import base64
import json
import logging

import dockerpycreds
import six

from . import errors
from .utils import config

INDEX_NAME = 'docker.io'
INDEX_URL = 'https://index.{0}/v1/'.format(INDEX_NAME)
TOKEN_USERNAME = '<token>'

log = logging.getLogger(__name__)


def resolve_repository_name(repo_name):
    if '://' in repo_name:
        raise errors.InvalidRepository(
            'Repository name cannot contain a scheme ({0})'.format(repo_name)
        )

    index_name, remote_name = split_repo_name(repo_name)
    if index_name[0] == '-' or index_name[-1] == '-':
        raise errors.InvalidRepository(
            'Invalid index name ({0}). Cannot begin or end with a'
            ' hyphen.'.format(index_name)
        )
    return resolve_index_name(index_name), remote_name


def resolve_index_name(index_name):
    index_name = convert_to_hostname(index_name)
    if index_name == 'index.' + INDEX_NAME:
        index_name = INDEX_NAME
    return index_name


def get_config_header(client, registry):
    log.debug('Looking for auth config')
    if not client._auth_configs:
        log.debug(
            "No auth config in memory - loading from filesystem"
        )
        client._auth_configs = load_config()
    authcfg = resolve_authconfig(
        client._auth_configs, registry, credstore_env=client.credstore_env
    )
    # Do not fail here if no authentication exists for this
    # specific registry as we can have a readonly pull. Just
    # put the header if we can.
    if authcfg:
        log.debug('Found auth config')
        # auth_config needs to be a dict in the format used by
        # auth.py username , password, serveraddress, email
        return encode_header(authcfg)
    log.debug('No auth config found')
    return None


def split_repo_name(repo_name):
    parts = repo_name.split('/', 1)
    if len(parts) == 1 or (
        '.' not in parts[0] and ':' not in parts[0] and parts[0] != 'localhost'
    ):
        # This is a docker index repo (ex: username/foobar or ubuntu)
        return INDEX_NAME, repo_name
    return tuple(parts)


def get_credential_store(authconfig, registry):
    if not registry or registry == INDEX_NAME:
        registry = 'https://index.docker.io/v1/'

    return authconfig.get('credHelpers', {}).get(registry) or authconfig.get(
        'credsStore'
    )


def resolve_authconfig(authconfig, registry=None, credstore_env=None):
    """
    Returns the authentication data from the given auth configuration for a
    specific registry. As with the Docker client, legacy entries in the config
    with full URLs are stripped down to hostnames before checking for a match.
    Returns None if no match was found.
    """

    if 'credHelpers' in authconfig or 'credsStore' in authconfig:
        store_name = get_credential_store(authconfig, registry)
        if store_name is not None:
            log.debug(
                'Using credentials store "{0}"'.format(store_name)
            )
            cfg = _resolve_authconfig_credstore(
                authconfig, registry, store_name, env=credstore_env
            )
            if cfg is not None:
                return cfg
            log.debug('No entry in credstore - fetching from auth dict')

    # Default to the public index server
    registry = resolve_index_name(registry) if registry else INDEX_NAME
    log.debug("Looking for auth entry for {0}".format(repr(registry)))

    authdict = authconfig.get('auths', {})
    if registry in authdict:
        log.debug("Found {0}".format(repr(registry)))
        return authdict[registry]

    for key, conf in six.iteritems(authdict):
        if resolve_index_name(key) == registry:
            log.debug("Found {0}".format(repr(key)))
            return conf

    log.debug("No entry found")
    return None


def _resolve_authconfig_credstore(authconfig, registry, credstore_name,
                                  env=None):
    if not registry or registry == INDEX_NAME:
        # The ecosystem is a little schizophrenic with index.docker.io VS
        # docker.io - in that case, it seems the full URL is necessary.
        registry = INDEX_URL
    log.debug("Looking for auth entry for {0}".format(repr(registry)))
    store = dockerpycreds.Store(credstore_name, environment=env)
    try:
        data = store.get(registry)
        res = {
            'ServerAddress': registry,
        }
        if data['Username'] == TOKEN_USERNAME:
            res['IdentityToken'] = data['Secret']
        else:
            res.update({
                'Username': data['Username'],
                'Password': data['Secret'],
            })
        return res
    except dockerpycreds.CredentialsNotFound as e:
        log.debug('No entry found')
        return None
    except dockerpycreds.StoreError as e:
        raise errors.DockerException(
            'Credentials store error: {0}'.format(repr(e))
        )


