from django.contrib.auth import get_user_model, authenticate, login as django_login, logout as django_logout
from django.utils.http import urlsafe_base64_encode, urlsafe_base64_decode
from django.utils.encoding import force_bytes, force_str

from .serializers import *
from .permissions import *
from .models import CustomUser
from .tokens import *
from .tasks import (
    send_password_reset_email_task, send_email_verification_task,
    send_email_change_verification_task, send_email_change_notification_task,
)
from django.conf import settings
import logging
logger = logging.getLogger(__name__)

from .filters import UserFilter

from rest_framework import generics, permissions, status, viewsets
from rest_framework.response import Response
from rest_framework_simplejwt.tokens import RefreshToken
from rest_framework.views import APIView
from rest_framework.viewsets import ModelViewSet
from rest_framework.permissions import IsAuthenticated, AllowAny

from rest_framework_simplejwt.tokens import RefreshToken
from rest_framework_simplejwt.exceptions import TokenError, AuthenticationFailed, InvalidToken
from django_filters.rest_framework import DjangoFilterBackend

from drf_spectacular.utils import extend_schema, OpenApiResponse, OpenApiExample, OpenApiParameter
from vontor_cz.turnstile import verify_turnstile


User = get_user_model()

#general user view API
 

from rest_framework_simplejwt.views import TokenObtainPairView

#---------------------------------------------TOKENY------------------------------------------------

# Custom Token obtaining view
@extend_schema(
    tags=["account", "public"],
    summary="Obtain JWT access and refresh tokens (cookie-based)",
    description="Authenticate user and obtain JWT access and refresh tokens. You can use either email or username.",
    request=CustomTokenObtainPairSerializer,
    responses={
        200: OpenApiResponse(response=CustomTokenObtainPairSerializer, description="Tokens returned successfully."),
        401: OpenApiResponse(description="Invalid credentials or inactive user."),
    },
)
class CookieTokenObtainPairView(TokenObtainPairView):
    serializer_class = CustomTokenObtainPairSerializer


    def post(self, request, *args, **kwargs):
        turnstile_token = request.data.get("turnstile_token", "")
        remote_ip = request.META.get("HTTP_X_FORWARDED_FOR", request.META.get("REMOTE_ADDR", ""))
        if not verify_turnstile(turnstile_token, remote_ip):
            return Response({"detail": "Ověření CAPTCHA selhalo."}, status=status.HTTP_400_BAD_REQUEST)

        serializer = self.get_serializer(data=request.data)
        try:
            serializer.is_valid(raise_exception=True)
        except TokenError as e:
            raise InvalidToken(e.args[0])

        access = serializer.validated_data.get("access")
        refresh = serializer.validated_data.get("refresh")

        # Create a Django session so AuthMiddlewareStack authenticates WebSocket connections
        django_login(request, serializer.user, backend='django.contrib.auth.backends.ModelBackend')

        response = Response(serializer.validated_data, status=status.HTTP_200_OK)

        jwt_settings = settings.SIMPLE_JWT

        # Access token cookie
        response.set_cookie(
            key=jwt_settings.get("AUTH_COOKIE", "access_token"),
            value=access,
            httponly=jwt_settings.get("AUTH_COOKIE_HTTP_ONLY", True),
            secure=jwt_settings.get("AUTH_COOKIE_SECURE", not settings.DEBUG),
            samesite=jwt_settings.get("AUTH_COOKIE_SAMESITE", "Lax"),
            path=jwt_settings.get("AUTH_COOKIE_PATH", "/"),
            max_age=5 * 60,  # 5 minut
        )

