from django.shortcuts import get_object_or_404
from .models import ProcessInstance
from common.consts import UserRoles


def scope_instances_queryset(user, queryset=None):
    """Return a queryset of ProcessInstance scoped by the user's role.

    If no profile/role, returns an empty queryset.
    """
    qs = queryset if queryset is not None else ProcessInstance.objects.all()
    profile = getattr(user, 'profile', None)
    if not profile:
        return qs.none()
    try:
        if profile.has_role(UserRoles.INSTALLER):
            # Only instances assigned to this installer
            from installations.models import InstallationAssignment
            assign_ids = InstallationAssignment.objects.filter(installer=user).values_list('process_instance', flat=True)
            return qs.filter(id__in=assign_ids)
        if profile.has_role(UserRoles.BROKER):
            return qs.filter(broker=profile.broker)
        if profile.has_role(UserRoles.ACCOUNTANT) or profile.has_role(UserRoles.MANAGER):
            return qs.filter(broker__affairs__county=profile.county)
        if profile.has_role(UserRoles.ADMIN):
            return qs
        # if profile.has_role(UserRoles.WATER_RESOURCE_MANAGER) or profile.has_role(UserRoles.HEADQUARTER):
        #     return qs.filter(well__county=profile.county)
        # Fallback: no special scope
        # return qs
    except Exception:
        return qs.none()


def count_incomplete_instances(user):
    """Count non-completed, non-deleted requests within the user's scope."""
    base = ProcessInstance.objects.select_related('well').filter(is_deleted=False).exclude(status='completed')
    return scope_instances_queryset(user, base).count()


def user_can_access_instance(user, instance: ProcessInstance) -> bool:
    """Check if user can access a specific instance based on scoping rules."""
    try:
        scoped = scope_instances_queryset(user, ProcessInstance.objects.filter(id=instance.id))
        return scoped.exists()
    except Exception:
        return False


def get_scoped_instance_or_404(request, instance_id: int) -> ProcessInstance:
    """Return instance only if it's within the user's scope; otherwise 404.

    Use this in any view receiving instance_id from URL to prevent URL tampering.
    """
    base = ProcessInstance.objects.filter(is_deleted=False)
    qs = scope_instances_queryset(request.user, base)
    return get_object_or_404(qs, id=instance_id)


def scope_wells_queryset(user, queryset=None):
    """Return a queryset of Well scoped by the user's role (parity with instances)."""
    try:
        from wells.models import Well
        qs = queryset if queryset is not None else Well.objects.all()
        profile = getattr(user, 'profile', None)
        if not profile:
            return qs.none()
        if profile.has_role(UserRoles.ADMIN):
            return qs
        if profile.has_role(UserRoles.BROKER):
            return qs.filter(broker=profile.broker)
        if profile.has_role(UserRoles.ACCOUNTANT) or profile.has_role(UserRoles.MANAGER):
            return qs.filter(broker__affairs__county=profile.county)
        if profile.has_role(UserRoles.INSTALLER):
            # Wells that have instances assigned to this installer
            from installations.models import InstallationAssignment
            assign_ids = InstallationAssignment.objects.filter(installer=user).values_list('process_instance', flat=True)
            inst_qs = ProcessInstance.objects.filter(id__in=assign_ids)
            return qs.filter(process_instances__in=inst_qs).distinct()
        # Fallback
        return qs.none()
    except Exception:
        return qs.none() if 'qs' in locals() else []


def scope_customers_queryset(user, queryset=None):
    """Return a queryset of customer Profiles scoped by user's role.

    Assumes queryset is Profiles already filtered to customers, otherwise we filter here.
    """
    try:
        from accounts.models import Profile
        qs = queryset if queryset is not None else Profile.objects.all()
        # Ensure we're only looking at customer profiles
        from common.consts import UserRoles as UR
        qs = qs.filter(roles__slug=UR.CUSTOMER.value, is_deleted=False)

        profile = getattr(user, 'profile', None)
        if not profile:
            return qs.none()
        if profile.has_role(UserRoles.ADMIN):
            return qs
        if profile.has_role(UserRoles.BROKER):
            return qs.filter(broker=profile.broker)
        if profile.has_role(UserRoles.ACCOUNTANT) or profile.has_role(UserRoles.MANAGER):
            return qs.filter(county=profile.county)
        if profile.has_role(UserRoles.INSTALLER):
            # Customers that are representatives of instances assigned to this installer
            from installations.models import InstallationAssignment
            assign_ids = InstallationAssignment.objects.filter(installer=user).values_list('process_instance', flat=True)
            rep_ids = ProcessInstance.objects.filter(id__in=assign_ids).values_list('representative', flat=True)
            return qs.filter(user_id__in=rep_ids)
        # Fallback
        return qs.none()
    except Exception:
        return qs.none() if 'qs' in locals() else []