"""
Billing Models for Credit System
"""
from decimal import Decimal
from django.db import models
from django.core.validators import MinValueValidator
from django.conf import settings
from igny8_core.auth.models import AccountBaseModel
from simple_history.models import HistoricalRecords


# Centralized payment method choices - single source of truth
PAYMENT_METHOD_CHOICES = [
    ('stripe', 'Stripe (Credit/Debit Card)'),
    ('paypal', 'PayPal'),
    ('bank_transfer', 'Bank Transfer (Manual)'),
    ('local_wallet', 'Local Wallet (Manual)'),
    ('manual', 'Manual Payment'),
]


class CreditTransaction(AccountBaseModel):
    """Track all credit transactions (additions, deductions)"""
    TRANSACTION_TYPE_CHOICES = [
        ('purchase', 'Purchase'),
        ('subscription', 'Subscription Renewal'),
        ('refund', 'Refund'),
        ('deduction', 'Usage Deduction'),
        ('adjustment', 'Manual Adjustment'),
    ]
    
    transaction_type = models.CharField(max_length=20, choices=TRANSACTION_TYPE_CHOICES, db_index=True)
    amount = models.IntegerField(help_text="Positive for additions, negative for deductions")
    balance_after = models.IntegerField(help_text="Credit balance after this transaction")
    description = models.CharField(max_length=255)
    metadata = models.JSONField(default=dict, help_text="Additional context (AI call details, etc.)")
    
    # Payment FK - preferred over reference_id string
    payment = models.ForeignKey(
        'billing.Payment',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='credit_transactions',
        help_text='Payment that triggered this credit transaction'
    )
    
    # Deprecated: Use payment FK instead
    reference_id = models.CharField(
        max_length=255,
        blank=True,
        help_text="DEPRECATED: Use payment FK. Legacy reference (e.g., payment id, invoice id)"
    )
    
    created_at = models.DateTimeField(auto_now_add=True)
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_credit_transactions'
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['account', 'transaction_type']),
            models.Index(fields=['account', 'created_at']),
        ]
    
    def __str__(self):
        account = getattr(self, 'account', None)
        return f"{self.get_transaction_type_display()} - {self.amount} credits - {account.name if account else 'No Account'}"


class CreditUsageLog(AccountBaseModel):
    """Detailed log of credit usage per AI operation"""
    OPERATION_TYPE_CHOICES = [
        ('clustering', 'Keyword Clustering'),
        ('idea_generation', 'Content Ideas Generation'),
        ('content_generation', 'Content Generation'),
        ('image_generation', 'Image Generation'),
        ('image_prompt_extraction', 'Image Prompt Extraction'),
        ('linking', 'Internal Linking'),
        ('optimization', 'Content Optimization'),
        ('reparse', 'Content Reparse'),
        ('site_page_generation', 'Site Page Generation'),
        ('site_structure_generation', 'Site Structure Generation'),
        ('ideas', 'Content Ideas Generation'),  # Legacy
        ('content', 'Content Generation'),  # Legacy
        ('images', 'Image Generation'),  # Legacy
    ]
    
    operation_type = models.CharField(max_length=50, choices=OPERATION_TYPE_CHOICES, db_index=True)
    credits_used = models.IntegerField(validators=[MinValueValidator(0)])
    cost_usd = models.DecimalField(max_digits=10, decimal_places=4, null=True, blank=True)
    model_used = models.CharField(max_length=100, blank=True)
    tokens_input = models.IntegerField(null=True, blank=True, validators=[MinValueValidator(0)])
    tokens_output = models.IntegerField(null=True, blank=True, validators=[MinValueValidator(0)])
    related_object_type = models.CharField(max_length=50, blank=True)  # 'keyword', 'cluster', 'task'
    related_object_id = models.IntegerField(null=True, blank=True)
    metadata = models.JSONField(default=dict)
    created_at = models.DateTimeField(auto_now_add=True)
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_credit_usage_logs'
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['account', 'operation_type']),
            models.Index(fields=['account', 'created_at']),
            models.Index(fields=['account', 'operation_type', 'created_at']),
        ]
    
    def __str__(self):
        account = getattr(self, 'account', None)
        return f"{self.get_operation_type_display()} - {self.credits_used} credits - {account.name if account else 'No Account'}"


class CreditCostConfig(models.Model):
    """
    Token-based credit pricing configuration.
    ALL operations use token-to-credit conversion.
    """
    # Operation identification
    operation_type = models.CharField(
        max_length=50,
        unique=True,
        choices=CreditUsageLog.OPERATION_TYPE_CHOICES,
        help_text="AI operation type"
    )
    
