# -*- encoding: utf-8 -*-
#
# Copyright 2013 Hewlett-Packard Development Company, L.P.
#
# 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.


"""SQLAlchemy storage backend."""

from oslo_config import cfg
from oslo_db import exception as db_exc
from oslo_db.sqlalchemy import session as db_session
from oslo_db.sqlalchemy import utils as db_utils
from oslo_log import log
from sqlalchemy.orm import exc

from watcher import _i18n
from watcher.common import exception
from watcher.common import utils
from watcher.db import api
from watcher.db.sqlalchemy import models
from watcher.objects import audit as audit_objects

CONF = cfg.CONF
LOG = log.getLogger(__name__)
_ = _i18n._

_FACADE = None


def _create_facade_lazily():
    global _FACADE
    if _FACADE is None:
        _FACADE = db_session.EngineFacade.from_config(CONF)
    return _FACADE


def get_engine():
    facade = _create_facade_lazily()
    return facade.get_engine()


def get_session(**kwargs):
    facade = _create_facade_lazily()
    return facade.get_session(**kwargs)


def get_backend():
    """The backend is this module itself."""
    return Connection()


def model_query(model, *args, **kwargs):
    """Query helper for simpler session usage.

    :param session: if present, the session to use
    """

    session = kwargs.get('session') or get_session()
    query = session.query(model, *args)
    return query


def add_identity_filter(query, value):
    """Adds an identity filter to a query.

    Filters results by ID, if supplied value is a valid integer.
    Otherwise attempts to filter results by UUID.

    :param query: Initial query to add filter to.
    :param value: Value for filtering results by.
    :return: Modified query.
    """
    if utils.is_int_like(value):
        return query.filter_by(id=value)
    elif utils.is_uuid_like(value):
        return query.filter_by(uuid=value)
    else:
        raise exception.InvalidIdentity(identity=value)


def _paginate_query(model, limit=None, marker=None, sort_key=None,
                    sort_dir=None, query=None):
    if not query:
        query = model_query(model)
    sort_keys = ['id']
    if sort_key and sort_key not in sort_keys:
        sort_keys.insert(0, sort_key)
    query = db_utils.paginate_query(query, model, limit, sort_keys,
                                    marker=marker, sort_dir=sort_dir)
    return query.all()


class Connection(api.BaseConnection):
    """SqlAlchemy connection."""

    def __init__(self):
        pass

    def _add_audit_templates_filters(self, query, filters):
        if filters is None:
            filters = []

        if 'name' in filters:
            query = query.filter_by(name=filters['name'])
        if 'host_aggregate' in filters:
            query = query.filter_by(host_aggregate=filters['host_aggregate'])
        if 'goal' in filters:
            query = query.filter_by(goal=filters['goal'])

        return query

    def _add_audits_filters(self, query, filters):
        if filters is None:
            filters = []

        if 'type' in filters:
            query = query.filter_by(type=filters['type'])
        if 'state' in filters:
            query = query.filter_by(state=filters['state'])
        if 'audit_template_id' in filters:
            query = query.filter_by(
                audit_template_id=filters['audit_template_id'])
        if 'audit_template_uuid' in filters:
            query = query.join(
                models.AuditTemplate,
                models.Audit.audit_template_id == models.AuditTemplate.id)
            query = query.filter(
                models.AuditTemplate.uuid == filters['audit_template_uuid'])
        if 'audit_template_name' in filters:
            query = query.join(
                models.AuditTemplate,
                models.Audit.audit_template_id == models.AuditTemplate.id)
            query = query.filter(
                models.AuditTemplate.name ==
                filters['audit_template_name'])
        return query

    def _add_action_plans_filters(self, query, filters):
        if filters is None:
            filters = []

        if 'state' in filters:
            query = query.filter_by(state=filters['state'])
        if 'audit_id' in filters:
            query = query.filter_by(audit_id=filters['audit_id'])
        if 'audit_uuid' in filters:
            query = query.join(models.Audit,
                               models.ActionPlan.audit_id == models.Audit.id)
            query = query.filter(models.Audit.uuid == filters['audit_uuid'])
        return query

    def _add_actions_filters(self, query, filters):
        if filters is None:
            filters = []

        if 'action_plan_id' in filters:
            query = query.filter_by(action_plan_id=filters['action_plan_id'])
        if 'action_plan_uuid' in filters:
            query = query.join(
                models.ActionPlan,
                models.Action.action_plan_id == models.ActionPlan.id)
            query = query.filter(
                models.ActionPlan.uuid == filters['action_plan_uuid'])
        if 'audit_uuid' in filters:
            stmt = model_query(models.ActionPlan).join(
                models.Audit,
                models.Audit.id == models.ActionPlan.audit_id)\
                .filter_by(uuid=filters['audit_uuid']).subquery()
            query = query.filter_by(action_plan_id=stmt.c.id)