def convert_to_hostname(url):
    return url.replace('http://', '').replace('https://', '').split('/', 1)[0]


def decode_auth(auth):
    if isinstance(auth, six.string_types):
        auth = auth.encode('ascii')
    s = base64.b64decode(auth)
    login, pwd = s.split(b':', 1)
    return login.decode('utf8'), pwd.decode('utf8')


def encode_header(auth):
    auth_json = json.dumps(auth).encode('ascii')
    return base64.urlsafe_b64encode(auth_json)


def parse_auth(entries, raise_on_error=False):
    """
    Parses authentication entries

    Args:
      entries:        Dict of authentication entries.
      raise_on_error: If set to true, an invalid format will raise
                      InvalidConfigFile

    Returns:
      Authentication registry.
    """

    conf = {}
    for registry, entry in six.iteritems(entries):
        if not isinstance(entry, dict):
            log.debug(
                'Config entry for key {0} is not auth config'.format(registry)
            )
            # We sometimes fall back to parsing the whole config as if it was
            # the auth config by itself, for legacy purposes. In that case, we
            # fail silently and return an empty conf if any of the keys is not
            # formatted properly.
            if raise_on_error:
                raise errors.InvalidConfigFile(
                    'Invalid configuration for registry {0}'.format(registry)
                )
            return {}
        if 'identitytoken' in entry:
            log.debug('Found an IdentityToken entry for registry {0}'.format(
                registry
            ))
            conf[registry] = {
                'IdentityToken': entry['identitytoken']
            }
            continue  # Other values are irrelevant if we have a token, skip.

        if 'auth' not in entry:
            # Starting with engine v1.11 (API 1.23), an empty dictionary is
            # a valid value in the auths config.
            # https://github.com/docker/compose/issues/3265
            log.debug(
                'Auth data for {0} is absent. Client might be using a '
                'credentials store instead.'.format(registry)
            )
            conf[registry] = {}
            continue

        username, password = decode_auth(entry['auth'])
        log.debug(
            'Found entry (registry={0}, username={1})'
            .format(repr(registry), repr(username))
        )

        conf[registry] = {
            'username': username,
            'password': password,
            'email': entry.get('email'),
            'serveraddress': registry,
        }
    return conf


def load_config(config_path=None, config_dict=None):
    """
    Loads authentication data from a Docker configuration file in the given
    root directory or if config_path is passed use given path.
    Lookup priority:
        explicit config_path parameter > DOCKER_CONFIG environment variable >
        ~/.docker/config.json > ~/.dockercfg
    """

    if not config_dict:
        config_file = config.find_config_file(config_path)

        if not config_file:
            return {}
        try:
            with open(config_file) as f:
                config_dict = json.load(f)
        except (IOError, KeyError, ValueError) as e:
            # Likely missing new Docker config file or it's in an
            # unknown format, continue to attempt to read old location
            # and format.
            log.debug(e)
            return _load_legacy_config(config_file)

    res = {}
    if config_dict.get('auths'):
        log.debug("Found 'auths' section")
        res.update({
            'auths': parse_auth(config_dict.pop('auths'), raise_on_error=True)
        })
    if config_dict.get('credsStore'):
        log.debug("Found 'credsStore' section")
        res.update({'credsStore': config_dict.pop('credsStore')})
    if config_dict.get('credHelpers'):
        log.debug("Found 'credHelpers' section")
        res.update({'credHelpers': config_dict.pop('credHelpers')})
    if res:
        return res

    log.debug(
        "Couldn't find auth-related section ; attempting to interpret "
        "as auth-only file"
    )
    return {'auths': parse_auth(config_dict)}


def _load_legacy_config(config_file):
    log.debug("Attempting to parse legacy auth file format")
    try:
        data = []
        with open(config_file) as f:
            for line in f.readlines():
                data.append(line.strip().split(' = ')[1])
            if len(data) < 2:
                # Not enough data
                raise errors.InvalidConfigFile(
                    'Invalid or empty configuration file!'
                )

        username, password = decode_auth(data[0])
        return {'auths': {
            INDEX_NAME: {
                'username': username,
                'password': password,
                'email': data[1],
                'serveraddress': INDEX_URL,
            }
        }}
    except Exception as e:
        log.debug(e)
        pass

    log.debug("All parsing attempts failed - returning empty config")
    return {}
