# Copyright 2016 Blue Box, an IBM Company
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Several handy validation functions that go beyond simple type checking.
Defined here so these can also be used at deeper levels than the API.
"""


import re

import netaddr
from oslo_config import cfg
import rfc3986

from octavia.common import constants
from octavia.common import exceptions
from octavia.common import utils


CONF = cfg.CONF


def url(url, require_scheme=True):
    """Raises an error if the url doesn't look like a URL."""
    try:
        if not rfc3986.is_valid_uri(url, require_scheme=require_scheme):
            raise exceptions.InvalidURL(url=url)
        p_url = rfc3986.urlparse(rfc3986.normalize_uri(url))
        if require_scheme:
            if p_url.scheme != 'http' and p_url.scheme != 'https':
                raise exceptions.InvalidURL(url=url)
    except Exception:
        raise exceptions.InvalidURL(url=url)
    return True


def url_path(url_path):
    """Raises an error if the url_path doesn't look like a URL Path."""
    try:
        p_url = rfc3986.urlparse(rfc3986.normalize_uri(url_path))

        if (
            p_url.scheme or p_url.userinfo or p_url.host or
            p_url.port or
            p_url.path is None
        ):
            raise exceptions.InvalidURLPath(url_path=url_path)
    except Exception:
        raise exceptions.InvalidURLPath(url_path=url_path)
    return True


def header_name(header, what=None):
    """Raises an error if header does not look like an HTML header name."""
    p = re.compile(constants.HTTP_HEADER_NAME_REGEX)
    if not p.match(header):
        raise exceptions.InvalidString(what=what)
    return True


def cookie_value_string(value, what=None):
    """Raises an error if the value string contains invalid characters."""
    p = re.compile(constants.HTTP_COOKIE_VALUE_REGEX)
    if not p.match(value):
        raise exceptions.InvalidString(what=what)
    return True


def header_value_string(value, what=None):
    """Raises an error if the value string contains invalid characters."""
    p = re.compile(constants.HTTP_HEADER_VALUE_REGEX)
    q = re.compile(constants.HTTP_QUOTED_HEADER_VALUE_REGEX)
    if not p.match(value) and not q.match(value):
        raise exceptions.InvalidString(what=what)
    return True


def regex(regex):
    """Raises an error if the string given is not a valid regex."""
    try:
        re.compile(regex)
    except Exception as e:
        raise exceptions.InvalidRegex(e=str(e))
    return True


# Note that we can evaluate this outside the context of any L7 Policy because
# L7 rules must be internally consistent.
def l7rule_data(l7rule):
    """Raises an error if the l7rule given is invalid in some way."""
    if l7rule.type == constants.L7RULE_TYPE_HEADER:
        if not l7rule.key:
            raise exceptions.InvalidL7Rule(msg='L7 rule type requires a key')
        header_name(l7rule.key, what='key')
        if l7rule.compare_type == constants.L7RULE_COMPARE_TYPE_REGEX:
            regex(l7rule.value)
        elif l7rule.compare_type in (
                constants.L7RULE_COMPARE_TYPE_STARTS_WITH,
                constants.L7RULE_COMPARE_TYPE_ENDS_WITH,
                constants.L7RULE_COMPARE_TYPE_CONTAINS,
                constants.L7RULE_COMPARE_TYPE_EQUAL_TO):
            header_value_string(l7rule.value, what='header value')
        else:
            raise exceptions.InvalidL7Rule(msg='invalid comparison type '
                                           'for rule type')

    elif l7rule.type == constants.L7RULE_TYPE_COOKIE:
        if not l7rule.key:
            raise exceptions.InvalidL7Rule(msg='L7 rule type requires a key')
        header_name(l7rule.key, what='key')
        if l7rule.compare_type == constants.L7RULE_COMPARE_TYPE_REGEX:
            regex(l7rule.value)
        elif l7rule.compare_type in (
                constants.L7RULE_COMPARE_TYPE_STARTS_WITH,
                constants.L7RULE_COMPARE_TYPE_ENDS_WITH,
                constants.L7RULE_COMPARE_TYPE_CONTAINS,
                constants.L7RULE_COMPARE_TYPE_EQUAL_TO):
            cookie_value_string(l7rule.value, what='cookie value')
        else:
            raise exceptions.InvalidL7Rule(msg='invalid comparison type '
                                           'for rule type')

    elif l7rule.type in (constants.L7RULE_TYPE_HOST_NAME,
                         constants.L7RULE_TYPE_PATH):
        if l7rule.compare_type in (
                constants.L7RULE_COMPARE_TYPE_STARTS_WITH,
                constants.L7RULE_COMPARE_TYPE_ENDS_WITH,
                constants.L7RULE_COMPARE_TYPE_CONTAINS,
                constants.L7RULE_COMPARE_TYPE_EQUAL_TO):
            header_value_string(l7rule.value, what='comparison value')
        elif l7rule.compare_type == constants.L7RULE_COMPARE_TYPE_REGEX:
            regex(l7rule.value)
        else:
            raise exceptions.InvalidL7Rule(msg='invalid comparison type '
                                           'for rule type')

    elif l7rule.type == constants.L7RULE_TYPE_FILE_TYPE:
        if l7rule.compare_type == constants.L7RULE_COMPARE_TYPE_REGEX:
            regex(l7rule.value)
        elif l7rule.compare_type == constants.L7RULE_COMPARE_TYPE_EQUAL_TO:
            header_value_string(l7rule.value, what='comparison value')
        else:
            raise exceptions.InvalidL7Rule(msg='invalid comparison type '
                                           'for rule type')

    else:
        raise exceptions.InvalidL7Rule(msg='invalid rule type')
    return True


def sanitize_l7policy_api_args(l7policy, create=False):
    """Validate and make consistent L7Policy API arguments.

