from django.contrib.auth.decorators import user_passes_test
from django.core.exceptions import ValidationError
from django.contrib.auth import get_user_model, authenticate, login
from django.contrib.auth.models import User
from django.contrib.auth.password_validation import validate_password
from django.db import transaction

from IoTAnalyzer.exception_handling import handle_exceptions
from django.contrib.auth import logout


# Create user
@handle_exceptions
@transaction.atomic
def register_user(request, username, password, is_superuser, is_staff):
    # Input validation
    if not username or not isinstance(username, str):
        raise ValidationError("Ungültiger Username")
    username = username.strip()
    if not username:
        raise ValidationError("Username darf nicht leer sein")
    if not password or not isinstance(password, str):
        raise ValidationError("Ungültiges Passwort")  # Corrected, was previously "Ungültiger Username"
    password = password.strip()
    if not password:
        raise ValidationError("Passwort darf nicht leer sein")

    if User.objects.filter(username=username).exists():
        raise ValidationError("User existiert bereits")

    # Correction: do not pass `request` as an argument
    user = User.objects.create_user(
        username=username,
        password=password,
        is_superuser=is_superuser,
        is_staff=is_staff
    )

    return {"status": "success", "message": "User wurde erfolgreich erstellt"}



# Delete user
@handle_exceptions
@transaction.atomic
def delete_user(request, user_id):
    # Input validation
    if not user_id or not isinstance(user_id, int):
        raise ValidationError("Ungültige Id")
        # Check that the user is not deleting themselves
    if request.user.id == user_id:
        raise ValidationError("Sie können Ihren eigenen Account nicht löschen")
    user = User.objects.filter(id=user_id)
    if not user.exists():
        raise ValidationError("User existiert nicht")
    else:
        user.delete()
    return {"status": "success", "message": "User wurde erfolgreich gelöscht"}


# Reset password
@handle_exceptions
@transaction.atomic
def set_password(request, user_id, new_password):
    # Input validation
    if not isinstance(user_id, int):
        raise ValidationError("Ungültige User ID")

    if not isinstance(new_password, str):
        raise ValidationError("Ungültiges Passwort Format")

    new_password = new_password.strip()
    if not new_password:
        raise ValidationError("Passwort darf nicht leer sein")

    # Fetch user
    try:
        user = User.objects.get(id=user_id)
    except User.DoesNotExist:
        raise ValidationError("User existiert nicht")

    # Permission check
    if request.user.id != user_id and  request.user.is_superuser and request.user.is_staff:
        raise ValidationError("Keine Berechtigung zum Ändern des Passworts")

    # Password validation using Django's built-in validators
    try:
        validate_password(new_password, user)
    except ValidationError as e:
        raise ValidationError(e.messages)

    # Set and save password
    user.set_password(new_password)
    user.last_login = None
    user.save()

    return {"status": "success", "message": "Passwort erfolgreich geändert"}
from django.utils.timezone import now


@handle_exceptions
@transaction.atomic
def change_password(request, user_id, new_password):
    # Input validation
    if not isinstance(user_id, int):
        raise ValidationError("Ungültige User ID")

    if not isinstance(new_password, str):
        raise ValidationError("Ungültiges Passwort Format")

    new_password = new_password.strip()
    if not new_password:
        raise ValidationError("Passwort darf nicht leer sein")

    # Fetch user
    try:
        user = User.objects.get(id=user_id)
    except User.DoesNotExist:
        raise ValidationError("User existiert nicht")



    # Password validation using Django's built-in validators
    try:
        validate_password(new_password, user)
    except ValidationError as e:
        raise ValidationError(e.messages)

    # Set and save password
    user.set_password(new_password)
    user.last_login = now()  # Sets last_login to the current date
    user.save()

    return {"status": "success", "message": "Passwort erfolgreich geändert", "last_login": user.last_login}


@handle_exceptions
@transaction.atomic
def login_user(request, username, password):
    # Input validation
    if not username or not isinstance(username, str):
        raise ValidationError("Ungültiger Username")

    username = username.strip()
    if not username:
        raise ValidationError("Username darf nicht leer sein")

    if not password or not isinstance(password, str):
        raise ValidationError("Ungültiges Passwort")

    password = password.strip()
    if not password:
        raise ValidationError("Passwort darf nicht leer sein")

    user = authenticate(username=username, password=password)
    if user is None:
        raise ValidationError("Falscher Username oder Passwort")
    
    # Check the last login
    resetPassword = user.last_login is None

    # If a password reset is required, do not perform a login
    if resetPassword:
        return False, {"message": "Erster Login erkannt. Passwort muss zurückgesetzt werden.", "resetPassword": True, "user" : {"id": user.id, "username": user.username}}
    
    # Log the user in
    login(request, user)
    
    user_info = {
        'id': user.id,
        'username': user.username,
        'changePassword': resetPassword,
        'role': 'superuser' if user.is_superuser else 'staff' if user.is_staff else 'user'
    }
    
    return True, {"message": "Login erfolgreich", "user": user_info}

    
@handle_exceptions
@transaction.atomic
def logout_user(request, user_id):
        # Input validation
        if not isinstance(user_id, int):
            raise ValidationError("Ungültige User ID")

        # Fetch user
        try:
            user = User.objects.get(id=user_id)
        except User.DoesNotExist:
            raise ValidationError("User existiert nicht")

        # Permission check
        if request.user.id != user_id:
            raise ValidationError("Keine Berechtigung zum Ausloggen dieses Benutzers")

        # Log the user out
        logout(request)

        return {"message": "Logout erfolgreich"}


# Function to list all users with their roles
#@user_passes_test(lambda u: u.is_superuser)
def list_users(request):
    try:
        users = User.objects.all().order_by('username')
        user_list = []

        for user in users:
            user_info = {
                'id': user.id,
                'username': user.username,
                'password': user.password,
                'email': user.email,
                'role': 'superuser' if user.is_superuser else 'staff' if user.is_staff else 'user'
            }
            user_list.append(user_info)

        return {
            'status': 'success',
            'data': user_list
        }

    except Exception as e:
        if isinstance(e, User.DoesNotExist):
            raise ValidationError("Keine Benutzer gefunden")
        raise ValidationError("Fehler beim Abrufen der Benutzerliste: {}").format(str(e))