# -*- coding: utf-8 -*-
# config.py
# Copyright (C) 2015-2018 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
"""
Configuration for a LEAP provider.
"""
import binascii
import json
import os
import pkg_resources
import platform
import shutil
import sys

from collections import defaultdict
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.x509 import load_pem_x509_certificate
from urlparse import urlparse

from twisted.cred.credentials import Anonymous
from twisted.internet import defer
from twisted.logger import Logger
from twisted.web.client import downloadPage

from leap.bitmask.bonafide._http import httpRequest
from leap.bitmask.bonafide.errors import NotConfiguredError, NetworkError
from leap.bitmask.bonafide.provider import Discovery
from leap.bitmask.bonafide.session import Session
from leap.bitmask.util import here, STANDALONE

from leap.common.check import leap_assert
from leap.common.config import get_path_prefix as common_get_path_prefix
from leap.common.files import mkdir_p, get_mtime
from leap.common.http import HTTPClient


APPNAME = "bonafide"
if platform.system() == 'Windows':
    ENDPOINT = "tcp://127.0.0.1:5001"
else:
    ENDPOINT = "ipc:///tmp/%s.sock" % APPNAME

SERVICE = 'service'
ALLOW_ANONYMOUS = 'allow_anonymous'


def get_path_prefix(standalone=False):
    return common_get_path_prefix(standalone)


_preffix = get_path_prefix()
log = Logger()


def get_provider_path(domain, config='provider.json'):
    """
    Returns relative path for provider configs.

    :param domain: the domain to which this providerconfig belongs to.
    :type domain: str
    :returns: the path
    :rtype: str
    """
    # TODO sanitize domain
    leap_assert(domain is not None, 'get_provider_path: We need a domain')
    return os.path.join('providers', domain, config)


def get_ca_cert_path(basedir, domain):
    leap_assert(domain is not None, 'get_provider_path: We need a domain')

    enc_domain = domain.encode(sys.getfilesystemencoding())
    cert_path = os.path.join(basedir, 'providers', enc_domain, 'keys', 'ca',
                             'cacert.pem')
    if not is_file(cert_path):
        pinned_cert = get_pinned_path(domain, '.pem')
        if is_file(pinned_cert):
            return pinned_cert
    return cert_path


def update_modification_ts(path):
    """
    Sets modification time of a file to current time.

    :param path: the path to set ts to.
    :type path: str
    :returns: modification time
    :rtype: datetime object
    """
    os.utime(path, None)
    return get_mtime(path)


def is_file(path):
    """
    Returns True if the path exists and is a file.
    """
    return os.path.isfile(path)


def is_empty_file(path):
    """
    Returns True if the file at path is empty.
    """
    return os.stat(path).st_size is 0


def make_address(user, provider):
    """
    Return a full identifier for an user, as a email-like
    identifier.

    :param user: the username
    :type user: basestring
    :param provider: the provider domain
    :type provider: basestring
    """
    return '%s@%s' % (user, provider)


def get_username_and_provider(full_id):
    return full_id.split('@')


def list_providers():
    path = os.path.join(_preffix, "leap", "providers")
    path = os.path.expanduser(path)
    if not os.path.isdir(path):
        os.makedirs(path)
    configured = os.listdir(path)

    pinned = os.listdir(get_pinned_path())
    pinned = [provider[:-5] for provider in pinned if provider[-5:] == ".json"]

    return set(configured + pinned)


def delete_provider(domain):
    path = os.path.join(_preffix, "leap", "providers", domain)
    path = os.path.expanduser(path)
    if not os.path.exists(path):
        raise NotConfiguredError("Provider %s is not configured, can't be "
                                 "deleted" % (domain,))
    shutil.rmtree(path)
    Provider.providers[domain] = None


def get_pinned_path(domain=None, extension='.json'):
    if domain is None:
        filename = ''
    else:
        filename = domain.encode(sys.getfilesystemencoding()) + extension

    if STANDALONE:
        return os.path.join(here(), "..", "apps", "providers", filename)

    return pkg_resources.resource_filename(
        'leap.bitmask.bonafide.providers', filename)


class Provider(object):