        # Refresh token cookie
        response.set_cookie(
            key="refresh_token",
            value=refresh,
            httponly=True,
            secure=not settings.DEBUG,
            samesite="Lax",
            path="/",
            max_age=7 * 24 * 60 * 60,  # 7 dní
        )

        return response

@extend_schema(
    tags=["account", "public"],
    summary="Refresh JWT token using cookie",
    description="Refresh JWT access and refresh tokens using the refresh token stored in cookie.",
    responses={
        200: OpenApiResponse(description="Tokens refreshed successfully."),
        400: OpenApiResponse(description="Refresh token cookie not found."),
        401: OpenApiResponse(description="Invalid refresh token."),
    },
)
class CookieTokenRefreshView(APIView):
    def post(self, request):
        refresh_token = request.COOKIES.get('refresh_token')
        if not refresh_token:
            return Response({"detail": "Refresh token cookie not found."}, status=status.HTTP_400_BAD_REQUEST)

        try:
            refresh = RefreshToken(refresh_token)
            access_token = str(refresh.access_token)
            new_refresh_token = str(refresh)  # volitelně nový refresh token

            response = Response({
                "access": access_token,
                "refresh": new_refresh_token,
            })

            # Nastav nové HttpOnly cookies
            # Access token cookie (např. 5 minut platnost)
            response.set_cookie(
                "access_token",
                access_token,
                httponly=True,
                secure=not settings.DEBUG,
                samesite="Lax",
                max_age=5 * 60,
                path="/",
            )

            # Refresh token cookie (delší platnost, např. 7 dní)
            response.set_cookie(
                "refresh_token",
                new_refresh_token,
                httponly=True,
                secure=not settings.DEBUG,
                samesite="Lax",
                max_age=7 * 24 * 60 * 60,
                path="/",
            )

            return response

        except TokenError:
            return Response({"detail": "Invalid refresh token."}, status=status.HTTP_401_UNAUTHORIZED)
        
#---------------------------------------------LOGOUT------------------------------------------------

@extend_schema(
    tags=["account", "public"],
    summary="Logout user (delete access and refresh token cookies)",
    description="Logs out the user by deleting access and refresh token cookies.",
    responses={
        200: OpenApiResponse(description="Logout successful."),
    },
)
class LogoutView(APIView):
    permission_classes = [AllowAny]

    def post(self, request):
        django_logout(request)  # destroy Django session (used for WebSocket auth)
        response = Response({"detail": "Logout successful"}, status=status.HTTP_200_OK)
        response.delete_cookie("access_token", path="/")
        response.delete_cookie("refresh_token", path="/")
        return response

#--------------------------------------------------------------------------------------------------------------

@extend_schema(
    tags=["account"],
    summary="List, retrieve, update, and delete users.",
    description="Displays all users with filtering and ordering options. Requires authentication and appropriate role.",
    responses={
        200: OpenApiResponse(response=CustomUserSerializer, description="User(s) retrieved successfully."),
        403: OpenApiResponse(description="Permission denied."),
    },
)
class UserView(viewsets.ModelViewSet):
    queryset = User.objects.all()
    serializer_class = CustomUserSerializer
    filter_backends = [DjangoFilterBackend]
    filterset_class = UserFilter

    # Require authentication and role permission
    permission_classes = [IsAuthenticated]

    class Meta:
        model = CustomUser
        extra_kwargs = {
            "email": {"help_text": "Unikátní e-mailová adresa uživatele."},
            "phone_number": {"help_text": "Telefonní číslo ve formátu +420123456789."},
            "role": {"help_text": "Role uživatele určující jeho oprávnění v systému."},
            "account_type": {"help_text": "Typ účtu – firma nebo fyzická osoba."},
            "email_verified": {"help_text": "Určuje, zda je e-mail ověřen."},
            "create_time": {"help_text": "Datum a čas registrace uživatele (pouze pro čtení).", "read_only": True},
            "var_symbol": {"help_text": "Variabilní symbol pro platby, pokud je vyžadován."},
            "bank_account": {"help_text": "Číslo bankovního účtu uživatele."},
            "ICO": {"help_text": "IČO firmy, pokud se jedná o firemní účet."},
            "RC": {"help_text": "Rodné číslo pro fyzické osoby."},
            "city": {"help_text": "Město trvalého pobytu / sídla."},
            "street": {"help_text": "Ulice a číslo popisné."},
            "PSC": {"help_text": "PSČ místa pobytu / sídla."},
            "GDPR": {"help_text": "Souhlas se zpracováním osobních údajů."},
            "is_active": {"help_text": "Stav aktivace uživatele."},
        }

