cas_wrapper/cas_wrapper.py

import json
from typing import Dict

from plumbum import local, ProcessExecutionError


class CasWrapper:
    """
    The python wrapper around binary `cas`
    from Codenotary Community Attestation Service
    """

    binary_name = 'cas'

    def __init__(
            self,
            cas_api_key: str,
            cas_signer_id: str,
    ):
        if self.binary_name not in local:
            raise FileNotFoundError(
                'Binary CAS is not found in PATH on the machine',
            )
        self._cas_api_key = cas_api_key
        self._cas_signer_id = cas_signer_id
        with local.env(
                CAS_API_KEY=self._cas_api_key,
                SIGNER_ID=self._cas_signer_id
        ):
            self._cas = local['cas']
            self._cas['login']()

    def notarize(
            self,
            local_path: str,
            metadata: Dict = None,
    ) -> str:
        """
        Wrapper around `cas notarize`
        :param local_path: path to a local Git repo
        :param metadata: additional metadata
        :return: hash of notarized commit
        :rtype: str
        """
        command = self._cas[
            'notarize',
            local_path,
            '-o',
            'json',
        ]
        if metadata is not None:
            for key, value in metadata.items():
                command = command[
                    '-a',
                    f'{key}={value}',
                ]
        result_of_execution = command()
        return json.loads(result_of_execution)['hash']

    def authenticate(
            self,
            local_path: str,
    ):
        """
        Wrapper around `cas authenticate`
        :param local_path: path to a local Git repo
               (should be started from `git://`)
               or to a single local file
        :return: true if a commit is trusted, vice versa - false
        :rtype: bool
        """
        command = self._cas[
            'authenticate',
            local_path,
            '-o',
            'json',
        ]
        try:
            result_of_execution = command()
        except ProcessExecutionError:
            # in case if commit is untrusted
            result_of_execution = command(retcode=1)
        return not bool(json.loads(result_of_execution)['status'])