    SERVICES_MAP = {
        'openvpn': ['eip'],
        'mx': ['soledad', 'smtp']}

    log = Logger()
    providers = defaultdict(None)

    @classmethod
    def get(self, domain, autoconf=False, basedir=None,
            cert_path=None):
        if domain not in self.providers:
            self.providers[domain] = Provider(domain, autoconf, basedir,
                                              cert_path)
        return self.providers[domain]

    def __init__(self, domain, autoconf=False, basedir=None,
                 cert_path=None):
        if not basedir:
            basedir = os.path.join(_preffix, 'leap')
        self._basedir = os.path.expanduser(basedir)
        self._domain = domain
        self._disco = Discovery('https://%s' % domain)
        self._provider_config = None

        self.first_bootstrap = defer.Deferred()

        is_configured = self.is_configured()
        if not cert_path and is_configured:
            cert_path = self._get_ca_cert_path()
        self._http = HTTPClient(cert_path)

        self._load_provider_json()

        if not is_configured:
            if autoconf:
                self.log.debug(
                    'BOOTSTRAP: provider %s not initialized, '
                    'downloading files...' % domain)
                self.bootstrap()
            else:
                raise NotConfiguredError("Provider %s is not configured"
                                         % (domain,))
        else:
            self.log.debug(
                'BOOTSTRAP: Provider is already initialized, checking if '
                'there are newest config files...')
            self.bootstrap(replace_if_newer=True)

    @property
    def domain(self):
        return self._domain

    @property
    def api_uri(self):
        if not self._provider_config:
            return None
        return self._provider_config.api_uri

    @property
    def version(self):
        if not self._provider_config:
            return 1
        return int(self._provider_config.api_version)

    def is_configured(self):
        provider_json = self._get_provider_json_path()
        pinned_json = get_pinned_path(self._domain)
        if not is_file(provider_json) and not is_file(pinned_json):
            return False

        provider_cert = self._get_ca_cert_path()
        pinned_cert = get_pinned_path(self._domain, '.pem')
        if not is_file(provider_cert) and not is_file(pinned_cert):
            return False
        return True

    def config(self, service=None):
        if not service:
            if not self._provider_config:
                self._load_provider_json()
            return self._provider_config.dict()

        path = self._get_service_config_path(service)
        try:
            with open(path, 'r') as config:
                config = Record(**json.load(config))
        except IOError:
            raise ValueError("Service " + service +
                             " not found in provider " + self._domain)
        return config

    def bootstrap(self, replace_if_newer=False):
        domain = self._domain
        self.log.debug('Bootstrapping provider %s' % domain)

        def first_bootstrap_done(ignored):
            if self._allows_anonymous():
                # we continue bootstrapping, we do not
                # need to wait for authentication.
                return
            try:
                self.first_bootstrap.callback('got config')
            except defer.AlreadyCalledError:
                pass

        def first_bootstrap_error(failure):
            self.first_bootstrap.errback(failure)
            return failure

        d = self.maybe_download_provider_info(replace=replace_if_newer)
        d.addCallback(self.maybe_download_ca_cert, replace_if_newer)
        d.addCallback(self.validate_ca_cert)
        d.addCallbacks(first_bootstrap_done, first_bootstrap_error)
        d.addCallback(self.maybe_download_services_config)
        self.ongoing_bootstrap = d

    def _allows_anonymous(self):
        config = self.config()
        try:
            anon = config.get(SERVICE).get(ALLOW_ANONYMOUS, False)
        except ValueError:
            anon = False
        return anon

    def callWhenMainConfigReady(self, cb, *args, **kw):
        d = self.first_bootstrap
        d.addCallback(lambda _: cb(*args, **kw))
        return d

    def callWhenReady(self, cb, *args, **kw):
        d = self.ongoing_bootstrap
        d.addCallback(lambda _: cb(*args, **kw))
        return d

