import random
import uuid

from django.conf import settings
from django.utils import timezone
from drf_spectacular.utils import extend_schema
from rest_framework import status
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from rest_framework.views import APIView

from .authentication import issue_access_token
from .models import OTPCode, Session, User
from .serializers import (
    GuestSessionRequestSerializer,
    GuestSessionResponseSerializer,
    LoginRequestSerializer,
    LoginResponseSerializer,
    RefreshRequestSerializer,
    RefreshResponseSerializer,
    RequestOTPRequestSerializer,
    RequestOTPResponseSerializer,
    SetGradeRequestSerializer,
    SetGradeResponseSerializer,
)


class GuestSessionView(APIView):
    """POST /api/auth/session — ایجاد سشن مهمان"""

    @extend_schema(
        request=GuestSessionRequestSerializer,
        responses=GuestSessionResponseSerializer,
        tags=['Identity & Profile (accounts)'],
    )
    def post(self, request):
        serializer = GuestSessionRequestSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        device_id = serializer.validated_data['deviceId']

        user, is_new_user = User.objects.get_or_create(
            device_id=device_id,
            is_guest=True,
            defaults={'name': ''},
        )

        token = issue_access_token(user.id)

        data = {
            'userId': str(user.id),
            'token': token,
            'isNewUser': is_new_user,
            'isGuest': True,
        }
        return Response(GuestSessionResponseSerializer(data).data)


class RequestOTPView(APIView):
    """
    POST /api/auth/otp/request — درخواست کد OTP (کمکی، برای تست از طریق Swagger)
    در محیط توسعه، کد ساخته‌شده در پاسخ برگردونده می‌شه تا نیازی به SMS واقعی نباشه.
    """

    @extend_schema(
        request=RequestOTPRequestSerializer,
        responses=RequestOTPResponseSerializer,
        tags=['Identity & Profile (accounts)'],
    )
    def post(self, request):
        serializer = RequestOTPRequestSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        phone = serializer.validated_data['phone']

        code = f'{random.randint(0, 9999):04d}'
        OTPCode.objects.create(
            phone=phone,
            code=code,
            expires_at=timezone.now() + timezone.timedelta(minutes=5),
        )
        data = {
            'success': True,
            'devOtp': code,
            'note': f'در پروداکشن این کد پیامک می‌شه؛ برای تست همیشه {settings.DEV_MASTER_OTP} هم قبول می‌شه.',
        }
        return Response(RequestOTPResponseSerializer(data).data)


class LoginView(APIView):
    """POST /api/auth/login — ورود با OTP"""

    @extend_schema(
        request=LoginRequestSerializer,
        responses=LoginResponseSerializer,
        tags=['Identity & Profile (accounts)'],
    )
    def post(self, request):
        serializer = LoginRequestSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        phone = serializer.validated_data['phone']
        otp = serializer.validated_data['otp']

        valid = False
        if otp == settings.DEV_MASTER_OTP:
            valid = True
        else:
            otp_qs = OTPCode.objects.filter(
                phone=phone, code=otp, is_used=False, expires_at__gte=timezone.now()
            ).order_by('-id')
            otp_obj = otp_qs.first()
            if otp_obj:
                otp_obj.is_used = True
                otp_obj.save(update_fields=['is_used'])
                valid = True

        if not valid:
            return Response({'detail': 'کد OTP نامعتبر یا منقضی‌شده است.'}, status=status.HTTP_400_BAD_REQUEST)

        user, created = User.objects.get_or_create(
            phone=phone,
            defaults={'is_guest': False, 'name': ''},
        )
        if user.is_guest:
            user.is_guest = False
            user.save(update_fields=['is_guest'])

        if created:
            # ثبت‌نام واقعی (نه guest session): آفرهای auto_assign_on_signup
            # (مثل یک هفته رایگان) از طریق discount/receivers.py روی همین
            # سیگنال اعمال می‌شن؛ این ویو از وجود آفر/discount چیزی نمی‌دونه.
            from .signals import user_registered
            user_registered.send(sender=User, user_id=user.id)

        refresh_token = uuid.uuid4().hex
        Session.objects.create(
            user=user,
            refresh_token=refresh_token,
            device_id=request.data.get('deviceId', ''),
            expires_at=timezone.now() + timezone.timedelta(days=settings.REFRESH_TOKEN_TTL_DAYS),
        )
        access_token = issue_access_token(user.id)

        data = {
            'userId': str(user.id),
            'token': access_token,
            'refreshToken': refresh_token,
        }
        return Response(LoginResponseSerializer(data).data)


class RefreshTokenView(APIView):
    """POST /api/auth/refresh — تمدید توکن"""

    @extend_schema(
        request=RefreshRequestSerializer,
        responses=RefreshResponseSerializer,
        tags=['Identity & Profile (accounts)'],
    )
    def post(self, request):
        serializer = RefreshRequestSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        refresh_token = serializer.validated_data['refreshToken']

        session = Session.objects.filter(
            refresh_token=refresh_token, revoked=False, expires_at__gte=timezone.now()
        ).first()
        if not session:
            return Response({'detail': 'رفرش‌توکن نامعتبر یا منقضی‌شده است.'}, status=status.HTTP_401_UNAUTHORIZED)

        access_token = issue_access_token(session.user_id)
        data = {'token': access_token, 'expiresIn': settings.ACCESS_TOKEN_TTL_SECONDS}
        return Response(RefreshResponseSerializer(data).data)


class SetUserGradeView(APIView):
    """POST /api/user/grade — ثبت پایه‌ی کاربر (نیاز به احراز هویت)"""

    permission_classes = [IsAuthenticated]

    @extend_schema(
        request=SetGradeRequestSerializer,
        responses=SetGradeResponseSerializer,
        tags=['Identity & Profile (accounts)'],
    )
    def post(self, request):
        serializer = SetGradeRequestSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        grade_id = serializer.validated_data['gradeId']

        user = request.user
        user.grade_id = grade_id
        user.save(update_fields=['grade_id'])

        data = {'success': True, 'gradeId': grade_id}
        return Response(SetGradeResponseSerializer(data).data)