# zabbix_utils
#
# Copyright (C) 2001-2023 Zabbix SIA
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify,
# merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software
# is furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.

import ssl
import json
import base64
import logging
import urllib.request as ul
from textwrap import shorten

from uuid import uuid4
from os import environ as env
from urllib.error import URLError

from typing import Callable, Optional, Any

from .types import APIVersion
from .common import ModuleUtils
from .logger import EmptyHandler, SensitiveFilter
from .exceptions import APIRequestError, APINotSupported, ProcessingError
from .version import __version__, __min_supported__, __max_supported__


log = logging.getLogger(__name__)
log.addHandler(EmptyHandler())
log.addFilter(SensitiveFilter())


class APIObject():
    """Zabbix API object.

    Args:
        name (str): Zabbix API object name.
        parent (class): Zabbix API parent of the object.
    """

    def __init__(self, name: str, parent: Callable):
        self.object = name
        self.parent = parent

    def __getattr__(self, name: str) -> Callable:
        """Dynamic creation of an API method.

        Args:
            name (str): Zabbix API object method name.

        Raises:
            TypeError: Raises if gets unexpected arguments.

        Returns:
            Callable: Zabbix API method.
        """

        # For compatibility with Python less 3.9 versions
        def removesuffix(string: str, suffix: str) -> str:
            return str(string[:-len(suffix)]) if suffix and string.endswith(suffix) else string

        def func(*args: Any, **kwargs: Any) -> Any:
            if args and kwargs:
                raise TypeError("Only args or kwargs should be used.")

            # Support '_' suffix to avoid conflicts with python keywords
            method = removesuffix(self.object, '_') + "." + removesuffix(name, '_')

            # Support passing list of ids and params as a dict
            params = kwargs or (
                (args[0] if type(args[0]) in (list, dict,) else list(args)) if args else None)

            log.debug("Executing %s method", method)

            need_auth = method not in ModuleUtils.UNAUTH_METHODS

            return self.parent.send_api_request(
                method,
                params,
                need_auth
            ).get('result')

        return func


class ZabbixAPI():
    """Provide interface for working with Zabbix API.

    Args:
        url (str, optional): Zabbix API URL. Defaults to `http://localhost/zabbix/api_jsonrpc.php`.
        token (str, optional): Zabbix API token. Defaults to `None`.
        user (str, optional): Zabbix API username. Defaults to `None`.
        password (str, optional): Zabbix API user's password. Defaults to `None`.
        http_user (str, optional): Basic Authentication username. Defaults to `None`.
        http_password (str, optional): Basic Authentication password. Defaults to `None`.
        skip_version_check (bool, optional): Skip version compatibility check. Defaults to `False`.
        validate_certs (bool, optional): Specifying certificate validation. Defaults to `True`.
        timeout (int, optional): Connection timeout to Zabbix API. Defaults to `30`.
    """

    __version = None
    __use_token = False
    __session_id = None
    __basic_cred = None

    def __init__(self, url: Optional[str] = None, token: Optional[str] = None,
                 user: Optional[str] = None, password: Optional[str] = None,
                 http_user: Optional[str] = None, http_password: Optional[str] = None,
                 skip_version_check: bool = False, validate_certs: bool = True,
                 ssl_context: Optional[ssl.SSLContext] = None, timeout: int = 30):

        url = url or env.get('ZABBIX_URL') or 'http://localhost/zabbix/api_jsonrpc.php'
        user = user or env.get('ZABBIX_USER') or None
        password = password or env.get('ZABBIX_PASSWORD') or None
        token = token or env.get('ZABBIX_TOKEN') or None

        self.url = ModuleUtils.check_url(url)
        self.validate_certs = validate_certs
        self.timeout = timeout

        # HTTP Auth unsupported since Zabbix 7.2
        if http_user and http_password:
            self.__basic_auth(http_user, http_password)

        if ssl_context is not None:
            if not isinstance(ssl_context, ssl.SSLContext):
                raise TypeError(
                    'Parameter "ssl_context" must be an "ssl.SSLContext".') from None
        self.ssl_context = ssl_context

        self.__check_version(skip_version_check)

        if self.version > 7.0 and http_user and http_password:
            raise APINotSupported("HTTP authentication unsupported since Zabbix 7.2.")

        if token or user or password:
            self.login(token, user, password)

    def __getattr__(self, name: str) -> Callable:
        """Dynamic creation of an API object.

        Args:
            name (str): Zabbix API method name.

        Returns:
            APIObject: Zabbix API object instance.
        """

        return APIObject(name, self)

    def __enter__(self) -> Callable:
        return self

    def __exit__(self, *args) -> None:
        self.logout()

    def __basic_auth(self, user: str, password: str) -> None:
        """Enable Basic Authentication using.

        Args:
            user (str): Basic Authentication username.
            password (str): Basic Authentication password.
        """

        log.debug(
            "Enable Basic Authentication with username:%s password:%s",
            user,
            ModuleUtils.HIDING_MASK
        )

        self.__basic_cred = base64.b64encode(
            f"{user}:{password}".encode()
        ).decode()

    def api_version(self) -> APIVersion:
        """Return object of Zabbix API version.

        Returns:
            APIVersion: Object of Zabbix API version
        """

        if self.__version is None:
            self.__version = APIVersion(self.apiinfo.version())
        return self.__version

    @property
    def version(self) -> APIVersion:
        """Return object of Zabbix API version.

        Returns:
            APIVersion: Object of Zabbix API version.
        """

        return self.api_version()

    def login(self, token: Optional[str] = None, user: Optional[str] = None,
              password: Optional[str] = None) -> None:
        """Login to Zabbix API.

