# pointer.py - Git-LFS pointer serialization

#

# 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 re

from mercurial.i18n import _

from mercurial import (

    error,

)

class InvalidPointer(error.RevlogError):

    pass

class gitlfspointer(dict):

    VERSION = 'https://git-lfs.github.com/spec/v1'

    def __init__(self, *args, **kwargs):

        self['version'] = self.VERSION

    @classmethod

    def deserialize(cls, text):

        try:

            return cls(l.split(' ', 1) for l in text.splitlines()).validate()

        except ValueError: # l.split returns 1 item instead of 2

            raise InvalidPointer(_('cannot parse git-lfs text: %r') % text)

    def serialize(self):

        sortkeyfunc = lambda x: (x[0] != 'version', x)

        items = sorted(self.validate().iteritems(), key=sortkeyfunc)

        return ''.join('%s %s\n' % (k, v) for k, v in items)

    def oid(self):

        return self['oid'].split(':')[-1]

    def size(self):

        return int(self['size'])

    # regular expressions used by _validate

    # see https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md

    _keyre = re.compile(br'\A[a-z0-9.-]+\Z')

    _valuere = re.compile(br'\A[^\n]*\Z')

    _requiredre = {

        'size': re.compile(br'\A[0-9]+\Z'),

        'oid': re.compile(br'\Asha256:[0-9a-f]{64}\Z'),

        'version': re.compile(br'\A%s\Z' % re.escape(VERSION)),

    }

    def validate(self):

        """raise InvalidPointer on error. return self if there is no error"""

        requiredcount = 0

        for k, v in self.iteritems():

            if k in self._requiredre:

                if not self._requiredre[k].match(v):

                    raise InvalidPointer(_('unexpected value: %s=%r') % (k, v))

                requiredcount += 1

            elif not self._keyre.match(k):

                raise InvalidPointer(_('unexpected key: %s') % k)

            if not self._valuere.match(v):

                raise InvalidPointer(_('unexpected value: %s=%r') % (k, v))

        if len(self._requiredre) != requiredcount:

            miss = sorted(set(self._requiredre.keys()).difference(self.keys()))

            raise InvalidPointer(_('missed keys: %s') % ', '.join(miss))

        return self

deserialize = gitlfspointer.deserialize