEADER = struct.Struct(

    ">{}s32s32s{}sLB".format(len(V2_FORMAT_MARKER), v2.TREE_METADATA_SIZE)

)

class DirstateDocket(object):

    data_filename_pattern = b'dirstate.%s'

    def __init__(self, parents, data_size, tree_metadata, uuid):

        self.parents = parents

        self.data_size = data_size

        self.tree_metadata = tree_metadata

        self.uuid = uuid

    @classmethod

    def with_new_uuid(cls, parents, data_size, tree_metadata):

        return cls(parents, data_size, tree_metadata, docket_mod.make_uid())

    @classmethod

    def parse(cls, data, nodeconstants):

        if not data:

            parents = (nodeconstants.nullid, nodeconstants.nullid)

            return cls(parents, 0, b'', None)

        marker, p1, p2, meta, data_size, uuid_size = HEADER.unpack_from(data)

        if marker != V2_FORMAT_MARKER:

            raise ValueError("expected dirstate-v2 marker")

        uuid = data[HEADER.size : HEADER.size + uuid_size]

        p1 = p1[: nodeconstants.nodelen]

        p2 = p2[: nodeconstants.nodelen]

        return cls((p1, p2), data_size, meta, uuid)

    def serialize(self):

        p1, p2 = self.parents

        header = HEADER.pack(

            V2_FORMAT_MARKER,

            p1,

            p2,

            self.tree_metadata,

            self.data_size,

            len(self.uuid),

        )

        return header + self.uuid

    def data_filename(self):

        return self.data_filename_pattern % self.uuid