import logging

from django.http import HttpResponse
from django.utils import timezone
from django.utils.decorators import method_decorator
from django.views.decorators.csrf import csrf_exempt
from rest_framework.authentication import SessionAuthentication
from rest_framework.exceptions import AuthenticationFailed
from rest_framework.permissions import AllowAny, IsAuthenticated
from rest_framework.response import Response
from rest_framework import status
from rest_framework.views import APIView

from apps.api.authentication import ApiKeyAuthentication
from apps.api.errors import api_error
from apps.api.generation import (
    ApiRequestError,
    generate_image_response,
    generate_title_response,
)
from apps.api.serializers import (
    GenerateImageRequestSerializer,
    GenerateTitleRequestSerializer,
    RechargeCreateRequestSerializer,
    RechargeStatusRequestSerializer,
)
from apps.api.throttles import GenerateRateThrottle, throttle_api_auth_failure
from apps.ai.catalog import get_public_model_catalog
from apps.billing.models import RechargeOrder
from apps.billing.payment_gateways import (
    PaymentOrderCreateError,
    PaymentQueryUnavailableError,
    PaymentVerificationError,
    query_payment_order,
    verify_alipay_callback,
    verify_wechat_callback,
)
from apps.billing.pricing import NoExchangeRateError
from apps.billing.services import (
    InvalidRechargeOrderStateError,
    RechargeAmountMismatchError,
    RechargeCallbackError,
    RechargeOrderCreateError,
    RechargeOrderNotFoundError,
    RechargePayMethodMismatchError,
    apply_recharge_payment,
    create_recharge_order,
    get_balance_snapshot,
    query_and_apply_recharge_payment,
)
from apps.portal.models import DownloadRelease

logger = logging.getLogger(__name__)


class ExternalApiView(APIView):
    authentication_classes = (ApiKeyAuthentication,)
    permission_classes = (IsAuthenticated,)

    def permission_denied(self, request, message=None, code=None):
        if request.authenticators and not request.successful_authenticator:
            throttle_api_auth_failure(request)
            raise AuthenticationFailed(api_error("unauthorized", "缺失或无效 API Key"))
        super().permission_denied(request, message=message, code=code)


class GenerateTitleView(ExternalApiView):
    throttle_classes = (GenerateRateThrottle,)

    def post(self, request):
        serializer = GenerateTitleRequestSerializer(data=request.data)
        if not serializer.is_valid():
            return Response(
                api_error("bad_request", "参数错误"),
                status=status.HTTP_400_BAD_REQUEST,
            )
        try:
            data = generate_title_response(
                user=request.user,
                api_key=request.auth,
                request_data=serializer.validated_data,
            )
        except ApiRequestError as exc:
            return Response(exc.as_response_data(), status=exc.http_status)
        return Response(data, status=status.HTTP_200_OK)


class GenerateImageView(ExternalApiView):
    throttle_classes = (GenerateRateThrottle,)

    def post(self, request):
        serializer = GenerateImageRequestSerializer(data=request.data)
        if not serializer.is_valid():
            return Response(
                api_error("bad_request", "参数错误"),
                status=status.HTTP_400_BAD_REQUEST,
            )
        try:
            data = generate_image_response(
                user=request.user,
                api_key=request.auth,
                request=request,
                request_data=serializer.validated_data,
            )
        except ApiRequestError as exc:
            return Response(exc.as_response_data(), status=exc.http_status)
        return Response(data, status=status.HTTP_200_OK)


class BalanceView(ExternalApiView):
    def get(self, request):
        balance = get_balance_snapshot(request.user)
        username = request.user.get_username()
        display_name = request.user.get_full_name() or username
        return Response(
            {
                "user": username,
                "points_balance": balance.points_balance,
                "account": {
                    "username": username,
                    "display_name": display_name,
                },
            },
            status=status.HTTP_200_OK,
        )


class ModelsView(ExternalApiView):
    def get(self, request):
        return Response(
            {"models": get_public_model_catalog()},
            status=status.HTTP_200_OK,
        )


def _release_unpublished_response(platform: str) -> dict:
    return {
        "platform": platform,
        "release": None,
        "message": "暂未发布",
    }


def _absolute_download_url(request, release: DownloadRelease) -> str:
    download_url = release.download_url
    if not download_url:
        return ""
    if download_url.startswith(("http://", "https://")):
        return download_url
    return request.build_absolute_uri(download_url)


class ClientLatestReleaseView(APIView):
    authentication_classes = ()
    permission_classes = (AllowAny,)

    def get(self, request):
        platform = (
            request.query_params.get("platform")
            or DownloadRelease.Platform.WINDOWS
        ).strip().lower()
        if platform not in DownloadRelease.Platform.values:
            return Response(
                api_error("bad_request", "参数错误"),
                status=status.HTTP_400_BAD_REQUEST,
            )

        release = (
            DownloadRelease.objects.filter(platform=platform, is_current=True)
            .order_by("-created_at", "-id")
            .first()
        )
        if release is None:
            return Response(
                _release_unpublished_response(platform),
                status=status.HTTP_200_OK,
            )

        download_url = _absolute_download_url(request, release)
        if not download_url:
            return Response(
                _release_unpublished_response(platform),
                status=status.HTTP_200_OK,
            )

        return Response(
            {
                "platform": platform,
                "release": {
                    "version": release.version,
                    "download_url": download_url,
                    "sha256": release.sha256,
                    "release_notes": release.release_notes,
                    "force_update": release.force_update,
                    "published_at": timezone.localtime(release.updated_at).isoformat(),
                },
            },
            status=status.HTTP_200_OK,
        )


class PortalSessionApiView(APIView):
    authentication_classes = (SessionAuthentication,)
    permission_classes = (IsAuthenticated,)


