from datetime import timedelta
from datetime import datetime
import logging
import urllib.request
import urllib.parse
import json

log = logging.getLogger('grafana')

class Silencer():
    def __init__(self, url, apikey):
        self._url = url
        self._apikey = apikey

    def silence_alert(self):
        with urllib.request.urlopen(
                urllib.request.Request(
                    urllib.parse.urljoin(
                        self._url,
                        'api/alertmanager/grafana/api/v2/silences',
                    ),
                    headers={
                        'Authorization':
                            f'Bearer {self._apikey}',
                    },
                ),
                data=bytes(json.dumps({
                    "comment": "Openfoam run",
                    "createdBy": "Python OpenFoam run",
                    "endsAt": (datetime.utcnow() \
                        + timedelta(days=1)).isoformat(),
                    "matchers": [
                      {
                        "isEqual": True,
                        "isRegex": False,
                        "name": "alertname",
                        "value": "CPU Usage"
                      }
                    ],
                    "startsAt": datetime.utcnow().isoformat()
                }), 'utf-8')) as api_req:
            api_res = api_req.read()
            self._alertid = json.loads(api_res)['id']
            log.info(f'Grafana alerts silenced (id: {self._alertid})')

    def unsilence_alert(self):
        with urllib.request.urlopen(
                urllib.request.Request(
                    urllib.parse.urljoin(
                        self._url,
                        'api/alertmanager/grafana/api/v2/silence/'
                        f'{self._alertid}',
                    ),
                    headers={
                        'Authorization':
                            f'Bearer {self._apikey}',
                    },
                    method='DELETE')):
            log.info(f'Grafana silence (id: {self._alertid}) deleted')