from sqlalchemy import Column, Integer, String, Float, Boolean, DateTime, ForeignKey, Table
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func
from datetime import datetime

Base = declarative_base()

# Association table for many-to-many relationship between shopping events and products
shopping_event_products = Table(
    'shopping_event_products',
    Base.metadata,
    Column('id', Integer, primary_key=True, autoincrement=True),  # Artificial primary key
    Column('shopping_event_id', Integer, ForeignKey('shopping_events.id'), nullable=False),
    Column('product_id', Integer, ForeignKey('products.id'), nullable=False),
    Column('amount', Float, nullable=False),  # Amount of this product bought in this event
    Column('price', Float, nullable=False)  # Price of this product at the time of this shopping event
)

# Association table for many-to-many self-referential relationship between related products
related_products = Table(
    'related_products',
    Base.metadata,
    Column('id', Integer, primary_key=True, autoincrement=True),  # Artificial primary key
    Column('product_id', Integer, ForeignKey('products.id'), nullable=False),
    Column('related_product_id', Integer, ForeignKey('products.id'), nullable=False),
    Column('relationship_type', String, nullable=True),  # Optional: e.g., "size_variant", "brand_variant", "similar"
    Column('created_at', DateTime(timezone=True), server_default=func.now())
)

class BrandInShop(Base):
    __tablename__ = "brands_in_shops"
    
    id = Column(Integer, primary_key=True, index=True)
    shop_id = Column(Integer, ForeignKey("shops.id"), nullable=False)
    brand_id = Column(Integer, ForeignKey("brands.id"), nullable=False)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
    
    # Relationships
    shop = relationship("Shop", back_populates="brands_in_shop")
    brand = relationship("Brand", back_populates="shops_with_brand")

class Brand(Base):
    __tablename__ = "brands"
    
    id = Column(Integer, primary_key=True, index=True)
    name = Column(String, nullable=False, index=True)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
    
    # Relationships
    products = relationship("Product", back_populates="brand")
    shops_with_brand = relationship("BrandInShop", back_populates="brand")

class GroceryCategory(Base):
    __tablename__ = "grocery_categories"
    
    id = Column(Integer, primary_key=True, index=True)
    name = Column(String, nullable=False, index=True)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
    
    # Relationships
    products = relationship("Product", back_populates="category")

class Product(Base):
    __tablename__ = "products"
    
    id = Column(Integer, primary_key=True, index=True)
    name = Column(String, nullable=False, index=True)
    category_id = Column(Integer, ForeignKey("grocery_categories.id"), nullable=False)
    brand_id = Column(Integer, ForeignKey("brands.id"), nullable=True)
    organic = Column(Boolean, default=False)
    weight = Column(Float, nullable=True)  # in grams or kg
    weight_unit = Column(String, default="piece")  # "g", "kg", "ml", "l", "piece"
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
    
    # Relationships
    category = relationship("GroceryCategory", back_populates="products")
    brand = relationship("Brand", back_populates="products")
    shopping_events = relationship("ShoppingEvent", secondary=shopping_event_products, back_populates="products")
    
    # Self-referential many-to-many relationship for related products
    # We'll use a simpler approach without back_populates to avoid circular references
    related_products = relationship(
        "Product",
        secondary=related_products,
        primaryjoin="Product.id == related_products.c.product_id",
        secondaryjoin="Product.id == related_products.c.related_product_id",
        viewonly=True
    )

class Shop(Base):
    __tablename__ = "shops"
    
    id = Column(Integer, primary_key=True, index=True)
    name = Column(String, nullable=False, index=True)
    city = Column(String, nullable=False)
    address = Column(String, nullable=True)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
    
    # Relationships
    shopping_events = relationship("ShoppingEvent", back_populates="shop")
    brands_in_shop = relationship("BrandInShop", back_populates="shop")

class ShoppingEvent(Base):
    __tablename__ = "shopping_events"
    
    id = Column(Integer, primary_key=True, index=True)
    shop_id = Column(Integer, ForeignKey("shops.id"), nullable=False)
    date = Column(DateTime(timezone=True), nullable=False, default=datetime.utcnow)
    total_amount = Column(Float, nullable=True)  # Total cost of the shopping event
    notes = Column(String, nullable=True)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
    
    # Relationships
    shop = relationship("Shop", back_populates="shopping_events")
    products = relationship("Product", secondary=shopping_event_products, back_populates="shopping_events")