    def has_valid_certificate(self):
        pass

    def maybe_download_provider_info(self, replace=False):
        """
        Download the provider.json info from the main domain.
        This SHOULD only be used once with the DOMAIN url.
        """
        provider_json = self._get_provider_json_path()

        if is_file(provider_json) and not replace:
            return defer.succeed('provider_info_already_exists')

        folders, f = os.path.split(provider_json)
        mkdir_p(folders)

        uri = self._disco.get_provider_info_uri()
        met = self._disco.get_provider_info_method()

        def errback(failure):
            shutil.rmtree(folders)
            raise NetworkError(failure.getErrorMessage())

        d = httpRequest(
            self._http._agent,
            uri, method=met, saveto=provider_json)
        d.addCallback(lambda _: self._load_provider_json())
        d.addErrback(errback)
        return d

    def update_provider_info(self):
        """
        Get more recent copy of provider.json from the api URL.
        """
        pass

    def maybe_download_ca_cert(self, ignored, replace=False):
        """
        :rtype: deferred
        """
        # TODO: doesn't update the cert :((((
        enc_domain = self._domain.encode(sys.getfilesystemencoding())
        path = os.path.join(self._basedir, 'providers', enc_domain, 'keys',
                            'ca', 'cacert.pem')
        if not replace and is_file(path):
            return defer.succeed('ca_cert_path_already_exists')

        def errback(failure):
            raise NetworkError(failure.getErrorMessage())

        uri = self._get_ca_cert_uri()
        mkdir_p(os.path.split(path)[0])

        # We don't validate the TLS cert for this connection,
        # just check the fingerprint of the ca.cert
        d = downloadPage(uri, path)
        d.addCallback(self._reload_http_client)
        d.addErrback(errback)
        return d

    def _reload_http_client(self, ret):
        self._http = HTTPClient(self._get_ca_cert_path())
        return ret

    def validate_ca_cert(self, ignored):
        expected = self._get_expected_ca_cert_fingerprint()
        algo, expectedfp = expected.split(':')
        expectedfp = expectedfp.replace(' ', '')
        backend = default_backend()

        with open(self._get_ca_cert_path(), 'r') as f:
            certstr = f.read()
        cert = load_pem_x509_certificate(certstr, backend)
        hasher = getattr(hashes, algo)()
        fpbytes = cert.fingerprint(hasher)
        fp = binascii.hexlify(fpbytes)

        if fp != expectedfp:
            os.unlink(self._get_ca_cert_path())
            self.log.error("Fingerprint of CA cert doesn't match: %s <-> %s"
                           % (fp, expectedfp))
            raise NetworkError("The provider's CA fingerprint doesn't match")

    def _get_expected_ca_cert_fingerprint(self):
        try:
            fgp = self._provider_config.ca_cert_fingerprint
        except AttributeError:
            fgp = None
        return fgp

    # Services config files

    def has_fetched_services_config(self):
        return os.path.isfile(self._get_configs_path())

    def maybe_download_services_config(self, ignored):
        # TODO --- currently, some providers (mail.bitmask.net) raise 401
        # UNAUTHENTICATED if we try to get the services
        # See: # https://leap.se/code/issues/7906

        def first_bootstrap_done(ignored):
            try:
                self.first_bootstrap.callback('got config')
            except defer.AlreadyCalledError:
                pass

        uri, met, path = self._get_configs_download_params()
        d = httpRequest(
            self._http._agent, uri, method=met, saveto=path)
        d.addCallback(lambda _: self._load_provider_json())
        d.addCallback(
            lambda _: self._get_config_for_all_services(session=None))
        d.addCallback(first_bootstrap_done)
        d.addErrback(lambda _: 'ok for now')
        return d

    def download_services_config_with_auth(self, session):

        def verify_provider_configs(ignored):
            self._load_provider_configs()
            return True

        self._load_provider_json()
        uri, met, path = self._get_configs_download_params()

