"""
Finance forms for the Tenhal Multidisciplinary Healthcare Platform.

This module contains forms for invoices, payments, services, and packages.
"""

from django import forms
from django.forms import inlineformset_factory
from django.utils.translation import gettext_lazy as _
from crispy_forms.helper import FormHelper
from crispy_forms.layout import Layout, Fieldset, Row, Column, Submit, HTML

from .models import Invoice, InvoiceLineItem, Payment, Service, Package, PackageService, PackagePurchase, Payer


class InvoiceForm(forms.ModelForm):
    """
    Form for creating and editing invoices.
    """
    
    class Meta:
        model = Invoice
        fields = [
            'patient', 'payer', 'issue_date', 'due_date',
            'discount', 'tax',
            'notes',
        ]
        widgets = {
            'patient': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select patient'}),
            'payer': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select payer'}),
            'issue_date': forms.DateInput(attrs={'type': 'date', 'class': 'form-control'}),
            'due_date': forms.DateInput(attrs={'type': 'date', 'class': 'form-control'}),
            'discount': forms.NumberInput(attrs={'class': 'form-control', 'step': '0.01', 'min': '0'}),
            'tax': forms.NumberInput(attrs={'class': 'form-control', 'step': '0.01', 'min': '0'}),
            'notes': forms.Textarea(attrs={'rows': 3, 'class': 'form-control', 'placeholder': _('Optional notes')}),
        }
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        
        # Add CSS classes to all fields
        for field_name, field in self.fields.items():
            if 'class' not in field.widget.attrs:
                field.widget.attrs['class'] = 'form-control'
        
        self.helper = FormHelper()
        self.helper.form_method = 'post'
        self.helper.layout = Layout(
            Fieldset(
                _('Invoice Information'),
                Row(
                    Column('patient', css_class='form-group col-md-6 mb-0'),
                    Column('payer', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                Row(
                    Column('issue_date', css_class='form-group col-md-6 mb-0'),
                    Column('due_date', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                Row(
                    Column('discount', css_class='form-group col-md-6 mb-0'),
                    Column('tax', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                'notes',
            ),
            HTML('<hr><h5>{% trans "Line Items" %}</h5>'),
            Submit('submit', _('Save Invoice'), css_class='btn btn-primary')
        )


class InvoiceLineItemForm(forms.ModelForm):
    """
    Form for invoice line items.
    """
    
    class Meta:
        model = InvoiceLineItem
        fields = ['service', 'package', 'description', 'quantity']
        widgets = {
            'description': forms.TextInput(attrs={
                'placeholder': _('Optional description'),
                'class': 'form-control'
            }),
            'service': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select service'}),
            'package': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select package'}),
            'quantity': forms.NumberInput(attrs={'class': 'form-control', 'min': '1', 'step': '1', 'value': '1'}),
        }
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        
        # Make service and package not required since we'll handle validation
        self.fields['service'].required = False
        self.fields['package'].required = False
        
        # Add CSS classes
        for field_name, field in self.fields.items():
            if 'class' not in field.widget.attrs:
                field.widget.attrs['class'] = 'form-control'


# Inline formset for invoice line items
InvoiceLineItemFormSet = inlineformset_factory(
    Invoice,
    InvoiceLineItem,
    form=InvoiceLineItemForm,
    extra=0,
    can_delete=True,
    min_num=1,
    validate_min=True,
)


class PaymentForm(forms.ModelForm):
    """
    Form for recording payments.
    """
    
    class Meta:
        model = Payment
        fields = [
            'invoice', 'amount', 'method',
            'payment_date', 'transaction_id', 'notes',
        ]
        widgets = {
            'invoice': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select invoice'}),
            'method': forms.Select(attrs={'class': 'form-control'}),
            'payment_date': forms.DateTimeInput(attrs={'type': 'datetime-local', 'class': 'form-control'}),
            'transaction_id': forms.TextInput(attrs={'class': 'form-control', 'placeholder': _('Optional')}),
            'notes': forms.Textarea(attrs={'rows': 3, 'class': 'form-control', 'placeholder': _('Optional notes')}),
        }
    
    def __init__(self, *args, **kwargs):
        # Extract invoice_id if provided
        invoice_id = kwargs.pop('invoice_id', None)
        super().__init__(*args, **kwargs)
        
        # If invoice_id is provided, set it as initial value and make field read-only
        if invoice_id:
            self.fields['invoice'].initial = invoice_id
            self.fields['invoice'].disabled = True
            self.fields['invoice'].widget.attrs['readonly'] = True
            # Also set the instance if creating new payment
            if not self.instance.pk:
                from .models import Invoice
                try:
                    self.instance.invoice = Invoice.objects.get(pk=invoice_id)
                except Invoice.DoesNotExist:
                    pass
        
        # Add CSS classes to all fields
        for field_name, field in self.fields.items():
            if 'class' not in field.widget.attrs:
                field.widget.attrs['class'] = 'form-control'
        
        self.helper = FormHelper()
        self.helper.form_method = 'post'
        