    @extend_schema(
        tags=["account"],
        summary="Get permissions based on user role and action.",
        description="Determines permissions for various actions based on user role and ownership.",
        responses={
            200: OpenApiResponse(description="Permissions determined successfully."),
            403: OpenApiResponse(description="Permission denied."),
        },
    )
    def get_permissions(self):
        if self.action == 'create':
            return [OnlyRolesAllowed("admin")()]

        if self.action in ['list', 'retrieve']:
            return [IsAuthenticated()]

        if self.action in ['update', 'partial_update', 'destroy']:
            user = getattr(self, 'request', None) and getattr(self.request, 'user', None)
            if user and getattr(user, 'is_authenticated', False) and getattr(user, 'role', None) == 'admin':
                return [OnlyRolesAllowed("admin")()]
            lookup = self.kwargs.get('pk', '')
            if user and getattr(user, 'is_authenticated', False) and lookup and (
                str(getattr(user, 'id', '')) == lookup
            ):
                return [IsAuthenticated()]
            return [OnlyRolesAllowed("admin")()]

        return super().get_permissions()

    def get_serializer_class(self):
        user = getattr(self.request, 'user', None)

        is_admin = user and (getattr(user, 'role', None) == 'admin' or getattr(user, 'is_superuser', False))

        if self.action in ['retrieve', 'list'] and not is_admin:
            return PublicUserSerializer
        return CustomUserSerializer
        
        

# Get current user data
@extend_schema(
    tags=["account"],
    summary="Get current authenticated user",
    description="Returns details of the currently authenticated user based on JWT token or session.",
    responses={
        200: OpenApiResponse(response=CustomUserSerializer, description="Current user details."),
        401: OpenApiResponse(description="Unauthorized, user is not authenticated."),
    }
)
class CurrentUserView(APIView):
    permission_classes = [IsAuthenticated]

    def get(self, request):
        serializer = CustomUserSerializer(request.user)
        return Response(serializer.data)


@extend_schema(
    tags=["account"],
    summary="Change password for the authenticated user",
    request=ChangePasswordSerializer,
    responses={
        200: OpenApiResponse(description="Password changed successfully."),
        400: OpenApiResponse(description="Invalid current password or validation error."),
    },
)
class ChangePasswordView(APIView):
    permission_classes = [IsAuthenticated]

    def post(self, request):
        serializer = ChangePasswordSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        user = request.user

        if not user.check_password(serializer.validated_data['current_password']):
            return Response({"current_password": "Nesprávné heslo."}, status=status.HTTP_400_BAD_REQUEST)
        
        user.set_password(serializer.validated_data['new_password'])
        user.save()
        
        return Response({"detail": "Heslo bylo úspěšně změněno."})


#------------------------------------------------REGISTRACE--------------------------------------------------------------

#1. registration API
@extend_schema(
    tags=["account", "public"],
    summary="Register a new user (company or individual)",
    description="Register a new user (company or individual). The user will receive an email with a verification link.",
    request=UserRegistrationSerializer,
    responses={
        201: OpenApiResponse(response=UserRegistrationSerializer, description="User registered successfully."),
        400: OpenApiResponse(description="Invalid registration data."),
    },
)
class UserRegistrationViewSet(ModelViewSet):
    queryset = CustomUser.objects.all()
    serializer_class = UserRegistrationSerializer
    http_method_names = ['post']

    def create(self, request, *args, **kwargs):
        turnstile_token = request.data.get("turnstile_token", "")
        remote_ip = request.META.get("HTTP_X_FORWARDED_FOR", request.META.get("REMOTE_ADDR", ""))
        if not verify_turnstile(turnstile_token, remote_ip):
            return Response({"detail": "Ověření CAPTCHA selhalo."}, status=status.HTTP_400_BAD_REQUEST)

        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        user = serializer.save()

        try:
            send_email_verification_task.delay(user.id) # posílaní emailu pro potvrzení registrace - CELERY TASK
        except Exception as e:
            logger.error(f"Celery not available, using fallback. Error: {e}")
            send_email_verification_task(user.id) # posílaní emailu pro potvrzení registrace