    # Token-to-credit ratio (tokens per 1 credit)
    tokens_per_credit = models.IntegerField(
        default=100,
        validators=[MinValueValidator(1)],
        help_text="Number of tokens that equal 1 credit (e.g., 100 tokens = 1 credit)"
    )
    
    # Minimum credits (for very small token usage)
    min_credits = models.IntegerField(
        default=1,
        validators=[MinValueValidator(0)],
        help_text="Minimum credits to charge regardless of token usage"
    )
    
    # Price per credit (for revenue reporting)
    price_per_credit_usd = models.DecimalField(
        max_digits=10,
        decimal_places=4,
        default=Decimal('0.01'),
        validators=[MinValueValidator(Decimal('0.0001'))],
        help_text="USD price per credit (for revenue reporting)"
    )
    
    # Metadata
    display_name = models.CharField(max_length=100, help_text="Human-readable name")
    description = models.TextField(blank=True, help_text="What this operation does")
    
    # Status
    is_active = models.BooleanField(default=True, help_text="Enable/disable this operation")
    
    
    # Audit fields
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    updated_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='credit_cost_updates',
        help_text="Admin who last updated"
    )
    
    # Change tracking
    previous_tokens_per_credit = models.IntegerField(
        null=True,
        blank=True,
        help_text="Tokens per credit before last update (for audit trail)"
    )
    
    # History tracking
    history = HistoricalRecords()
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_credit_cost_config'
        verbose_name = 'Credit Cost Configuration'
        verbose_name_plural = 'Credit Cost Configurations'
        ordering = ['operation_type']
    
    def __str__(self):
        return f"{self.display_name} - {self.tokens_per_credit} tokens/credit"
    
    def save(self, *args, **kwargs):
        # Track token ratio changes
        if self.pk:
            try:
                old = CreditCostConfig.objects.get(pk=self.pk)
                if old.tokens_per_credit != self.tokens_per_credit:
                    self.previous_tokens_per_credit = old.tokens_per_credit
            except CreditCostConfig.DoesNotExist:
                pass
        super().save(*args, **kwargs)


class BillingConfiguration(models.Model):
    """
    System-wide billing configuration (Singleton).
    Global settings for token-credit pricing.
    """
    # Default token-to-credit ratio
    default_tokens_per_credit = models.IntegerField(
        default=100,
        validators=[MinValueValidator(1)],
        help_text="Default: How many tokens equal 1 credit (e.g., 100)"
    )
    
    # Credit pricing
    default_credit_price_usd = models.DecimalField(
        max_digits=10,
        decimal_places=4,
        default=Decimal('0.01'),
        validators=[MinValueValidator(Decimal('0.0001'))],
        help_text="Default price per credit in USD"
    )
    
    # Reporting settings
    enable_token_based_reporting = models.BooleanField(
        default=True,
        help_text="Show token metrics in all reports"
    )
    
    # Rounding settings
    ROUNDING_CHOICES = [
        ('up', 'Round Up'),
        ('down', 'Round Down'),
        ('nearest', 'Round to Nearest'),
    ]
    
    credit_rounding_mode = models.CharField(
        max_length=10,
        default='up',
        choices=ROUNDING_CHOICES,
        help_text="How to round fractional credits"
    )
    
    # Audit fields
    updated_at = models.DateTimeField(auto_now=True)
    updated_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        help_text="Admin who last updated"
    )
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_billing_configuration'
        verbose_name = 'Billing Configuration'
        verbose_name_plural = 'Billing Configuration'
    
    def save(self, *args, **kwargs):
        """Enforce singleton pattern"""
        self.pk = 1
        super().save(*args, **kwargs)
    