    This method is mainly meant to sanitize L7 Policy create and update
    API dictionaries, so that we strip 'None' values that don't apply for
    our particular update. This method does *not* verify that any
    redirect_pool_id exists in the database, but will raise an
    error if a redirect_url doesn't look like a URL.

    :param l7policy: The L7 Policy dictionary we are santizing / validating
    """
    if 'action' in l7policy.keys():
        if l7policy['action'] == constants.L7POLICY_ACTION_REJECT:
            l7policy.update({'redirect_url': None})
            l7policy.update({'redirect_pool_id': None})
            l7policy.pop('redirect_pool', None)
        elif l7policy['action'] == constants.L7POLICY_ACTION_REDIRECT_TO_URL:
            if not l7policy.get('redirect_url'):
                raise exceptions.InvalidL7PolicyArgs(
                    msg='redirect_url must not be None')
            l7policy.update({'redirect_pool_id': None})
            l7policy.pop('redirect_pool', None)
        elif l7policy['action'] == constants.L7POLICY_ACTION_REDIRECT_TO_POOL:
            if (not l7policy.get('redirect_pool_id') and
                    not l7policy.get('redirect_pool')):
                raise exceptions.InvalidL7PolicyArgs(
                    msg='redirect_pool_id or redirect_pool must not be None')
            l7policy.update({'redirect_url': None})
        else:
            raise exceptions.InvalidL7PolicyAction(
                action=l7policy['action'])
    if ((l7policy.get('redirect_pool_id') or
            l7policy.get('redirect_pool')) and l7policy.get('redirect_url')):
        raise exceptions.InvalidL7PolicyArgs(
            msg='Cannot specify redirect_pool_id and redirect_url '
                'at the same time')
    if l7policy.get('redirect_pool_id'):
        l7policy.update({
            'action': constants.L7POLICY_ACTION_REDIRECT_TO_POOL})
        l7policy.update({'redirect_url': None})
        l7policy.pop('redirect_pool', None)
    if l7policy.get('redirect_pool'):
        l7policy.update({
            'action': constants.L7POLICY_ACTION_REDIRECT_TO_POOL})
        l7policy.update({'redirect_url': None})
        l7policy.pop('redirect_pool_id', None)
    if l7policy.get('redirect_url'):
        url(l7policy['redirect_url'])
        l7policy.update({
            'action': constants.L7POLICY_ACTION_REDIRECT_TO_URL})
        l7policy.update({'redirect_pool_id': None})
        l7policy.pop('redirect_pool', None)

    # If we are creating, we need an action at this point
    if create and 'action' not in l7policy.keys():
        raise exceptions.InvalidL7PolicyAction(action='None')

    # See if we have anything left after that...
    if len(l7policy.keys()) == 0:
        raise exceptions.InvalidL7PolicyArgs(msg='Invalid update options')
    return l7policy


def port_exists(port_id):
    """Raises an exception when a port does not exist."""
    network_driver = utils.get_network_driver()
    try:
        port = network_driver.get_port(port_id)
    except Exception:
        raise exceptions.InvalidSubresource(resource='Port', id=port_id)
    return port


def subnet_exists(subnet_id):
    """Raises an exception when a subnet does not exist."""
    network_driver = utils.get_network_driver()
    try:
        subnet = network_driver.get_subnet(subnet_id)
    except Exception:
        raise exceptions.InvalidSubresource(resource='Subnet', id=subnet_id)
    return subnet


def network_exists_optionally_contains_subnet(network_id, subnet_id=None):
    """Raises an exception when a network does not exist.

    If a subnet is provided, also validate the network contains that subnet.
    """
    network_driver = utils.get_network_driver()
    try:
        network = network_driver.get_network(network_id)
    except Exception:
        raise exceptions.InvalidSubresource(resource='Network', id=network_id)
    if subnet_id:
        if not network.subnets or subnet_id not in network.subnets:
            raise exceptions.InvalidSubresource(resource='Subnet',
                                                id=subnet_id)
    return network


def network_allowed_by_config(network_id):
    if CONF.networking.valid_vip_networks:
        valid_networks = map(str.lower, CONF.networking.valid_vip_networks)
        if network_id not in valid_networks:
            raise exceptions.ValidationException(detail=_(
                'Supplied VIP network_id is not allowed by the configuration '
                'of this deployment.'))


def is_ip_member_of_cidr(address, cidr):
    if netaddr.IPAddress(address) in netaddr.IPNetwork(cidr):
        return True
    return False