        # Conditionally include invoice field in layout
        if invoice_id:
            # Hide invoice field when pre-selected
            layout_fields = [
                Row(
                    Column('amount', css_class='form-group col-md-6 mb-0'),
                    Column('method', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                Row(
                    Column('payment_date', css_class='form-group col-md-6 mb-0'),
                    Column('transaction_id', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                'notes',
            ]
        else:
            # Show invoice field when not pre-selected
            layout_fields = [
                'invoice',
                Row(
                    Column('amount', css_class='form-group col-md-6 mb-0'),
                    Column('method', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                Row(
                    Column('payment_date', css_class='form-group col-md-6 mb-0'),
                    Column('transaction_id', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                'notes',
            ]
        
        self.helper.layout = Layout(
            Fieldset(_('Payment Details'), *layout_fields),
            Submit('submit', _('Record Payment'), css_class='btn btn-success')
        )
    
    def clean(self):
        cleaned_data = super().clean()
        invoice = cleaned_data.get('invoice')
        amount = cleaned_data.get('amount')
        
        if invoice and amount:
            remaining = invoice.amount_due
            if amount > remaining:
                raise forms.ValidationError(
                    _('Payment amount (%(amount)s) exceeds remaining balance (%(remaining)s)') % {
                        'amount': amount,
                        'remaining': remaining
                    }
                )
        
        return cleaned_data


class ServiceForm(forms.ModelForm):
    """
    Form for managing services.
    """
    
    class Meta:
        model = Service
        fields = [
            'name_en', 'name_ar', 'code', 'clinic',
            'base_price', 'duration_minutes', 'description', 'is_active',
        ]
        widgets = {
            'name_en': forms.TextInput(attrs={'class': 'form-control'}),
            'name_ar': forms.TextInput(attrs={'class': 'form-control'}),
            'code': forms.TextInput(attrs={'class': 'form-control'}),
            'clinic': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select clinic'}),
            'base_price': forms.NumberInput(attrs={'class': 'form-control', 'step': '0.01', 'min': '0'}),
            'duration_minutes': forms.NumberInput(attrs={'class': 'form-control', 'min': '1'}),
            'description': forms.Textarea(attrs={'rows': 3, 'class': 'form-control'}),
            'is_active': forms.CheckboxInput(attrs={'class': 'form-check-input'}),
        }
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        
        # Add CSS classes to all fields
        for field_name, field in self.fields.items():
            if field_name == 'is_active':
                if 'class' not in field.widget.attrs:
                    field.widget.attrs['class'] = 'form-check-input'
            else:
                if 'class' not in field.widget.attrs:
                    field.widget.attrs['class'] = 'form-control'
        
        self.helper = FormHelper()
        self.helper.form_method = 'post'
        self.helper.layout = Layout(
            Fieldset(
                _('Service Information'),
                Row(
                    Column('name_en', css_class='form-group col-md-6 mb-0'),
                    Column('name_ar', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                Row(
                    Column('code', css_class='form-group col-md-4 mb-0'),
                    Column('clinic', css_class='form-group col-md-4 mb-0'),
                    Column('is_active', css_class='form-group col-md-4 mb-0'),
                    css_class='form-row'
                ),
                Row(
                    Column('base_price', css_class='form-group col-md-6 mb-0'),
                    Column('duration_minutes', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                'description',
            ),
            Submit('submit', _('Save Service'), css_class='btn btn-primary')
        )


class PackageForm(forms.ModelForm):
    """
    Form for creating service packages.
    """
    
    class Meta:
        model = Package
        fields = [
            'name_en', 'name_ar',
            'price', 'validity_days', 'description', 'is_active',
        ]
        widgets = {
            'name_en': forms.TextInput(attrs={'class': 'form-control'}),
            'name_ar': forms.TextInput(attrs={'class': 'form-control'}),
            'price': forms.NumberInput(attrs={'class': 'form-control', 'step': '0.01', 'min': '0'}),
            'validity_days': forms.NumberInput(attrs={'class': 'form-control', 'min': '1'}),
            'description': forms.Textarea(attrs={'rows': 3, 'class': 'form-control'}),
            'is_active': forms.CheckboxInput(attrs={'class': 'form-check-input'}),
        }
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        
        # Add CSS classes to all fields
        for field_name, field in self.fields.items():
            if field_name == 'is_active':
                if 'class' not in field.widget.attrs:
                    field.widget.attrs['class'] = 'form-check-input'
            else:
                if 'class' not in field.widget.attrs:
                    field.widget.attrs['class'] = 'form-control'


class PackageServiceForm(forms.ModelForm):
    """
    Form for package service items (service + session count).
    """
    
    class Meta:
        model = PackageService
        fields = ['service', 'sessions']
        widgets = {
            'service': forms.Select(attrs={'class': 'form-control select2', 'data-placeholder': 'Select service'}),
            'sessions': forms.NumberInput(attrs={'class': 'form-control', 'min': '1', 'value': '1'}),
        }
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        # Filter to show only active services
        self.fields['service'].queryset = Service.objects.filter(is_active=True)
        
        # Add CSS classes
        for field_name, field in self.fields.items():
            if 'class' not in field.widget.attrs:
                field.widget.attrs['class'] = 'form-control'