        Args:
            token (str, optional): Zabbix API token. Defaults to `None`.
            user (str, optional): Zabbix API username. Defaults to `None`.
            password (str, optional): Zabbix API user's password. Defaults to `None`.
        """

        if token:
            if self.version < 5.4:
                raise APINotSupported(
                    message="Token usage",
                    version=self.version
                )
            if user or password:
                raise ProcessingError(
                    "Token cannot be used with username and password")
            self.__use_token = True
            self.__session_id = token
            return

        if not user:
            raise ProcessingError("Username is missing")
        if not password:
            raise ProcessingError("User password is missing")

        if self.version < 5.4:
            user_cred = {
                "user": user,
                "password": password
            }
        else:
            user_cred = {
                "username": user,
                "password": password
            }

        log.debug(
            "Login to Zabbix API using username:%s password:%s", user, ModuleUtils.HIDING_MASK
        )
        self.__use_token = False
        self.__session_id = self.user.login(**user_cred)

        log.debug("Connected to Zabbix API version %s: %s", self.version, self.url)

    def logout(self) -> None:
        """Logout from Zabbix API."""

        if self.__session_id:
            if self.__use_token:
                self.__session_id = None
                self.__use_token = False
                return

            log.debug("Logout from Zabbix API")
            self.user.logout()
            self.__session_id = None
        else:
            log.debug("You're not logged in Zabbix API")

    def check_auth(self) -> bool:
        """Check authentication status in Zabbix API.

        Returns:
            bool: User authentication status (`True`, `False`)
        """

        if not self.__session_id:
            log.debug("You're not logged in Zabbix API")
            return False

        if self.__use_token:
            log.debug("Check auth session using token in Zabbix API")
            refresh_resp = self.user.checkAuthentication(token=self.__session_id)
        else:
            log.debug("Check auth session using sessionid in Zabbix API")
            refresh_resp = self.user.checkAuthentication(sessionid=self.__session_id)

        return bool(refresh_resp.get('userid'))

    def send_api_request(self, method: str, params: Optional[dict] = None,
                         need_auth=True) -> dict:
        """Function for sending request to Zabbix API.

        Args:
            method (str): Zabbix API method name.
            params (dict, optional): Params for request body. Defaults to `None`.
            need_auth (bool, optional): Authorization using flag. Defaults to `False`.

        Raises:
            ProcessingError: Wrapping built-in exceptions during request processing.
            APIRequestError: Wrapping errors from Zabbix API.

        Returns:
            dict: Dictionary with Zabbix API response.
        """

        request_json = {
            'jsonrpc': '2.0',
            'method': method,
            'params': params or {},
            'id': str(uuid4()),
        }

        headers = {
            'Accept': 'application/json',
            'Content-Type': 'application/json-rpc',
            'User-Agent': f"{__name__}/{__version__}"
        }

        if need_auth:
            if not self.__session_id:
                raise ProcessingError("You're not logged in Zabbix API")
            if self.version < 6.4:
                request_json['auth'] = self.__session_id
            elif self.version <= 7.0 and self.__basic_cred is not None:
                request_json['auth'] = self.__session_id
            else:
                headers["Authorization"] = f"Bearer {self.__session_id}"

        if self.__basic_cred is not None:
            headers["Authorization"] = f"Basic {self.__basic_cred}"

        log.debug(
            "Sending request to %s with body: %s",
            self.url,
            request_json
        )

        req = ul.Request(
            self.url,
            data=json.dumps(request_json).encode("utf-8"),
            headers=headers,
            method='POST'
        )
        req.timeout = self.timeout

        # Disable SSL certificate validation if needed.
        if not self.validate_certs:
            ctx = ssl.create_default_context()
            ctx.check_hostname = False
            ctx.verify_mode = ssl.CERT_NONE
        elif self.ssl_context is not None:
            ctx = self.ssl_context
        else:
            ctx = None

        try:
            resp = ul.urlopen(req, context=ctx)
            resp_json = json.loads(resp.read().decode('utf-8'))
        except URLError as err:
            raise ProcessingError(f"Unable to connect to {self.url}:", err) from None
        except ValueError as err:
            raise ProcessingError("Unable to parse json:", err) from None

        if method not in ModuleUtils.FILES_METHODS:
            log.debug(
                "Received response body: %s",
                resp_json
            )
        else:
            debug_json = resp_json.copy()
            if debug_json.get('result'):
                debug_json['result'] = shorten(debug_json['result'], 200, placeholder='...')
            log.debug(
                "Received response body (clipped): %s",
                json.dumps(debug_json, indent=4, separators=(',', ': '))
            )

        if 'error' in resp_json:
            err = resp_json['error'].copy()
            err['body'] = request_json.copy()
            raise APIRequestError(err)

        return resp_json

    def __check_version(self, skip_check: bool) -> None:

        skip_check_help = "If you're sure zabbix_utils will work properly with your current \
Zabbix version you can skip this check by \
specifying skip_version_check=True when create ZabbixAPI object."
        if self.version < __min_supported__:
            if skip_check:
                log.debug(
                    "Version of Zabbix API [%s] is less than the library supports. %s",
                    self.version,
                    "Further library use at your own risk!"
                )
            else:
                raise APINotSupported(
                    f"Version of Zabbix API [{self.version}] is not supported by the library. " +
                    f"The oldest supported version is {__min_supported__}.0. " + skip_check_help
                )

        if self.version > __max_supported__:
            if skip_check:
                log.debug(
                    "Version of Zabbix API [%s] is more than the library was tested on. %s",
                    self.version,
                    "Recommended to update the library. Further library use at your own risk!"
                )
            else:
                raise APINotSupported(
                    f"Version of Zabbix API [{self.version}] was not tested with the library. " +
                    f"The latest tested version is {__max_supported__}.0. " + skip_check_help
                )