import json
import math

from django.core.exceptions import ObjectDoesNotExist
from django.db.models import Q
from django.utils.functional import cached_property
from rest_framework import status
from rest_framework.decorators import action
from rest_framework.exceptions import NotFound, Throttled
from rest_framework.response import Response

from apps.alerts.incident_appearance.templaters import (
    AlertPhoneCallTemplater,
    AlertSlackTemplater,
    AlertSmsTemplater,
    AlertTelegramTemplater,
    AlertWebTemplater,
    TemplateLoader,
)
from apps.api.permissions import LegacyAccessControlRole
from apps.base.messaging import get_messaging_backends
from common.api_helpers.exceptions import BadRequest
from common.jinja_templater import apply_jinja_template
from common.jinja_templater.apply_jinja_template import JinjaTemplateError, JinjaTemplateWarning


class UpdateSerializerMixin:
    serializer_class = None
    update_serializer_class = None

    def get_serializer_class(self):
        if self.action in ["update", "partial_update"]:
            return self.get_update_serializer_class()
        return super().get_serializer_class()

    def get_update_serializer_class(self):
        assert self.update_serializer_class is not None, (
            "'%s' should either include a `update_serializer_class` attribute,"
            "or override the `get_update_serializer_class()` method." % self.__class__.__name__
        )
        return self.update_serializer_class


# Use this mixin at the very left of list of inherited SerializersMixins
class FilterSerializerMixin:
    serializer_class = None
    filter_serializer_class = None

    def get_serializer_class(self):
        is_filters_request = self.request.query_params.get("filters", "false") == "true"
        if self.action in ["list"] and is_filters_request:
            return self.get_filter_serializer_class()
        else:
            return super().get_serializer_class()

    def get_filter_serializer_class(self):
        assert self.filter_serializer_class is not None, (
            "'%s' should either include a `filter_serializer_class` attribute,"
            "or override the `get_update_serializer_class()` method." % self.__class__.__name__
        )
        return self.filter_serializer_class


# Use this mixin at the very left of list of inherited SerializersMixins
class ShortSerializerMixin:
    serializer_class = None
    short_serializer_class = None

    def get_serializer_class(self):
        is_short_request = self.request.query_params.get("short", "false") == "true"
        if self.action in ["list"] and is_short_request:
            return self.get_short_serializer_class()
        else:
            return super().get_serializer_class()

    def get_short_serializer_class(self):
        assert self.short_serializer_class is not None, (
            "'%s' should either include a `short_serializer_class` attribute,"
            "or override the `get_list_serializer_class()` method." % self.__class__.__name__
        )
        return self.short_serializer_class


class CreateSerializerMixin:
    serializer_class = None
    create_serializer_class = None

    def get_serializer_class(self):
        if self.action in ["create", "destroy"]:
            return self.get_create_serializer_class()
        return super().get_serializer_class()

    def get_create_serializer_class(self):
        assert self.create_serializer_class is not None, (
            "'%s' should either include a `create_serializer_class` attribute,"
            "or override the `get_update_serializer_class()` method." % self.__class__.__name__
        )
        return self.create_serializer_class


class ListSerializerMixin:
    serializer_class = None
    list_serializer_class = None

    def get_serializer_class(self):
        if self.action in ["retrieve", "list"]:
            return self.get_list_serializer_class()
        return super().get_serializer_class()

    def get_list_serializer_class(self):
        assert self.list_serializer_class is not None, (
            "'%s' should either include a `list_serializer_class` attribute,"
            "or override the `get_list_serializer_class()` method." % self.__class__.__name__
        )
        return self.list_serializer_class


class EagerLoadingMixin:
    @classmethod
    def setup_eager_loading(cls, queryset):
        if hasattr(cls, "SELECT_RELATED"):
            queryset = queryset.select_related(*cls.SELECT_RELATED)
        if hasattr(cls, "PREFETCH_RELATED"):
            queryset = queryset.prefetch_related(*cls.PREFETCH_RELATED)
        return queryset


class RateLimitHeadersMixin:
    # This mixin add RateLimit-Reset header to RateLimited response
    def handle_exception(self, exc):
        if isinstance(exc, Throttled):
            if exc.wait is not None:
                wait = f"{math.ceil(exc.wait)}"
            else:
                # if wait is none use maximum wait delay.
                # This case can be reproduced if decrease ratelimit when self.history is not empty
                wait = f"{350}"
            self.headers["RateLimit-Reset"] = wait
        return super().handle_exception(exc)


class OrderedModelSerializerMixin:
    def _change_position(self, order, instance):
        if order is not None:
            if order >= 0:
                instance.to(order)
            elif order == -1:
                instance.bottom()
            else:
                raise BadRequest(detail="Invalid value for position field")

    def _validate_order(self, order, filter_kwargs):
        if order is not None and (self.instance is None or self.instance.order != order):
            last_instance = self.Meta.model.objects.filter(**filter_kwargs).order_by("order").last()
            max_order = last_instance.order if last_instance else -1
            if self.instance is None:
                max_order += 1
            if order > max_order:
                raise BadRequest(detail="Invalid value for position field")

    def _validate_manual_order(self, order):
        """
        For manual ordering validate just that order is valid PositiveIntegrer.
        User of manual ordering is responsible for correct ordering.
        However, manual ordering not intended for use somewhere, except terraform provider.
        """