            
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
    
#2. confirming email
@extend_schema(
    tags=["account", "public"],
    summary="Verify user email via link",
    description="Verify user email using the link with uid and token.",
    parameters=[
        OpenApiParameter(name='uidb64', type=str, location=OpenApiParameter.PATH, description="User ID encoded in base64 from email link."),
        OpenApiParameter(name='token', type=str, location=OpenApiParameter.PATH, description="User token from email link."),
    ],
    responses={
        200: OpenApiResponse(description="Email successfully verified."),
        400: OpenApiResponse(description="Invalid or expired token."),
    },
)
class EmailVerificationView(APIView):
    def get(self, request, uidb64, token):
        try:
            uid = force_str(urlsafe_base64_decode(uidb64))
            user = User.objects.get(pk=uid)
        except (User.DoesNotExist, ValueError, TypeError):
            return Response({"error": "Neplatný odkaz."}, status=400)

        if account_activation_token.check_token(user, token):
            user.email_verified = True
            user.is_active = True  # Aktivace uživatele po ověření e-mailu
            user.save()
            
            return Response({"detail": "E-mail byl úspěšně ověřen. Účet je aktivován."})
        else:
            return Response({"error": "Token je neplatný nebo expirovaný."}, status=400)

#-------------------------------------------------END REGISTRACE-------------------------------------------------------------

#1. PasswordReset + send Email
@extend_schema(
    tags=["account", "public"],
    summary="Request password reset (send email)",
    description="Request password reset by providing registered email. An email with instructions will be sent.",
    request=PasswordResetRequestSerializer,
    responses={
        200: OpenApiResponse(description="Email with instructions sent."),
        400: OpenApiResponse(description="Invalid email or request data."),
    },
)
class PasswordResetRequestView(APIView):
    def post(self, request):
        serializer = PasswordResetRequestSerializer(data=request.data)
        if serializer.is_valid():
            try:
                user = User.objects.get(email=serializer.validated_data['email'])
            except User.DoesNotExist:
                # Always return 200 even if user doesn't exist to avoid user enumeration
                return Response({"detail": "E-mail s odkazem byl odeslán."})
            try:
                send_password_reset_email_task.delay(user.id) # posílaní emailu pro obnovení hesla - CELERY TASK
            except Exception as e:
                logger.error(f"Celery not available, using fallback. Error: {e}")
                send_password_reset_email_task(user.id) # posílaní emailu pro obnovení hesla registrace

            return Response({"detail": "E-mail s odkazem byl odeslán."})
        
        return Response(serializer.errors, status=400)
    
#2. Confirming reset
@extend_schema(
    tags=["account", "public"],
    summary="Confirm password reset via token",
    description="Confirm password reset using token from email.",
    request=PasswordResetConfirmSerializer,
    parameters=[
        OpenApiParameter(name='uidb64', type=str, location=OpenApiParameter.PATH, description="User ID encoded in base64 from email link."),
        OpenApiParameter(name='token', type=str, location=OpenApiParameter.PATH, description="Password reset token from email link."),
    ],
    responses={
        200: OpenApiResponse(description="Password changed successfully."),
        400: OpenApiResponse(description="Invalid token or request data."),
    },
)
class PasswordResetConfirmView(APIView):
    def post(self, request, uidb64, token):
        try:
            uid = force_str(urlsafe_base64_decode(uidb64))
            user = User.objects.get(pk=uid)
        except (TypeError, ValueError, OverflowError, User.DoesNotExist):
            return Response({"error": "Neplatný odkaz."}, status=400)

        if not password_reset_token.check_token(user, token):
            return Response({"error": "Token je neplatný nebo expirovaný."}, status=400)

        serializer = PasswordResetConfirmSerializer(data=request.data)
        if serializer.is_valid():
            user.set_password(serializer.validated_data['password'])
            user.save()
            return Response({"detail": "Heslo bylo úspěšně změněno."})
        return Response(serializer.errors, status=400)