    @classmethod
    def get_config(cls):
        """Get or create the singleton config"""
        config, created = cls.objects.get_or_create(pk=1)
        return config
    
    def __str__(self):
        return f"Billing Configuration (1 credit = {self.default_tokens_per_credit} tokens)"


class PlanLimitUsage(AccountBaseModel):
    """
    Track monthly usage of plan limits (ideas, words, images, prompts)
    Resets at start of each billing period
    """
    LIMIT_TYPE_CHOICES = [
        ('content_ideas', 'Content Ideas'),
        ('content_words', 'Content Words'),
        ('images_basic', 'Basic Images'),
        ('images_premium', 'Premium Images'),
        ('image_prompts', 'Image Prompts'),
    ]
    
    limit_type = models.CharField(
        max_length=50,
        choices=LIMIT_TYPE_CHOICES,
        db_index=True,
        help_text="Type of limit being tracked"
    )
    amount_used = models.IntegerField(
        default=0,
        validators=[MinValueValidator(0)],
        help_text="Amount used in current period"
    )
    
    # Billing period tracking
    period_start = models.DateField(
        help_text="Start date of billing period"
    )
    period_end = models.DateField(
        help_text="End date of billing period"
    )
    
    # Metadata
    metadata = models.JSONField(
        default=dict,
        blank=True,
        help_text="Additional tracking data (e.g., breakdown by site)"
    )
    
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_plan_limit_usage'
        verbose_name = 'Plan Limit Usage'
        verbose_name_plural = 'Plan Limit Usage Records'
        unique_together = [['account', 'limit_type', 'period_start']]
        ordering = ['-period_start', 'limit_type']
        indexes = [
            models.Index(fields=['account', 'limit_type']),
            models.Index(fields=['account', 'period_start', 'period_end']),
            models.Index(fields=['limit_type', 'period_start']),
        ]
    
    def __str__(self):
        account = getattr(self, 'account', None)
        return f"{account.name if account else 'No Account'} - {self.get_limit_type_display()} - {self.amount_used} used"
    
    def is_current_period(self):
        """Check if this record is for the current billing period"""
        from django.utils import timezone
        today = timezone.now().date()
        return self.period_start <= today <= self.period_end
    
    def remaining_allowance(self, plan_limit):
        """Calculate remaining allowance"""
        return max(0, plan_limit - self.amount_used)
    
    def percentage_used(self, plan_limit):
        """Calculate percentage of limit used"""
        if plan_limit == 0:
            return 0
        return min(100, int((self.amount_used / plan_limit) * 100))


class Invoice(AccountBaseModel):
    """
    Invoice for subscription or credit purchases
    Tracks billing invoices with line items and payment status
    """
    STATUS_CHOICES = [
        ('draft', 'Draft'),
        ('pending', 'Pending'),
        ('paid', 'Paid'),
        ('void', 'Void'),
        ('uncollectible', 'Uncollectible'),
    ]
    
    invoice_number = models.CharField(max_length=50, unique=True, db_index=True)
    
    # Subscription relationship
    subscription = models.ForeignKey(
        'igny8_core_auth.Subscription',
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='invoices',
        help_text='Subscription this invoice is for (if subscription-based)'
    )
    
    # Amounts
    subtotal = models.DecimalField(max_digits=10, decimal_places=2, default=0)
    tax = models.DecimalField(max_digits=10, decimal_places=2, default=0)
    total = models.DecimalField(max_digits=10, decimal_places=2, default=0)
    currency = models.CharField(max_length=3, default='USD')
    
    # Status
    status = models.CharField(max_length=20, choices=STATUS_CHOICES, default='pending', db_index=True)
    
    # Dates
    invoice_date = models.DateField(db_index=True)
    due_date = models.DateField()
    paid_at = models.DateTimeField(null=True, blank=True)
    
    # Line items
    line_items = models.JSONField(default=list, help_text="Invoice line items: [{description, amount, quantity}]")
    
    # Payment integration
    stripe_invoice_id = models.CharField(max_length=255, null=True, blank=True)
    payment_method = models.CharField(max_length=50, null=True, blank=True)
    
