"""
Form mixins for tenant-aware forms.

Provides mixins to handle hospital field visibility based on user role.
"""
from django import forms
from apps.organizations.models import Hospital


class HospitalFieldMixin:
    """
    Mixin to handle hospital field visibility based on user role.
    
    - PX Admins: See dropdown with all active hospitals
    - Others: Hidden field, auto-set to user's hospital
    
    Usage:
        class MyForm(HospitalFieldMixin, forms.ModelForm):
            class Meta:
                model = MyModel
                fields = ['hospital', ...]
            
            def __init__(self, *args, **kwargs):
                super().__init__(*args, **kwargs)
                # Hospital field is automatically configured
    
    In views:
        form = MyForm(user=request.user)
    """
    
    def __init__(self, *args, **kwargs):
        self.user = kwargs.pop('user', None)
        super().__init__(*args, **kwargs)
        
        if self.user and 'hospital' in self.fields:
            self._setup_hospital_field()
    
    def _setup_hospital_field(self):
        """Configure hospital field based on user role."""
        hospital_field = self.fields['hospital']
        
        if self.user.is_px_admin():
            # PX Admin: Show dropdown with all active hospitals
            hospital_field.queryset = Hospital.objects.filter(status='active').order_by('name')
            hospital_field.required = True
            # Update widget attrs instead of replacing widget to preserve choices
            hospital_field.widget.attrs.update({
                'class': 'w-full px-4 py-2.5 rounded-xl border border-slate-200 focus:border-navy focus:ring-2 focus:ring-navy/20 transition text-sm bg-white'
            })
        else:
            # Regular user: Hide field and set default
            hospital_field.widget = forms.HiddenInput()
            hospital_field.required = False
            
            # Set initial value to user's hospital
            if self.user.hospital:
                hospital_field.initial = self.user.hospital
                # Limit queryset to just user's hospital (for validation)
                hospital_field.queryset = Hospital.objects.filter(id=self.user.hospital.id)
            else:
                # User has no hospital - empty queryset
                hospital_field.queryset = Hospital.objects.none()
    
    def clean_hospital(self):
        """
        Ensure non-PX admins can only use their own hospital.
        PX Admins can select any hospital.
        """
        hospital = self.cleaned_data.get('hospital')
        
        if not self.user:
            return hospital
        
        if self.user.is_px_admin():
            # PX Admin must select a hospital
            if not hospital:
                raise forms.ValidationError("Please select a hospital.")
            return hospital
        else:
            # Non-PX admins: Force user's hospital
            if self.user.hospital:
                return self.user.hospital
            else:
                raise forms.ValidationError(
                    "You do not have a hospital assigned. Please contact your administrator."
                )


class DepartmentFieldMixin:
    """
    Mixin to handle department field filtering based on user's hospital.
    
    - Filters departments to only show those in the selected/current hospital
    - Works with HospitalFieldMixin
    
    Usage:
        class MyForm(HospitalFieldMixin, DepartmentFieldMixin, forms.ModelForm):
            class Meta:
                model = MyModel
                fields = ['hospital', 'department', ...]
    """
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        
        if 'department' in self.fields:
            self._setup_department_field()
    
    def _setup_department_field(self):
        """Configure department field with hospital-based filtering."""
        from apps.organizations.models import Department
        
        department_field = self.fields['department']
        
        # Get the hospital (either from form data or user's hospital)
        hospital = None
        if self.data.get('hospital'):
            try:
                hospital = Hospital.objects.get(id=self.data['hospital'])
            except Hospital.DoesNotExist:
                pass
        elif self.initial.get('hospital'):
            hospital = self.initial['hospital']
        elif self.instance and self.instance.pk and self.instance.hospital:
            hospital = self.instance.hospital
        elif self.user and self.user.hospital:
            hospital = self.user.hospital
        
        if hospital:
            # Filter departments to user's hospital
            department_field.queryset = Department.objects.filter(
                hospital=hospital,
                status='active'
            ).order_by('name')
        else:
            # No hospital context - empty queryset
            department_field.queryset = Department.objects.none()