        # https://docs.djangoproject.com/en/4.1/ref/models/fields/#positiveintegerfield
        MAX_POSITIVE_INTEGER = 2147483647
        if order is not None and order < 0 or order > MAX_POSITIVE_INTEGER:
            raise BadRequest(detail="Invalid value for position field")


class PublicPrimaryKeyMixin:
    def get_object(self):
        pk = self.kwargs["pk"]
        queryset = self.filter_queryset(self.get_queryset())

        try:
            obj = queryset.get(public_primary_key=pk)
        except ObjectDoesNotExist:
            raise NotFound

        # May raise a permission denied
        self.check_object_permissions(self.request, obj)

        return obj


class TeamFilteringMixin:
    """
    This mixin returns 403 and {"error_code": "wrong_team", "owner_team": {"name", "id", "email", "avatar_url"}}
    in case a requested instance doesn't belong to user's current_team.
    """

    TEAM_LOOKUP = "team"

    @property
    def available_teams_lookup_args(self):
        """
        This property returns a list of Q objects that are used to filter instances by teams available to the user.
        NOTE: use .distinct() after filtering by available teams as it may return duplicate instances.
        """
        available_teams_lookup_args = []
        if not self.request.user.role == LegacyAccessControlRole.ADMIN:
            available_teams_lookup_args = [
                Q(**{f"{self.TEAM_LOOKUP}__users": self.request.user})
                | Q(**{f"{self.TEAM_LOOKUP}__is_sharing_resources_to_all": True})
                | Q(**{f"{self.TEAM_LOOKUP}__isnull": True})
            ]
        return available_teams_lookup_args

    def retrieve(self, request, *args, **kwargs):
        try:
            return super().retrieve(request, *args, **kwargs)
        except NotFound:
            queryset = self.filter_queryset(self.get_queryset(ignore_filtering_by_available_teams=True))
            try:
                queryset.get(public_primary_key=self.kwargs["pk"])
            except ObjectDoesNotExist:
                raise NotFound
            return Response(data={"error_code": "wrong_team"}, status=status.HTTP_403_FORBIDDEN)

    @staticmethod
    def _getattr_with_related(obj, lookup):
        entries = lookup.split("__")

        result = getattr(obj, entries[0])
        for entry in entries[1:]:
            result = getattr(result, entry)

        return result

    @staticmethod
    def _remove_filter(lookup, queryset):
        """
        This method removes a lookup from queryset.
        E.g. for queryset = Instance.objects.filter(a=5, team=None), _remove_filter("team", queryset) will modify the
        queryset to Instance.objects.filter(a=5).
        """
        query = queryset.query
        q = Q(**{lookup: None})
        clause, _ = query._add_q(q, query.used_aliases)

        def filter_lookups(child):
            try:
                return child.lhs.target != clause.children[0].lhs.target
            except AttributeError:
                return child.children[0].lhs.target != clause.children[0].lhs.target

        query.where.children = list(filter(filter_lookups, query.where.children))


# TODO: move to separate file
SLACK = "slack"
WEB = "web"
PHONE_CALL = "phone_call"
SMS = "sms"
TELEGRAM = "telegram"
# templates with its own field in db, this concept replaced by messaging_backend_templates field
NOTIFICATION_CHANNEL_OPTIONS = [SLACK, WEB, PHONE_CALL, SMS, TELEGRAM]

TITLE = "title"
MESSAGE = "message"
IMAGE_URL = "image_url"
RESOLVE_CONDITION = "resolve_condition"
ACKNOWLEDGE_CONDITION = "acknowledge_condition"
GROUPING_ID = "grouping_id"
SOURCE_LINK = "source_link"
ROUTE = "route"

NOTIFICATION_CHANNEL_TO_TEMPLATER_MAP = {
    SLACK: AlertSlackTemplater,
    WEB: AlertWebTemplater,
    PHONE_CALL: AlertPhoneCallTemplater,
    SMS: AlertSmsTemplater,
    TELEGRAM: AlertTelegramTemplater,
}