    # Metadata
    notes = models.TextField(blank=True)
    metadata = models.JSONField(default=dict)
    
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_invoices'
        ordering = ['-invoice_date', '-created_at']
        indexes = [
            models.Index(fields=['account', 'status']),
            models.Index(fields=['account', 'invoice_date']),
            models.Index(fields=['invoice_number']),
        ]
    
    def __str__(self):
        return f"Invoice {self.invoice_number} - {self.account.name if self.account else 'No Account'}"

    # ------------------------------------------------------------------
    # Helpers to keep service code working with legacy field names
    # ------------------------------------------------------------------
    @property
    def subtotal_amount(self):
        return self.subtotal

    @property
    def tax_amount(self):
        return self.tax

    @property
    def total_amount(self):
        return self.total

    @property
    def billing_period_start(self):
        """Get from subscription - single source of truth"""
        if self.account and hasattr(self.account, 'subscription'):
            return self.account.subscription.current_period_start
        return None
    
    @property
    def billing_period_end(self):
        """Get from subscription - single source of truth"""
        if self.account and hasattr(self.account, 'subscription'):
            return self.account.subscription.current_period_end
        return None
    
    @property
    def billing_email(self):
        """Get from metadata snapshot or account"""
        if self.metadata and 'billing_snapshot' in self.metadata:
            return self.metadata['billing_snapshot'].get('email')
        return self.account.billing_email if self.account else None

    def add_line_item(self, description: str, quantity: int, unit_price: Decimal, amount: Decimal = None):
        """Append a line item and keep JSON shape consistent."""
        items = list(self.line_items or [])
        qty = quantity or 1
        amt = Decimal(amount) if amount is not None else Decimal(unit_price) * qty
        items.append({
            'description': description,
            'quantity': qty,
            'unit_price': str(unit_price),
            'amount': str(amt),
        })
        self.line_items = items

    def calculate_totals(self):
        """Recompute subtotal, tax, and total from line_items."""
        subtotal = Decimal('0')
        for item in self.line_items or []:
            try:
                subtotal += Decimal(str(item.get('amount') or 0))
            except Exception:
                pass
        self.subtotal = subtotal
        self.total = subtotal + (self.tax or Decimal('0'))


class Payment(AccountBaseModel):
    """
    Payment record for invoices
    Supports: Stripe, PayPal, Manual (Bank Transfer, Local Wallet)
    """
    STATUS_CHOICES = [
        ('pending_approval', 'Pending Approval'),  # Manual payment submitted by user
        ('succeeded', 'Succeeded'),                # Payment approved and processed
        ('failed', 'Failed'),                      # Payment rejected or failed
        ('refunded', 'Refunded'),                  # Payment refunded (rare)
    ]
    
    # Use centralized payment method choices
    PAYMENT_METHOD_CHOICES = PAYMENT_METHOD_CHOICES
    
    invoice = models.ForeignKey(Invoice, on_delete=models.CASCADE, related_name='payments')
    
    # Amount
    amount = models.DecimalField(max_digits=10, decimal_places=2)
    currency = models.CharField(max_length=3, default='USD')
    
    # Status
    status = models.CharField(max_length=20, choices=STATUS_CHOICES, default='pending_approval', db_index=True)
    
    # Payment method
    payment_method = models.CharField(max_length=50, choices=PAYMENT_METHOD_CHOICES, db_index=True)
    
    # Stripe integration
    stripe_payment_intent_id = models.CharField(max_length=255, null=True, blank=True)
    stripe_charge_id = models.CharField(max_length=255, null=True, blank=True)
    
    # PayPal integration
    paypal_order_id = models.CharField(max_length=255, null=True, blank=True)
    paypal_capture_id = models.CharField(max_length=255, null=True, blank=True)
    
    # Manual payment details
    manual_reference = models.CharField(
        max_length=255,
        blank=True,
        help_text="Bank transfer reference, wallet transaction ID, etc."
    )
    manual_notes = models.TextField(blank=True, help_text="Admin notes for manual payments")
    admin_notes = models.TextField(blank=True, help_text="Internal notes on approval/rejection")
    approved_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='approved_payments'
    )
    approved_at = models.DateTimeField(null=True, blank=True)
    
