"""
.. module: lemur.certificates.models
    :platform: Unix
    :copyright: (c) 2015 by Netflix Inc., see AUTHORS for more
    :license: Apache, see LICENSE for more details.
.. moduleauthor:: Kevin Glisson <kglisson@netflix.com>
"""
import arrow
from datetime import timedelta

from flask import current_app

from cryptography import x509
from cryptography.hazmat.primitives.asymmetric import rsa

from idna.core import InvalidCodepoint

from sqlalchemy.orm import relationship
from sqlalchemy.sql.expression import case, extract
from sqlalchemy.ext.hybrid import hybrid_property
from sqlalchemy import event, Integer, ForeignKey, String, PassiveDefault, func, Column, Text, Boolean

from sqlalchemy_utils.types.arrow import ArrowType

import lemur.common.utils

from lemur.database import db
from lemur.extensions import sentry

from lemur.utils import Vault
from lemur.common import defaults

from lemur.plugins.base import plugins

from lemur.extensions import metrics

from lemur.models import certificate_associations, certificate_source_associations, \
    certificate_destination_associations, certificate_notification_associations, \
    certificate_replacement_associations, roles_certificates

from lemur.domains.models import Domain
from lemur.policies.models import RotationPolicy


def get_sequence(name):
    if '-' not in name:
        return name, None

    parts = name.split('-')
    end = parts.pop(-1)
    root = '-'.join(parts)

    if len(end) == 8:
        return root + '-' + end, None

    try:
        end = int(end)
    except ValueError:
        end = None

    return root, end


def get_or_increase_name(name):
    certificates = Certificate.query.filter(Certificate.name.ilike('{0}%'.format(name))).all()

    if not certificates:
        return name

    ends = [0]
    root, end = get_sequence(name)
    for cert in certificates:
        root, end = get_sequence(cert.name)
        if end:
            ends.append(end)

    return '{0}-{1}'.format(root, max(ends) + 1)


class Certificate(db.Model):
    __tablename__ = 'certificates'
    id = Column(Integer, primary_key=True)
    owner = Column(String(128), nullable=False)
    name = Column(String(128), unique=True)
    description = Column(String(1024))
    notify = Column(Boolean, default=True)

    body = Column(Text(), nullable=False)
    chain = Column(Text())
    private_key = Column(Vault)

    issuer = Column(String(128))
    serial = Column(String(128))
    cn = Column(String(128))
    deleted = Column(Boolean, index=True)

    not_before = Column(ArrowType)
    not_after = Column(ArrowType)
    date_created = Column(ArrowType, PassiveDefault(func.now()), nullable=False)

    signing_algorithm = Column(String(128))
    status = Column(String(128))
    bits = Column(Integer())
    san = Column(String(1024))  # TODO this should be migrated to boolean

    rotation = Column(Boolean, default=False)
    user_id = Column(Integer, ForeignKey('users.id'))
    authority_id = Column(Integer, ForeignKey('authorities.id', ondelete="CASCADE"))
    root_authority_id = Column(Integer, ForeignKey('authorities.id', ondelete="CASCADE"))
    rotation_policy_id = Column(Integer, ForeignKey('rotation_policies.id'))

    notifications = relationship('Notification', secondary=certificate_notification_associations, backref='certificate')
    destinations = relationship('Destination', secondary=certificate_destination_associations, backref='certificate')
    sources = relationship('Source', secondary=certificate_source_associations, backref='certificate')
    domains = relationship('Domain', secondary=certificate_associations, backref='certificate')
    roles = relationship('Role', secondary=roles_certificates, backref='certificate')
    replaces = relationship('Certificate',
                            secondary=certificate_replacement_associations,
                            primaryjoin=id == certificate_replacement_associations.c.certificate_id,  # noqa
                            secondaryjoin=id == certificate_replacement_associations.c.replaced_certificate_id,  # noqa
                            backref='replaced')

    logs = relationship('Log', backref='certificate')
    endpoints = relationship('Endpoint', backref='certificate')
    rotation_policy = relationship("RotationPolicy")

    sensitive_fields = ('private_key',)

    def __init__(self, **kwargs):
        cert = lemur.common.utils.parse_certificate(kwargs['body'])

        self.issuer = defaults.issuer(cert)
        self.cn = defaults.common_name(cert)
        self.san = defaults.san(cert)
        self.not_before = defaults.not_before(cert)
        self.not_after = defaults.not_after(cert)

        # when destinations are appended they require a valid name.
        if kwargs.get('name'):
            self.name = get_or_increase_name(defaults.text_to_slug(kwargs['name']))
        else:
            self.name = get_or_increase_name(
                defaults.certificate_name(self.cn, self.issuer, self.not_before, self.not_after, self.san))

        self.owner = kwargs['owner']
        self.body = kwargs['body'].strip()

        if kwargs.get('private_key'):
            self.private_key = kwargs['private_key'].strip()

        if kwargs.get('chain'):
            self.chain = kwargs['chain'].strip()

        self.notify = kwargs.get('notify', True)
        self.destinations = kwargs.get('destinations', [])
        self.notifications = kwargs.get('notifications', [])
        self.description = kwargs.get('description')
        self.roles = list(set(kwargs.get('roles', [])))
        self.replaces = kwargs.get('replaces', [])
        self.rotation = kwargs.get('rotation')
        self.rotation_policy = kwargs.get('rotation_policy')
        self.signing_algorithm = defaults.signing_algorithm(cert)
        self.bits = defaults.bitstrength(cert)
        self.serial = defaults.serial(cert)

        for domain in defaults.domains(cert):
            self.domains.append(Domain(name=domain))