@extend_schema(
    tags=["account"],
    summary="Resend email verification",
    description="Resends the verification email to the currently authenticated user. Limited to once per minute.",
    responses={
        200: OpenApiResponse(description="Verification email sent."),
        400: OpenApiResponse(description="Email is already verified."),
        429: OpenApiResponse(description="Rate limited — seconds_remaining returned."),
    },
)
class ResendEmailVerificationView(APIView):
    permission_classes = [IsAuthenticated]
    COOLDOWN = 60  # seconds

    def post(self, request):
        from django.core.cache import cache
        import time

        user = request.user
        if user.email_verified:
            return Response({"detail": "E-mail je již ověřen."}, status=status.HTTP_400_BAD_REQUEST)

        cache_key = f"resend_verification_{user.id}"
        sent_at = cache.get(cache_key)
        if sent_at is not None:
            remaining = int(self.COOLDOWN - (time.time() - sent_at))
            if remaining > 0:
                return Response(
                    {"detail": "Příliš mnoho pokusů.", "seconds_remaining": remaining},
                    status=status.HTTP_429_TOO_MANY_REQUESTS,
                )

        cache.set(cache_key, time.time(), timeout=self.COOLDOWN)
        try:
            send_email_verification_task.delay(user.id)
        except Exception as e:
            logger.error(f"Celery not available, using fallback. Error: {e}")
            send_email_verification_task(user.id)
        return Response({"detail": "Ověřovací e-mail byl odeslán."})


@extend_schema(
    tags=["account"],
    summary="Request email address change",
    description="Validates current password + Turnstile, stores pending_email, sends confirmation link to the new address and a notification to the old one.",
    responses={
        200: OpenApiResponse(description="Confirmation email sent to new address."),
        400: OpenApiResponse(description="Wrong password, duplicate email, or failed CAPTCHA."),
    },
)
class ChangeEmailView(APIView):
    permission_classes = [IsAuthenticated]

    def post(self, request):
        turnstile_token = request.data.get("turnstile_token", "")
        remote_ip = request.META.get("HTTP_X_FORWARDED_FOR", request.META.get("REMOTE_ADDR", ""))
        if not verify_turnstile(turnstile_token, remote_ip):
            return Response({"detail": "Ověření CAPTCHA selhalo."}, status=status.HTTP_400_BAD_REQUEST)

        serializer = ChangeEmailSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        user = request.user
        if not user.check_password(serializer.validated_data["current_password"]):
            return Response({"current_password": "Nesprávné heslo."}, status=status.HTTP_400_BAD_REQUEST)

        new_email = serializer.validated_data["new_email"]
        old_email = user.email

        user.pending_email = new_email
        uid = urlsafe_base64_encode(force_bytes(user.pk))
        token = user.generate_email_verification_token(save=False)
        user.save(update_fields=["pending_email", "email_verification_token", "email_verification_sent_at"])

        verify_url = f"{settings.FRONTEND_URL}/account/confirm-email-change/{uid}/{token}/"

        try:
            send_email_change_verification_task.delay(user.id, new_email, verify_url)
            send_email_change_notification_task.delay(user.id, old_email, new_email)
        except Exception as e:
            logger.error(f"Celery not available, using fallback. Error: {e}")
            send_email_change_verification_task(user.id, new_email, verify_url)
            send_email_change_notification_task(user.id, old_email, new_email)

        return Response({"detail": "Ověřovací e-mail byl odeslán na novou adresu."})


@extend_schema(
    tags=["account"],
    summary="Confirm email address change via link",
    description="Verifies uid + token from the confirmation email, swaps email to pending_email.",
    parameters=[
        OpenApiParameter(name="uidb64", type=str, location=OpenApiParameter.PATH),
        OpenApiParameter(name="token", type=str, location=OpenApiParameter.PATH),
    ],
    responses={
        200: OpenApiResponse(description="Email changed successfully."),
        400: OpenApiResponse(description="Invalid or expired link."),
    },
)
class ConfirmEmailChangeView(APIView):
    def get(self, request, uidb64, token):
        ip = request.META.get("HTTP_X_FORWARDED_FOR", request.META.get("REMOTE_ADDR", "unknown"))
        try:
            uid = force_str(urlsafe_base64_decode(uidb64))
            user = User.objects.get(pk=uid)
        except (User.DoesNotExist, ValueError, TypeError):
            return Response({"error": "Neplatný odkaz."}, status=status.HTTP_400_BAD_REQUEST)

