from django.contrib.auth import authenticate, login, logout
from rest_framework import permissions, status
from rest_framework.response import Response
from rest_framework.views import APIView

from .migration_service import apply_visitor_migration
from .models import UserSession, VisitorMigration
from .serializers import RegisterSerializer, UserSerializer


def client_ip(request):
    forwarded = request.META.get("HTTP_X_FORWARDED_FOR")
    return forwarded.split(",")[0].strip() if forwarded else request.META.get("REMOTE_ADDR")


class RegisterView(APIView):
    permission_classes = [permissions.AllowAny]

    def post(self, request):
        serializer = RegisterSerializer(
            data=request.data,
            context={"ip_address": client_ip(request)},
        )
        serializer.is_valid(raise_exception=True)
        user = serializer.save()
        login(request, user)
        self._record_session(request, user)
        payload = UserSerializer(user).data
        payload["visitor_migration_pending"] = hasattr(user, "visitor_migration")
        return Response(payload, status=status.HTTP_201_CREATED)

    @staticmethod
    def _record_session(request, user):
        if not request.session.session_key:
            request.session.save()
        UserSession.objects.update_or_create(
            session_key=request.session.session_key,
            defaults={
                "user": user,
                "user_agent": request.headers.get("User-Agent", "")[:300],
                "ip_address": client_ip(request),
            },
        )


class LoginView(APIView):
    permission_classes = [permissions.AllowAny]

    def post(self, request):
        user = authenticate(
            request,
            username=request.data.get("username", ""),
            password=request.data.get("password", ""),
        )
        if user is None or not user.is_active:
            return Response(
                {"error": {"code": "invalid_credentials", "message": "用户名或密码错误"}},
                status=status.HTTP_400_BAD_REQUEST,
            )
        login(request, user)
        RegisterView._record_session(request, user)
        return Response(UserSerializer(user).data)


class LogoutView(APIView):
    def post(self, request):
        if request.session.session_key:
            UserSession.objects.filter(session_key=request.session.session_key).delete()
        logout(request)
        return Response(status=status.HTTP_204_NO_CONTENT)


class MeView(APIView):
    def get(self, request):
        return Response(UserSerializer(request.user).data)

    def patch(self, request):
        serializer = UserSerializer(request.user, data=request.data, partial=True)
        serializer.is_valid(raise_exception=True)
        serializer.save()
        return Response(serializer.data)


class VisitorMigrationView(APIView):
    def get(self, request):
        migration = VisitorMigration.objects.filter(user=request.user).first()
        if migration is None:
            return Response({"pending": False, "summary": {}})
        return Response(
            {
                "pending": migration.status == VisitorMigration.Status.PENDING,
                "status": migration.status,
                "summary": migration.summary,
            }
        )

    def post(self, request):
        migration = VisitorMigration.objects.filter(user=request.user).first()
        if migration is None:
            return Response(
                {"error": {"code": "no_visitor_data", "message": "没有待迁移的游客数据"}},
                status=status.HTTP_404_NOT_FOUND,
            )
        migration = apply_visitor_migration(request.user)
        return Response(
            {
                "pending": False,
                "status": migration.status,
                "summary": migration.summary,
            }
        )