        if 'state' in filters:
            query = query.filter_by(state=filters['state'])
        if 'alarm' in filters:
            query = query.filter_by(alarm=filters['alarm'])

        return query

    def get_audit_template_list(self, context, filters=None, limit=None,
                                marker=None, sort_key=None, sort_dir=None):

        query = model_query(models.AuditTemplate)
        query = self._add_audit_templates_filters(query, filters)
        if not context.show_deleted:
            query = query.filter_by(deleted_at=None)

        return _paginate_query(models.AuditTemplate, limit, marker,
                               sort_key, sort_dir, query)

    def create_audit_template(self, values):
        # ensure defaults are present for new audit_templates
        if not values.get('uuid'):
            values['uuid'] = utils.generate_uuid()

        audit_template = models.AuditTemplate()
        audit_template.update(values)

        try:
            audit_template.save()
        except db_exc.DBDuplicateEntry:
            raise exception.AuditTemplateAlreadyExists(uuid=values['uuid'],
                                                       name=values['name'])
        return audit_template

    def get_audit_template_by_id(self, context, audit_template_id):
        query = model_query(models.AuditTemplate)
        query = query.filter_by(id=audit_template_id)
        try:
            audit_template = query.one()
            if not context.show_deleted:
                if audit_template.deleted_at is not None:
                    raise exception.AuditTemplateNotFound(
                        audit_template=audit_template_id)
            return audit_template
        except exc.NoResultFound:
            raise exception.AuditTemplateNotFound(
                audit_template=audit_template_id)

    def get_audit_template_by_uuid(self, context, audit_template_uuid):
        query = model_query(models.AuditTemplate)
        query = query.filter_by(uuid=audit_template_uuid)

        try:
            audit_template = query.one()
            if not context.show_deleted:
                if audit_template.deleted_at is not None:
                    raise exception.AuditTemplateNotFound(
                        audit_template=audit_template_uuid)
            return audit_template
        except exc.NoResultFound:
            raise exception.AuditTemplateNotFound(
                audit_template=audit_template_uuid)

    def get_audit_template_by_name(self, context, audit_template_name):
        query = model_query(models.AuditTemplate)
        query = query.filter_by(name=audit_template_name)
        try:
            audit_template = query.one()
            if not context.show_deleted:
                if audit_template.deleted_at is not None:
                    raise exception.AuditTemplateNotFound(
                        audit_template=audit_template_name)
            return audit_template
        except exc.MultipleResultsFound:
            raise exception.Conflict(
                _('Multiple audit templates exist with the same name.'
                  ' Please use the audit template uuid instead'))
        except exc.NoResultFound:
            raise exception.AuditTemplateNotFound(
                audit_template=audit_template_name)

    def destroy_audit_template(self, audit_template_id):
        session = get_session()
        with session.begin():
            query = model_query(models.AuditTemplate, session=session)
            query = add_identity_filter(query, audit_template_id)

            try:
                query.one()
            except exc.NoResultFound:
                raise exception.AuditTemplateNotFound(node=audit_template_id)

            query.delete()

    def update_audit_template(self, audit_template_id, values):
        if 'uuid' in values:
            msg = _("Cannot overwrite UUID for an existing AuditTemplate.")
            raise exception.InvalidParameterValue(err=msg)

        return self._do_update_audit_template(audit_template_id, values)

    def _do_update_audit_template(self, audit_template_id, values):
        session = get_session()
        with session.begin():
            query = model_query(models.AuditTemplate, session=session)
            query = add_identity_filter(query, audit_template_id)
            try:
                ref = query.with_lockmode('update').one()
            except exc.NoResultFound:
                raise exception.AuditTemplateNotFound(
                    audit_template=audit_template_id)

            ref.update(values)
        return ref

    def soft_delete_audit_template(self, audit_template_id):
        session = get_session()
        with session.begin():
            query = model_query(models.AuditTemplate, session=session)
            query = add_identity_filter(query, audit_template_id)

            try:
                query.one()
            except exc.NoResultFound:
                raise exception.AuditTemplateNotFound(node=audit_template_id)

            query.soft_delete()

    def get_audit_list(self, context, filters=None, limit=None, marker=None,
                       sort_key=None, sort_dir=None):
        query = model_query(models.Audit)
        query = self._add_audits_filters(query, filters)
        if not context.show_deleted:
            query = query.filter(~(models.Audit.state == 'DELETED'))

        return _paginate_query(models.Audit, limit, marker,
                               sort_key, sort_dir, query)

