from sqlalchemy import create_engine, Column, Integer, String, Float, DateTime
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy.sql import func
import os

# Database URL from environment variable
DATABASE_URL = os.getenv("DATABASE_URL")
if not DATABASE_URL:
    # Fallback to constructing from individual variables
    POSTGRES_USER = os.getenv("POSTGRES_USER", "fastapi_user")
    POSTGRES_PASSWORD = os.getenv("POSTGRES_PASSWORD", "fastapi_password")
    POSTGRES_HOST = os.getenv("POSTGRES_HOST", "postgres")
    POSTGRES_PORT = os.getenv("POSTGRES_PORT", "5432")
    POSTGRES_DB = os.getenv("POSTGRES_DB", "fastapi_db")
    DATABASE_URL = f"postgresql://{POSTGRES_USER}:{POSTGRES_PASSWORD}@{POSTGRES_HOST}:{POSTGRES_PORT}/{POSTGRES_DB}"

# Create SQLAlchemy engine
engine = create_engine(DATABASE_URL)

# Create SessionLocal class
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# Create Base class
Base = declarative_base()

# Database model
class Item(Base):
    __tablename__ = "items"

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String, nullable=False)
    description = Column(String, nullable=True)
    price = Column(Float, nullable=False)
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

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

# Create tables
def create_tables():
    Base.metadata.create_all(bind=engine)