def _recharge_order_response(order: RechargeOrder) -> dict:
    is_expired = bool(
        order.status == RechargeOrder.Status.PENDING
        and order.expires_at is not None
        and order.expires_at <= timezone.now()
    )
    return {
        "order_no": order.order_no,
        "amount": f"{order.amount_money:.2f}",
        "currency": order.currency,
        "exchange_rate": f"{order.exchange_rate:.4f}",
        "points_granted": order.points_granted,
        "pay_method": order.pay_method,
        "status": order.status,
        "code_url": order.code_url,
        "expires_at": order.expires_at.isoformat() if order.expires_at else None,
        "paid_at": order.paid_at.isoformat() if order.paid_at else None,
        "is_expired": is_expired,
    }


class RechargeCreateView(PortalSessionApiView):
    def post(self, request):
        serializer = RechargeCreateRequestSerializer(data=request.data)
        if not serializer.is_valid():
            return Response(
                api_error("bad_request", "参数错误"),
                status=status.HTTP_400_BAD_REQUEST,
            )

        try:
            order = create_recharge_order(
                user=request.user,
                amount=serializer.validated_data["amount"],
                pay_method=serializer.validated_data["pay_method"],
            )
        except NoExchangeRateError:
            return Response(
                api_error("no_exchange_rate", "未配置当前币种汇率"),
                status=status.HTTP_400_BAD_REQUEST,
            )
        except RechargeOrderCreateError:
            return Response(
                api_error("bad_request", "充值下单参数错误"),
                status=status.HTTP_400_BAD_REQUEST,
            )
        except PaymentOrderCreateError:
            return Response(
                api_error("payment_order_create_failed", "支付下单失败"),
                status=status.HTTP_502_BAD_GATEWAY,
            )

        return Response(_recharge_order_response(order), status=status.HTTP_201_CREATED)


class RechargeStatusView(PortalSessionApiView):
    def get(self, request):
        serializer = RechargeStatusRequestSerializer(data=request.query_params)
        if not serializer.is_valid():
            return Response(
                api_error("bad_request", "参数错误"),
                status=status.HTTP_400_BAD_REQUEST,
            )

        order_no = serializer.validated_data["order_no"]
        order = RechargeOrder.objects.filter(
            user=request.user,
            order_no=order_no,
        ).first()
        if order is None:
            return Response(
                api_error("order_not_found", "充值订单不存在"),
                status=status.HTTP_404_NOT_FOUND,
            )

        if order.status == RechargeOrder.Status.PENDING:
            try:
                result = query_and_apply_recharge_payment(order.order_no, query_payment_order)
                order = result.order
            except (PaymentQueryUnavailableError, PaymentOrderCreateError):
                order.refresh_from_db()
            except RechargeCallbackError as exc:
                logger.warning(
                    "Rejected active recharge query result for %s: %s",
                    order.order_no,
                    exc.__class__.__name__,
                )
                return Response(
                    api_error(exc.code, "支付查单结果与本地订单不一致"),
                    status=status.HTTP_400_BAD_REQUEST,
                )
            except Exception as exc:  # pragma: no cover - external gateway/runtime.
                logger.warning(
                    "Active recharge query failed for %s: %s",
                    order.order_no,
                    exc.__class__.__name__,
                )
                order.refresh_from_db()

        return Response(_recharge_order_response(order), status=status.HTTP_200_OK)


class RechargeCallbackView(APIView):
    authentication_classes = ()
    permission_classes = ()

    @staticmethod
    def _error_response(exc: Exception):
        if isinstance(exc, PaymentVerificationError):
            return (
                api_error("signature_invalid", "支付回调验签失败"),
                status.HTTP_400_BAD_REQUEST,
            )
        if isinstance(exc, RechargeAmountMismatchError):
            return (
                api_error("amount_mismatch", "支付回调金额与本地订单金额不一致"),
                status.HTTP_400_BAD_REQUEST,
            )
        if isinstance(exc, RechargeCallbackError):
            return api_error(exc.code, "支付回调处理失败"), status.HTTP_400_BAD_REQUEST
        return api_error("bad_request", "支付回调处理失败"), status.HTTP_400_BAD_REQUEST


@method_decorator(csrf_exempt, name="dispatch")
class WechatRechargeCallbackView(RechargeCallbackView):
    def post(self, request):
        try:
            payment = verify_wechat_callback(request.headers, request.body)
            apply_recharge_payment(payment)
        except (
            PaymentVerificationError,
            RechargeAmountMismatchError,
            InvalidRechargeOrderStateError,
            RechargeOrderNotFoundError,
            RechargePayMethodMismatchError,
        ) as exc:
            logger.warning("Rejected WeChat recharge callback: %s", exc.__class__.__name__)
            data, http_status = self._error_response(exc)
            return Response(data, status=http_status)
        return Response({"code": "SUCCESS", "message": "成功"}, status=status.HTTP_200_OK)


@method_decorator(csrf_exempt, name="dispatch")
class AlipayRechargeCallbackView(RechargeCallbackView):
    def post(self, request):
        try:
            payload = request.data.dict() if hasattr(request.data, "dict") else dict(request.data)
            payment = verify_alipay_callback(payload)
            apply_recharge_payment(payment)
        except (
            PaymentVerificationError,
            RechargeAmountMismatchError,
            InvalidRechargeOrderStateError,
            RechargeOrderNotFoundError,
            RechargePayMethodMismatchError,
        ) as exc:
            logger.warning("Rejected Alipay recharge callback: %s", exc.__class__.__name__)
            return HttpResponse("fail", status=status.HTTP_400_BAD_REQUEST)
        return HttpResponse("success", content_type="text/plain", status=status.HTTP_200_OK)