"""Vendor Product model with override pattern.

This model represents a vendor's copy of a marketplace product with the ability
to override any field. The override pattern works as follows:
- NULL value = inherit from marketplace_product
- Non-NULL value = vendor-specific override

This allows vendors to customize pricing, images, descriptions etc. while
still being able to "reset to source" by setting values back to NULL.
"""

from sqlalchemy import (
    Boolean,
    Column,
    Float,
    ForeignKey,
    Index,
    Integer,
    String,
    UniqueConstraint,
)
from sqlalchemy.dialects.sqlite import JSON
from sqlalchemy.orm import relationship

from app.core.database import Base
from models.database.base import TimestampMixin


class Product(Base, TimestampMixin):
    """Vendor-specific product with override capability.

    Each vendor can have their own version of a marketplace product with
    custom pricing, images, and other overrides. Fields set to NULL
    inherit their value from the linked marketplace_product.
    """

    __tablename__ = "products"

    id = Column(Integer, primary_key=True, index=True)
    vendor_id = Column(Integer, ForeignKey("vendors.id"), nullable=False)
    marketplace_product_id = Column(
        Integer, ForeignKey("marketplace_products.id"), nullable=False
    )

    # === VENDOR REFERENCE ===
    vendor_sku = Column(String, index=True)  # Vendor's internal SKU

    # === PRODUCT IDENTIFIERS ===
    # GTIN (Global Trade Item Number) - barcode for EAN matching with orders
    # Populated from MarketplaceProduct.gtin during product import
    gtin = Column(String(50), index=True)  # EAN/UPC barcode number
    gtin_type = Column(String(20))  # Format: gtin13, gtin14, gtin12, gtin8, isbn13, isbn10

    # === OVERRIDABLE FIELDS (NULL = inherit from marketplace_product) ===
    # Pricing
    price = Column(Float)
    sale_price = Column(Float)
    currency = Column(String(3))

    # Product Info
    brand = Column(String)
    condition = Column(String)
    availability = Column(String)

    # Media
    primary_image_url = Column(String)
    additional_images = Column(JSON)

    # Digital Product Overrides
    download_url = Column(String)
    license_type = Column(String(50))

    # === SUPPLIER TRACKING ===
    supplier = Column(String(50))  # 'codeswholesale', 'internal', etc.
    supplier_product_id = Column(String)  # Supplier's product reference
    supplier_cost = Column(Float)  # What we pay the supplier
    margin_percent = Column(Float)  # Markup percentage

    # === VENDOR-SPECIFIC (No inheritance) ===
    is_featured = Column(Boolean, default=False)
    is_active = Column(Boolean, default=True)
    display_order = Column(Integer, default=0)

    # Inventory Settings
    min_quantity = Column(Integer, default=1)
    max_quantity = Column(Integer)

    # Digital Fulfillment
    fulfillment_email_template = Column(String)  # Template name for digital delivery

    # === RELATIONSHIPS ===
    vendor = relationship("Vendor", back_populates="products")
    marketplace_product = relationship(
        "MarketplaceProduct", back_populates="vendor_products"
    )
    translations = relationship(
        "ProductTranslation",
        back_populates="product",
        cascade="all, delete-orphan",
    )
    inventory_entries = relationship(
        "Inventory", back_populates="product", cascade="all, delete-orphan"
    )

    # === CONSTRAINTS & INDEXES ===
    __table_args__ = (
        UniqueConstraint(
            "vendor_id", "marketplace_product_id", name="uq_vendor_marketplace_product"
        ),
        Index("idx_product_vendor_active", "vendor_id", "is_active"),
        Index("idx_product_vendor_featured", "vendor_id", "is_featured"),
        Index("idx_product_vendor_sku", "vendor_id", "vendor_sku"),
        Index("idx_product_supplier", "supplier", "supplier_product_id"),
    )

    # === OVERRIDABLE FIELDS LIST ===
    OVERRIDABLE_FIELDS = [
        "price",
        "sale_price",
        "currency",
        "brand",
        "condition",
        "availability",
        "primary_image_url",
        "additional_images",
        "download_url",
        "license_type",
    ]

    def __repr__(self):
        return (
            f"<Product(id={self.id}, vendor_id={self.vendor_id}, "
            f"vendor_sku='{self.vendor_sku}')>"
        )

    # === EFFECTIVE PROPERTIES (Override Pattern) ===

    @property
    def effective_price(self) -> float | None:
        """Get price (vendor override or marketplace fallback)."""
        if self.price is not None:
            return self.price
        mp = self.marketplace_product
        return mp.price_numeric if mp else None

    @property
    def effective_sale_price(self) -> float | None:
        """Get sale price (vendor override or marketplace fallback)."""
        if self.sale_price is not None:
            return self.sale_price
        mp = self.marketplace_product
        return mp.sale_price_numeric if mp else None

    @property
    def effective_currency(self) -> str:
        """Get currency (vendor override or marketplace fallback)."""
        if self.currency is not None:
            return self.currency
        mp = self.marketplace_product
        return mp.currency if mp else "EUR"

    @property
    def effective_brand(self) -> str | None:
        """Get brand (vendor override or marketplace fallback)."""
        if self.brand is not None:
            return self.brand
        mp = self.marketplace_product
        return mp.brand if mp else None

    @property
    def effective_condition(self) -> str | None:
        """Get condition (vendor override or marketplace fallback)."""
        if self.condition is not None:
            return self.condition
        mp = self.marketplace_product
        return mp.condition if mp else None

