# Copyright 2017 Catalyst IT Limited
#
#    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.

from datetime import datetime
from datetime import timedelta

from oslo_config import cfg
from oslo_log import log as logging
from oslo_service import threadgroup
from oslo_utils import timeutils

from qinling import context
from qinling.db import api as db_api
from qinling.db.sqlalchemy import models
from qinling import rpc
from qinling import status
from qinling.utils import constants
from qinling.utils import executions
from qinling.utils import jobs
from qinling.utils.openstack import keystone as keystone_utils

LOG = logging.getLogger(__name__)
CONF = cfg.CONF
_periodic_tasks = {}


def handle_function_service_expiration(ctx, engine_client, orchestrator):
    context.set_ctx(ctx)

    delta = timedelta(seconds=CONF.engine.function_service_expiration)
    expiry_time = datetime.utcnow() - delta

    results = db_api.get_functions(
        fields=['id'],
        sort_keys=['updated_at'],
        insecure=True,
        updated_at={'lte': expiry_time}
    )

    expiry_ids = [ret.id for ret in results]

    if not expiry_ids:
        return

    mappings = db_api.get_function_service_mappings(
        function_id={'in': expiry_ids}
    )

    with db_api.transaction():
        for m in mappings:
            LOG.info('Deleting service mapping for function %s', m.function_id)

            engine_client.delete_function(m.function_id)
            db_api.delete_function_service_mapping(m.function_id)


def handle_job(engine_client):
    for job in db_api.get_next_jobs(timeutils.utcnow() + timedelta(seconds=3)):
        LOG.debug("Processing job: %s, function: %s", job.id, job.function_id)

        try:
            # Setup context before schedule job.
            ctx = keystone_utils.create_trust_context(
                job.trust_id, job.project_id
            )
            context.set_ctx(ctx)

            if (job.count is not None and job.count > 0):
                job.count -= 1

            # Job delete/update is done using UPDATE ... FROM ... WHERE
            # non-locking clause.
            if job.count == 0:
                modified = db_api.conditional_update(
                    models.Job,
                    {
                        'status': status.DONE,
                        'count': 0
                    },
                    {
                        'id': job.id,
                        'status': status.RUNNING
                    },
                    insecure=True,
                )
            else:
                next_time = jobs.get_next_execution_time(
                    job.pattern,
                    job.next_execution_time
                )

                modified = db_api.conditional_update(
                    models.Job,
                    {
                        'next_execution_time': next_time,
                        'count': job.count
                    },
                    {
                        'id': job.id,
                        'next_execution_time': job.next_execution_time
                    },
                    insecure=True,
                )

            if not modified:
                LOG.warning(
                    'Job %s has been already handled by another periodic '
                    'task.', job.id
                )
                continue

            LOG.debug(
                "Starting to execute function %s by job %s",
                job.function_id, job.id
            )

            params = {
                'function_id': job.function_id,
                'input': job.function_input,
                'sync': False,
                'description': constants.EXECUTION_BY_JOB % job.id
            }
            executions.create_execution(engine_client, params)
        except Exception:
            LOG.exception("Failed to process job %s", job.id)
        finally:
            context.set_ctx(None)


def start_function_mapping_handler(orchestrator):
    tg = threadgroup.ThreadGroup(1)
    engine_client = rpc.get_engine_client()

    tg.add_timer(
        300,
        handle_function_service_expiration,
        ctx=context.Context(),
        engine_client=engine_client,
        orchestrator=orchestrator
    )
    _periodic_tasks[constants.PERIODIC_FUNC_MAPPING_HANDLER] = tg

    LOG.info('Function mapping handler started.')


def start_job_handler():
    tg = threadgroup.ThreadGroup(1)
    engine_client = rpc.get_engine_client()

    tg.add_timer(
        3,
        handle_job,
        engine_client=engine_client,
    )
    _periodic_tasks[constants.PERIODIC_JOB_HANDLER] = tg

    LOG.info('Job handler started.')


def stop(task=None):
    if not task:
        for name, tg in _periodic_tasks.items():
            LOG.info('Stopping periodic task: %s', name)
            tg.stop()
            del _periodic_tasks[name]
    else:
        tg = _periodic_tasks.get(task)
        if tg:
            LOG.info('Stopping periodic task: %s', task)
            tg.stop()
            del _periodic_tasks[task]