import logging
from datetime import timedelta

import requests
from celery import shared_task
from django.template import Context, Template
from django.utils import timezone

from infrasynth.shared.settings_utils import get_setting

from .models import OutboundDelivery, OutboundSubscription
from .signals import outbound_delivery_failed, outbound_delivery_succeeded
from .signature import sign_payload

logger = logging.getLogger(__name__)


@shared_task(
    name="infrasynth.webhooks.deliver_webhook",
    bind=True,
    max_retries=5,
    default_retry_delay=60,
)
def deliver_webhook(self, subscription_id, event_name, payload, payload_template, tenant_id=None):
    """Delivers an outbound webhook with HMAC signature and retry/backoff."""
    from infrasynth.tenancy.context import tenant_context
    from infrasynth.tenancy.models import Tenant

    try:
        subscription = OutboundSubscription.all_objects.select_related("endpoint").get(pk=subscription_id)
    except OutboundSubscription.DoesNotExist:
        logger.warning("Subscription %s not found", subscription_id)
        return None

    tenant = Tenant.objects.filter(pk=tenant_id).first() if tenant_id else subscription.tenant
    with tenant_context(tenant):
        return _deliver_webhook_inner(self, subscription, event_name, payload, payload_template, tenant)


def _deliver_webhook_inner(self, subscription, event_name, payload, payload_template, tenant):
    endpoint = subscription.endpoint
    body = _build_payload(payload, payload_template)

    delivery = OutboundDelivery.all_objects.create(
        tenant=tenant or subscription.tenant,
        subscription=subscription,
        payload=body,
        status=OutboundDelivery.Status.RETRYING,
        attempt=self.request.retries + 1,
    )

    headers = {"Content-Type": "application/json"}
    headers.update(endpoint.headers or {})
    headers[get_setting("INFRASYNTH_WEBHOOKS", "SIGNATURE_HEADER", "X-Webhook-Signature")] = sign_payload(
        endpoint.secret, body
    )

    timeout = endpoint.timeout_seconds or get_setting("INFRASYNTH_WEBHOOKS", "DEFAULT_TIMEOUT_SECONDS", 10)

    try:
        response = requests.post(
            endpoint.url,
            data=body,
            headers=headers,
            timeout=timeout,
        )
    except requests.RequestException as exc:
        return _handle_failure(self, delivery, subscription, endpoint, str(exc))

    delivery.response_status = response.status_code
    delivery.response_body = response.text[:4000]
    delivery.completed_at = timezone.now()

    if 200 <= response.status_code < 300:
        delivery.status = OutboundDelivery.Status.SUCCESS
        delivery.save()
        outbound_delivery_succeeded.send(
            sender=OutboundDelivery,
            delivery_id=delivery.id,
            event_name=event_name,
            status_code=response.status_code,
        )
        logger.info(
            "Webhook delivered: %s -> %s (%s)",
            event_name,
            endpoint.url,
            response.status_code,
        )
        return delivery.id

    delivery.save()
    return _handle_failure(
        self,
        delivery,
        subscription,
        endpoint,
        f"HTTP {response.status_code}: {response.text[:500]}",
    )


def _build_payload(payload: dict, payload_template: str) -> str:
    import json

    if payload_template:
        try:
            template = Template(payload_template)
            return template.render(Context({"event": payload, "payload": payload}))
        except Exception:  # noqa: BLE001
            logger.exception("Failed to render webhook payload template")
    return json.dumps(payload, default=str)


def _handle_failure(self, delivery, subscription, endpoint, error: str):
    max_retries = int(
        (endpoint.retry_policy or {}).get("max_retries", get_setting("INFRASYNTH_WEBHOOKS", "MAX_RETRIES", 5))
    )
    backoff = (endpoint.retry_policy or {}).get(
        "backoff", get_setting("INFRASYNTH_WEBHOOKS", "RETRY_BACKOFF", "exponential")
    )
    initial_delay = int(get_setting("INFRASYNTH_WEBHOOKS", "RETRY_INITIAL_DELAY_SECONDS", 60))

    delivery.status = OutboundDelivery.Status.RETRYING
    delivery.response_body = error[:4000] if not delivery.response_body else delivery.response_body

    if self.request.retries < max_retries:
        countdown = initial_delay * (2**self.request.retries) if backoff == "exponential" else initial_delay
        delivery.next_retry_at = timezone.now() + timedelta(seconds=countdown)
        delivery.save()
        logger.warning("Webhook delivery failed (attempt %s): %s", self.request.retries + 1, error)
        raise self.retry(exc=Exception(error), countdown=countdown) from None

    delivery.status = OutboundDelivery.Status.FAILED
    delivery.completed_at = timezone.now()
    delivery.save()
    outbound_delivery_failed.send(
        sender=OutboundDelivery,
        delivery_id=delivery.id,
        event_name=delivery.subscription.event_name,
        error=error,
    )
    logger.error("Webhook delivery gave up: %s", error)
    return None


@shared_task(
    name="infrasynth.webhooks.process_inbound_event",
    bind=True,
    max_retries=3,
    default_retry_delay=60,
)
def process_inbound_event(self, event_id, tenant_id=None):
    """Runs the endpoint's handler against a verified inbound event."""
    from django.utils.module_loading import import_string

    from infrasynth.tenancy.context import tenant_context
    from infrasynth.tenancy.models import Tenant

    from .inbound.handlers import HMACInboundHandler
    from .models import InboundEvent
    from .signals import inbound_event_processed

    try:
        event = InboundEvent.all_objects.select_related("endpoint").get(pk=event_id)
    except InboundEvent.DoesNotExist:
        logger.warning("Inbound event %s not found", event_id)
        return None

    tenant = Tenant.objects.filter(pk=tenant_id).first() if tenant_id else event.tenant
    with tenant_context(tenant):
        handler = None
        if event.endpoint.handler:
            try:
                handler = import_string(event.endpoint.handler)()
            except (ImportError, TypeError):
                handler = None
        handler = handler or HMACInboundHandler()
        try:
            result = handler.process(event.event_type, event.raw_payload)
        except Exception as exc:  # noqa: BLE001
            logger.exception("Inbound event %s processing failed", event_id)
            event.error = str(exc)
            event.save(update_fields=["error"])
            raise self.retry(exc=exc) from exc

        event.result = result if isinstance(result, dict) else {"result": result}
        event.is_processed = True
        event.error = ""
        event.processed_at = timezone.now()
        event.save(update_fields=["result", "is_processed", "error", "processed_at"])
        inbound_event_processed.send(
            sender=InboundEvent,
            tenant_id=str(event.tenant_id) if event.tenant_id else None,
            event_id=event.id,
            event_type=event.event_type,
            result=event.result,
        )
        return event.id