    def create_audit(self, values):
        # ensure defaults are present for new audits
        if not values.get('uuid'):
            values['uuid'] = utils.generate_uuid()

        if values.get('state') is None:
            values['state'] = audit_objects.State.PENDING

        audit = models.Audit()
        audit.update(values)

        try:
            audit.save()
        except db_exc.DBDuplicateEntry:
            raise exception.AuditAlreadyExists(uuid=values['uuid'])
        return audit

    def get_audit_by_id(self, context, audit_id):
        query = model_query(models.Audit)
        query = query.filter_by(id=audit_id)
        try:
            audit = query.one()
            if not context.show_deleted:
                if audit.state == 'DELETED':
                    raise exception.AuditNotFound(audit=audit_id)
            return audit
        except exc.NoResultFound:
            raise exception.AuditNotFound(audit=audit_id)

    def get_audit_by_uuid(self, context, audit_uuid):
        query = model_query(models.Audit)
        query = query.filter_by(uuid=audit_uuid)

        try:
            audit = query.one()
            if not context.show_deleted:
                if audit.state == 'DELETED':
                    raise exception.AuditNotFound(audit=audit_uuid)
            return audit
        except exc.NoResultFound:
            raise exception.AuditNotFound(audit=audit_uuid)

    def destroy_audit(self, audit_id):
        def is_audit_referenced(session, audit_id):
            """Checks whether the audit is referenced by action_plan(s)."""
            query = model_query(models.ActionPlan, session=session)
            query = self._add_action_plans_filters(
                query, {'audit_id': audit_id})
            return query.count() != 0

        session = get_session()
        with session.begin():
            query = model_query(models.Audit, session=session)
            query = add_identity_filter(query, audit_id)

            try:
                audit_ref = query.one()
            except exc.NoResultFound:
                raise exception.AuditNotFound(audit=audit_id)

            if is_audit_referenced(session, audit_ref['id']):
                raise exception.AuditReferenced(audit=audit_id)

            query.delete()

    def update_audit(self, audit_id, values):
        if 'uuid' in values:
            msg = _("Cannot overwrite UUID for an existing Audit.")
            raise exception.InvalidParameterValue(err=msg)

        return self._do_update_audit(audit_id, values)

    def _do_update_audit(self, audit_id, values):
        session = get_session()
        with session.begin():
            query = model_query(models.Audit, session=session)
            query = add_identity_filter(query, audit_id)
            try:
                ref = query.with_lockmode('update').one()
            except exc.NoResultFound:
                raise exception.AuditNotFound(audit=audit_id)

            ref.update(values)
        return ref

    def soft_delete_audit(self, audit_id):
        session = get_session()
        with session.begin():
            query = model_query(models.Audit, session=session)
            query = add_identity_filter(query, audit_id)

            try:
                query.one()
            except exc.NoResultFound:
                raise exception.AuditNotFound(node=audit_id)

            query.soft_delete()

    def get_action_list(self, context, filters=None, limit=None, marker=None,
                        sort_key=None, sort_dir=None):
        query = model_query(models.Action)
        query = self._add_actions_filters(query, filters)
        if not context.show_deleted:
            query = query.filter(~(models.Action.state == 'DELETED'))
        return _paginate_query(models.Action, limit, marker,
                               sort_key, sort_dir, query)

    def create_action(self, values):
        # ensure defaults are present for new actions
        if not values.get('uuid'):
            values['uuid'] = utils.generate_uuid()

        action = models.Action()
        action.update(values)
        try:
            action.save()
        except db_exc.DBDuplicateEntry:
            raise exception.ActionAlreadyExists(uuid=values['uuid'])
        return action

    def get_action_by_id(self, context, action_id):
        query = model_query(models.Action)
        query = query.filter_by(id=action_id)
        try:
            action = query.one()
            if not context.show_deleted:
                if action.state == 'DELETED':
                    raise exception.ActionNotFound(
                        action=action_id)
            return action
        except exc.NoResultFound:
            raise exception.ActionNotFound(action=action_id)

    def get_action_by_uuid(self, context, action_uuid):
        query = model_query(models.Action)
        query = query.filter_by(uuid=action_uuid)
        try:
            action = query.one()
            if not context.show_deleted:
                if action.state == 'DELETED':
                    raise exception.ActionNotFound(
                        action=action_uuid)
            return action
        except exc.NoResultFound:
            raise exception.ActionNotFound(action=action_uuid)

    def destroy_action(self, action_id):
        session = get_session()
        with session.begin():
            query = model_query(models.Action, session=session)
            query = add_identity_filter(query, action_id)
            count = query.delete()
            if count != 1:
                raise exception.ActionNotFound(action_id)

