#!/usr/bin/env python
#
# Copyright 2015 Hewlett-Packard
#
# 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 distutils import spawn
import sys
import threading
import time

from apscheduler.schedulers import background
from freezerclient import utils as client_utils
from oslo_config import cfg
from oslo_log import log

from freezer.scheduler import arguments
from freezer.scheduler import scheduler_job
from freezer.scheduler import utils
from freezer.utils import utils as freezer_utils
from freezer.utils import winutils

if winutils.is_windows():
    from freezer.scheduler import win_daemon
else:
    from freezer.scheduler import daemon as linux_daemon

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


class FreezerScheduler(object):
    def __init__(self, apiclient, interval, job_path, concurrent_jobs=1):
        # config_manager
        self.client = apiclient
        self.freezerc_executable = spawn.find_executable('freezer-agent')
        if self.freezerc_executable is None:
            # Needed in the case of a non-activated virtualenv
            self.freezerc_executable = spawn.find_executable(
                'freezer-agent', path=':'.join(sys.path))
        LOG.debug('Freezer-agent found at {0}'
                  .format(self.freezerc_executable))
        self.job_path = job_path
        self._client = None
        self.lock = threading.Lock()
        job_defaults = {
            'coalesce': True,
            'max_instances': 1
        }
        executors = {
            'default': {'type': 'threadpool', 'max_workers': 1},
            'threadpool': {'type': 'threadpool',
                           'max_workers': concurrent_jobs}
        }
        self.scheduler = background.BackgroundScheduler(
            job_defaults=job_defaults,
            executors=executors)

        if self.client:
            self.scheduler.add_job(self.poll, 'interval',
                                   seconds=interval, id='api_poll',
                                   executor='default')

        self.add_job = self.scheduler.add_job
        self.remove_job = self.scheduler.remove_job
        self.jobs = {}

    def get_jobs(self):
        if self.client:
            job_doc_list = utils.get_active_jobs_from_api(self.client)
            try:
                utils.save_jobs_to_disk(job_doc_list, self.job_path)
            except Exception as e:
                LOG.error('Unable to save jobs to {0}. '
                          '{1}'.format(self.job_path, e))
            return job_doc_list
        else:
            return utils.get_jobs_from_disk(self.job_path)

    def start_session(self, session_id, job_id, session_tag):
        if self.client:
            return self.client.sessions.start_session(session_id,
                                                      job_id,
                                                      session_tag)
        else:
            raise Exception("Unable to start session: api not in use.")

    def end_session(self, session_id, job_id, session_tag, result):
        if self.client:
            return self.client.sessions.end_session(session_id,
                                                    job_id,
                                                    session_tag,
                                                    result)
        else:
            raise Exception("Unable to end session: api not in use.")

    def upload_metadata(self, metadata_doc):
        if self.client:
            self.client.backups.create(metadata_doc)

    def start(self):
        utils.do_register(self.client)
        self.poll()
        self.scheduler.start()
        try:
            while True:
                # Due to the new Background scheduler nature, we need to keep
                # the main thread alive.
                time.sleep(1)
        except (KeyboardInterrupt, SystemExit):
            # Not strictly necessary if daemonic mode is enabled but
            # should be done if possible
            self.scheduler.shutdown(wait=False)

    def update_job(self, job_id, job_doc):
        if self.client:
            try:
                return self.client.jobs.update(job_id, job_doc)
            except Exception as e:
                LOG.error("Job update error: {0}".format(e))

    def update_job_schedule(self, job_id, job_schedule):
        """
        Pushes to the API the updates the job_schedule information
        of the job_doc