# Inline formset for package services
PackageServiceFormSet = inlineformset_factory(
    Package,
    PackageService,
    form=PackageServiceForm,
    extra=0,  # Start with 1 empty form
    can_delete=True,
    min_num=1,
    validate_min=True,
)


class PackagePurchaseForm(forms.ModelForm):
    """
    Form for purchasing packages.
    """
    
    class Meta:
        model = PackagePurchase
        fields = ['patient', 'package', 'purchase_date', 'expiry_date']
        widgets = {
            'patient': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select patient'}),
            'package': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select package'}),
            'purchase_date': forms.DateInput(attrs={'type': 'date', 'class': 'form-control'}),
            'expiry_date': forms.DateInput(attrs={'type': 'date', 'class': 'form-control'}),
        }
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        
        # Add CSS classes to all fields
        for field_name, field in self.fields.items():
            if 'class' not in field.widget.attrs:
                field.widget.attrs['class'] = 'form-control'
        
        self.helper = FormHelper()
        self.helper.form_method = 'post'
        self.helper.layout = Layout(
            'patient',
            'package',
            Row(
                Column('purchase_date', css_class='form-group col-md-6 mb-0'),
                Column('expiry_date', css_class='form-group col-md-6 mb-0'),
                css_class='form-row'
            ),
            Submit('submit', _('Purchase Package'), css_class='btn btn-success')
        )


class PayerForm(forms.ModelForm):
    """
    Form for managing insurance payers.
    """
    
    class Meta:
        model = Payer
        fields = [
            'patient', 'name', 'payer_type',
            'policy_number', 'coverage_percentage',
            'is_active', 'notes',
        ]
        widgets = {
            'patient': forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select patient'}),
            'name': forms.TextInput(attrs={'class': 'form-control'}),
            'payer_type': forms.Select(attrs={'class': 'form-control'}),
            'policy_number': forms.TextInput(attrs={'class': 'form-control'}),
            'coverage_percentage': forms.NumberInput(attrs={'class': 'form-control', 'min': '0', 'max': '100', 'step': '0.01'}),
            'is_active': forms.CheckboxInput(attrs={'class': 'form-check-input'}),
            'notes': forms.Textarea(attrs={'rows': 2, 'class': 'form-control'}),
        }
    
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        
        # Add CSS classes to all fields
        for field_name, field in self.fields.items():
            if field_name == 'is_active':
                if 'class' not in field.widget.attrs:
                    field.widget.attrs['class'] = 'form-check-input'
            else:
                if 'class' not in field.widget.attrs:
                    field.widget.attrs['class'] = 'form-control'
        
        self.helper = FormHelper()
        self.helper.form_method = 'post'
        self.helper.layout = Layout(
            Fieldset(
                _('Payer Information'),
                'patient',
                Row(
                    Column('name', css_class='form-group col-md-6 mb-0'),
                    Column('payer_type', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                Row(
                    Column('policy_number', css_class='form-group col-md-6 mb-0'),
                    Column('coverage_percentage', css_class='form-group col-md-6 mb-0'),
                    css_class='form-row'
                ),
                'is_active',
                'notes',
            ),
            Submit('submit', _('Save Payer'), css_class='btn btn-primary')
        )


class InvoiceSearchForm(forms.Form):
    """
    Form for searching invoices.
    """
    
    search_query = forms.CharField(
        required=False,
        label=_('Search'),
        widget=forms.TextInput(attrs={
            'placeholder': _('Invoice #, Patient name, MRN...'),
            'class': 'form-control'
        })
    )
    status = forms.ChoiceField(
        required=False,
        label=_('Status'),
        choices=[('', _('All'))] + list(Invoice.Status.choices),
        widget=forms.Select(attrs={'class': 'form-control'})
    )
    payer = forms.ModelChoiceField(
        required=False,
        label=_('Payer'),
        queryset=None,  # Will be set in __init__
        widget=forms.Select(attrs={'class': 'form-select select2', 'data-placeholder': 'Select payer'})
    )
    date_from = forms.DateField(
        required=False,
        label=_('From Date'),
        widget=forms.DateInput(attrs={'type': 'date', 'class': 'form-control'})
    )
    date_to = forms.DateField(
        required=False,
        label=_('To Date'),
        widget=forms.DateInput(attrs={'type': 'date', 'class': 'form-control'})
    )
    
    def __init__(self, *args, **kwargs):
        tenant = kwargs.pop('tenant', None)
        super().__init__(*args, **kwargs)
        
        if tenant:
            self.fields['payer'].queryset = Payer.objects.filter(tenant=tenant, is_active=True)
        
        self.helper = FormHelper()
        self.helper.form_method = 'get'
        self.helper.layout = Layout(
            Row(
                Column('search_query', css_class='form-group col-md-4 mb-0'),
                Column('status', css_class='form-group col-md-2 mb-0'),
                Column('payer', css_class='form-group col-md-2 mb-0'),
                Column('date_from', css_class='form-group col-md-2 mb-0'),
                Column('date_to', css_class='form-group col-md-2 mb-0'),
                css_class='form-row'
            ),
            Submit('search', _('Search'), css_class='btn btn-primary')
        )