# Copyright 2013 NEC Corporation.  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.
"""
Internal implementation of request Body validating middleware.

"""

import base64

import jsonschema
from oslo.utils import timeutils
import rfc3986
import six

from nova import exception
from nova.i18n import _
from nova.openstack.common import uuidutils


@jsonschema.FormatChecker.cls_checks('date-time')
def _validate_datetime_format(instance):
    try:
        timeutils.parse_isotime(instance)
    except ValueError:
        return False
    else:
        return True


@jsonschema.FormatChecker.cls_checks('base64')
def _validate_base64_format(instance):
    try:
        base64.decodestring(instance)
    except base64.binascii.Error:
        return False

    return True


@jsonschema.FormatChecker.cls_checks('uuid')
def _validate_uuid_format(instance):
    return uuidutils.is_uuid_like(instance)


@jsonschema.FormatChecker.cls_checks('uri')
def _validate_uri(instance):
    return rfc3986.is_valid_uri(instance, require_scheme=True,
                                require_authority=True)


class _SchemaValidator(object):
    """A validator class

    This class is changed from Draft4Validator to validate minimum/maximum
    value of a string number(e.g. '10'). This changes can be removed when
    we tighten up the API definition and the XML conversion.
    Also FormatCheckers are added for checking data formats which would be
    passed through nova api commonly.

    """
    validator = None
    validator_org = jsonschema.Draft4Validator

    def __init__(self, schema):
        validators = {
            'minimum': self._validate_minimum,
            'maximum': self._validate_maximum,
        }
        validator_cls = jsonschema.validators.extend(self.validator_org,
                                                     validators)
        format_checker = jsonschema.FormatChecker()
        self.validator = validator_cls(schema, format_checker=format_checker)

    def validate(self, *args, **kwargs):
        try:
            self.validator.validate(*args, **kwargs)
        except jsonschema.ValidationError as ex:
            # NOTE: For whole OpenStack message consistency, this error
            #       message has been written as the similar format of WSME.
            if len(ex.path) > 0:
                detail = _("Invalid input for field/attribute %(path)s."
                           " Value: %(value)s. %(message)s") % {
                               'path': ex.path.pop(), 'value': ex.instance,
                               'message': ex.message
                           }
            else:
                detail = ex.message
            raise exception.ValidationError(detail=detail)
        except TypeError as ex:
            # NOTE: If passing non string value to patternProperties parameter,
            #       TypeError happens. Here is for catching the TypeError.
            detail = six.text_type(ex)
            raise exception.ValidationError(detail=detail)

    def _number_from_str(self, instance):
        try:
            value = int(instance)
        except (ValueError, TypeError):
            try:
                value = float(instance)
            except (ValueError, TypeError):
                return None
        return value

    def _validate_minimum(self, validator, minimum, instance, schema):
        instance = self._number_from_str(instance)
        if instance is None:
            return
        return self.validator_org.VALIDATORS['minimum'](validator, minimum,
                                                        instance, schema)

    def _validate_maximum(self, validator, maximum, instance, schema):
        instance = self._number_from_str(instance)
        if instance is None:
            return
        return self.validator_org.VALIDATORS['maximum'](validator, maximum,
                                                        instance, schema)
