#!/usr/bin/env python3
#
# Copyright (C) 2014-2019  Codethink Limited
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.


import json
import logging
import time
import urllib.request, urllib.error, urllib.parse

import cliapp


class JobInfo(object):

    def __init__(self, job_id, exit_code, exit_timestamp, start_timestamp):
        self.job_id = job_id
        self.exit_code = exit_code
        self.exit_timestamp = exit_timestamp
        self.start_timestamp = start_timestamp

    def __repr__(self):
        return 'JobInfo(%s,%s,%s,%s)' % (
            self.job_id, self.exit_code, self.exit_timestamp,
            self.start_timestamp)


class OldJobRemover(cliapp.Application):

    def add_settings(self):
        self.settings.string(
            ['webapp-host'],
            'address of WEBAPP',
            default='localhost')

        self.settings.integer(
            ['webapp-port'],
            'port of WEBAPP',
            default=12765)

        ONE_MINUTE = 60
        ONE_HOUR = 60 * ONE_MINUTE
        ONE_DAY = 24 * ONE_HOUR

        self.settings.integer(
            ['max-age-in-seconds', 'max-age'],
            'maximum age of a finished job in seconds',
            metavar='SECONDS',
            default=3 * ONE_DAY)

        self.settings.integer(
            ['debug-now'],
            'for tests and debugging, '
            'set current time to SECONDS since the epoch '
            '(set to 0 to use real time',
            metavar='SECONDS')

    def process_args(self, args):
        logging.info('Removing old jobs from Lorry Controller STATEDB')

        for job_id in sorted(self.list_jobs()):
            try:
                job_info = self.get_job_info(job_id)
            except urllib.error.HTTPError as e:
                logging.warning(
                    'Trouble getting job info for job %s: %s' %
                    (job_id, str(e)))
                continue

            # If the start time of this job is less than max-age ago,
            # then the finish time of this job, and every job with a
            # higher ID, must be less than max-age ago.  So we can
            # stop now.
            if self.was_started_too_recently(job_info):
                break

            if self.is_old(job_info):
                self.remove_job(job_info.job_id)

    def list_jobs(self):
        data = self.get('/1.0/list-jobs')
        obj = json.loads(data.decode('utf-8'))
        return obj['job_ids']

    def get(self, path):
        url = self.make_url(path)
        with urllib.request.urlopen(url) as f:
            return f.read()

    def make_url(self, path):
        scheme = 'http'
        netloc = '%s:%s' % (
            self.settings['webapp-host'], self.settings['webapp-port'])
        query = None
        fragment = None
        parts = (scheme, netloc, path, query, fragment)
        return urllib.parse.urlunsplit(parts)

    def get_job_info(self, job_id):
        data = self.get('/1.0/job/%s' % job_id)
        obj = json.loads(data.decode('utf-8'))
        exit_code = obj['exit']
        if obj['job_ended']:
            exit_timestamp = self.parse_timestamp(obj['job_ended'])
        else:
            exit_timestamp = None
        start_timestamp = self.parse_timestamp(obj['job_started'])
        return JobInfo(job_id, exit_code, exit_timestamp, start_timestamp)

    def parse_timestamp(self, timestamp):
        return time.mktime(time.strptime(timestamp, '%Y-%m-%d %H:%M:%S UTC'))

    def is_old(self, job_info):
        if job_info.exit_timestamp is None:
            return False
        current_time = self.get_current_time()
        age_in_seconds = current_time - job_info.exit_timestamp
        return age_in_seconds >= self.settings['max-age-in-seconds']

    def was_started_too_recently(self, job_info):
        current_time = self.get_current_time()
        age_in_seconds = current_time - job_info.start_timestamp
        return age_in_seconds < self.settings['max-age-in-seconds']

    def get_current_time(self):
        if self.settings['debug-now']:
            return self.settings['debug-now']
        return time.time()

    def remove_job(self, job_id):
        logging.info('Removing job %s', job_id)
        self.post('/1.0/remove-job', 'job_id=%s' % job_id)

    def post(self, path, data):
        url = self.make_url(path)
        with urllib.request.urlopen(url, data.encode('utf-8')) as f:
            f.read()


OldJobRemover().run()