# Copyright 2013 Red Hat, Inc.
# 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.

import inspect

from oslo_utils import strutils
from oslo_utils import uuidutils
import wsme
from wsme import types as wtypes

from magnum.common import exception
from magnum.common import utils
from magnum.i18n import _


class MacAddressType(wtypes.UserType):
    """A simple MAC address type."""

    basetype = wtypes.text
    name = 'macaddress'

    @staticmethod
    def validate(value):
        return utils.validate_and_normalize_mac(value)

    @staticmethod
    def frombasetype(value):
        if value is None:
            return None
        return MacAddressType.validate(value)


class NameType(wtypes.UserType):
    """A logical name type."""

    basetype = wtypes.text
    name = 'name'

    @staticmethod
    def validate(value):
        if not utils.is_name_safe(value):
            raise exception.InvalidName(name=value)
        return value

    @staticmethod
    def frombasetype(value):
        if value is None:
            return None
        return NameType.validate(value)


class UuidType(wtypes.UserType):
    """A simple UUID type."""

    basetype = wtypes.text
    name = 'uuid'

    @staticmethod
    def validate(value):
        if not uuidutils.is_uuid_like(value):
            raise exception.InvalidUUID(uuid=value)
        return value

    @staticmethod
    def frombasetype(value):
        if value is None:
            return None
        return UuidType.validate(value)


class BooleanType(wtypes.UserType):
    """A simple boolean type."""

    basetype = wtypes.text
    name = 'boolean'

    @staticmethod
    def validate(value):
        try:
            return strutils.bool_from_string(value, strict=True)
        except ValueError as e:
            # raise Invalid to return 400 (BadRequest) in the API
            raise exception.Invalid(e)

    @staticmethod
    def frombasetype(value):
        if value is None:
            return None
        return BooleanType.validate(value)


class MultiType(wtypes.UserType):
    """A complex type that represents one or more types.

    Used for validating that a value is an instance of one of the types.

    :param types: Variable-length list of types.

    """
    basetype = wtypes.text

    def __init__(self, *types):
        self.types = types

    def __str__(self):
        return ' | '.join(map(str, self.types))

    def validate(self, value):
        for t in self.types:
            try:
                return wtypes.validate_value(t, value)
            except (exception.InvalidUUID, ValueError):
                pass
        else:
            raise ValueError(
                _("Wrong type. Expected '%(type)s', got '%(value)s'")
                % {'type': self.types, 'value': type(value)})


macaddress = MacAddressType()
uuid = UuidType()
name = NameType()
uuid_or_name = MultiType(UuidType, NameType)
boolean = BooleanType()


class JsonPatchType(wtypes.Base):
    """A complex type that represents a single json-patch operation."""

    path = wtypes.wsattr(wtypes.StringType(pattern='^(/[\w-]+)+$'),
                         mandatory=True)
    op = wtypes.wsattr(wtypes.Enum(str, 'add', 'replace', 'remove'),
                       mandatory=True)
    value = MultiType(wtypes.text, int)

    # The class of the objects being patched. Override this in subclasses.
    # Should probably be a subclass of magnum.api.controllers.base.APIBase.
    _api_base = None

    # Attributes that are not required for construction, but which may not be
    # removed if set. Override in subclasses if needed.
    _extra_non_removable_attrs = set()

    # Set of non-removable attributes, calculated lazily.
    _non_removable_attrs = None

    @staticmethod
    def internal_attrs():
        """Returns a list of internal attributes.

        Internal attributes can't be added, replaced or removed. This
        method may be overwritten by derived class.

        """
        return ['/created_at', '/id', '/links', '/updated_at',
                '/uuid', '/project_id', '/user_id']

    @classmethod
    def non_removable_attrs(cls):
        """Returns a set of names of attributes that may not be removed.

        Attributes whose 'mandatory' property is True are automatically added
        to this set. To add additional attributes to the set, override the
        field _extra_non_removable_attrs in subclasses, with a set of the form
        {'/foo', '/bar'}.
        """
        if cls._non_removable_attrs is None:
            cls._non_removable_attrs = cls._extra_non_removable_attrs.copy()
            if cls._api_base:
                fields = inspect.getmembers(cls._api_base,
                                            lambda a: not inspect.isroutine(a))
                for name, field in fields:
                    if getattr(field, 'mandatory', False):
                        cls._non_removable_attrs.add('/%s' % name)
        return cls._non_removable_attrs

    @staticmethod
    def validate(patch):
        if patch.path in patch.internal_attrs():
            msg = _("'%s' is an internal attribute and can not be updated")
            raise wsme.exc.ClientSideError(msg % patch.path)

        if patch.path in patch.non_removable_attrs() and patch.op == 'remove':
            msg = _("'%s' is a mandatory attribute and can not be removed")
            raise wsme.exc.ClientSideError(msg % patch.path)

        if patch.op != 'remove':
            if not patch.value:
                msg = _("'add' and 'replace' operations needs value")
                raise wsme.exc.ClientSideError(msg)

        ret = {'path': patch.path, 'op': patch.op}
        if patch.value:
            ret['value'] = patch.value
        return ret
