#!/opt/imunify360/venv/bin/python3
"""
The watchdog script that checks the webshield and restarts it if error found
"""
import json
import logging
import logging.handlers
import os
import requests
import subprocess
import time
import uuid
import yaml

import sentry_sdk
from sentry_sdk import configure_scope

logging.raiseExceptions = False


class Watchdog:

    port = 52224
    request_timeout = 4
    subprocess_timeout = 30
    config_path = '/etc/sysconfig/imunify360/imunify360-merged.config'
    user_agent = 'Webshield-watchdog-agent'
    sentry_dsn_path = '/usr/share/imunify360-webshield/sentry'
    package_name = 'imunify360-webshield-bundle'
    license_path = '/var/imunify360/license.json'
    flag_path = '/var/imunify360/webshield_broken'
    integration_path = '/etc/sysconfig/imunify360/integration.conf'
    services_full = ('imunify360-webshield', 'imunify360-webshield-ssl-cache')
    services_ws_only = ('imunify360-webshield',)


    def __init__(self):
        self.services = (self.services_ws_only if
            os.path.exists(self.integration_path) else self.services_full)
        self.is_enabled = self._get_config_status()
        self.is_running = self._get_current_status()
        self.sentry_dsn = self._get_dsn()
        self.log_level = logging.INFO
        self.logger = self._setup_logging()

    def _setup_logging(self):
        logger = logging.getLogger('imunify360-webshield-watchdog')
        logger.setLevel(self.log_level)
        handler = logging.handlers.SysLogHandler('/dev/log')
        formatter = logging.Formatter('%(name)s: %(message)s')
        handler.formatter = formatter
        logger.addHandler(handler)
        self._init_sentry()
        return logger

    @classmethod
    def _get_server_id(cls):
        try:
            with open(cls.license_path) as f:
                data = json.load(f)
        except Exception:
            return 'none'
        return data.get('id', 'none')

    @classmethod
    def _get_dsn(cls):
        try:
            with open(cls.sentry_dsn_path) as f:
                return f.read().strip()
        except Exception:
            return

    def _init_sentry(self):
        sentry_sdk.init(dsn=self.sentry_dsn, release=self._imunify360_version())
        with configure_scope() as scope:
            scope.user = {'id': self._get_server_id()}

    @classmethod
    def _get_config_status(cls):
        with open(cls.config_path) as f:
            parsed_config = yaml.safe_load(f)
        if not 'WEBSHIELD' in parsed_config:
            return False
        return parsed_config["WEBSHIELD"].get('enable', False)

    def _get_current_status(self, attempts=3, wait=5):
        for i in range(attempts):
            errors = 0
            for service in self.services:
                try:
                    proc = subprocess.run(['service', service, 'status'],
                        stdout=subprocess.DEVNULL,
                        stderr=subprocess.DEVNULL,
                        timeout=self.subprocess_timeout)
                except subprocess.TimeoutExpired:
                    errors = 124
                    continue
                errors += proc.returncode
            if not errors:
                return True
            time.sleep(wait)
        return False

    def _make_http_request(self, i):
        url = "http://0.0.0.0:{}/selfcheck?uuid={}".format(
            self.port, uuid.uuid4())
        curr_timeout = self.request_timeout * i
        try:
            requests.get(
                url,
                headers={'User-Agent': self.user_agent},
                allow_redirects=False,
                timeout=curr_timeout)
        except Exception:
            return False
        return True

    def _check_http_request(self):
        for i in range(1, 4):
            if self._make_http_request(i):
                return True
            time.sleep(2)
        return False

    def _call_service(self, action='restart'):
        service = self.services[0]
        try:
            proc = subprocess.run(
                ['service', service, action],
                stdout=subprocess.DEVNULL,
                stderr=subprocess.DEVNULL,
                timeout=self.subprocess_timeout)
        except subprocess.TimeoutExpired:
            return False
        if proc.returncode != 0:
            return False
        return True

    @classmethod
    def _collect_output(cls, cmd):
        try:
            cp = subprocess.run(
                cmd,
                stdin=subprocess.DEVNULL,
                stdout=subprocess.PIPE,
                stderr=subprocess.DEVNULL,
                timeout=cls.subprocess_timeout)
        except (OSError, subprocess.TimeoutExpired):
            return ''
        if cp.returncode != 0:
            return ''
        return cp.stdout.decode()

    @classmethod
    def _get_rpm_version(cls):
        cmd = ['rpm', '-q', '--queryformat=%{VERSION}-%{RELEASE}',
               cls.package_name]
        return cls._collect_output(cmd)

    @classmethod
    def _get_dpkg_version(cls):
        cmd = ['dpkg', '--status', cls.package_name]
        out = cls._collect_output(cmd)
        if not out:
            return
        for line in out.splitlines():
            if line.startswith("Version:"):
                return line.strip().split()[1]

    @classmethod
    def _imunify360_version(cls):
        version = cls._get_rpm_version()
        if not version:
            version = cls._get_dpkg_version()
        return version

    @classmethod
    def _get_flag_timestamp(cls):
        try:
            with open(cls.flag_path) as o:
                return int(o.read().strip())
        except Exception:
            pass

    @classmethod
    def _put_flag_timestamp(cls):
        tms = int(time.time())
        try:
            with open(cls.flag_path, 'w') as w:
                w.write("{}".format(tms))
        except Exception:
            pass

    @classmethod
    def _set_flag(cls):
        tms = cls._get_flag_timestamp()
        if not tms or time.time() - tms >= 86400:    # 24h
            cls._put_flag_timestamp()
            return True
        return False

    @classmethod
    def _remove_flag_if_exists(cls):
        if not os.path.exists(cls.flag_path):
            return False
        try:
            os.unlink(cls.flag_path)
            return True
        except Exception:
            pass

    def run(self):
        if self.is_enabled and self.is_running:
            result = self._check_http_request()
            if not result:
                done = self._set_flag()
                if done:    # File has been created or updated
                    self.logger.error(
                        '%s is inaccessible', self.services[0])
                    self._call_service('restart')
            else:
                done = self._remove_flag_if_exists()
                if done:    # File has been deleted
                    self.logger.info('%s is resumed.', self.services[0])
            return

        if self.is_enabled and not self.is_running:
            done = self._set_flag()
            if done:
                self.logger.error(
                        '%s is not running. Restart.', self.services[0])
                self._call_service('restart')
            return

        if not self.is_enabled and self.is_running:
            self.logger.warning(
                    '%s is running while being disabled. Stopping...',
                    self.services[0])
            self._call_service('stop')
            return

        self.logger.info('%s is disabled. OK', self.services[0])


if __name__ == '__main__':
    w = Watchdog()
    w.run()