        d = session.fetch_provider_configs(uri, path, met)
        d.addCallback(verify_provider_configs)
        d.addCallback(lambda _: self._get_config_for_all_services(session))
        return d

    def _get_configs_download_params(self):
        uri = self._disco.get_configs_uri()
        met = self._disco.get_configs_method()
        path = self._get_configs_path()
        return uri, met, path

    def offers_service(self, service):
        if service not in self.SERVICES_MAP.keys():
            raise RuntimeError('Unknown service: %s' % service)
        return service in self._provider_config.services

    def is_service_enabled(self, service):
        # TODO implement on some config file
        return True

    def has_config_for_service(self, service):
        has_file = os.path.isfile
        path = self._get_service_config_path
        smap = self.SERVICES_MAP

        result = all([has_file(path(subservice)) for
                      subservice in smap[service]])
        return result

    def has_config_for_all_services(self):
        self._load_provider_json()
        if not self._provider_config:
            return False
        all_services = self._provider_config.services
        has_all = all(
            [self.has_config_for_service(service) for service in
             all_services])
        return has_all

    def _get_provider_json_path(self):
        domain = self._domain.encode(sys.getfilesystemencoding())
        provider_json_path = os.path.join(
            self._basedir, get_provider_path(domain, config='provider.json'))
        return provider_json_path

    def _get_configs_path(self):
        domain = self._domain.encode(sys.getfilesystemencoding())
        configs_path = os.path.join(
            self._basedir, get_provider_path(domain, config='configs.json'))
        return configs_path

    def _get_service_config_path(self, service):
        domain = self._domain.encode(sys.getfilesystemencoding())
        configs_path = os.path.join(
            self._basedir, get_provider_path(
                domain, config='%s-service.json' % service))
        return configs_path

    def _get_ca_cert_path(self):
        return get_ca_cert_path(self._basedir, self._domain)

    def _get_ca_cert_uri(self):
        try:
            uri = self._provider_config.ca_cert_uri
            uri = str(uri)
        except Exception:
            uri = None
        return uri

    def _load_provider_json(self):
        path = self._get_provider_json_path()
        if not is_file(path):
            self.log.debug('cannot LOAD provider config path %s' % path)
            path = get_pinned_path(self._domain)
            if not is_file(path):
                return

            self.log.debug('using pinned provider %s' % path)

        with open(path, 'r') as config:
            self._provider_config = Record(**json.load(config))

        api_uri = self._provider_config.api_uri
        if api_uri:
            parsed = urlparse(api_uri)
            self._disco.netloc = parsed.netloc

    def _get_config_for_all_services(self, session):
        if session is None:
            provider_cert = self._get_ca_cert_path()
            session = Session(Anonymous(), self.api_uri, provider_cert)

        services_dict = self._load_provider_configs()
        configs_path = self._get_configs_path()
        with open(configs_path) as jsonf:
            services_dict = Record(**json.load(jsonf)).services
        pending = []
        base = self._disco.get_base_uri()
        for service in self._provider_config.services:
            if service in self.SERVICES_MAP.keys():
                for subservice in self.SERVICES_MAP[service]:
                    uri = base + str(services_dict[subservice])
                    path = self._get_service_config_path(subservice)
                    d = session.fetch_provider_configs(
                        uri, path, method='GET')
                    pending.append(d)
        return defer.gatherResults(pending)

    def _load_provider_configs(self):
        configs_path = self._get_configs_path()
        with open(configs_path) as jsonf:
            services_dict = Record(**json.load(jsonf)).services
        return services_dict


class Record(object):
    def __init__(self, **kw):
        self.__dict__.update(kw)

    def dict(self):
        return self.__dict__


if __name__ == '__main__':
    from twisted.internet.task import react

    def main(reactor, *args):
        provider = Provider('cdev.bitmask.net', autoconf=True)
        return provider.callWhenReady(print_done)

    def print_done():
        print '>>> bootstrapping done!!!'

    react(main, [])