# add additionally supported messaging backends
for backend_id, backend in get_messaging_backends():
    if backend.templater is not None:
        NOTIFICATION_CHANNEL_OPTIONS.append(backend.slug)
        NOTIFICATION_CHANNEL_TO_TEMPLATER_MAP[backend.slug] = backend.get_templater_class()

APPEARANCE_TEMPLATE_NAMES = [TITLE, MESSAGE, IMAGE_URL]
BEHAVIOUR_TEMPLATE_NAMES = [RESOLVE_CONDITION, ACKNOWLEDGE_CONDITION, GROUPING_ID, SOURCE_LINK]
ROUTE_TEMPLATE_NAMES = [ROUTE]
ALL_TEMPLATE_NAMES = APPEARANCE_TEMPLATE_NAMES + BEHAVIOUR_TEMPLATE_NAMES + ROUTE_TEMPLATE_NAMES


class PreviewTemplateException(Exception):
    pass


class PreviewTemplateMixin:
    @action(methods=["post"], detail=True)
    def preview_template(self, request, pk):
        template_body = request.data.get("template_body", None)
        template_name = request.data.get("template_name", None)
        payload = request.data.get("payload", None)

        try:
            alert_to_template = self.get_alert_to_template(payload=payload)
            if alert_to_template is None:
                raise BadRequest(detail="Alert to preview does not exist")
        except PreviewTemplateException as e:
            raise BadRequest(detail=str(e))

        if template_body is None or template_name is None:
            response = {"preview": None}
            return Response(response, status=status.HTTP_200_OK)

        notification_channel, attr_name = self.parse_name_and_notification_channel(template_name)
        if attr_name is None:
            raise BadRequest(detail={"template_name": "Template name is missing"})
        if attr_name not in ALL_TEMPLATE_NAMES:
            raise BadRequest(detail={"template_name": "Unknown template name"})
        if attr_name in APPEARANCE_TEMPLATE_NAMES:
            if notification_channel is None:
                raise BadRequest(detail={"notification_channel": "notification_channel is required"})
            if notification_channel not in NOTIFICATION_CHANNEL_OPTIONS:
                raise BadRequest(detail={"notification_channel": "Unknown notification_channel"})

        if attr_name in APPEARANCE_TEMPLATE_NAMES:

            class PreviewTemplateLoader(TemplateLoader):
                def get_attr_template(self, attr, alert_receive_channel, render_for=None):
                    if attr == attr_name and render_for == notification_channel:
                        return template_body
                    else:
                        return super().get_attr_template(attr, alert_receive_channel, render_for)

            templater_cls = NOTIFICATION_CHANNEL_TO_TEMPLATER_MAP[notification_channel]
            templater = templater_cls(alert_to_template)
            templater.template_manager = PreviewTemplateLoader()
            try:
                templated_alert = templater.render()
            except (JinjaTemplateError, JinjaTemplateWarning) as e:
                return Response({"preview": e.fallback_message}, status.HTTP_200_OK)

            templated_attr = getattr(templated_alert, attr_name)

        elif attr_name in BEHAVIOUR_TEMPLATE_NAMES:
            try:
                templated_attr = apply_jinja_template(template_body, payload=alert_to_template.raw_request_data)
            except (JinjaTemplateError, JinjaTemplateWarning) as e:
                return Response({"preview": e.fallback_message}, status.HTTP_200_OK)
        elif attr_name in ROUTE_TEMPLATE_NAMES:
            try:
                templated_attr = apply_jinja_template(template_body, payload=alert_to_template.raw_request_data)
            except (JinjaTemplateError, JinjaTemplateWarning) as e:
                return Response({"preview": e.fallback_message}, status.HTTP_200_OK)
        else:
            templated_attr = None
        response = {"preview": templated_attr}
        return Response(response, status=status.HTTP_200_OK)

    def get_alert_to_template(self, payload=None):
        raise NotImplementedError

    @staticmethod
    def parse_name_and_notification_channel(template_param):
        template_param = template_param.replace("_template", "")
        attr_name = None
        destination = None
        if template_param.startswith(tuple(BEHAVIOUR_TEMPLATE_NAMES)):
            attr_name = template_param
        if template_param.startswith(tuple(ROUTE_TEMPLATE_NAMES)):
            attr_name = template_param
        elif template_param.startswith(tuple(NOTIFICATION_CHANNEL_OPTIONS)):
            for notification_channel in NOTIFICATION_CHANNEL_OPTIONS:
                if template_param.startswith(notification_channel):
                    destination = notification_channel
                    attr_name = template_param[len(destination) + 1 :]
                    break
        return destination, attr_name


class GrafanaHeadersMixin:
    @cached_property
    def grafana_context(self) -> dict:
        return json.loads(self.request.headers.get("X-Grafana-Context"))

    @cached_property
    def instance_context(self) -> dict:
        return json.loads(self.request.headers["X-Instance-Context"])