        if not user.pending_email:
            return Response({"error": "Žádná čekající změna e-mailu."}, status=status.HTTP_400_BAD_REQUEST)

        if not user.verify_email_token(token):
            return Response({"error": "Token je neplatný nebo expirovaný."}, status=status.HTTP_400_BAD_REQUEST)

        old_email = user.email
        user.email = user.pending_email
        user.pending_email = None
        user.email_verified = True
        user.save(update_fields=["email", "pending_email", "email_verified"])
        logger.info("Email changed for user %s: %s → %s (IP: %s)", user.pk, old_email, user.email, ip)

        return Response({"detail": "E-mail byl úspěšně změněn."})


@extend_schema(
    tags=["account"],
    summary="Change username",
    description="Updates the username. Requires Turnstile. Limited to once per 30 days.",
    responses={
        200: OpenApiResponse(description="Username changed."),
        400: OpenApiResponse(description="Duplicate name, invalid characters, or failed CAPTCHA."),
        429: OpenApiResponse(description="Rate limited — days_remaining returned."),
    },
)
class ChangeUsernameView(APIView):
    permission_classes = [IsAuthenticated]
    COOLDOWN_DAYS = 30

    def post(self, request):
        from django.core.cache import cache
        import time

        turnstile_token = request.data.get("turnstile_token", "")
        remote_ip = request.META.get("HTTP_X_FORWARDED_FOR", request.META.get("REMOTE_ADDR", ""))
        if not verify_turnstile(turnstile_token, remote_ip):
            return Response({"detail": "Ověření CAPTCHA selhalo."}, status=status.HTTP_400_BAD_REQUEST)

        serializer = ChangeUsernameSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)

        user = request.user
        cache_key = f"username_change_{user.id}"
        changed_at = cache.get(cache_key)
        if changed_at is not None:
            remaining_days = int(self.COOLDOWN_DAYS - (time.time() - changed_at) / 86400)
            if remaining_days > 0:
                return Response(
                    {"detail": "Příliš brzy.", "days_remaining": remaining_days},
                    status=status.HTTP_429_TOO_MANY_REQUESTS,
                )

        user.username = serializer.validated_data["new_username"]
        user.save(update_fields=["username"])
        cache.set(cache_key, time.time(), timeout=self.COOLDOWN_DAYS * 86400)

        return Response({"detail": "Uživatelské jméno bylo změněno.", "username": user.username})


@extend_schema(
    tags=["account"],
    summary="Delete own account",
    description="Soft-deletes the authenticated user's account after password confirmation. Clears auth cookies.",
    responses={
        204: OpenApiResponse(description="Account deleted."),
        400: OpenApiResponse(description="Wrong password."),
    },
)
class DeleteAccountView(APIView):
    permission_classes = [IsAuthenticated]

    def post(self, request):
        user = request.user

        turnstile_token = request.data.get("turnstile_token", "")
        remote_ip = request.META.get("HTTP_X_FORWARDED_FOR", request.META.get("REMOTE_ADDR", ""))
        if not verify_turnstile(turnstile_token, remote_ip):
            return Response({"detail": "Ověření CAPTCHA selhalo."}, status=status.HTTP_400_BAD_REQUEST)

        password = request.data.get("current_password", "")
        if not password or not user.check_password(password):
            return Response({"current_password": "Nesprávné heslo."}, status=status.HTTP_400_BAD_REQUEST)

        logger.info("Account deletion requested for user %s (id=%s)", user.username, user.pk)
        django_logout(request)
        user.delete()

        response = Response(status=status.HTTP_204_NO_CONTENT)
        response.delete_cookie("access_token", path="/")
        response.delete_cookie("refresh_token", path="/")
        return response