from __future__ import annotations

from datetime import datetime, timezone as dt_timezone

import jwt
from django.conf import settings
from django.db.models import Q
from django.db.models import Prefetch
from django.utils.dateparse import parse_datetime
from rest_framework import serializers, status
from rest_framework.response import Response
from rest_framework.views import APIView

from account.models import ShopModel

from .models import OrderModel, OrderItemModel


TOROB_PUBLIC_KEY = """
-----BEGIN PUBLIC KEY-----
MCowBQYDK2VwAyEAt6Mu4T0pBORY11W+QeM35UsmLO3vsf+6yKpFDEImFk0=
-----END PUBLIC KEY-----
"""


class TorobTokenError(Exception):
    pass


class TorobOrderQuerySerializer(serializers.Serializer):
    purchase_timestamp_gt = serializers.CharField(required=True)
    limit = serializers.IntegerField(required=True, min_value=1, max_value=1000)

    def validate_purchase_timestamp_gt(self, value):
        parsed = parse_datetime(value.replace("Z", "+00:00"))
        if parsed is None:
            raise serializers.ValidationError("purchase_timestamp_gt must be a valid ISO 8601 timestamp.")
        if parsed.tzinfo is None:
            parsed = parsed.replace(tzinfo=dt_timezone.utc)
        return parsed.astimezone(dt_timezone.utc)


def _utc_iso(value: datetime) -> str:
    return value.astimezone(dt_timezone.utc).isoformat().replace("+00:00", "Z")


def _shop_product_url(request, product) -> str:
    domain = getattr(settings, "DOMAIN", None) or getattr(settings, "API_DOMAIN", None) or request.get_host()
    if domain.startswith("http://") or domain.startswith("https://"):
        base = domain.rstrip("/")
    else:
        base = f"https://{domain}".rstrip("/")
    return f"{base}/product/{product.slug}/"


def _get_hostname_from_request(request) -> str:
    """Extract hostname for JWT audience validation.
    
    Returns the full host including port if present, as JWT audience
    should match exactly what Torob expects in the token.
    """
    return request.get_host()


def _validate_torob_token(request) -> None:
    token = request.headers.get("X-Torob-Token")
    version = request.headers.get("X-Torob-Token-Version")

    if version != "1":
        raise TorobTokenError("invalid token version")
    if not token:
        raise TorobTokenError("missing token")

    jwt.decode(
        token,
        key=TOROB_PUBLIC_KEY,
        algorithms=["EdDSA"],
        audience=_get_hostname_from_request(request),
    )


def _resolve_order_status(order: OrderModel) -> str | None:
    if order.status in {"RECEIVED", "POSTED"}:
        return "completed"
    if order.status == "CANCELED":
        return "cancelled"
    return None


def _order_shop_enabled(order: OrderModel) -> bool:
    shop_ids = set()
    for item in order.items.select_related("product__product__shop").all():
        shop = getattr(item.product.product, "shop", None)
        if shop is not None:
            shop_ids.add(shop.id)

    if not shop_ids:
        return False

    return ShopModel.objects.filter(id__in=shop_ids, torob_order_tracking_enabled=True).count() == len(shop_ids)


def _serialize_order(order: OrderModel, request) -> dict:
    products = []
    for item in order.items.select_related("product__product", "product__product__category").all():
        product = item.product.product
        products.append(
            {
                "product_url": _shop_product_url(request, product),
                "product_price": int(item.price_after_special_discount() // item.quantity) if item.quantity else int(item.price),
                "quantity": int(item.quantity),
            }
        )

    payload = {
        "order_id": str(order.id),
        "purchase_timestamp": _utc_iso(order.created_at),
        "last_updated_timestamp": _utc_iso(order.updated_at or order.created_at),
        "torob_clid": order.torob_clid,
        "status": _resolve_order_status(order),
        "order_value": int(order.final_price or 0),
        "phone_number": order.user.phone if order.user else None,
        "products": products,
    }

    return {key: value for key, value in payload.items() if value is not None}


class TorobOrderTrackingView(APIView):
    authentication_classes = []
    permission_classes = []

    def get(self, request):
        if not settings.TOROB_ORDER_TRACKING_ENABLED:
            return Response({"error": "order tracking is disabled"}, status=status.HTTP_403_FORBIDDEN)

        try:
            _validate_torob_token(request)
        except TorobTokenError as exc:
            return Response({"error": str(exc)}, status=status.HTTP_401_UNAUTHORIZED)
        except jwt.PyJWTError:
            return Response({"error": "invalid token"}, status=status.HTTP_401_UNAUTHORIZED)

        serializer = TorobOrderQuerySerializer(data=request.query_params)
        serializer.is_valid(raise_exception=True)
        since = serializer.validated_data["purchase_timestamp_gt"]
        limit = serializer.validated_data["limit"]

        orders = (
            OrderModel.objects.select_related("user")
            .prefetch_related(
                Prefetch(
                    "items",
                    queryset=OrderItemModel.objects.select_related("product__product", "product__product__shop"),
                )
            )
            .filter(Q(created_at__gt=since) | Q(updated_at__gt=since))
            .order_by("created_at", "id")
        )

        serialized = []
        disabled_match_found = False
        for order in orders:
            status_value = _resolve_order_status(order)
            if not status_value:
                continue
            if not order.torob_clid:
                continue
            if not _order_shop_enabled(order):
                disabled_match_found = True
                continue
            serialized.append(_serialize_order(order, request))
            if len(serialized) >= limit:
                break

        if not serialized and disabled_match_found:
            return Response({"error": "order tracking access is disabled for this shop"}, status=status.HTTP_403_FORBIDDEN)

        return Response({"success": True, "data": serialized}, status=status.HTTP_200_OK)