    def update_action(self, action_id, values):
        # NOTE(dtantsur): this can lead to very strange errors
        if 'uuid' in values:
            msg = _("Cannot overwrite UUID for an existing Action.")
            raise exception.InvalidParameterValue(err=msg)

        return self._do_update_action(action_id, values)

    def _do_update_action(self, action_id, values):
        session = get_session()
        with session.begin():
            query = model_query(models.Action, session=session)
            query = add_identity_filter(query, action_id)
            try:
                ref = query.with_lockmode('update').one()
            except exc.NoResultFound:
                raise exception.ActionNotFound(action=action_id)

            ref.update(values)
        return ref

    def soft_delete_action(self, action_id):
        session = get_session()
        with session.begin():
            query = model_query(models.Action, session=session)
            query = add_identity_filter(query, action_id)

            try:
                query.one()
            except exc.NoResultFound:
                raise exception.ActionNotFound(node=action_id)

            query.soft_delete()

    def get_action_plan_list(
        self, context, columns=None, filters=None, limit=None,
            marker=None, sort_key=None, sort_dir=None):
        query = model_query(models.ActionPlan)
        query = self._add_action_plans_filters(query, filters)
        if not context.show_deleted:
            query = query.filter(~(models.ActionPlan.state == 'DELETED'))

        return _paginate_query(models.ActionPlan, limit, marker,
                               sort_key, sort_dir, query)

    def create_action_plan(self, values):
        # ensure defaults are present for new audits
        if not values.get('uuid'):
            values['uuid'] = utils.generate_uuid()

        action_plan = models.ActionPlan()
        action_plan.update(values)

        try:
            action_plan.save()
        except db_exc.DBDuplicateEntry:
            raise exception.ActionPlanAlreadyExists(uuid=values['uuid'])
        return action_plan

    def get_action_plan_by_id(self, context, action_plan_id):
        query = model_query(models.ActionPlan)
        query = query.filter_by(id=action_plan_id)
        try:
            action_plan = query.one()
            if not context.show_deleted:
                if action_plan.state == 'DELETED':
                    raise exception.ActionPlanNotFound(
                        action_plan=action_plan_id)
            return action_plan
        except exc.NoResultFound:
            raise exception.ActionPlanNotFound(action_plan=action_plan_id)

    def get_action_plan_by_uuid(self, context, action_plan__uuid):
        query = model_query(models.ActionPlan)
        query = query.filter_by(uuid=action_plan__uuid)

        try:
            action_plan = query.one()
            if not context.show_deleted:
                if action_plan.state == 'DELETED':
                    raise exception.ActionPlanNotFound(
                        action_plan=action_plan__uuid)
            return action_plan
        except exc.NoResultFound:
            raise exception.ActionPlanNotFound(action_plan=action_plan__uuid)

    def destroy_action_plan(self, action_plan_id):
        def is_action_plan_referenced(session, action_plan_id):
            """Checks whether the action_plan is referenced by action(s)."""
            query = model_query(models.Action, session=session)
            query = self._add_actions_filters(
                query, {'action_plan_id': action_plan_id})
            return query.count() != 0

        session = get_session()
        with session.begin():
            query = model_query(models.ActionPlan, session=session)
            query = add_identity_filter(query, action_plan_id)

            try:
                action_plan_ref = query.one()
            except exc.NoResultFound:
                raise exception.ActionPlanNotFound(action_plan=action_plan_id)

            if is_action_plan_referenced(session, action_plan_ref['id']):
                raise exception.ActionPlanReferenced(
                    action_plan=action_plan_id)

            query.delete()

    def update_action_plan(self, action_plan_id, values):
        if 'uuid' in values:
            msg = _("Cannot overwrite UUID for an existing Audit.")
            raise exception.InvalidParameterValue(err=msg)

        return self._do_update_action_plan(action_plan_id, values)

    def _do_update_action_plan(self, action_plan_id, values):
        session = get_session()
        with session.begin():
            query = model_query(models.ActionPlan, session=session)
            query = add_identity_filter(query, action_plan_id)
            try:
                ref = query.with_lockmode('update').one()
            except exc.NoResultFound:
                raise exception.ActionPlanNotFound(action_plan=action_plan_id)

            ref.update(values)
        return ref

    def soft_delete_action_plan(self, action_plan_id):
        session = get_session()
        with session.begin():
            query = model_query(models.ActionPlan, session=session)
            query = add_identity_filter(query, action_plan_id)

            try:
                query.one()
            except exc.NoResultFound:
                raise exception.ActionPlanNotFound(node=action_plan_id)

            query.soft_delete()