    # Timestamps
    processed_at = models.DateTimeField(null=True, blank=True)
    failed_at = models.DateTimeField(null=True, blank=True)
    refunded_at = models.DateTimeField(null=True, blank=True)
    
    # Error tracking
    failure_reason = models.TextField(blank=True)
    
    # Metadata
    metadata = models.JSONField(default=dict)
    
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    
    # History tracking
    history = HistoricalRecords()
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_payments'
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['account', 'status']),
            models.Index(fields=['account', 'payment_method']),
            models.Index(fields=['invoice', 'status']),
        ]
    
    def __str__(self):
        return f"Payment {self.id} - {self.get_payment_method_display()} - {self.amount} {self.currency}"


class CreditPackage(models.Model):
    """
    One-time credit purchase packages
    Defines available credit bundles for purchase
    """
    name = models.CharField(max_length=100)
    slug = models.SlugField(unique=True, db_index=True)
    
    # Credits
    credits = models.IntegerField(validators=[MinValueValidator(1)])
    
    # Pricing
    price = models.DecimalField(max_digits=10, decimal_places=2)
    discount_percentage = models.IntegerField(default=0, help_text="Discount percentage (0-100)")
    
    # Stripe
    stripe_product_id = models.CharField(max_length=255, null=True, blank=True)
    stripe_price_id = models.CharField(max_length=255, null=True, blank=True)
    
    # PayPal
    paypal_plan_id = models.CharField(max_length=255, null=True, blank=True)
    
    # Status
    is_active = models.BooleanField(default=True, db_index=True)
    is_featured = models.BooleanField(default=False, help_text="Show as featured package")
    
    # Display
    description = models.TextField(blank=True)
    features = models.JSONField(default=list, help_text="Bonus features or highlights")
    
    # Sort order
    sort_order = models.IntegerField(default=0, help_text="Display order (lower = first)")
    
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_credit_packages'
        ordering = ['sort_order', 'price']
    
    def __str__(self):
        return f"{self.name} - {self.credits} credits - ${self.price}"


class PaymentMethodConfig(models.Model):
    """
    Configure payment methods availability per country
    Allows enabling/disabling manual payments by region
    """
    # Use centralized choices
    PAYMENT_METHOD_CHOICES = PAYMENT_METHOD_CHOICES
    
    country_code = models.CharField(
        max_length=2,
        db_index=True,
        help_text="ISO 2-letter country code (e.g., US, GB, IN)"
    )
    payment_method = models.CharField(max_length=50, choices=PAYMENT_METHOD_CHOICES)
    is_enabled = models.BooleanField(default=True)
    
    # Display info
    display_name = models.CharField(max_length=100, blank=True)
    instructions = models.TextField(blank=True, help_text="Payment instructions for users")
    
    # Manual payment details (for bank_transfer/local_wallet)
    bank_name = models.CharField(max_length=255, blank=True)
    account_number = models.CharField(max_length=255, blank=True)
    routing_number = models.CharField(max_length=255, blank=True)
    swift_code = models.CharField(max_length=255, blank=True)
    
    # Additional fields for local wallets
    wallet_type = models.CharField(max_length=100, blank=True, help_text="E.g., PayTM, PhonePe, etc.")
    wallet_id = models.CharField(max_length=255, blank=True)
    
    # Webhook configuration (Stripe/PayPal)
    webhook_url = models.URLField(blank=True, help_text="Webhook URL for payment gateway callbacks")
    webhook_secret = models.CharField(max_length=255, blank=True, help_text="Webhook secret for signature verification")
    api_key = models.CharField(max_length=255, blank=True, help_text="API key for payment gateway integration")
    api_secret = models.CharField(max_length=255, blank=True, help_text="API secret for payment gateway integration")
    