    @property
    def active(self):
        return self.notify

    @property
    def organization(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        return defaults.organization(cert)

    @property
    def organizational_unit(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        return defaults.organizational_unit(cert)

    @property
    def country(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        return defaults.country(cert)

    @property
    def state(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        return defaults.state(cert)

    @property
    def location(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        return defaults.location(cert)

    @property
    def key_type(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        if isinstance(cert.public_key(), rsa.RSAPublicKey):
            return 'RSA{key_size}'.format(key_size=cert.public_key().key_size)

    @property
    def validity_remaining(self):
        return abs(self.not_after - arrow.utcnow())

    @property
    def validity_range(self):
        return self.not_after - self.not_before

    @property
    def subject(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        return cert.subject

    @property
    def public_key(self):
        cert = lemur.common.utils.parse_certificate(self.body)
        return cert.public_key()

    @hybrid_property
    def expired(self):
        if self.not_after <= arrow.utcnow():
            return True

    @expired.expression
    def expired(cls):
        return case(
            [
                (cls.not_after <= arrow.utcnow(), True)
            ],
            else_=False
        )

    @hybrid_property
    def revoked(self):
        if 'revoked' == self.status:
            return True

    @revoked.expression
    def revoked(cls):
        return case(
            [
                (cls.status == 'revoked', True)
            ],
            else_=False
        )

    @hybrid_property
    def in_rotation_window(self):
        """
        Determines if a certificate is available for rotation based
        on the rotation policy associated.
        :return:
        """
        now = arrow.utcnow()
        end = now + timedelta(days=self.rotation_policy.days)

        if self.not_after <= end:
            return True

    @in_rotation_window.expression
    def in_rotation_window(cls):
        """
        Determines if a certificate is available for rotation based
        on the rotation policy associated.
        :return:
        """
        return case(
            [
                (extract('day', cls.not_after - func.now()) <= RotationPolicy.days, True)
            ],
            else_=False
        )

    @property
    def extensions(self):
        # setup default values
        return_extensions = {
            'sub_alt_names': {'names': []}
        }

        try:
            cert = lemur.common.utils.parse_certificate(self.body)
            for extension in cert.extensions:
                value = extension.value
                if isinstance(value, x509.BasicConstraints):
                    return_extensions['basic_constraints'] = value

                elif isinstance(value, x509.SubjectAlternativeName):
                    return_extensions['sub_alt_names']['names'] = value

                elif isinstance(value, x509.ExtendedKeyUsage):
                    return_extensions['extended_key_usage'] = value

                elif isinstance(value, x509.KeyUsage):
                    return_extensions['key_usage'] = value

                elif isinstance(value, x509.SubjectKeyIdentifier):
                    return_extensions['subject_key_identifier'] = {'include_ski': True}

                elif isinstance(value, x509.AuthorityInformationAccess):
                    return_extensions['certificate_info_access'] = {'include_aia': True}

                elif isinstance(value, x509.AuthorityKeyIdentifier):
                    aki = {
                        'use_key_identifier': False,
                        'use_authority_cert': False
                    }

                    if value.key_identifier:
                        aki['use_key_identifier'] = True

                    if value.authority_cert_issuer:
                        aki['use_authority_cert'] = True

                    return_extensions['authority_key_identifier'] = aki

                # TODO: Don't support CRLDistributionPoints yet https://github.com/Netflix/lemur/issues/662
                elif isinstance(value, x509.CRLDistributionPoints):
                    current_app.logger.warning('CRLDistributionPoints not yet supported for clone operation.')

                # TODO: Not supporting custom OIDs yet. https://github.com/Netflix/lemur/issues/665
                else:
                    current_app.logger.warning('Custom OIDs not yet supported for clone operation.')
        except InvalidCodepoint as e:
            sentry.captureException()
            current_app.logger.warning('Unable to parse extensions due to underscore in dns name')
        except ValueError as e:
            sentry.captureException()
            current_app.logger.warning('Unable to parse')
            current_app.logger.exception(e)

        return return_extensions

    def __repr__(self):
        return "Certificate(name={name})".format(name=self.name)


@event.listens_for(Certificate.destinations, 'append')
def update_destinations(target, value, initiator):
    """
    Attempt to upload certificate to the new destination

    :param target:
    :param value:
    :param initiator:
    :return:
    """
    destination_plugin = plugins.get(value.plugin_name)

    try:
        if target.private_key:
            destination_plugin.upload(target.name, target.body, target.private_key, target.chain, value.options)
    except Exception as e:
        current_app.logger.exception(e)
        metrics.send('destination_upload_failure', 'counter', 1,
                     metric_tags={'certificate': target.name, 'destination': value.label})


@event.listens_for(Certificate.replaces, 'append')
def update_replacement(target, value, initiator):
    """
    When a certificate is marked as 'replaced' we should not notify.

    :param target:
    :param value:
    :param initiator:
    :return:
    """
    value.notify = False