    @property
    def effective_availability(self) -> str | None:
        """Get availability (vendor override or marketplace fallback)."""
        if self.availability is not None:
            return self.availability
        mp = self.marketplace_product
        return mp.availability if mp else None

    @property
    def effective_primary_image_url(self) -> str | None:
        """Get primary image (vendor override or marketplace fallback)."""
        if self.primary_image_url is not None:
            return self.primary_image_url
        mp = self.marketplace_product
        return mp.image_link if mp else None

    @property
    def effective_additional_images(self) -> list | None:
        """Get additional images (vendor override or marketplace fallback)."""
        if self.additional_images is not None:
            return self.additional_images
        mp = self.marketplace_product
        if mp and mp.additional_images:
            return mp.additional_images
        return None

    @property
    def is_digital(self) -> bool:
        """Check if this is a digital product."""
        mp = self.marketplace_product
        return mp.is_digital if mp else False

    @property
    def product_type(self) -> str:
        """Get product type from marketplace product."""
        mp = self.marketplace_product
        return mp.product_type_enum if mp else "physical"

    # === INVENTORY PROPERTIES ===

    # Constant for unlimited inventory (digital products)
    UNLIMITED_INVENTORY = 999999

    @property
    def has_unlimited_inventory(self) -> bool:
        """Check if product has unlimited inventory.

        Digital products have unlimited inventory by default.
        They don't require physical stock tracking.
        """
        return self.is_digital

    @property
    def total_inventory(self) -> int:
        """Calculate total inventory across all locations.

        Digital products return unlimited inventory.
        """
        if self.has_unlimited_inventory:
            return self.UNLIMITED_INVENTORY
        return sum(inv.quantity for inv in self.inventory_entries)

    @property
    def available_inventory(self) -> int:
        """Calculate available inventory (total - reserved).

        Digital products return unlimited inventory since they
        don't have physical stock constraints.
        """
        if self.has_unlimited_inventory:
            return self.UNLIMITED_INVENTORY
        return sum(inv.available_quantity for inv in self.inventory_entries)

    # === OVERRIDE INFO METHOD ===

    def get_override_info(self) -> dict:
        """Get all fields with inheritance flags.

        Returns a dict with effective values, override flags, and source values.
        Similar to Vendor.get_contact_info_with_inheritance().
        """
        mp = self.marketplace_product
        return {
            # Price
            "price": self.effective_price,
            "price_overridden": self.price is not None,
            "price_source": mp.price_numeric if mp else None,
            # Sale Price
            "sale_price": self.effective_sale_price,
            "sale_price_overridden": self.sale_price is not None,
            "sale_price_source": mp.sale_price_numeric if mp else None,
            # Currency
            "currency": self.effective_currency,
            "currency_overridden": self.currency is not None,
            "currency_source": mp.currency if mp else None,
            # Brand
            "brand": self.effective_brand,
            "brand_overridden": self.brand is not None,
            "brand_source": mp.brand if mp else None,
            # Condition
            "condition": self.effective_condition,
            "condition_overridden": self.condition is not None,
            "condition_source": mp.condition if mp else None,
            # Availability
            "availability": self.effective_availability,
            "availability_overridden": self.availability is not None,
            "availability_source": mp.availability if mp else None,
            # Images
            "primary_image_url": self.effective_primary_image_url,
            "primary_image_url_overridden": self.primary_image_url is not None,
            "primary_image_url_source": mp.image_link if mp else None,
            # Product type info
            "is_digital": self.is_digital,
            "product_type": self.product_type,
        }

    # === RESET METHODS ===

    def reset_field_to_source(self, field_name: str) -> bool:
        """Reset a single field to inherit from marketplace product.

        Args:
            field_name: Name of the field to reset

        Returns:
            True if field was reset, False if field is not overridable
        """
        if field_name in self.OVERRIDABLE_FIELDS:
            setattr(self, field_name, None)
            return True
        return False

    def reset_all_to_source(self) -> None:
        """Reset all overridable fields to inherit from marketplace product."""
        for field in self.OVERRIDABLE_FIELDS:
            setattr(self, field, None)

    def reset_fields_to_source(self, field_names: list[str]) -> list[str]:
        """Reset multiple fields to inherit from marketplace product.

        Args:
            field_names: List of field names to reset

        Returns:
            List of fields that were successfully reset
        """
        reset_fields = []
        for field in field_names:
            if self.reset_field_to_source(field):
                reset_fields.append(field)
        return reset_fields

    # === TRANSLATION HELPERS ===

    def get_translation(self, language: str) -> "ProductTranslation | None":
        """Get vendor translation for a specific language."""
        for t in self.translations:
            if t.language == language:
                return t
        return None

    def get_effective_title(self, language: str = "en") -> str | None:
        """Get title with vendor override or marketplace fallback."""
        # Check vendor translation first
        translation = self.get_translation(language)
        if translation and translation.title:
            return translation.title

        # Fall back to marketplace translation
        mp = self.marketplace_product
        if mp:
            return mp.get_title(language)

        return None

    def get_effective_description(self, language: str = "en") -> str | None:
        """Get description with vendor override or marketplace fallback."""
        # Check vendor translation first
        translation = self.get_translation(language)
        if translation and translation.description:
            return translation.description

        # Fall back to marketplace translation
        mp = self.marketplace_product
        if mp:
            return mp.get_description(language)

        return None