        :param job_id: id of the job to modify
        :param job_schedule: dict containing the job_scheduler information
        :return: None
        """
        doc = {'job_schedule': job_schedule}
        self.update_job(job_id, doc)

    def update_job_status(self, job_id, status):
        doc = {'job_schedule': {'status': status}}
        self.update_job(job_id, doc)

    def is_scheduled(self, job_id):
        return self.scheduler.get_job(job_id) is not None

    def create_job(self, job_doc):
        job = scheduler_job.Job.create(self, self.freezerc_executable, job_doc)
        self.jobs[job.id] = job
        LOG.info("Created job {0}".format(job.id))
        return job

    def poll(self):
        try:
            work_job_doc_list = self.get_jobs()
        except Exception as e:
            LOG.error("Unable to get jobs: {0}".format(e))
            return

        work_job_id_list = []

        # create job if necessary, then let it process its events
        for job_doc in work_job_doc_list:
            job_id = job_doc['job_id']
            work_job_id_list.append(job_id)
            job = self.jobs.get(job_id, None) or self.create_job(job_doc)

            # check for abort status
            if job_doc['job_schedule']['event'] == 'abort':
                pid = int(job_doc['job_schedule']['current_pid'])
                utils.terminate_subprocess(pid, 'freezer-agent')

            job.process_event(job_doc)

        # request removal of any job that has been removed in the api
        for job_id, job in self.jobs.items():
            if job_id not in work_job_id_list:
                job.remove()

        remove_list = [job_id for job_id, job in self.jobs.items()
                       if job.can_be_removed()]

        for k in remove_list:
            self.jobs.pop(k)

    def stop(self):
        sys.exit()

    def reload(self):
        LOG.warning("reload not supported")


def main():
    possible_actions = ['start', 'stop', 'restart', 'status', 'reload']

    arguments.parse_args(possible_actions)
    arguments.setup_logging()

    if CONF.action not in possible_actions:
        CONF.print_help()
        return 65  # os.EX_DATAERR

    apiclient = None
    if CONF.no_api is False:
        try:
            if CONF.enable_v1_api:
                apiclient = client_utils.get_client_instance(opts=CONF,
                                                             api_version='1')
            else:
                apiclient = client_utils.get_client_instance(opts=CONF,
                                                             api_version='2')

            if CONF.client_id:
                apiclient.client_id = CONF.client_id
        except Exception as e:
            LOG.error(e)
            print(e)
            sys.exit(1)
    else:
        if winutils.is_windows():
            print("--no-api mode is not available on windows")
            return 69  # os.EX_UNAVAILABLE

    freezer_utils.create_dir(CONF.jobs_dir, do_log=False)
    freezer_scheduler = FreezerScheduler(apiclient=apiclient,
                                         interval=int(CONF.interval),
                                         job_path=CONF.jobs_dir,
                                         concurrent_jobs=CONF.concurrent_jobs)

    if CONF.no_daemon:
        print('Freezer Scheduler running in no-daemon mode')
        LOG.debug('Freezer Scheduler running in no-daemon mode')
        if winutils.is_windows():
            daemon = win_daemon.NoDaemon(daemonizable=freezer_scheduler)
        else:
            daemon = linux_daemon.NoDaemon(daemonizable=freezer_scheduler)
    else:
        if winutils.is_windows():
            daemon = win_daemon.Daemon(daemonizable=freezer_scheduler,
                                       interval=int(CONF.interval),
                                       job_path=CONF.jobs_dir,
                                       insecure=CONF.insecure,
                                       concurrent_jobs=CONF.concurrent_jobs)
        else:
            daemon = linux_daemon.Daemon(daemonizable=freezer_scheduler)

    if CONF.action == 'start':
        daemon.start()
    elif CONF.action == 'stop':
        daemon.stop()
    elif CONF.action == 'restart':
        daemon.restart()
    elif CONF.action == 'reload':
        daemon.reload()
    elif CONF.action == 'status':
        daemon.status()

    # os.RETURN_CODES are only available to posix like systems, on windows
    # we need to translate the code to an actual number which is the equivalent
    return 0  # os.EX_OK


if __name__ == '__main__':
    sys.exit(main())
