from sqlalchemy import create_engine, Column, String, BigInteger, ForeignKey, TIMESTAMP, UniqueConstraint
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship, sessionmaker
from datetime import datetime

Base = declarative_base()


class Token(Base):
    __tablename__ = 'tokens'

    id = Column(String(42), primary_key=True)
    name = Column(String(255), nullable=True)
    symbol = Column(String(32), nullable=True)
    total_supply = Column(String, nullable=True)


class Pair(Base):
    __tablename__ = 'pairs'

    id = Column(String(42), primary_key=True)
    token0 = Column(String(42), ForeignKey('tokens.id'), nullable=False)
    token1 = Column(String(42), ForeignKey('tokens.id'), nullable=False)
    created_at = Column(TIMESTAMP, default=datetime.utcnow)

    # Ensuring the combination of token0, token1, and pool_address is unique
    __table_args__ = (UniqueConstraint('token0', 'token1', name='_token_pool_uc'),)

    # Relationships
    token0_rel = relationship("Token", foreign_keys=[token0])
    token1_rel = relationship("Token", foreign_keys=[token1])


# Engine creation
engine = create_engine('sqlite:///uniswap.db', echo=True)

# Create tables
Base.metadata.create_all(engine)

# Create a session factory
SessionLocal = sessionmaker(bind=engine)

# Dependency to get a database session
def get_session():
    session = SessionLocal()
    try:
        yield session
    finally:
        session.close()