    # Order/priority
    sort_order = models.IntegerField(default=0)
    
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_payment_method_config'
        unique_together = [['country_code', 'payment_method']]
        ordering = ['country_code', 'sort_order']
        verbose_name = 'Payment Method Configuration'
        verbose_name_plural = 'Payment Method Configurations'
    
    def __str__(self):
        return f"{self.country_code} - {self.get_payment_method_display()}"


class AccountPaymentMethod(AccountBaseModel):
    """
    Account-scoped payment methods (Stripe/PayPal/manual bank/wallet).
    Only metadata/refs are stored here; no secrets.
    """
    # Use centralized choices
    PAYMENT_METHOD_CHOICES = PAYMENT_METHOD_CHOICES

    type = models.CharField(max_length=50, choices=PAYMENT_METHOD_CHOICES, db_index=True)
    display_name = models.CharField(max_length=100, help_text="User-visible label", default='')
    is_default = models.BooleanField(default=False, db_index=True)
    is_enabled = models.BooleanField(default=True, db_index=True)
    is_verified = models.BooleanField(default=False, db_index=True)
    country_code = models.CharField(max_length=2, blank=True, default='', help_text="ISO-2 country code (optional)")

    # Manual/bank/local wallet details (non-sensitive metadata)
    instructions = models.TextField(blank=True, default='')
    metadata = models.JSONField(default=dict, blank=True, help_text="Provider references or display metadata")

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        app_label = 'billing'
        db_table = 'igny8_account_payment_methods'
        ordering = ['-is_default', 'display_name', 'id']
        indexes = [
            models.Index(fields=['account', 'is_default']),
            models.Index(fields=['account', 'type']),
        ]
        unique_together = [['account', 'display_name']]

    def __str__(self):
        return f"{self.account_id} - {self.display_name} ({self.type})"


class AIModelConfig(models.Model):
    """
    AI Model Configuration - Database-driven model pricing and capabilities.
    Replaces hardcoded MODEL_RATES and IMAGE_MODEL_RATES from constants.py
    
    Two pricing models:
    - Text models: Cost per 1M tokens (input/output), credits calculated AFTER AI call
    - Image models: Cost per image, credits calculated BEFORE AI call
    """
    
    MODEL_TYPE_CHOICES = [
        ('text', 'Text Generation'),
        ('image', 'Image Generation'),
        ('embedding', 'Embedding'),
    ]
    
    PROVIDER_CHOICES = [
        ('openai', 'OpenAI'),
        ('anthropic', 'Anthropic'),
        ('runware', 'Runware'),
        ('google', 'Google'),
    ]
    
    # Basic Information
    model_name = models.CharField(
        max_length=100,
        unique=True,
        db_index=True,
        help_text="Model identifier used in API calls (e.g., 'gpt-4o-mini', 'dall-e-3')"
    )
    
    display_name = models.CharField(
        max_length=200,
        help_text="Human-readable name shown in UI (e.g., 'GPT-4o mini - Fast & Affordable')"
    )
    
    model_type = models.CharField(
        max_length=20,
        choices=MODEL_TYPE_CHOICES,
        db_index=True,
        help_text="Type of model - determines which pricing fields are used"
    )
    
    provider = models.CharField(
        max_length=50,
        choices=PROVIDER_CHOICES,
        db_index=True,
        help_text="AI provider (OpenAI, Anthropic, etc.)"
    )
    
    # Text Model Pricing (Only for model_type='text')
    input_cost_per_1m = models.DecimalField(
        max_digits=10,
        decimal_places=4,
        null=True,
        blank=True,
        validators=[MinValueValidator(Decimal('0.0001'))],
        help_text="Cost per 1 million input tokens (USD). For text models only."
    )
    
    output_cost_per_1m = models.DecimalField(
        max_digits=10,
        decimal_places=4,
        null=True,
        blank=True,
        validators=[MinValueValidator(Decimal('0.0001'))],
        help_text="Cost per 1 million output tokens (USD). For text models only."
    )
    
    context_window = models.IntegerField(
        null=True,
        blank=True,
        validators=[MinValueValidator(1)],
        help_text="Maximum input tokens (context length). For text models only."
    )
    
    max_output_tokens = models.IntegerField(
        null=True,
        blank=True,
        validators=[MinValueValidator(1)],
        help_text="Maximum output tokens per request. For text models only."
    )
    
    # Image Model Pricing (Only for model_type='image')
    cost_per_image = models.DecimalField(
        max_digits=10,
        decimal_places=4,
        null=True,
        blank=True,
        validators=[MinValueValidator(Decimal('0.0001'))],
        help_text="Fixed cost per image generation (USD). For image models only."
    )
    
    valid_sizes = models.JSONField(
        null=True,
        blank=True,
        help_text='Array of valid image sizes (e.g., ["1024x1024", "1024x1792"]). For image models only.'
    )
    
    # Capabilities
    supports_json_mode = models.BooleanField(
        default=False,
        help_text="True for models with JSON response format support"
    )
    
    supports_vision = models.BooleanField(
        default=False,
        help_text="True for models that can analyze images"
    )
    
    supports_function_calling = models.BooleanField(
        default=False,
        help_text="True for models with function calling capability"
    )
    
    # Status & Configuration
    is_active = models.BooleanField(
        default=True,
        db_index=True,
        help_text="Enable/disable model without deleting"
    )
    
    is_default = models.BooleanField(
        default=False,
        db_index=True,
        help_text="Mark as default model for its type (only one per type)"
    )
    
    sort_order = models.IntegerField(
        default=0,
        help_text="Control order in dropdown lists (lower numbers first)"
    )
    
    # Metadata
    description = models.TextField(
        blank=True,
        help_text="Admin notes about model usage, strengths, limitations"
    )
    
    release_date = models.DateField(
        null=True,
        blank=True,
        help_text="When model was released/added"
    )
    
    deprecation_date = models.DateField(
        null=True,
        blank=True,
        help_text="When model will be removed"
    )
    
    # Audit Fields
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    updated_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name='ai_model_updates',
        help_text="Admin who last updated"
    )
    
    # History tracking
    history = HistoricalRecords()
    
    class Meta:
        app_label = 'billing'
        db_table = 'igny8_ai_model_config'
        verbose_name = 'AI Model Configuration'
        verbose_name_plural = 'AI Model Configurations'
        ordering = ['model_type', 'sort_order', 'model_name']
        indexes = [
            models.Index(fields=['model_type', 'is_active']),
            models.Index(fields=['provider', 'is_active']),
            models.Index(fields=['is_default', 'model_type']),
        ]
    
    def __str__(self):
        return self.display_name
    
    def save(self, *args, **kwargs):
        """Ensure only one is_default per model_type"""
        if self.is_default:
            # Unset other defaults for same model_type
            AIModelConfig.objects.filter(
                model_type=self.model_type,
                is_default=True
            ).exclude(pk=self.pk).update(is_default=False)
        super().save(*args, **kwargs)
    
    def get_cost_for_tokens(self, input_tokens, output_tokens):
        """Calculate cost for text models based on token usage"""
        if self.model_type != 'text':
            raise ValueError("get_cost_for_tokens only applies to text models")
        
        if not self.input_cost_per_1m or not self.output_cost_per_1m:
            raise ValueError(f"Model {self.model_name} missing cost_per_1m values")
        
        cost = (
            (Decimal(input_tokens) * self.input_cost_per_1m) +
            (Decimal(output_tokens) * self.output_cost_per_1m)
        ) / Decimal('1000000')
        
        return cost
    
    def get_cost_for_images(self, num_images):
        """Calculate cost for image models"""
        if self.model_type != 'image':
            raise ValueError("get_cost_for_images only applies to image models")
        
        if not self.cost_per_image:
            raise ValueError(f"Model {self.model_name} missing cost_per_image")
        
        return self.cost_per_image * Decimal(num_images)
    
    def validate_size(self, size):
        """Check if size is valid for this image model"""
        if self.model_type != 'image':
            raise ValueError("validate_size only applies to image models")
        
        if not self.valid_sizes:
            return True  # No size restrictions
        
        return size in self.valid_sizes
    
    def get_display_with_pricing(self):
        """For dropdowns: show model with pricing"""
        if self.model_type == 'text':
            return f"{self.display_name} - ${self.input_cost_per_1m}/${self.output_cost_per_1m} per 1M"
        elif self.model_type == 'image':
            return f"{self.display_name} - ${self.cost_per_image} per image"
        return self.display_name